TY - JOUR ID - 2188 TI - Two Distinct Jacalin-Related Lectins with a Different Specificity and Subcellular Location Are Major Vegetative Storage Proteins in the Bark of the Black Mulberry Tree JO - Plant Physiol. PY - 2002 SP - 757-769 AU - Van Damme, E. J. M. AU - Hause, B. AU - Hu, J. AU - Barre, A. AU - Rougé, P. AU - Proost, P. AU - Peumans, W. J. AU - VL - 130 UR - DO - 10.1104/pp.005892 AB - Using a combination of protein isolation/characterization and molecular cloning, we have demonstrated that the bark of the black mulberry tree (Morus nigra) accumulates large quantities of a galactose-specific (MornigaG) and a mannose (Man)-specific (MornigaM) jacalin-related lectin. MornigaG resembles jacalin with respect to its molecular structure, specificity, and co- and posttranslational processing indicating that it follows the secretory pathway and eventually accumulates in the vacuolar compartment. In contrast, MornigaM represents a novel type of highly active Man-specific jacalin-related lectin that is synthesized without signal peptide or other vacuolar targeting sequences, and accordingly, accumulates in the cytoplasm. The isolation and cloning, and immunocytochemical localization of MornigaG and MornigaM not only demonstrates that jacalin-related lectins act as vegetative storage proteins in bark, but also allows a detailed comparison of a vacuolar galactose-specific and a cytoplasmic Man-specific jacalin-related lectin from a single species. Moreover, the identification of MornigaM provides the first evidence, to our knowledge, that bark cells accumulate large quantities of a cytoplasmic storage protein. In addition, due to its high activity, abundance, and ease of preparation, MornigaM is of great potential value for practical applications as a tool and bioactive protein in biological and biomedical research. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2187 TI - Interactions between sterol biosynthesis genes in embryonic development of Arabidopsis JO - Plant J. PY - 2002 SP - 61-73 AU - Schrick, K. AU - Mayer, U. AU - Martin, G. AU - Bellini, C. AU - Kuhnt, C. AU - Schmidt, J. AU - Jürgens, G. AU - VL - 31 UR - DO - 10.1046/j.1365-313X.2002.01333.x AB - The sterol biosynthesis pathway of Arabidopsis produces a large set of structurally related phytosterols including sitosterol and campesterol, the latter being the precursor of the brassinosteroids (BRs). While BRs are implicated as phytohormones in post‐embryonic growth, the functions of other types of steroid molecules are not clear. Characterization of the fackel (fk ) mutants provided the first hint that sterols play a role in plant embryogenesis. FK encodes a sterol C‐14 reductase that acts upstream of all known enzymatic steps corresponding to BR biosynthesis mutants. Here we report that genetic screens for fk‐like seedling and embryonic phenotypes have identified two additional genes coding for sterol biosynthesis enzymes: CEPHALOPOD (CPH), a C‐24 sterol methyl transferase, and HYDRA1 (HYD1), a sterol C‐8,7 isomerase. We describe genetic interactions between cph , hyd1 and fk , and studies with 15‐azasterol, an inhibitor of sterol C‐14 reductase. Our experiments reveal that FK and HYD1 act sequentially, whereas CPH acts independently of these genes to produce essential sterols. Similar experiments indicate that the BR biosynthesis gene DWF1 acts independently of FK , whereas BR receptor gene BRI1 acts downstream of FK to promote post‐embryonic growth. We found embryonic patterning defects in cph mutants and describe a GC–MS analysis of cph tissues which suggests that steroid molecules in addition to BRs play critical roles during plant embryogenesis. Taken together, our results imply that the sterol biosynthesis pathway is not a simple linear pathway but a complex network of enzymes that produce essential steroid molecules for plant growth and development. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2186 TI - In Situ Formation of Allyl Ketones via Hiyama−Nozaki Reactions Followed by a Chromium-Mediated Oppenauer Oxidation JO - J. Org. Chem. PY - 2002 SP - 1975-1981 AU - Schrekker, H. S. AU - de Bolster, M. W. G. AU - Orru, R. V. A. AU - Wessjohann, L. A. AU - VL - 67 UR - DO - 10.1021/jo001750u AB - In Hiyama−Nozaki reactions of allylchromium with aldehydes the expected products are homoallylalcohols. However, oxidation products derived from these, predominantly allyl ketones, can be common side products. This can be explained by an Oppenauer−(Meerwein−Ponndorf−Verley)-type mechanism (OMPV-reaction). The amount of oxidation is strongly dependent on the substitution pattern of the reaction partners and the reaction conditions. An appropriate choice of these can lead to preferential formation of ketones instead of the alcohols. In addition to its synthetic usefulness, the oxidation−reduction equilibrium is of the utmost importance for the design of enantioselective Hiyama−Nozaki reactions because it is also a potential racemization pathway. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2185 TI - Evidence for the direct 2β‐ and 3β‐hydroxylation of [2H2]GA20‐13‐O‐[6′‐2H2]glucoside in seedlings of Phaseolus coccineus JO - Physiol. Plant. PY - 2002 SP - 144-147 AU - Schneider, G. AU - Fuchs, P. AU - Schmidt, J. AU - VL - 116 UR - DO - 10.1034/j.1399-3054.2002.1160202.x AB - [17‐2H2]GA20‐13‐O‐[6′‐2H2]glucoside was synthesized and applied to seedlings of Phaseolus coccineus L. After incubation for 72 h the conjugate metabolites were purified and shown by LC‐ESI‐tandem‐MS and GC‐MS to be [17‐2H2]GA1‐13‐O‐[6′‐2H2]glucoside and [17‐2H2]GA29‐13‐O‐[6′‐2H2]glucoside. This is the first evidence for the conversion of intact GA‐O‐glucosides, and represents an additional metabolic pathway of the gibberellin metabolism in P. coccineus L. The results indicate that intact GA‐O‐glucosides are accepted by 2‐ and 3‐oxidases in the plant. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2184 TI - Heterologous Expression and Characterization of Human Glutaminyl Cyclase: Evidence for a Disulfide Bond with Importance for Catalytic Activity JO - Biochemistry PY - 2002 SP - 10849-10857 AU - Schilling, S. AU - Hoffmann, T. AU - Rosche, F. AU - Manhart, S. AU - Wasternack, C. AU - Demuth, H.-U. AU - VL - 41 UR - DO - 10.1021/bi0260381 AB - Glutaminyl cyclase (QC, EC 2.3.2.5) catalyzes the formation of pyroglutamate residues from glutamine at the N-terminus of peptides and proteins. In the current study, human QC was functionally expressed in the secretory pathway of Pichia pastoris, yielding milligram quantities after purification from the supernatant of a 5 L fermentation. Initial characterization studies of the recombinant QC using MALDI-TOF mass spectrometry revealed correct proteolytic processing and N-glycosylation at both potential sites with similar 2 kDa extensions. CD spectral analysis indicated a high α-helical content, which contrasts with plant QC from Carica papaya. The kinetic parameters for conversion of H-Gln-Tyr-Ala-OH by recombinant human QC were almost identical to those previously reported for purified bovine pituitary QC. However, the results obtained for conversion of H-Gln-Gln-OH, H-Gln-NH2, and H-Gln-AMC were found to be contradictory to previous studies on human QC expressed intracellularly in E. coli. Expression of QC in E. coli showed that approximately 50% of the protein did not contain a disulfide bond that is present in the entire QC expressed in P. pastoris. Further, the enzyme was consistently inactivated by treatment with 15 mM DTT, whereas deglycosylation had no effect on enzymatic activity. Analysis of the fluorescence spectra of the native, reduced, and unfolded human QC point to a conformational change of the protein upon treatment with DTT. In terms of the different enzymatic properties, the consequences of QC expression in different environments are discussed. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2183 TI - Continuous Spectrometric Assays for Glutaminyl Cyclase Activity JO - Anal. Biochem. PY - 2002 SP - 49-56 AU - Schilling, S. AU - Hoffmann, T. AU - Wermann, M. AU - Heiser, U. AU - Wasternack, C. AU - Demuth, H.-U. AU - VL - 303 UR - DO - 10.1006/abio.2001.5560 AB - The enzymatic conversion of one chromogenic substrate, -glutamine-p-nitroanilide, and two fluorogenic substrates, -glutaminyl-2-naphthylamide and -glutaminyl-4-methylcoumarinylamide, into their respective pyroglutamic acid derivatives by glutaminyl cyclase (QC) was estimated by introducing a new coupled assay using pyroglutamyl aminopeptidase as the auxiliary enzyme. For the purified papaya QC, the kinetic parameters were found to be in the range of those previously reported for other glutaminyl peptides, such as Gln-Gln, Gln-Ala, or Gln-tert-butyl ester. The assay can be performed in the presence of ammonia up to a concentration of 50 mM. Increasing ionic strength, e.g., potassium chloride up to 300 mM, resulted in an increase in enzymatic activity of about 20%. This is the first report of a fast, continuous, and reliable determination of QC activity, even in the presence of ammonium ions, during the course of protein purification and enzymatic analysis. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2182 TI - Molecular characterization of root-specific chalcone synthases from Cassia alata JO - Planta PY - 2002 SP - 64-71 AU - Samappito, S. AU - Page, J. AU - Schmidt, J. AU - De-Eknamkul, W. AU - Kutchan, T. M. AU - VL - 216 UR - DO - 10.1007/s00425-002-0872-8 AB - Three cDNAs encoding very similar but unique isoforms of chalcone synthase (EC 2.3.1.74) were isolated from a cDNA library prepared from RNA from root tissue of the Thai medicinal plant Cassia alata L. (ringworm bush, Leguminosae). Gene transcript for these three type-III polyketide synthases was found to accumulate predominantly in roots. The heterologously expressed enzymes accepted acetyl-, n-butyryl-, isovaleryl-, n-hexanoyl-, benzoyl-, cinnamoyl-, and p-coumaroyl-CoA as starter molecules and together with the co-substrate malonyl-CoA, formed multiple products. With the exception of the assay in which acetyl-CoA was used as the starter molecule, all substrates yielded a phloroglucinol derivative resulting from three sequential condensations of acetate units derived from three malonyl-CoA decarboxylations. Every substrate tested also produced two pyrone derivatives, one resulting from two acetate unit condensations (a bis-noryangonin-type pyrone derailment product) and one resulting from three acetate unit condensations (a 4-coumaroyltriacetic acid lactone-type pyrone derailment). C. alata accumulates the flavonoids quercetin, naringenin and kaempferol in roots, suggesting that the in planta function of these enzymes is the biosynthesis of root flavonoids. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2181 TI - Development of RGA-CAPS markers and genetic mapping of candidate genes for sugarcane mosaic virus resistance in maize JO - Theor. Appl. Genet. PY - 2002 SP - 355-363 AU - Quint, M. AU - Mihaljevic, R. AU - Dussle, C. AU - Xu, M. AU - Melchinger, A. AU - Lübberstedt, T. AU - VL - 105 UR - DO - 10.1007/s00122-002-0953-x AB - Three previously published resistance gene analogues (RGAs), pic13, pic21 and pic19, were mapped in relation to sugarcane mosaic virus (SCMV) resistance genes (Scmv1, Scmv2) in maize. We cloned these RGAs from six inbreds including three SCMV-resistant lines (D21, D32, FAP1360A) and three SCMV-susceptible lines (D145, D408, F7). Pairwise sequence alignments among the six inbreds revealed a frequency of one single nucleotide polymorphism (SNP) per 33 bp for the three RGAs, indicating a high degree of polymorphism and a high probability of success in converting RGAs into codominant cleaved amplified polymorphic sequence (CAPS) markers compared to other sequences. SNPs were used to develop CAPS markers for mapping of the three RGAs in relation to Scmv1 (chromosome 6) and Scmv2 (chromosome 3), and for pedigree analyses of resistant inbred lines. By genetic mapping pic21 was shown to be different from Scmv2, whereas pic19 and pic13 are still candidates for Scmv1 and Scmv2, respectively, due to genetic mapping and consistent restriction patterns of ancestral lines. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2180 TI - A Pathogen-Responsive cDNA from Potato Encodes a Protein with Homology to a Phosphate Starvation-Induced Phosphatase JO - Plant Cell Physiol. PY - 2002 SP - 1049-1053 AU - Petters, J. AU - Göbel, C. AU - Scheel, D. AU - Rosahl, S. AU - VL - 43 UR - DO - 10.1093/pcp/pcf117 AB - Infiltration of potato leaves with the phytopathogenic bacteria Pseudomonas syringae pv. maculicola induces local and systemic defense gene expression as well as increased resistance against subsequent pathogen attacks. By cDNA-AFLP a gene was identified that is activated locally in potato leaves in response to bacterial infiltration and after infection with Phytophthora infestans, the causal agent of late blight disease. The encoded protein has high homology to a phosphate starvation-induced acid phosphatase from tomato. Possibly, decreased phosphate availability after pathogen infection acts as a signal for the activation of the potato phosphatase gene. