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Publikation

Otto, M.; Naumann, C.; Brandt, W.; Wasternack, C.; Hause, B.; Activity Regulation by Heteromerization of Arabidopsis Allene Oxide Cyclase Family Members Plants 5, 3, (2016) DOI: 10.3390/plants5010003

Jasmonates (JAs) are lipid-derived signals in plant stress responses and development. A crucial step in JA biosynthesis is catalyzed by allene oxide cyclase (AOC). Four genes encoding functional AOCs (AOC1, AOC2, AOC3 and AOC4) have been characterized for Arabidopsis thaliana in terms of organ- and tissue-specific expression, mutant phenotypes, promoter activities and initial in vivo protein interaction studies suggesting functional redundancy and diversification, including first hints at enzyme activity control by protein-protein interaction. Here, these analyses were extended by detailed analysis of recombinant proteins produced in Escherichia coli. Treatment of purified AOC2 with SDS at different temperatures, chemical cross-linking experiments and protein structure analysis by molecular modelling approaches were performed. Several salt bridges between monomers and a hydrophobic core within the AOC2 trimer were identified and functionally proven by site-directed mutagenesis. The data obtained showed that AOC2 acts as a trimer. Finally, AOC activity was determined in heteromers formed by pairwise combinations of the four AOC isoforms. The highest activities were found for heteromers containing AOC4 + AOC1 and AOC4 + AOC2, respectively. All data are in line with an enzyme activity control of all four AOCs by heteromerization, thereby supporting a putative fine-tuning in JA formation by various regulatory principles.
Bücher und Buchkapitel

Dorka, R.; Miersch, O.; Hause, B.; Weik, P.; Wasternack, C.; Chronobiologische Phänomene und Jasmonatgehalt bei Viscum album L. 49-66, (2009)

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Bücher und Buchkapitel

Wasternack, C.; Hause, B.; Stenzel, I.; Goetz, S.; Feussner, I.; Miersch, O.; Jasmonate signaling in tomato – The input of tissue-specific occurrence of allene oxide cyclase and JA metabolites (Benning C., Ollrogge, J.). 107-111, (2007)

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Publikation

Gerhardt, B.; Fischer, K.; Balkenhohl, T. J.; Pohnert, G.; Kühn, H.; Wasternack, C.; Feussner, I.; Lipoxygenase-mediated metabolism of storage lipids in germinating sunflower cotyledons and β-oxidation of (9Z,11E,13S)-13-hydroxy-octadeca-9,11-dienoic acid by the cotyledonary glyoxysomes Planta 220, 919-930, (2005) DOI: 10.1007/s00425-004-1408-1

During the early stages of germination, a lipid-body lipoxygenase is expressed in the cotyledons of sunflowers (Helianthus annuus L.). In order to obtain evidence for the in vivo activity of this enzyme during germination, we analyzed the lipoxygenase-dependent metabolism of polyunsaturated fatty acids esterified in the storage lipids. For this purpose, lipid bodies were isolated from etiolated sunflower cotyledons at different stages of germination, and the storage triacylglycerols were analyzed for oxygenated derivatives. During the time course of germination the amount of oxygenated storage lipids was strongly augmented, and we detected triacylglycerols containing one, two or three residues of (9Z,11E,13S)-13-hydro(pero)xy-octadeca-9,11-dienoic acid. Glyoxysomes from etiolated sunflower cotyledons converted (9Z,11E,13S)-13-hydroxy-octadeca-9,11-dienoic acid to (9Z,11E)-13-oxo-octadeca-9,11-dienoic acid via an NADH-dependent dehydrogenase reaction. Both oxygenated fatty acid derivatives were activated to the corresponding CoA esters and subsequently metabolized to compounds of shorter chain length. Cofactor requirement and formation of acetyl-CoA indicate degradation via β-oxidation. However, β-oxidation only proceeded for two consecutive cycles, leading to accumulation of a medium-chain metabolite carrying an oxo group at C-9, equivalent to C-13 of the parent (9Z,11E,13S)-13-hydroxy-octadeca-9,11-dienoic acid. Short-chain β-oxidation intermediates were not detected during incubation. Similar results were obtained when 13-hydroxy octadecanoic acid was used as β-oxidation substrate. On the other hand, the degradation of (9Z,11E)-octadeca-9,11-dienoic acid was accompanied by the appearance of short-chain β-oxidation intermediates in the reaction mixture. The results suggest that the hydroxyl/oxo group at C-13 of lipoxygenase-derived fatty acids forms a barrier to continuous β-oxidation by glyoxysomes.
Bücher und Buchkapitel

Weichert, H.; Maucher, H.; Hornung, E.; Wasternack, C.; Feussner, I.; Shift in Fatty Acid and Oxylipin Pattern of Tomato Leaves Following Overexpression of the Allene Oxide Cyclase 275-278, (2003) DOI: 10.1007/978-94-017-0159-4_64