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2179 TI - Cell death and salicylate- and jasmonate-dependent stress responses in Arabidopsis are controlled by single cet genes JO - Planta PY - 2002 SP - 120-128 AU - Nibbe, M. AU - Hilpert, B. AU - Wasternack, C. AU - Miersch, O. AU - Apel, K. AU - VL - 216 UR - DO - 10.1007/s00425-002-0907-1 AB - The jasmonic acid (JA)-dependent regulation of the Thi2.1 gene had previously been exploited for setting up a genetic screen for the isolation of signal transduction mutants of Arabidopsis thaliana (L.) Heynh. that constitutively express the thionin gene. Several cet mutants had been isolated which showed a constitutive expression of the thionin gene. These cet mutants, except for one, also showed spontaneous leaf cell necrosis and were up-regulated in the expression of the PR1 gene, reactions often associated with the systemic acquired resistance (SAR) pathway. Four of these cet mutants, cet1, cet2, cet3 and cet4.1 were crossed with the fad triple and coi1 mutants that are blocked at two steps within the JA-dependent signaling pathway, and with transgenic NahG plants that are deficient in salicylic acid (SA) and are unable to activate SAR. Analysis of the various double-mutant lines revealed that the four cet genes act within a signaling cascade at or prior to branch points from which not only JA-dependent signals but also SA-dependent signaling and cell death pathways diverge. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2178 TI - Apotirucallane triterpenoids from Luvunga sarmentosa (Rutaceae) JO - Phytochemistry PY - 2002 SP - 747-754 AU - Lien, T. P. AU - Kamperdick, C. AU - Schmidt, J. AU - Adam, G. AU - Sung, T. V. AU - VL - 60 UR - DO - 10.1016/S0031-9422(02)00156-5 AB - The leaves of Luvunga sarmentosa (Bl.) Kurz. yielded eight apotirucallane triterpenoids named luvungins A–G, and 1α-acetoxyluvungin A. Characteristic of the structure are the seven-membered lactone-ring A, the α-hydroxyl or α-acetoxyl group at C-7 and an oxygen bridge in the side chain giving five-, six- or seven-membered rings, respectively. Because of a hemiacetal function at C-21, luvungin C occurred as a mixture of 21-epimers. The structures have been elucidated on the basis of MS and NMR spectral data. In addition, two known coumarins ostruthin (6-geranyl-7-hydroxycoumarin) and 8-geranyl-7-hydroxycoumarin as well as five known triterpenes friedelin, flindissone, melianone, niloticin and limonin were isolated.The leaves of Luvunga sarmentosa (Bl.) Kurz. yielded eight apotirucallane triterpenoids named luvungins A–G and 1α-acetoxyluvungin A. Characteristic for the luvungins were the seven-membered lactone-ring A, the α-hydroxyl or α-acetoxyl group at C-7 and an oxygen bridge in the side chain giving five-, six- or seven-membered rings. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2177 TI - Methyltransferase genes in Streptomyces rishiriensis: new coumermycin derivatives from gene-inactivation experiments JO - Microbiol. PY - 2002 SP - 3317-3326 AU - Li, S.-M. AU - Westrich, L. AU - Schmidt, J. AU - Kuhnt, C. AU - Heide, L. AU - VL - 148 UR - DO - 10.1099/00221287-148-10-3317 AB - The coumarin antibiotic coumermycin A1 contains at least eight methyl groups, presumably derived from S-adenosylmethionine. Two putative methyltransferase genes, couO and couP, of the coumermycin A1 biosynthetic gene cluster were inactivated by in-frame deletion. In the resulting mutants, coumermycin A1 production was abolished. New coumermycin derivatives were accumulated instead, and were identified by HPLC-MS using selected reaction monitoring via electrospray ionization. couO mutants accumulated a coumermycin derivative lacking the methyl groups at C-8 of the characteristic aminocoumarin rings, whereas in the couP mutant a coumermycin derivative lacking the methyl groups at the 4-hydroxyl groups of the two deoxysugar moieties was identified. These results provided evidence that couO encodes a C-methyltransferase responsible for the transfer of a methyl group to C-8 of the aminocoumarin ring, and couP an O-methyltransferase for methylation of 4-OH of the sugar in the biosynthesis of coumermycin A1, respectively. C-methylation of the aminocoumarin ring is considered as an early step of coumermycin biosynthesis. Nevertheless, the intermediates with the non-methylated aminocoumarin ring were accepted by the enzymes catalysing the subsequent steps of the pathway. The new, demethylated secondary metabolites were produced in an amount at least as high as that of coumermycin A1 in the wild-type. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2176 TI - Calcium-dependent protein kinases: versatile plant signalling components necessary for pathogen defence JO - Trends Plant Sci. PY - 2002 SP - 97-98 AU - Lee, J. AU - Rudd, J. J. AU - VL - 7 UR - DO - 10.1016/S1360-1385(02)02229-X AB - Plant stress adaptation often uses changes in cytosolic Ca2+ to bring about responses via changing the activity of Ca2+-sensor proteins including Ca2+-dependent protein kinases (CDPK). The activity of a tobacco CDPK(s) is essential for elicitation of the hypersensitive reaction, a typical plant defence response. Moreover, it is becoming apparent that CDPKs might also facilitate cross-talk between different Ca2+-mediated stress signalling pathways. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2175 TI - Selective Inhibition of the Collagenolytic Activity of Human Cathepsin K by Altering Its S2 Subsite Specificity JO - Biochemistry PY - 2002 SP - 8447-8454 AU - Lecaille, F. AU - Choe, Y. AU - Brandt, W. AU - Li, Z. AU - Craik, C. S. AU - Brömme, D. AU - VL - 41 UR - DO - 10.1021/bi025638x AB - The primary specificity of papain-like cysteine proteases (family C1, clan CA) is determined by S2−P2 interactions. Despite the high amino acid sequence identities and structural similarities between cathepsins K and L, only cathepsin K is capable of cleaving interstitial collagens in their triple helical domains. To investigate this specificity, we have engineered the S2 pocket of human cathepsin K into a cathepsin L-like subsite. Using combinatorial fluorogenic substrate libraries, the P1−P4 substrate specificity of the cathepsin K variant, Tyr67Leu/Leu205Ala, was determined and compared with those of cathepsins K and L. The introduction of the double mutation into the S2 subsite of cathepsin K rendered the unique S2 binding preference of the protease for proline and leucine residues into a cathepsin L-like preference for bulky aromatic residues. Homology modeling and docking calculations supported the experimental findings. The cathepsin L-like S2 specificity of the mutant protein and the integrity of its catalytic site were confirmed by kinetic analysis of synthetic di- and tripeptide substrates as well as pH stability and pH activity profile studies. The loss of the ability to accept proline in the S2 binding pocket by the mutant protease completely abolished the collagenolytic activity of cathepsin K whereas its overall gelatinolytic activity remained unaffected. These results indicate that Tyr67 and Leu205 play a key role in the binding of proline residues in the S2 pocket of cathepsin K and are required for its unique collagenase activity. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2174 TI - FQR1, a Novel Primary Auxin-Response Gene, Encodes a Flavin Mononucleotide-Binding Quinone Reductase JO - Plant Physiol. PY - 2002 SP - 578-590 AU - Laskowski, M. J. AU - Dreher, K. A. AU - Gehring, M. A. AU - Abel, S. AU - Gensler, A. L. AU - Sussex, I. M. AU - VL - 128 UR - DO - 10.1104/pp.010581 AB - FQR1 is a novel primary auxin-response gene that codes for a flavin mononucleotide-binding flavodoxin-like quinone reductase. Accumulation of FQR1 mRNA begins within 10 min of indole-3-acetic acid application and reaches a maximum of approximately 10-fold induction 30 min after treatment. This increase in FQR1 mRNA abundance is not diminished by the protein synthesis inhibitor cycloheximide, demonstrating thatFQR1 is a primary auxin-response gene. Sequence analysis reveals that FQR1 belongs to a family of flavin mononucleotide-binding quinone reductases. Partially purified His-tagged FQR1 isolated fromEscherichia coli catalyzes the transfer of electrons from NADH and NADPH to several substrates and exhibits in vitro quinone reductase activity. Overexpression of FQR1 in plants leads to increased levels of FQR1 protein and quinone reductase activity, indicating that FQR1 functions as a quinone reductase in vivo. In mammalian systems, glutathione S-transferases and quinone reductases are classified as phase II detoxification enzymes. We hypothesize that the auxin-inducible glutathioneS-transferases and quinone reductases found in plants also act as detoxification enzymes, possibly to protect against auxin-induced oxidative stress. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2173 TI - Accumulation of tyrosol glucoside in transgenic potato plants expressing a parsley tyrosine decarboxylase JO - Phytochemistry PY - 2002 SP - 683-689 AU - Landtag, J. AU - Baumert, A. AU - Degenkolb, T. AU - Schmidt, J. AU - Wray, V. AU - Scheel, D. AU - Strack, D. AU - Rosahl, S. AU - VL - 60 UR - DO - 10.1016/S0031-9422(02)00161-9 AB - As part of the response to pathogen infection, potato plants accumulate soluble and cell wall-bound phenolics such as hydroxycinnamic acid tyramine amides. Since incorporation of these compounds into the cell wall leads to a fortified barrier against pathogens, raising the amounts of hydroxycinnamic acid tyramine amides might positively affect the resistance response. To this end, we set out to increase the amount of tyramine, one of the substrates of the hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)-transferase reaction, by placing a cDNA encoding a pathogen-induced tyrosine decarboxylase from parsley under the control of the 35S promoter and introducing the construct into potato plants via Agrobacterium tumefaciens-mediated transformation. While no alterations were observed in the pattern and quantity of cell wall-bound phenolic compounds in transgenic plants, the soluble fraction contained several new compounds. The major one was isolated and identified as tyrosol glucoside by liquid chromatography–electrospray ionization–high resolution mass spectrometry and NMR analyses. Our results indicate that expression of a tyrosine decarboxylase in potato does not channel tyramine into the hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl)-transferase reaction but rather unexpectedly, into a different pathway leading to the formation of a potential storage compound.Expression of a parsley tyrosine decarboxylase in potato unexpectedly channels tyramine into a pathway leading to the formation of tyrosol glucoside. A2 - C1 - Bioorganic Chemistry; Biochemistry of Plant Interactions ER - TY - JOUR ID - 2172 TI - Systemic Accumulation of 12-oxo-phytodienoic Acid in SAR-induced Potato Plants JO - Eur. J. Plant Pathol. PY - 2002 SP - 279-283 AU - Landgraf, P. AU - Feussner, I. AU - Hunger, A. AU - Scheel, D. AU - Rosahl, S. AU - VL - 108 UR - DO - 10.1023/A:1015132615650 AB - In potato plants induced for systemic resistance by infiltration with Pseudomonas syringae pv. maculicola, 12-oxo-phytodienoic acid (OPDA) accumulated in infiltrated leaves as well as in non-treated leaves of infected plants. In contrast, jasmonic acid (JA) levels increased only in infiltrated leaves, suggesting that the biosynthetic precursor of JA, OPDA, might play a role in systemic acquired resistance. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2171 TI - Synthesis and crystal structure of [26,27-2H6] 24-epi-cathasterone JO - J. Chem. Soc., Perkin Trans. 1 PY - 2002 SP - 2022-2027 AU - Kolbe, A. AU - Fuchs, P. AU - Porzel, A. AU - Baumeister, U. AU - Kolbe, A. AU - Adam, G. AU - VL - 2002 UR - DO - 10.1039/B203323B AB - The first synthesis of [26,27-2H6]24-epi-cathasterone 8via (20S)-3β-acetoxy-6,6-(ethylenedioxy)-20-formyl-5α-pregnane 5 starting from stigmasterol is described. The aldehyde 5 was alkylated with lithium butyldimethyl-(E)-2,3-dimethyl[3,3,3,4,4,4-2H6]butenylaluminate 6 prepared from 3-[2H3]methyl[4,4,4-2H3]but-1-yne. The structure was determined using spectral data and X-ray crystallographic analysis. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2170 TI - Syntheses of Dexamethasone Conjugates of the Phytohormones Gibberellin A3 and 24-Epicastasterone JO - Collect. Czech. Chem. Commun. PY - 2002 SP - 103-114 AU - Kolbe, A. AU - Kramell, R. AU - Porzel, A. AU - Schmidt, J. AU - Schneider, G. AU - Adam, G. AU - VL - 67 UR - DO - 10.1135/cccc20020103 AB - The syntheses of N-[10-(9α-fluoro-11β,17α-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carboxamido)decyl]gibberellamide (7) and 6-[({N-[10-(9α-fluoro-11β,17α-dihydroxy- 16α-methyl-3-oxoandrosta-1,4-diene-17β-carboxamido)decyl]carbamoyl}methoxy)imino]-24-epicastasterone (10) are described. [(Benzotriazol-1-yl)oxy]bis(pyrrolidin-1-yl)methylium hexafluorophosphate (HBPyU) was used as the coupling agent for the reaction of gibberellic acid as well as of 24-epicastasterone-O-(carboxymethyl)oxime with N-(10-aminodecyl)- 9α-fluoro-11β,17α-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carboxamide (4). The gibberellic acid conjugate 7 was also synthesised by the coupling of succinimidyl gibberellate 6 with amine 4. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2169 TI - Mitogen-activated protein kinase cascades in plants: a new nomenclature JO - Trends Plant Sci. PY - 2002 SP - 301-308 AU - Ichimura, K. AU - Shinozaki, K. AU - Tena, G. AU - Sheen, J. AU - Henry, Y. AU - Champion, A. AU - Kreis, M. AU - Zhang, S. AU - Hirt, H. AU - Wilson, C. AU - Heberle-Bors, E. AU - Ellis, B. E. AU - Morris, P. C. AU - Innes, R. W. AU - Ecker, J. R. AU - Scheel, D. AU - Klessig, D. F. AU - Machida, Y. AU - Mundy, J. AU - Ohashi, Y. AU - Walker, J. C. AU - VL - 7 UR - DO - 10.1016/S1360-1385(02)02302-6 AB - Mitogen-activated protein kinase (MAPK) cascades are universal signal transduction modules in eukaryotes, including yeasts, animals and plants. These protein phosphorylation cascades link extracellular stimuli to a wide range of cellular responses. In plants, MAPK cascades are involved in responses to various biotic and abiotic stresses, hormones, cell division and developmental processes. Completion of the Arabidopsis genome-sequencing project has revealed the existence of 20 MAPKs, 10 MAPK kinases and 60 MAPK kinase kinases. Here, we propose a simplified nomenclature for Arabidopsis MAPKs and MAPK kinases that might also serve as a basis for standard annotation of these gene families in all plants. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2168 TI - Spectral dependence of flavonol and betacyanin accumulation in Mesembryanthemum crystallinum under enhanced ultraviolet radiation JO - Plant Cell Environ. PY - 2002 SP - 1145-1154 AU - Ibdah, M. AU - Krins, A. AU - Seidlitz, H. K. AU - Heller, W. AU - Strack, D. AU - Vogt, T. AU - VL - 25 UR - DO - 10.1046/j.1365-3040.2002.00895.x AB - Mesembryanthemum crystallinum L. (Aizoaceae) is a drought‐ and salt‐tolerant halophyte that is able to endure harsh environmental conditions. Upon irradiation with high light irradiance (1200–1500 µ mol m−2 s−1) it displays a rapid cell‐specific accumulation of plant secondary metabolites in the upper leaf epidermis; a phenomenon that is not detectable with salt or drought treatment. The accumulation of these compounds, the betacyanins and acylated flavonol glycosides, increases if the plants are exposed to polychromatic radiation with a progressively decreasing short‐wave cut‐off in the ultraviolet range. The response is localized in the epidermal bladder cells on the tips of young leaves and epidermal layers of fully expanded leaves. It is demonstrated that the accumulation of flavonols and betacyanins can be described by a weakly sigmoid dose function in combination with an exponential decrease of the response function of the plant with increasing wavelength. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2167 TI - Functional studies on the role of reactive oxygen intermediates in the resistance of barley against powdery mildew JO - Plant Protect. Sci. PY - 2002 SP - 458-460 AU - Huckelhoven, R. AU - Trujillo, M. AU - Dechert, C. AU - Schultheiss, H. AU - Kogel, K.-H. AU - VL - 38 UR - DO - 10.17221/10523-PPS AB - The role of reactive oxygen intermediate (ROI) accumulation in resistance and susceptibility of plants to parasitic fungi is still little understood. We examined the spatial and temporal occurrence of different ROIs in barley after inoculation with the biotrophic fungus Blumeria graminis f.sp. hordei (Bgh, barley powdery mildew fungus). Using histochemical analyses, we collected correlative data indicating that H2O2 and O2•– play different roles in background penetration resistance to Bgh. To study the role of O2•– in detail, we isolated barley cDNAs encoding a NADPH oxidase GP91PHOX homologue and a RACB homologue, which may be involved in NADPH oxidase activation. Interestingly, transient silencing of RACB or GP91PHOX via sequence-specific RNA interference enhanced penetration resistance of barley to Bgh. Together, data reveal rather a negative than a positive role of superoxide generation in background resistance of barley to Bgh. A2 - C1 - ER - TY - JOUR ID - 2166 TI - Diazabicyclononanones, a potent class of kappa opioid analgesics JO - Farmaco PY - 2002 SP - 531-534 AU - Holzgrabe, U. AU - Cambareri, A. AU - Kuhl, U. AU - Siener, T. AU - Brandt, W. AU - Straßburger, W. AU - Friderichs, E. AU - Englberger, W. AU - Kögel, B. AU - Haurand, M. AU - VL - 57 UR - DO - 10.1016/S0014-827X(02)01243-0 AB - The 1,5-dimethyl 3,7-diaza-3,7-dimethyl-9-oxo-2,4-di-2-pyridine-bicyclo[3.3.1]nonane-1,5-dicarboxylate, HZ2, has a high and selective affinity for the kappa opioid receptor and an antinociceptive activity comparable to morphine. In addition, it is characterized by a long duration of action and a high oral bioavailability. QSAR studies within series of kappa agonists revealed a chair-boat conformation of a double protonated HZ2 characterized by an almost parallel orientation of the C9 carbonyl group and the N7-H group and at least one aromatic ring to be the pharmacophoric arrangement. Structural variations showed that the pyridine rings in 2 and 4 position can be replaced with p-methoxy-, m-hydroxy- and m-fluoro-substituted phenyl rings. However, all other substituents have to be kept the same for a high affinity to the kappa receptor. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2165 TI - Diazabicyclononanones, a new class of opioid-type analgesics JO - Sci. Cult. PY - 2002 SP - 1-4 AU - Holzgrabe, U. AU - Friderichs, E. AU - Englberger, W. AU - Strassberger, W. AU - Maurand, M. AU - Brandt, W. AU - Camberri, A. AU - Kuhl, U. AU - Siener, T. AU - VL - 68 UR - AB - A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2164 TI - Induction of Jasmonate Biosynthesis in Arbuscular Mycorrhizal Barley Roots JO - Plant Physiol. PY - 2002 SP - 1213-1220 AU - Hause, B. AU - Maier, W. AU - Miersch, O. AU - Kramell, R. AU - Strack, D. AU - VL - 130 UR - DO - 10.1104/pp.006007 AB - Colonization of barley (Hordeum vulgare cv Salome) roots by an arbuscular mycorrhizal fungus, Glomus intraradices Schenck & Smith, leads to elevated levels of endogenous jasmonic acid (JA) and its amino acid conjugate JA-isoleucine, whereas the level of the JA precursor, oxophytodienoic acid, remains constant. The rise in jasmonates is accompanied by the expression of genes coding for an enzyme of JA biosynthesis (allene oxide synthase) and of a jasmonate-induced protein (JIP23). In situ hybridization and immunocytochemical analysis revealed that expression of these genes occurred cell specifically within arbuscule-containing root cortex cells. The concomitant gene expression indicates that jasmonates are generated and act within arbuscule-containing cells. By use of a near-synchronous mycorrhization, analysis of temporal expression patterns showed the occurrence of transcript accumulation 4 to 6 d after the appearance of the first arbuscules. This suggests that the endogenous rise in jasmonates might be related to the fully established symbiosis rather than to the recognition of interacting partners or to the onset of interaction. Because the plant supplies the fungus with carbohydrates, a model is proposed in which the induction of JA biosynthesis in colonized roots is linked to the stronger sink function of mycorrhizal roots compared with nonmycorrhizal roots. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 2163 TI - Immunolocalization of 1-O-sinapoylglucose:malate sinapoyltransferase in Arabidopsis thaliana JO - Planta PY - 2002 SP - 26-32 AU - Hause, B. AU - Meyer, K. AU - Viitanen, P. AU - Chapple, C. AU - Strack, D. AU - VL - 215 UR - DO - 10.1007/s00425-001-0716-y AB - The serine carboxypeptidase-like protein 1-O-sinapoylglucose:malate sinapoyltransferase (SMT) catalyzes the transfer of the sinapoyl moiety of 1-O-sinapoylglucose to malate in the formation of sinapoylmalate in some members of the Brassicaceae. Rabbit polyclonal monospecific antibodies were raised against the recombinant SMT produced in Escherichia coli from the corresponding Arabidopsis thaliana (L.) Heynh. cDNA. Immunoblot analysis of protein from different Arabidopsis tissues showed that the SMT is produced in all plant organs, except in the seeds and young seedlings. The enzyme was most abundant in older seedlings as well as in rosette leaves and the flowering stem of the plant. Minor amounts were found in the cauline leaves, flower buds and siliques. Traces were detected in the root and flowers. Arabidopsis and transgenic tobacco (Nicotiana tabacum L.) plants expressing the full-length Arabidopsis SMT containing an N-terminal signal peptide showed apparent molecular masses of the protein of 52–55 kDa. The difference of ca. 8 kDa compared to the recombinant protein produced in E. coli was shown to be due to post-translational N-glycosylation of SMT in plants. Immunofluorescent labeling of Arabidopsis leaf sections localized SMT to the central vacuoles of mesophyll and epidermal cells. Comparable leaf sections of an SMT deletion mutant showed no vacuolar immunofluorescent labeling. We conclude that Arabidopsis SMT is synthesized as a precursor protein that is targeted to the endoplasmic reticulum where the signal peptide is removed. The correct N-terminus of the recombinantly produced SMT protein lacking the signal peptide was confirmed by Edman degradation. The protein is probably glycosylated in the Golgi apparatus from where it is subsequently routed to the vacuole. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2162 TI - Identification of Arabidopsis mutants with altered glucosinolate profiles based on isothiocyanate bioactivity JO - Plant Sci. PY - 2002 SP - 143-152 AU - Grubb, C. D. AU - Gross, H. B. AU - Chen, D. L. AU - Abel, S. AU - VL - 162 UR - DO - 10.1016/S0168-9452(01)00550-7 AB - Glucosinolates are a diverse class of nitrogen- and sulfur-containing secondary metabolites. They are rapidly hydrolyzed on tissue disruption to a number of biologically active compounds that are increasingly attracting interest as anticarcinogenic phytochemicals and crop protectants. Several glucosinolate-derived isothiocyanates are potent chemopreventive agents that favorably modulate carcinogen metabolism in mammals. Methylsulfinylalkyl isothiocyanates, in particular the 4-methylsulfinylbutyl derivative, are selective and potent inducers of mammalian detoxification enzymes such as quinone reductase (QR). Cruciferous plants including Arabidopsis thaliana (L.) Heyhn, synthesize methylsulfinylalkyl glucosinolates, which are derived from methionine. Using a colorimetric assay for QR activity in murine hepatoma cells and high performance liquid chromatography (HPLC) analysis of desulfoglucosinolates, we have demonstrated a strong positive correlation between leaf QR inducer potency and leaf content of methionine-derived glucosinolates in various A. thaliana ecotypes and available glucosinolate mutants. In a molecular genetic approach to glucosinolate biosynthesis, we screened 3000 chemically mutagenized M2 plants of the Columbia ecotype for altered leaf QR inducer potency. Subsequent HPLC analysis of progeny of putative mutants identified six lines with significant and heritable changes in leaf glucosinolate content and composition. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2161 TI - Oxylipin profiling in pathogen-infected potato leaves JO - BBA-Mol. Cell Biol. Lipids PY - 2002 SP - 55-64 AU - Göbel, C. AU - Feussner, I. AU - Hamberg, M. AU - Rosahl, S. AU - VL - 1584 UR - DO - 10.1016/S1388-1981(02)00268-8 AB - Plants respond to pathogen attack with a multicomponent defense response. Synthesis of oxylipins via the lipoxygenase (LOX) pathway appears to be an important factor for establishment of resistance in a number of pathosystems. In potato cells, pathogen-derived elicitors preferentially stimulate the 9-LOX-dependent metabolism of polyunsaturated fatty acids (PUFAs). Here we show by oxylipin profiling that potato plants react to pathogen infection with increases in the amounts of the 9-LOX-derived 9,10,11- and 9,12,13-trihydroxy derivatives of linolenic acid (LnA), the divinyl ethers colnelenic acid (CnA) and colneleic acid (CA) as well as 9-hydroxy linolenic acid. Accumulation of these compounds is faster and more pronounced during the interaction of potato with the phytopathogenic bacterium Pseudomonas syringae pv. maculicola, which does not lead to disease, compared to the infection of potato with Phytophthora infestans, the causal agent of late blight disease. Jasmonic acid (JA), a 13-LOX-derived oxylipin, accumulates in potato leaves after infiltration with P. syringae pv. maculicola, but not after infection with P. infestans. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2160 TI - (E)-4-Hydroxy-3-methylbut-2-enyl Diphosphate: An Intermediate in the Formation of Terpenoids in Plant Chromoplasts JO - Angew. Chem. Int. Ed. PY - 2002 SP - 2604-2607 AU - Gao, W. AU - Loeser, R. AU - Raschke, M. AU - Dessoy, M. A. AU - Fulhorst, M. AU - Alpermann, H. AU - Wessjohann, L. A. AU - Zenk, M. H. AU - VL - 41 UR - DO - 10.1002/1521-3773(20020715)41:14<2604::AID-ANIE2604>3.0.CO;2-S AB - The missing link in the new deoxyxylulose phosphate metabolic pathway leading to the biosynthesis of plant terpenoids has been identified. The intermediate between the cyclic diphosphate 1 and the basic isoprenoid building blocks dimethylallyl diphosphate and isopentenyl diphosphate has been shown for the first time to be (E )‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate (2 ) by incorporation of tritium‐labeled 2 into phytoene. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2159 TI - Cloning and analysis of the simocyclinone biosynthetic gene cluster of Streptomyces antibioticus Tü 6040 JO - Arch. Microbiol. PY - 2002 SP - 102-114 AU - Galm, U. AU - Schimana, J. AU - Fiedler, H.-P. AU - Schmidt, J. AU - Li, S.-M. AU - Heide, L. AU - VL - 178 UR - DO - 10.1007/s00203-002-0429-z AB - The biosynthetic gene cluster of the aminocoumarin antibiotic simocyclinone D8 was cloned by screening a cosmid library of Streptomyces antibioticus Tü 6040 with a heterologous probe from a gene encoding a cytochrome P450 enzyme involved in the biosynthesis of the aminocoumarin antibiotic novobiocin. Sequence analysis of a 39.4-kb region revealed the presence of 38 ORFs. Six of the identified ORFs showed striking similarity to genes from the biosynthetic gene clusters of the aminocoumarin antibiotics novobiocin and coumermycin A1. Simocyclinone also contains an angucyclinone moiety, and 12 of the ORFs showed high sequence similarity to biosynthetic genes of other angucyclinone antibiotics. Possible functions within the biosynthesis of simocyclinone D8 could be assigned to 23 ORFs by comparison with sequences in GenBank. Experimental proof for the function of the identified gene cluster was provided by a gene inactivation experiment, which resulted in the abolishment of the formation of the aminocoumarin moiety of simocyclinone. Feeding of the mutant with the aminocoumarin moiety of novobiocin led to a new, artificial simocyclinone derivative. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2158 TI - Flavone-coumarin hybrids from Gnidia socotrana JO - Phytochemistry PY - 2002 SP - 873-878 AU - Franke, K. AU - Porzel, A. AU - Schmidt, J. AU - VL - 61 UR - DO - 10.1016/S0031-9422(02)00358-8 AB - Phytochemical investigation of leaves and twigs of Gnidia socotrana (Balf. f.) Gilg (Thymelaeaceae), a plant occurring endemically on Socotra Island (Yemen), afforded six novel natural products: two compounds consisting of a flavone and a coumarin moiety connected by a C–C linkage, 7,7′-dihydroxy-3,8′-biscoumarin and three substances with the rare spiro-bis-γ-lactone structure. The structures were elucidated on the basis of their spectroscopic data.Two flavone-coumarin hybrids representing a new structural type of natural products as well as a biscoumarin and three spiro-bis-γ-lactones were isolated from leaves and twigs of Gnidia socotrana (Thymelaeaceae) and identified by spectroscopic data. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2157 TI - Amino acid alterations in isoforms of the effector protein NIP1 from Rhynchosporium secalis have similar effects on its avirulence- and virulence-associated activities on barley JO - Physiol. Mol. Plant Pathol. PY - 2002 SP - 299-302 AU - Fiegen, M. AU - Knogge, W. AU - VL - 61 UR - DO - 10.1006/pmpp.2002.0442 AB - The secreted effector protein NIP1 from the barley pathogen Rhynchosporium secalis is a specific elicitor of defense reactions in host plants carrying the resistance gene Rrs1. In addition, it has activities associated with fungal virulence; independent of the plant genotype it stimulates the plant plasma membrane H+-ATPase and induces leaf necrosis. Four NIP1 isoforms differing in single amino acid residues were isolated from various naturally occurring fungal strains. All three activities of the protein (race specificity, H+-ATPase stimulation, necrosis induction) were affected by the amino acid alterations in a similar way suggesting that they are mediated through a single plant receptor. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2156 TI - The lipoxygenase pathway JO - Annu. Rev. Plant Biol. PY - 2002 SP - 275-297 AU - Feussner, I. AU - Wasternack, C. AU - VL - 53 UR - DO - 10.1146/annurev.arplant.53.100301.135248 AB - Lipid peroxidation is common to all biological systems, both appearing in developmentally and environmentally regulated processes of plants. The hydroperoxy polyunsaturated fatty acids, synthesized by the action of various highly specialized forms of lipoxygenases, are substrates of at least seven different enzyme families. Signaling compounds such as jasmonates, antimicrobial and antifungal compounds such as leaf aldehydes or divinyl ethers, and a plant-specific blend of volatiles including leaf alcohols are among the numerous products. Cloning of many lipoxygenases and other key enzymes within the lipoxygenase pathway, as well as analyses by reverse genetic and metabolic profiling, revealed new reactions and the first hints of enzyme mechanisms, multiple functions, and regulation. These aspects are reviewed with respect to activation of this pathway as an initial step in the interaction of plants with pathogens, insects, or abiotic stress and at distinct stages of development. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2155 TI - Stimulation of carotenoid metabolism in arbuscular mycorrhizal roots JO - Planta PY - 2002 SP - 148-154 AU - Fester, T. AU - Schmidt, D. AU - Lohse, S. AU - Walter, M. H. AU - Giuliano, G. AU - Bramley, P. M. AU - Fraser, P. D. AU - Hause, B. AU - Strack, D. AU - VL - 216 UR - DO - 10.1007/s00425-002-0917-z AB - Development of arbuscular mycorrhizal roots is correlated with accumulation of various isoprenoids, i.e. acyclic C14 polyene 'mycorradicin' and C13 cyclohexenone derivatives. We present data indicating a strong stimulation of carotenoid metabolism in such roots. Carotenoid profiling revealed mycorrhiza-specific accumulation of ζ-carotene in Zea mays and Medicago truncatula. Precursor accumulation after inhibition of phytoene desaturase (Pds) activity by norflurazon indicated an increased phytoene biosynthetic capacity in mycorrhizal roots of all species analyzed. Nicotiana tabacum plants transformed with a PDS promoter-GUS construct showed a cell-specific induction of PDS promoter activity in root cells containing arbuscules. Mycorradicin biosynthesis and, partially, mycorrhization were impaired in maize mutants deficient in carotenoid biosynthesis. These data indicate that (1) mycorradicin is probably synthesized via a C40 precursor carotenoid, (2) carotenoid biosynthesis is induced in mycorrhizal roots, (3) induction occurs, at least partially, at the transcriptional level, and (4) that this may play a functional role during mycorrhization. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2154 TI - Occurrence and Localization of Apocarotenoids in Arbuscular Mycorrhizal Plant Roots JO - Plant Cell Physiol. PY - 2002 SP - 256-265 AU - Fester, T. AU - Hause, B. AU - Schmidt, D. AU - Halfmann, K. AU - Schmidt, J. AU - Wray, V. AU - Hause, G. AU - Strack, D. AU - VL - 43 UR - DO - 10.1093/pcp/pcf029 AB - The core structure of the yellow pigment from arbuscular mycorrhizal (AM) maize roots contains the apocarotenoids mycorradicin (an acyclic C14 polyene) and blumenol C cellobioside (a C13 cyclohexenone diglucoside). The pigment seems to be a mixture of different esterification products of these apocarotenoids. It is insoluble in water and accumulates as hydrophobic droplets in the vacuoles of root cortical cells. Screening 58 species from 36 different plant families, we detected mycorradicin in mycorrhizal roots of all Liliopsida analyzed and of a considerable number of Rosopsida, but also species were found in which mycorradicin was undetectable in mycorrhizal roots. Kinetic experiments and microscopic analyses indicate that accumulation of the yellow pigment is correlated with the concomitant degradation of arbuscules and the extensive plastid network covering these haustorium-like fungal structures. The role of the apocarotenoids in mycorrhizal roots is still unknown. The potential C40 carotenoid precursors, however, are more likely to be of functional importance in the development and functioning of arbuscules. A2 - C1 - Bioorganic Chemistry; Cell and Metabolic Biology ER - TY - JOUR ID - 2153 TI - A mycorrhiza-responsive protein in wheat roots JO - Mycorrhiza PY - 2002 SP - 219-222 AU - Fester, T. AU - Kiess, M. AU - Strack, D. AU - VL - 12 UR - DO - 10.1007/s00572-002-0173-x AB - A small protein, designated Myk15, was found to be strongly induced in wheat (Triticum aestivum) roots colonized by the arbuscular mycorrhizal fungus Glomus intraradices. This protein, which is most abundant in root fractions characterized by strong mycorrhizal colonization, has been characterized using two-dimensional polyacrylamide gel electrophoresis and microsequencing. It has an apparent molecular mass of 15 kDa and an isoelectric point of 4.5. The N-terminal sequence has high similarity to a peptide sequence deduced from an expressed sequence tag (EST) clone derived from Medicago truncatula roots colonized by G. intraradices. This EST clone is predicted to code for a protein with a similar size and isoelectric point as Myk15. The N-terminus of the deduced M. truncatula protein contains a highly hydrophobic stretch of 24 amino acid residues preceding the region with high similarity to the Myk15 N-terminus. This hydrophobic stretch is predicted to form a transmembrane α-helix and may correspond to a cleavable targeting domain. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2152 TI - Study of Chaperone-Like Activity of Human Haptoglobin: Conformational Changes under Heat Shock Conditions and Localization of Interaction Sites JO - Biol. Chem. PY - 2002 SP - 1667-1676 AU - Ettrich, R. AU - Brandt, W. AU - Kopecký, V. AU - Baumruk, V. AU - Hofbauerová, K. AU - Pavlícek, Z. AU - VL - 383 UR - DO - 10.1515/BC.2002.187 AB - With respect to the mechanism of chaperonelike activity, we examined the behavior of haptoglobin under heat shock conditions. Secondary structure changes during heat treatment were followed by circular dichroism, Raman and infrared spectroscopy. A model of the haptoglobin tetramer, based on its sequence homology with serine proteases and the CCP modules, has been proposed. Sequence regions responsible for the chaperonelike activity were not fully identical with the region that takes part in formation of the hemoglobinhaptoglobin complex. We can postulate the presence of at least two different chaperonebinding sites on each haptoglobin heavy chain. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2151 TI - The Arabidopsis Mutant cev1 Links Cell Wall Signaling to Jasmonate and Ethylene Responses JO - Plant Cell PY - 2002 SP - 1557-1566 AU - Ellis, C. AU - Karafyllidis, I. AU - Wasternack, C. AU - Turner, J. G. AU - VL - 14 UR - DO - 10.1105/tpc.002022 AB - Biotic and abiotic stresses stimulate the synthesis of jasmonates and ethylene, which, in turn, induce the expression of genes involved in stress response and enhance defense responses. The cev1 mutant has constitutive expression of stress response genes and has enhanced resistance to fungal pathogens. Here, we show that cev1 plants have increased production of jasmonate and ethylene and that its phenotype is suppressed by mutations that interrupt jasmonate and ethylene signaling. Genetic mapping, complementation analysis, and sequence analysis revealed that CEV1 is the cellulose synthase CeSA3. CEV1 was expressed predominantly in root tissues, and cev1 roots contained less cellulose than wild-type roots. Significantly, the cev1 mutant phenotype could be reproduced by treating wild-type plants with cellulose biosynthesis inhibitors, and the cellulose synthase mutant rsw1 also had constitutive expression of VSP. We propose that the cell wall can signal stress responses in plants. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2150 TI - Conversion of AFLP fragments tightly linked to SCMV resistance genes Scmv1 and Scmv2 into simple PCR-based markers JO - Theor. Appl. Genet. PY - 2002 SP - 1190-1195 AU - Dussle, C. AU - Quint, M. AU - Xu, M. AU - Melchinger, A. AU - Lübberstedt, T. AU - VL - 105 UR - DO - 10.1007/s00122-002-0964-7 AB - In a previous study, bulked segregant analysis with amplified fragment length polymorphisms (AFLPs) identified several markers closely linked to the sugarcane mosaic virus resistance genes Scmv1 on chromosome 6 and Scmv2 on chromosome 3. Six AFLP markers (E33M61-2, E33M52, E38M51, E82M57, E84M59 and E93M53) were located on chromosome 3 and two markers (E33M61-1 and E35M62-1) on chromosome 6. Our objective in the present study was to sequence the respective AFLP bands in order to convert these dominant markers into more simple and reliable polymerase chain reaction (PCR)-based sequence-tagged site markers. Six AFLP markers resulted either in complete identical sequences between the six inbreds investigated in this study or revealed single nucleotide polymorphisms within the inbred lines and were, therefore, not converted. One dominant AFLP marker (E35M62-1) was converted into an insertion/deletion (indel) marker and a second AFLP marker (E33M61-2) into a cleaved amplified polymorphic sequence marker. Mapping of both converted PCR-based markers confirmed their localization to the same chromosome region (E33M61-2 on chromosome 3; E35M62-1 on chromosome 6) as the original AFLP markers. Thus, these markers will be useful for marker-assisted selection and facilitate map-based cloning of SCMV resistance genes. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2149 TI - A Transporter in the Endoplasmic Reticulum of Schizosaccharomyces pombe Cells Mediates Zinc Storage and Differentially Affects Transition Metal Tolerance JO - J. Biol. Chem. PY - 2002 SP - 18215-18221 AU - Clemens, S. AU - Bloss, T. AU - Vess, C. AU - Neumann, D. AU - Nies, D. H. AU - zur Nieden, U. AU - VL - 277 UR - DO - 10.1074/jbc.M201031200 AB - The cation diffusion facilitator (CDF) family represents a class of ubiquitous metal transporters. Inactivation of a CDF in Schizosaccharomyces pombe, Zhf, causes drastically different effects on the tolerance toward various metals. A deletion mutant is Zn2+/Co2+-hypersensitive yet displays significantly enhanced Cd2+ and Ni2+ tolerance. Accumulation of zinc, cobalt, and cadmium is reduced in mutant cells. Non-vacuolar zinc content, as measured by analytical electron microscopy, is lower in zhf− cells compared with wild-type cells in the presence of elevated Zn2+concentrations. The protective effect against cadmium toxicity is independent of the phytochelatin detoxification pathway. Phytochelatin synthase-deficient cells show extremely enhanced (about 200-fold) cadmium tolerance when zhf is disrupted. Immunogold labeling indicates endoplasmic reticulum (ER) localization of Zhf. Electron spectroscopic imaging shows that accumulation of zinc coincides with Zhf localization, demonstrating a major role of the ER for metal storage and the involvement of Zhf in cellular zinc homeostasis. Also, these observations indicate that Cd2+ions exert their toxic effects on cellular metabolism in the ER rather than in the cytosol. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2197 TI - Genetic analysis of the biosynthesis of the pyrrole and carbamoyl moieties of coumermycin A1 and novobiocin JO - Mol. Gen. Genomics PY - 2002 SP - 387-396 AU - Xu, H. AU - Wang, Z.-X. AU - Schmidt, J. AU - Heide, L. AU - Li, S.-M. AU - VL - 268 UR - DO - 10.1007/s00438-002-0759-1 AB - The aminocoumarin antibiotic coumermycin A1 contains a central and two terminal pyrrole moieties. The coumermycin gene cluster in Streptomyces rishiriensis contains three genes (couN3, couN4 and couN5) that show sequence similarity to genes involved in the biosynthesis of the pyrrole moieties of pyoluteorin in Pseudomonas fluorescens and of undecylprodiginine in S. coelicolor. The gene couN3, which codes for a putative L-prolyl-S-PCP dehydrogenase, and the gene couN4, which encodes a putative L-prolyl-AMP ligase, were disrupted using in-frame deletion and insertional inactivation, respectively. HPLC analysis of culture extracts showed that formation of the two terminal pyrrole moieties was abolished in the couN3 - und couN4 - mutants. The mutants accumulated coumermycin D, which contains only the central pyrrole moiety. This result not only confirmed the involvement of couN3 and couN4 in the biosynthesis of the terminal pyrrole-2-carboxylic acid moieties of coumermycin A1, but also indicated, for the first time, that the central 3-methylpyrrole-2,4-dicarboxylic acid unit of the coumermycins is formed by a biosynthetic pathway that differs from that used to assemble the terminal pyrrole moieties. novN, a putative carbamoyl transferase gene from the gene cluster for novobiocin biosynthesis in S. spheroides was expressed in the couN3 - mutant. This led to the formation of bis-carbamoylated coumermycin D, a novel compound of the coumermycin series. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2196 TI - Metabolic profiling of oxylipins in germinating cucumber seedlings - lipoxygenase-dependent degradation of triacylglycerols and biosynthesis of volatile aldehydes JO - Planta PY - 2002 SP - 612-619 AU - Weichert, H. AU - Kolbe, A. AU - Kraus, A. AU - Wasternack, C. AU - Feussner, I. AU - VL - 215 UR - DO - 10.1007/s00425-002-0779-4 AB - A particular isoform of lipoxygenase (LOX) localized on lipid bodies was shown by earlier investigations to play a role in initiating the mobilization of triacylglycerols during seed germination. Here, further physiological functions of LOXs within whole cotyledons of cucumber (Cucumis sativus L.) were analyzed by measuring the endogenous amounts of LOX-derived products. The lipid-body LOX-derived esterified (13S)-hydroperoxy linoleic acid was the dominant metabolite of the LOX pathway in this tissue. It accumulated to about 14 µmol/g fresh weight, which represented about 6% of the total amount of linoleic acid in cotyledons. This LOX product was not only reduced to its hydroxy derivative, leading to degradation by β-oxidation, but alternatively it was metabolized by fatty acid hydroperoxide lyase leading to formation of hexanal as well. Furthermore, the activities of LOX forms metabolizing linolenic acid were detected by measuring the accumulation of volatile aldehydes and the allene oxide synthase-derived metabolite jasmonic acid. The first evidence is presented for an involvement of a lipid-body LOX form in the production of volatile aldehydes. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2195 TI - Direct analysis of single leaf disks for chemopreventive glucosinolates JO - Phytochem. Anal. PY - 2002 SP - 152-157 AU - Wang, Q. AU - Grubb, C. D. AU - Abel, S. AU - VL - 13 UR - DO - 10.1002/pca.636 AB - Natural isothiocyanates, produced during plant tissue damage from methionine‐derived glucosinolates, are potent inducers of mammalian phase 2 detoxification enzymes such as quinone reductase (QR). A greatly simplified bioassay for glucosinolates based on induction and colorimetric detection of QR activity in murine hepatoma cells is described. It is demonstrated that excised leaf disks of Arabidopsis thaliana (ecotype Columbia) can directly and reproducibly substitute for cell‐free leaf extracts as inducers of murine QR, which reduces sample preparation to a minimum and maximizes throughput. A comparison of 1 and 3 mm diameter leaf disks indicated that QR inducer potency was proportional to disk circumference (extent of tissue damage) rather than to area. When compared to the QR inducer potency of the corresponding amount of extract, 1 mm leaf disks were equally effective, whereas 3 mm disks were 70% as potent. The QR inducer potency of leaf disks correlated positively with the content of methionine‐derived glucosinolates, as shown by the analysis of wild‐type plants and mutant lines with lower or higher glucosinolate content. Thus, the microtitre plate‐based assay of single leaf disks provides a robust and inexpensive visual method for rapidly screening large numbers of plants in mapping populations or mutant collections and may be applicable to other glucosinolate‐producing species. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2194 TI - Two distantly related genes encoding 1-deoxy-D-xylulose 5-phosphate synthases: differential regulation in shoots and apocarotenoid-accumulating mycorrhizal roots JO - Plant J. PY - 2002 SP - 243-254 AU - Walter, M. H. AU - Hans, J. AU - Strack, D. AU - VL - 31 UR - DO - 10.1046/j.1365-313X.2002.01352.x AB - Isopentenyl diphosphate, the universal precursor of isoprenoids, is synthesized by two separate routes, one in the cytosol and the other in plastids. The initial step of the plastidial pathway is catalysed by 1‐deoxy‐d ‐xylulose 5‐phosphate synthase (DXS), which was previously thought to be encoded by a single‐copy gene. We have identified two distinct classes of DXS‐like cDNAs from the model legume Medicago truncatula . The deduced mature MtDXS1 and MtDXS2 proteins, excluding the predicted plastid‐targeting peptides, are similar in size (72.7 and 71.2 kDa) yet share only 70% identity in their amino acid sequences, and both encode functional DXS proteins as shown by heterologous expression in Escherichia coli. Available DXS sequences from other plants can easily be assigned to either class 1 or class 2. Partial sequences of multiple DXS genes in a single genome may be found in the databases of several monocot and dicot plants. Blot analyses of RNA from M. truncatula , maize, tomato and tobacco demonstrate preferential expression of DXS1 genes in many developing plant tissues except roots. By contrast, DXS2 transcript levels are low in most tissues but are strongly stimulated in roots upon colonization by mycorrhizal fungi, correlated with accumulation of carotenoids and apocarotenoids. Monoterpene‐synthesizing gland cells of leaf trichomes appear to be another site of DXS2 gene activity. The potential importance of DXS1 in many housekeeping functions and a still hypothetical role of DXS2 in the biosynthesis of secondary isoprenoids is discussed. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2193 TI - Synthesis of 2,24-Diepicastasterone and 3,24-Diepicastasterone as Potential Brassinosteroid Metabolites of the Cockroach Periplaneta americana JO - Collect. Czech. Chem. Commun. PY - 2002 SP - 91-102 AU - Voigt, B. AU - Porzel, A. AU - Adam, G. AU - Golsch, D. AU - Adam, W. AU - Wagner, C. AU - Merzweiler, K. AU - VL - 67 UR - DO - 10.1135/cccc20020091 AB - Investigations of the metabolic conversion of the phytohormone 24-epicastasterone (1) in the cockroach Periplaneta americana (L.) required the synthesis of 2,24-diepicastasterone (4), 3,24-diepicastasterone (7b) and 2-dehydro-3,24-diepicastasterone (9) as reference standards. 2,24-Diepicastasterone (4) was synthesized from 2α,3α-epoxy derivative 2 as well as from the 2β,3β-epoxy-22,23-diol 3 by acid-catalyzed water addition to the epoxy function leading to the desired 2β,3α-trans functionality. 3,24-Diepicastasterone (7b) was prepared by NaBH4-reduction of the 3-oxo derivative 6. Upon deprotection conditions from the ketol acetonides 6 and 8 in both cases 2-dehydro-3,24-diepicastasterone (9) was obtained. The structure of 2,24-diepicastasterone (4) was confirmed by X-ray analysis. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2192 TI - Substrate specificity and sequence analysis define a polyphyletic origin of betanidin 5- and 6-O-glucosyltransferase from Dorotheanthus bellidiformis JO - Planta PY - 2002 SP - 492-495 AU - Vogt, T. AU - VL - 214 UR - DO - 10.1007/s00425-001-0685-1 AB - Betanidin 6-O-glucosyltransferase (6-GT) is involved in the glycosylation of betacyanins, which replace the chromogenic anthocyanins as flower colorants in the Caryophyllales. The 6-GT cDNA was cloned from a cDNA library of Dorotheanthus bellidiformis (Burm. f.) N.E. Br., and the amino acid and nucleotide sequences were shown to be distinctly different from the corresponding betanidin 5-O-glucosyltransferase (5-GT) from the same plant species. Although both enzymes share very similar substrates, the proteins show only 19% amino acid sequence identity. In contrast, the protein sequence of the 6-GT showed significant identity to GTs from other species and may identify a new cluster of putative anthocyanidin GTs. Therefore, 6-GT and 5-GT apparently have evolved independently from ancestral glucosyltransferases involved in flavonoid biosynthesis. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2191 TI - Stimulation of jasmonic acid production in Zea Mays L. infected by the maize rough dwarf virus - Río Cuarto. Reversion of symptoms by salicylic acid JO - Biocell PY - 2002 SP - 369-374 AU - Vigliocco, A. AU - Bonamico, B. AU - Alemano, S. AU - Miersch, O. AU - Abdala, G. AU - VL - 26 UR - https://www.techscience.com/biocell/v26n3/34012 AB - In the present paper we study the possible biological relevance of endogenous jasmonic acid (JA) and exogenous salicylic acid (SA) in a plant-microbial system maize-virus. The virus disease "Mal de Río Cuarto" is caused by the maize rough dwarf virus - Río Cuarto. The characteristic symptoms are the appearance of galls or "enations" in leaves, shortening of the stem internodes, poor radical system and general stunting. Changes in JA and protein pattern in maize control and infected plants of a virus-tolerant cultivar were investigated. Healthy and infected-leaf discs were collected for JA measurement at different post-infection times (20, 40, 60 and 68 days). JA was also measured in roots on day 60 after infection. For SDS-PAGE protein analysis, leaf discs were also harvested on day 60 after infection. Infected leaves showed higher levels of JA than healthy leaves, and the rise in endogenous JA coincided with the enation formation. The soluble protein amount did not show differences between infected and healthy leaves; moreover, no difference in the expression of soluble protein was revealed by SDS-PAGE. Our results show that the octadecanoid pathway was stimulated in leaves and roots of the tolerant maize cultivar when infected by this virus. This finding, together with fewer plants with the disease symptoms, suggest that higher foliar and roots JA content may be related to disease tolerance. SA exogenous treatment caused the reversion of the dwarfism symptom. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2190 TI - NHL25 and NHL3, Two NDR1/HIN1-Like Genes in Arabidopsis thaliana with Potential Role(s) in Plant Defense JO - Mol. Plant Microbe Interact. PY - 2002 SP - 608-616 AU - Varet, A. AU - Parker, J. AU - Tornero, P. AU - Nass, N. AU - Nürnberger, T. AU - Dangl, J. L. AU - Scheel, D. AU - Lee, J. AU - VL - 15 UR - DO - 10.1094/MPMI.2002.15.6.608 AB - The Arabidopsis genome contains 28 genes with sequence homology to the Arabidopsis NDR1 gene and the tobacco HIN1 gene. Expression analysis of eight of these genes identified two (NHL25 and NHL3 for NDR1/HIN1-like) that show pathogen-dependent mRNA accumulation. Transcripts did not accumulate during infection with virulent Pseudomonas syringae pv. tomato DC3000 but did accumulate specifically when the bacteria carried any of the four avirulence genes avrRpm1, avrRpt2, avrB, or avrRps4. Furthermore, expression of avrRpt2 in plants containing the corresponding resistance gene, RPS2, was sufficient to induce transcript accumulation. However, during infection with an avirulent oomycete, Peronospora parasitica isolate Cala-2, only NHL25 expression was reproducibly induced. Salicylic acid (SA) treatment can induce expression of NHL25 and NHL3. Studies performed on nahG plants showed that, during interaction with avirulent bacteria, only the expression of NHL25 but not that of NHL3 was affected. This suggests involvement of separate SA-dependent and SA-independent pathways, respectively, in the transcriptional activation of these genes. Bacteria-induced gene expression was not abolished in ethylene- (etr1-3 and ein2-1) and jasmonate- (coi1-1) insensitive mutants or in mutants impaired in disease resistance (ndr1-1 and pad4-1). Interestingly, NHL3 transcripts accumulated after infiltration with the avirulent hrcC mutant of Pseudomonas syringae pv. tomato DC3000 and nonhost bacteria but not with the virulent Pseudomonas syringae pv. tomato DC3000, suggesting that virulent bacteria may suppress NHL3 expression during pathogenesis. Hence, the expression patterns and sequence homology to NDR1 and HIN1 suggest one or more potential roles for these genes in plant resistance. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2189 TI - A Dual Role for Microbial Pathogen-Derived Effector Proteins in Plant Disease and Resistance JO - Crit. Rev. Plant Sci. PY - 2002 SP - 229-271 AU - van't Slot, K. A. E. AU - Knogge, W. AU - VL - 21 UR - DO - 10.1080/0735-260291044223 AB - Many proteins from plant pathogens affecting the interaction with the host plant have dual functions: they promote virulence on the host species and they function as avirulence determinants by eliciting defense reactions in host cultivars expressing the appropriate resistance genes. In viruses all proteins encoded by the small genomes can be expected to be essential for viral development in the host. However, in different plants surveillance systems have evolved that are able to recognize most of these proteins. Bacteria and fungi have specialized pathogenicity and virulence genes. Many of the latter were originally identified through the resistance gene-dependent elicitor activity of their products. Their role in virulence only became apparent when they were inactivated or transferred to different microbes or after their ectopic expression in host plants. Many microbes appear to maintain these genes despite their disadvantageous effect, introducing only few mutations to abolish the interaction of their products with the plant recognition system. This has been interpreted as been indicative of a virulence function of the gene products that is not impaired by the mutations. Alternatively, in particular in bacteria there is now evidence that pathogenicity was acquired through horizontal gene transfer. Genes supporting virulence in the donor organism's original host appear to have traveled along. Being gratuitous in the new situation, they may have been inactivated without loss of any beneficial function for the pathogen. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2148 TI - A long way ahead: understanding and engineering plant metal accumulation JO - Trends Plant Sci. PY - 2002 SP - 309-315 AU - Clemens, S. AU - Palmgren, M. G. AU - Krämer, U. AU - VL - 7 UR - DO - 10.1016/S1360-1385(02)02295-1 AB - Some plants can hyperaccumulate metal ions that are toxic to virtually all other organisms at low dosages. This trait could be used to clean up metal-contaminated soils. Moreover, the accumulation of heavy metals by plants determines both the micronutrient content and the toxic metal content of our food. Complex interactions of transport and chelating activities control the rates of metal uptake and storage. In recent years, several key steps have been identified at the molecular level, enabling us to initiate transgenic approaches to engineer the transition metal content of plants. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2147 TI - Jasmonate methyl ester induces the synthesis of a cytoplasmic/nuclear chitooligosaccharide‐binding lectin in tobacco leaves JO - FASEB J. PY - 2002 SP - 905-907 AU - Chen, Y. AU - Peumans, W. J. AU - Hause, B. AU - Bras, J. AU - Kumar, M. AU - Proost, P. AU - Barre, A. AU - Rougé, P. AU - Van Damme, E. J. M. AU - VL - 16 UR - DO - 10.1096/fj.01-0598fje AB - In contrast to animal lectins, no evidence has indicated the occurrence of plant lectins, which recognize and bind “endogenous” receptors and accordingly are involved in recognition mechanisms within the organism itself. Here we show that the plant hormone jasmonic acid methyl ester (JAME) induces in leaves of Nicotiana tabacum (var. Samsun NN) the expression of a lectin that is absent from untreated plants. The lectin specifically binds to oligomers of N‐acetylglucosamine and is detected exclusively in the cytoplasm and the nucleus. Both the subcellular location and specificity indicate that the Nicotiana tabacum agglutinin (called Nictaba) may be involved in the regulation of gene expression in stressed plants through specific protein‐carbohydrate interactions with regulatory cytoplasmic/nuclear glycoproteins. Searches in the databases revealed that many flowering plants contain sequences encoding putative homologues of the tobacco lectin, which suggest that Nictaba is the prototype of a widespread or possibly ubiquitous family of lectins with a specific endogenous role. A2 - C1 - Cell and Metabolic Biology ER - TY - JOUR ID - 2146 TI - Chemotaxonomy of the tribe Antidesmeae (Euphorbiaceae): antidesmone and related compounds JO - Phytochemistry PY - 2002 SP - 489-496 AU - Buske, A. AU - Schmidt, J. AU - Hoffmann, P. AU - VL - 60 UR - DO - 10.1016/S0031-9422(02)00117-6 AB - Selected species of the tribe Antidesmeae (Euphorbiaceae, subfamily Phyllanthoideae) have been screened for antidesmone occurrence and its content by quantitative HPLC (UV) and qualitative LC–MS/MS analysis. The LC–MS analysis allowing the additional detection of 17,18-bis-nor-antidesmone, 18-nor-antidesmone, 8-dihydroantidesmone and 8-deoxoantidesmone was carried out in the selected reaction monitoring (SRM) mode. Leaf material from herbarium specimens of 13 Antidesma spp., Hyeronima alchorneoides and Thecacoris stenopetala (all subtribe Antidesminae), as well as Maesobotrya barteri, Aporosa octandra (both Scepinae) and Uapaca robynsii (Uapacinae) were analysed. Additionally, freshly collected samples of different plant parts of two Antidesma spp. were investigated to ensure the significance of the results on herbarium specimens and to compare the antidesmone content in bark, root and leaves. Antidesmone could be unambiguously identified in 12 of 13 Antidesma spp., as well as in the two other investigated genera of subtribe Antidesminae, in levels of up to 65 mg/kg plant dry weight. Antidesmone was not found in specimens from other subtribes. Antidesmone-derived compounds occur in much lower concentrations than antidesmone.Selected species of the tribe Antidesmeae (Euphorbiaceae, subfamily Phyllanthoideae) have been screened for the occurrence of antidesmone and some derived compounds by HPLC and LC–MS/MS analysis, including selected reaction monitoring (SRM). Antidesmone could be identified in 12 of 13 Antidesma species as well as in the two other investigated genera of subtribe Antidesminae. It was not found in specimens from other subtribes. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2145 TI - Pep-13, a plant defense-inducing pathogen-associated pattern from Phytophthora transglutaminases JO - EMBO J. PY - 2002 SP - 6681-6688 AU - Brunner, F. AU - Rosahl, S. AU - Lee, J. AU - Rudd, J. J. AU - Geiler, C. AU - Kauppinen, S. AU - Rasmussen, G. AU - Scheel, D. AU - Nürnberger, T. AU - VL - 21 UR - DO - 10.1093/emboj/cdf667 AB - Innate immunity, an ancient form of defense against microbial infection, is well described for animals and is also suggested to be important for plants. Discrimination from self is achieved through receptors that recognize pathogen‐associated molecular patterns (PAMPs) not found in the host. PAMPs are evolutionarily conserved structures which are functionally important and, thus, not subject to frequent mutation. Here we report that the previously described peptide elicitor of defense responses in parsley, Pep‐13, constitutes a surface‐exposed fragment within a novel calcium‐dependent cell wall transglutaminase (TGase) from Phytophthora sojae . TGase transcripts and TGase activity are detectable in all Phytophthora species analyzed, among which are some of the most destructive plant pathogens. Mutational analysis within Pep‐13 identified the same amino acids indispensable for both TGase and defense‐eliciting activity. Pep‐13, conserved among Phytophthora TGases, activates defense in parsley and potato, suggesting its function as a genus‐specific recognition determinant for the activation of plant defense in host and non‐host plants. In summary, plants may recognize PAMPs with characteristics resembling those known to trigger innate immune responses in animals. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2144 TI - A β-glucosidase/xylosidase from the phytopathogenic oomycete, Phytophthora infestans JO - Phytochemistry PY - 2002 SP - 689-696 AU - Brunner, F. AU - Wirtz, W. AU - Rose, J. K. C. AU - Darvill, A. G. AU - Govers, F. AU - Scheel, D. AU - Nürnberger, T. AU - VL - 59 UR - DO - 10.1016/S0031-9422(02)00045-6 AB - An 85-kDa β-glucosidase/xylosidase (BGX1) was purified from the axenically grown phytopathogenic oomycete, Phytophthora infestans. The bgx1 gene encodes a predicted 61-kDa protein product which, upon removal of a 21 amino acid leader peptide, accumulates in the apoplastic space. Extensive N-mannosylation accounts for part of the observed molecular mass difference. BGX1 belongs to family 30 of the glycoside hydrolases and is the first such oomycete enzyme deposited in public databases. The bgx1 gene was found in various Phytophthora species, but is apparently absent in species of the related genus, Pythium. Despite significant sequence similarity to human and murine lysosomal glucosylceramidases, BGX1 demonstrated neither glucocerebroside nor galactocerebroside-hydrolyzing activity. The native enzyme exhibited glucohydrolytic activity towards 4-methylumbelliferyl (4-MU) β-d-glucopyranoside and, to lesser extent, towards 4-MU-d-xylopyranoside, but not towards 4-MU-β-d-glucopyranoside. BGX1 did not hydrolyze carboxymethyl cellulose, cellotetraose, chitosan or xylan, suggesting high substrate specificity and/or specific cofactor requirements for enzymatic activity.A β-glucosidase/xylosidase was purified from the phytopathogenic oomycete, Phytophthora infestans. The encoding gene is the first such sequence reported from a species of the kingdom chromista. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2143 TI - Struktur- Wirkungsbeziehungen von Opioiden: Agonist oder Antagonist? JO - Pharmazie in unserer Zeit PY - 2002 SP - 60-68 AU - Brandt, W. AU - VL - 31 UR - DO - 10.1002/1615-1003(200201)31:1<60::AID-PAUZ60>3.0.CO;2-L AB - Die Charakterisierung der pharmakophoren Strukturmerkmale der Opioide, die für deren Affinität und Spezifität zu ihren Rezeptoren verantwortlich sind, steht nach wie vor im Mittelpunkt vieler Untersuchungen mittels experimenteller und theoretischer Methoden. In der Vergangenheit konnten molekulare Modelle entwickelt werden, die zur Charakterisierung der wichtigsten pharmakophoren Elemente von μ‐, δ, ‐und κ‐ selektiven Opioiden führten. Diese Modelle können die Grundlage zur Entwicklung weiterer spezifischer Opioide mit reduzierten Nebenwirkungen darstellen. Die Kenntnis der Raumstruktur des Rinder‐Rhodopsin, eines zu den Opioidrezeptoren homologen G‐Protein‐gekoppelten Rezeptors, ermöglicht jetzt die Modellierung der Strukturen der Opioidrezeptoren. Durch eine detaillierte Analyse der potenziellen Bindungsstellen der Opioide an ihre Rezeptoren können neue Einblicke in die Zusammenhänge zwischen den chemischen Strukturen der Opioide und ihren Wirkungen gewonnen werden. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2142 TI - Predicted Alterations in Tertiary Structure of the N-Terminus of Na+/K+-ATPase α-Subunit Caused by Phosphorylation or Acidic Replacement of the PKC Phosphorylation Site Ser-23 JO - Cell Biochem. Biophys. PY - 2002 SP - 83-96 AU - Brandt, W. AU - Anders, A. AU - Vasilets, L. A. AU - VL - 37 UR - DO - 10.1385/CBB:37:2:083 AB - The protein kinase C (PKC)-mediated phosphorylation of the Na+/K+-ATPase α-subunit has been shown to play an important role in regulation of the Na+/K+-ATPase activity. In the rat α1-subunit, phosphorylation occurs at Ser-23 and results in inhibition of the transport function of the Na+/K+-ATPase, which is mimicked by replacing the Ser-23 by the negatively charged glutamic acid or by aspartic acid. Using comparative molecular modeling, we investigated whether phosphorylation or acidic replacement at position 23 causes a dramatic change in the molecular electrostatic potential at position 23 as a result of insertion of a negative charge of the phosphoryl group or Glu per se, or whether, alternatively, the modification causes larger-scale conformational changes in the N-terminus of the α-subunit. The results predict a considerable conformational change of the 30-residue stretch around Ser-23 when mutated to the residues carrying a net negative charge or being phosphorylated. The structural rearrangements occur within the N-terminal helix-loop-helix motif with a set of charged residues. This motif has structural homology with one in the Ca2+-ATPase and may form a function-related structural site in the P-type ATPases. Comparative molecular modeling indicates a lengthening of the interhelical loop and an order-to-disorder transition by disrupting a helix at position 23 because of posphorylation. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2141 TI - Facile and practical enantioselective synthesis of propargylic alcohols by direct addition of alkynes to aldehydes catalyzed by chiral disulfide–oxazolidine ligands JO - Tetrahedron PY - 2002 SP - 10413-10416 AU - Braga, A. L. AU - Appelt, H. R. AU - Silveira, C. C. AU - Wessjohann, L. A. AU - Schneider, P. H. AU - VL - 58 UR - DO - 10.1016/S0040-4020(02)01420-5 AB - The enantioselective alkynylation reaction of aldehydes with alkynes and diethylzinc, catalyzed by chiral disulfide–oxazolidine ligands, provides a simple, practical and inexpensive method to access chiral propargylic alcohols in good yields and satisfactory ee's. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2140 TI - Chiral diselenide ligands for the asymmetric copper-catalyzed conjugate addition of Grignard reagents to enones JO - Tetrahedron Lett. PY - 2002 SP - 7329-7331 AU - Braga, A. L. AU - Silva, S. J. N. AU - Lüdtke, D. S. AU - Drekener, R. L. AU - Silveira, C. C. AU - Rocha, J. B. T. AU - Wessjohann, L. A. AU - VL - 43 UR - DO - 10.1016/S0040-4039(02)01713-6 AB - The copper-catalyzed conjugate addition of Grignard reagents to enones in the presence of chiral diselenide oxazoline ligands has been studied and found to provide good yields and useful levels of asymmetric induction. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2139 TI - Characterization of the ZAT1p zinc transporter from Arabidopsis thaliana in microbial model organisms and reconstituted proteoliposomes JO - Planta PY - 2002 SP - 783-791 AU - Bloß, T. AU - Clemens, S. AU - Nies, D. H. AU - VL - 214 UR - DO - 10.1007/s00425-001-0677-1 AB - The ZAT1p zinc transporter from Arabidopsis thaliana (L.) Heynh. is a member of the cation diffusion facilitator (CDF) protein family. When heterologously expressed in Escherichia coli, ZAT1p bound zinc in a metal blot. Binding of zinc occurred mainly to the hydrophilic amino acid region from H182 to H232. A ZAT1p/ZAT1p*Δ(M1–I25) protein mixture was purified and reconstituted into proteoliposomes. Uptake of zinc into the proteoliposomes did not require a proton gradient across the liposomal membrane. ZAT1p did not transport cobalt, and transported cadmium at only 1% of the zinc transport rate. ZAT1p functioned as an uptake system for 65Zn2+ in two strains of the Gram-negative bacterium Ralstonia metallidurans, which were different in their content of zinc-efflux systems. The ZAT1 gene did not rescue increased zinc sensitivity of a ΔZRC1 single-mutant strain or of a ΔZRC1 ΔCOT1 double-mutant strain of Saccharomyces cerevisiae, but ZAT1 complemented this phenotype in a ΔSpZRC1 mutant strain of Schizosaccharomyces pombe. A2 - C1 - Biochemistry of Plant Interactions ER - TY - JOUR ID - 2138 TI - Coumarins give misleading absorbance with Ellman’s reagent suggestive of thiol conjugates JO - Analyst PY - 2002 SP - 333-336 AU - Berlich, M. AU - Menge, S. AU - Bruns, I. AU - Schmidt, J. AU - Schneider, B. AU - Krauss, G.-J. AU - VL - 127 UR - DO - 10.1039/B110988J AB - In the course of a screening for phytochelatins in cadmium-exposed bryophytes in the terrestrial mosses Polytrichum formosum and Atrichum undulatum we detected compounds with absorption properties and retention times similar to phytochelatins when applying the commonly used standard method RP-HPLC and post-column derivatization with thiol-specific DTNB (Ellman) reagent. Moreover, as with phytochelatins known in other plants, the concentrations of these compounds increased slightly after Cd stress. The concentration of the precursor glutathione (γ-ECG), however, increased in the presence of Cd. In order to verify the identity of these putative phytochelatins we performed LC-ESI-MS analyses as well as 1H NMR on extracts from P. formosum and A. undulatum. Spectroscopic investigations indicated that the detected compounds were neither phytochelatins nor other thiol compounds. From the results of HPLC-1H NMR and mass spectrometry we concluded that at least one of these substances was a coumarin, probably a 5,8-dihydroxy-7-methoxycoumarin-5-β-glucopyranoside, which has already been described for A. undulatum and P. formosum. The results of our investigations prove that under the basic pH conditions essential for the Ellman test for thiol compounds, coumarins show comparable UV/VIS absorption properties. Therefore, a positive post-column Ellman reaction cannot unambiguously prove the presence of thiol-containing compounds in plants. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2137 TI - Jasmonate-Induced Lipid Peroxidation in Barley Leaves Initiated by Distinct 13-LOX Forms of Chloroplasts JO - Biol. Chem. PY - 2002 SP - 1645-1657 AU - Bachmann, A. AU - Hause, B. AU - Maucher, H. AU - Garbe, E. AU - Vörös, K. AU - Weichert, H. AU - Wasternack, C. AU - Feussner, I. AU - VL - 383 UR - DO - 10.1515/BC.2002.185 AB - In addition to a previously characterized 13-lipoxygenase of 100 kDa encoded by LOX2:Hv:1 [Vörös et al., Eur. J. Biochem. 251 (1998), 36 44], two fulllength cDNAs (LOX2:Hv:2, LOX2:Hv:3) were isolated from barley leaves (Hordeum vulgare cv. Salome) and characterized. Both of them encode 13-lipoxygenases with putative target sequences for chloroplast import. Immunogold labeling revealed preferential, if not exclusive, localization of lipoxygenase proteins in the stroma. The ultrastructure of the chloroplast was dramatically altered following methyl jasmonate treatment, indicated by a loss of thylakoid membranes, decreased number of stacks and appearance of numerous osmiophilic globuli. The three 13-lipoxygenases are differentially expressed during treatment with jasmonate, salicylate, glucose or sorbitol. Metabolite profiling of free linolenic acid and free linoleic acid, the substrates of lipoxygenases, in water floated or jasmonatetreated leaves revealed preferential accumulation of linolenic acid. Remarkable amounts of free 9- as well as 13-hydroperoxy linolenic acid were found. In addition, metabolites of these hydroperoxides, such as the hydroxy derivatives and the respective aldehydes, appeared following methyl jasmonate treatment. These findings were substantiated by metabolite profiling of isolated chloroplasts, and subfractions including the envelope, the stroma and the thylakoids, indicating a preferential occurrence of lipoxygenasederived products in the stroma and in the envelope. These data revealed jasmonateinduced activation of the hydroperoxide lyase and reductase branch within the lipoxygenase pathway and suggest differential activity of the three 13-lipoxygenases under different stress conditions. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 2136 TI - The iridois and iridoid glycosid from the Rehmanuia glutinosa Rhizome JO - Vietnam J. Chem. PY - 2002 SP - 17-22 AU - Anh, N. T. H. AU - Sung, T. V. AU - Wessjohann, L. AU - Adam, G. AU - VL - 40 UR - vjs.ac.vn/index.php/vjchem/issue/view/362 AB - A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2135 TI - Some hydroxycinnamic acid esters of phenylethyl alcohol glycosides from Rehmannia glutinosa Libosch JO - Vietnam J. Chem. PY - 2002 SP - 175-179 AU - Anh, N. T. H. AU - Sung, T. V. AU - Wessjohann, L. A. AU - Adam, G. AU - VL - 40 UR - AB - A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 2134 TI - Phosphate sensing in higher plants JO - Physiol. Plant. PY - 2002 SP - 1-8 AU - Abel, S. AU - Ticconi, C. A. AU - Delatorre, C. A. AU - VL - 115 UR - DO - 10.1034/j.1399-3054.2002.1150101.x AB - Phosphate (Pi) plays a central role as reactant and effector molecule in plant cell metabolism. However, Pi is the least accessible macronutrient in many ecosystems and its low availability often limits plant growth. Plants have evolved an array of molecular and morphological adaptations to cope with Pi limitation, which include dramatic changes in gene expression and root development to facilitate Pi acquisition and recycling. Although physiological responses to Pi starvation have been increasingly studied and understood, the initial molecular events that monitor and transmit information on external and internal Pi status remain to be elucidated in plants. This review summarizes molecular and developmental Pi starvation responses of higher plants and the evidence for coordinated regulation of gene expression, followed by a discussion of the potential involvement of plant hormones in Pi sensing and of molecular genetic approaches to elucidate plant signalling of low Pi availability. Complementary genetic strategies in Arabidopsis thaliana have been developed that are expected to identify components of plant signal transduction pathways involved in Pi sensing. Innovative screening methods utilize reporter gene constructs, conditional growth on organophosphates and the inhibitory properties of the Pi analogue phosphite, which hold the promise for significant advances in our understanding of the complex mechanisms by which plants regulate Pi‐starvation responses. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2133 TI - Changes in jasmonate and gibberellin levels during development of potato plants (Solanum tuberosum) JO - Plant Growth Regul. PY - 2002 SP - 121-126 AU - Abdala, G. AU - Castro, G. AU - Miersch, O. AU - Pearce, D. AU - VL - 36 UR - DO - 10.1023/A:1015065011536 AB - Among the multiple environmental signals and hormonal factors regulatingpotato plant morphogenesis and controlling tuber induction, jasmonates (JAs)andgibberellins (GAs) are important components of the signalling pathways in theseprocesses. In the present study, with Solanum tuberosum L.cv. Spunta, we followed the endogenous changes of JAs and GAs during thedevelopmental stages of soil-grown potato plants. Foliage at initial growthshowed the highest jasmonic acid (JA) concentration, while in roots the highestcontent was observed in the stage of tuber set. In stolons at the developmentalstage of tuber set an important increase of JA was found; however, in tubersthere was no change in this compound during tuber set and subsequent growth.Methyl jasmonate (Me-JA) in foliage did not show the same pattern as JA; Me-JAdecreased during the developmental stages in which it was monitored, meanwhileJA increased during those stages. The highest total amount of JAs expressed asJA + Me-JA was found at tuber set. A very important peak ofJA in roots was coincident with that observed in stolons at tuber set. Also, aprogressive increase of this compound in roots was shown during the transitionof stolons to tubers. Of the two GAs monitored, gibberellic acid(GA3) was the most abundant in all the organs. While GA1and GA3 were also found in stolons at the time of tuber set, noothermeasurements of GAs were obtained for stolons at previous stages of plantdevelopment. Our results indicate that high levels of JA and GAs are found indifferent tissues, especially during stolon growth and tuber set. A2 - C1 - Molecular Signal Processing ER - TY - CHAP ID - 160 TI - Effects of Nonapeptides Derived From the N-terminal Structure of Human Immunodeficiency Virus-1 (HIV-1) Tat on Suppression of CD26-Dependent T Cell Growth T2 - Cellular Peptidases in Immune Functions and Diseases 2 PB - Adv. Exp. Med. Biol. PY - 2002 SP - 161-165 AU - Wrenger, S. AU - Reinhold, D. AU - Faust, J. AU - Mrestani-Klaus, C. AU - Brandt, W. AU - Fengler, A. AU - Neubert, K. AU - Ansorge, S. AU - VL - 477 UR - SN - 978-0-306-46826-1 DO - 10.1007/0-306-46826-3_18 AB - The human immunodeficiency virus-1 (HIV-1) transactivator Tat occurs extracellularly and exerts immunosuppressive effects. Interestingly, Tat inhibits dipeptidyl peptidase IV (DP IV) activity of the T cellactivation marker CD26. The short N-terminal nonapeptideTat(l-9), MDPVDPNIE, also inhibits DP IV activity and suppresses DNA synthesis of tetanus toxoid-stimulated peripheral blood mononuclear cells (PBMC). Here, we present the influence of amino acid exchanges in the first three positions of Tat(l-9). For instance, the replacement of D2 of Tat(l-9) by G or K generated peptides, which inhibit DP IV-catalyzed IL-2(1-12) cleavage nearly threefold stronger. Similar effects were observed on the suppression of DNA synthesis of Tetanus toxoid-stimulated PBMC. This correlation suggests that Tat(l-9)-deduced peptides mediate antiproliferative effects at least in part via specific DP IV interactions and supports the hypothesis that CD26 plays a key role in the regulation of lymphocyte growth. A2 - C1 - Bioorganic Chemistry ER - TY - CHAP ID - 159 TI - Jasmonates and octadecanoids: Signals in plant stress responses and development T2 - PB - Prog. Nucleic Acid Res. Mol. Biol. PY - 2002 SP - 165-221 AU - Wasternack, C. AU - Hause, B. AU - VL - 72 UR - DO - 10.1016/S0079-6603(02)72070-9 AB - Plants are sessile organisms. Consequently they have to adapt constantly to fluctuations in the environment. Some of these changes involve essential factors such as nutrients, light, and water. Plants have evolved independent systems to sense nutrients such as phosphate and nitrogen. However, many of the environmental factors may reach levels which represent stress for the plant. The fluctuations can range between moderate and unfavorable, and the factors can be of biotic or abiotic origin. Among the biotic factors influencing plant life are pathogens and herbivores. In case of bacteria and fungi, symbiotic interactions such as nitrogen-fixating nodules and mycorrhiza, respectively, may be established. In case of insects, a tritrophic interaction of herbivores, carnivores, and plants may occur mutualistically or parasitically. Among the numerous abiotic factors are low temperature, frost, heat, high light conditions, ultraviolet light, darkness, oxidation stress, hypoxia, wind, touch, nutrient imbalance, salt stress, osmotic adjustment, water deficit, and desiccation.In the last decade jasmonates were recognized as being signals in plant responses to most of these biotic and abiotic factors. Signaling via jasmonates was found to occur intracellularly, and systemically as well as interorganismically. Jasmonates are a group of ubiquitously occurring plant growth regulators originally found as the major constituents in the etheric oil of jasmine, and were first suggested to play a role in senescence due to a strong senescence-promoting effect. Subsequently, numerous developmental processes were described in which jasmonates exhibited hormone-like properties. Recent knowledge is reviewed here on jasmonates and their precursors, the octadecanoids. After discussing occurrence and biosynthesis, emphasis is placed upon the signal transduction pathways in plant stress responses in which jasmonates act a signal. Finally, examples are described on the role of jasmonates in developmental processes. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - CHAP ID - 158 TI - Oxidative burst and the role of reactive oxygen species in plant-pathogen interactions T2 - Oxidative Stress in Plants PB - PY - 2002 SP - 137-153 AU - Scheel, D. AU - VL - UR - AB - A2 - Inzé, D. & van Montagu, M., eds. C1 - Biochemistry of Plant Interactions ER - TY - CHAP ID - 157 TI - Cell-Cell Contact Between Lymphocytes and Fibroblast-Like Synovioctyes Induces Lymphocytic Expression of Aminopeptidase n/cd13 and Results in Lymphocytic Activation T2 - Cellular Peptidases in Immune Functions and Diseases 2 PB - Adv. Exp. Med. Biol. PY - 2002 SP - 57-66 AU - Riemann, D. AU - Röntsch, J. AU - Hause, B. AU - Langner, J. AU - Kehlen, A. AU - VL - 477 UR - SN - 978-0-306-46826-1 DO - 10.1007/0-306-46826-3_6 AB - A2 - C1 - Cell and Metabolic Biology ER - TY - CHAP ID - 156 TI - Selected cell cultures and induction methods for cloning and assaying cytochromes P450 in alkaloid pathways T2 - Cytochrome P450 Part C PB - Methods Enzymol. PY - 2002 SP - 370-381 AU - Kutchan, T. M. AU - Schröder, J. AU - VL - 357 UR - DO - 10.1016/S0076-6879(02)57695-3 AB - This chapter focuses on selected cell cultures and induction methods for cloning and assaying cytochromes P450 in alkaloid pathways. The biosynthesis of selected members of alkaloid classes for which the enzymatic steps are elucidated in the chapter, such as the monoterpenoid indole alkaloid vindoline and the isoquinoline alkaloids morphine, macarpine, and berberine, involves highly substrate-specific cytochromes P450. Although in vitro enzyme assays have been successfully developed for most of these cytochromes P450, purification to apparent homogeneity of cytochromes P450 from plant tissues has, in many cases, proved elusive because of the low abundance and instability of these proteins. Because many alkaloid biosynthetic pathways can be induced in plant cell culture, the differential expression of cytochrome P450 encoding genes involved in these pathways can be exploited in the cloning of these genes. The protocols described in the chapter are used successfully in the laboratories to clone and functionally express cytochrome P450-encoding cDNAs of alkaloid biosynthesis. A2 - C1 - ER - TY - CHAP ID - 155 TI - Avirulence Determinants and Elicitors T2 - Agricultural Applications PB - The Mycota PY - 2002 SP - 289-310 AU - Knogge, W. AU - VL - 11 UR - SN - 978-3-662-03059-2 DO - 10.1007/978-3-662-03059-2_15 AB - Being surrounded by putatively hostile microorganisms, but immobile and hence unable to escape, plants constantly need to be prepared for defensive battle. During their coevolution with heterotrophic parasites they have therefore acquired efficient passive, preformed barriers that provide protection against the majority of aggressors. In addition, however, plants have an arsenal of offensive weapons for counterattack at their disposal once the passive bulwark has failed. Usually, this weaponry is launched rapidly and decisively, thus negating any further progression of the invader in order to maintain the plant’s structural and functional integrity. A2 - C1 - Biochemistry of Plant Interactions ER - TY - CHAP ID - 154 TI - Development and Validation of Homology Models of Human Cathepsins K, S, H, and F T2 - Cellular Peptidases in Immune Functions and Diseases 2 PB - Adv. Exp. Med. Biol. PY - 2002 SP - 255-260 AU - Fengler, A. AU - Brandt, W. AU - VL - 477 UR - SN - 978-0-306-46826-1 DO - 10.1007/0-306-46826-3_27 AB - Models of the tertiary structures of cathepsins K, S, H, and F were constructed by using homology protein modelling methods and refinements by interactive graphics and energy minimisation. The predicted structures yield information regarding their substrate binding sites and indicate the residues surrounding these sites. The ligandbinding sites were characterised and compared with each other by means of calculated molecular electrostatic surface potentials. This will allow designing and development of new ligands specific for these cathepsins in future investigations. A2 - C1 - Bioorganic Chemistry ER - TY - CHAP ID - 153 TI - Down regulation of T-cell activation by synthetic dipeptidyl peptidase IV inhibitors with the N.terminal MXP sequence T2 - PEPTIDES 2002 PB - PY - 2002 SP - 750-751 AU - Faust, J. AU - Wrenger, S. AU - Reinhold, D. AU - Kähne, T. AU - Lorey, S. AU - Stöckel-Maschek, A. AU - Brandt, W. AU - Mrestani-Klaus, C. AU - Stiebitz, B. AU - Fuchs, P. AU - Ansorge, S. AU - Neubert, K. AU - VL - UR - AB - A2 - Bendetti, E. & Predone, C., eds. C1 - Bioorganic Chemistry ER - TY - CHAP ID - 152 TI - Molecular mechanisms that control plant tolerance to heavy metals and possible roles towards manipulating metal accumulation T2 - Plant Biotechnology and Transgenic Plants PB - PY - 2002 SP - 665-691 AU - Clemens, S. AU - Thomine, S. AU - Schroeder, J. I. AU - VL - UR - https://www.routledge.com/Plant-Biotechnology-and-Transgenic-Plants/Oksman-Caldentey-Barz/p/book/9780824707941 AB - A2 - C1 - Biochemistry of Plant Interactions ER - TY - CHAP ID - 151 TI - Review: Novel Cysteine Proteases of the Papain Family T2 - Cellular Peptidases in Immune Functions and Diseases 2 PB - Adv. Exp. Med. Biol. PY - 2002 SP - 241-254 AU - Bühling, F. AU - Fengler, A. AU - Brandt, W. AU - Welte, T. AU - Ansorge, S. AU - Nagler, D. K. AU - VL - 477 UR - SN - 978-0-306-46826-1 DO - 10.1007/0-306-46826-3_26 AB - A2 - C1 - Bioorganic Chemistry ER - TY - CHAP ID - 150 TI - Development of a Tertiary-Structure Model of the C-Terminal Domain of DPP IV T2 - Cellular Peptidases in Immune Functions and Diseases 2 PB - Adv. Exp. Med. Biol. PY - 2002 SP - 97-101 AU - Brandt, W. AU - VL - 477 UR - SN - 978-0-306-46826-1 DO - 10.1007/0-306-46826-3_9 AB - Based on the recently published structure of prolyl oligopeptidase (POP) a model of the C-terminal part of dipeptidyl peptidase IV (DPP IV) which contains the active site has been developed. The structure of the model of DPP IV shows considerable similarity to the structure of POP particularly in the active site. A hydrophobic pocket (Tyr666, Tyr670, Tyr 631, Val556) forms the S1-binding site for recognition of proline. Tyr547 may stabilise the oxyanion formed in the tetrahedral intermediates by a strong hydrogen bond. The positively charged N-terminus of ligands of DPP IV is recognised by forming a salt bridge with the acidic side chain Glu668. A second hydrophobic pocket (S2′ to S5′) may represent an important binding site for HIV-1 Tat-protein derivatives, chemokines and others. A2 - C1 - Bioorganic Chemistry ER -