Polyunsaturated fatty acids (PUFAs) are a source of numerous oxidation products, the oxylipins. In leaves, α-linolenic acid (α-LeA) is the preferential substrate for lipid peroxidation reactions. This reaction may be catalyzed either by a 9-lipoxygenase (9-LOX) or by a 13-LOX and oxygen is inserted regioselectively as well as stereospecifically leading to formation of 13S- or 9S-hydroperoxy octadecatrienoic acid (13-/9-HPOT; Brash, 1999). At least, seven different enzyme families or reaction branches within the LOX pathway can use these HPOTs or other hydroperoxy PUFAs leading to (i) keto-PUFAs (LOX); (ii) epoxy hydroxy-PUFAs (epoxy alcohol synthase, EAS); (iii) octadecanoids and jasmonates (allene oxide synthase, AOS); (iv) leaf aldehydes and leaf alcohols (hydroperoxide lyase, HPL); (v) hydroxy PUFAs (reductase); (vi) divinyl ether PUFAs (divinyl ether synthase, DES); and (vii) epoxy- or dihydrodiol-PUFAs (peroxygenase, PDX; Fig. 1; Feussner and Wasternack, 2002).
Bücher und Buchkapitel

Stumpe, M.; Stenzel, I.; Weichert, H.; Hause, B.; Feussner, I.; The Lipoxygenase Pathway in Mycorrhizal Roots of Medicago Truncatula 287-290, (2003) DOI: 10.1007/978-94-017-0159-4_67

Mycorrhizas are by far the most frequent occurring beneficial symbiotic interactions between plants and fungi. Species in >80% of extant plant families are capable of establishing an arbuscular mycorrhiza (AM). In relation to the development of the symbiosis the first molecular modifications are those associated with plant defense responses, which seem to be locally suppressed to levels compatible with symbiotic interaction (Gianinazzi-Pearson, 1996). AM symbiosis can, however, reduce root disease caused by several soil-borne pathogens. The mechanisms underlying this protective effect are still not well understood. In plants, products of the enzyme lipoxygenase (LOX) and the corresponding downstream enzymes, collectively named LOX pathway (Fig. 1B), are involved in wound healing, pest resistance, and signaling, or they have antimicrobial and antifungal activity (Feussner and Wasternack, 2002). The central reaction in this pathway is catalyzed by LOXs leading to formation of either 9- or 13-hydroperoxy octadeca(di/trien)oic acids (9/13-HPO(D/T); Brash, 1999). Thus LOXs may be divided into 9- and 13-LOXs (Fig. 1A). Seven different reaction branches within this pathway can use these hydroperoxy polyenoic fatty acids (PUFAs) leading to (i) keto PUFAs by a LOX; (ii) epoxy hydroxy-fatty acids by an epoxy alcohol synthase (EAS); (iii) octadecanoids and jasmonates via allene oxide synthase (AOS); (iv) leaf aldehydes and leaf alcohols via fatty acid hydroperoxide lyase (HPL); (v) hydroxy PUFAs (reductase); (vi) divinyl ether PUFAs via divinyl ether synthase (DES); and (vii) epoxy- or dihydrodiolPUFAs via peroxygenase (PDX; Feussner and Wasternack, 2002). AOS, HPL and DES belong to one subfamily of P450-containing enzymes, the CYP74 family (Feussner and Wasternack, 2002). Here, the involvement of this CYP74 enzyme family in mycorrhizal roots of M. truncatula during early stages of AM symbiosis formation was analyzed.
Bücher und Buchkapitel

Stenzel, I.; Hause, B.; Feussner, I.; Wasternack, C.; Transcriptional Activation of Jasmonate Biosynthesis Enzymes is not Reflected at Protein Level 267-270, (2003) DOI: 10.1007/978-94-017-0159-4_62

Jasmonic acid (JA) and its precursor 12-oxo phytodienoic acid (OPDA) are lipid-derived signals in plant stress responses and development (Wasternack and Hause, 2002). Within the wound-response pathway of tomato, a local response of expression of defense genes such as the proteinase inhibitor 2 gene (PIN2) is preceded by a rise in JA (Herde et al., 1996; Howe et al., 1996) and ethylene (O’Donnell et al., 1996). Mutants affected in JA biosynthesis such as defl (Howe et al., 1996) or spr-2 (Li et al., 2002) clearly indicated that JA biosynthesis is an ultimate part of wound signaling. It is less understood, however, how the rise in JA is regulated.
Publikation

Chen, D. L.; Delatorre, C. A.; Bakker, A.; Abel, S.; Conditional identification of phosphate-starvation-response mutants in Arabidopsis thaliana Planta 211, 13-22, (2000) DOI: 10.1007/s004250000271

Plants have evolved elaborate metabolic and developmental adaptations to low phosphorus availability. Biochemical responses to phosphate limitation include increased production and secretion of phosphate-acquisition proteins such as nucleases, acid phosphatases, and high-affinity phosphate transporters. However, the signal transduction pathways that sense phosphate availability and integrate the phosphate-starvation response in plants are unknown. We have devised a screen for conditional mutants in Arabidopsis thaliana (L.) Heynh. to dissect signaling of phosphate limitation. Our genetic screen is based on the facultative ability of wild-type Arabidopsis plants to metabolize exogenous DNA when inorganic phosphate is limiting. After screening 50,000 M2 seedlings, we isolated 22 confirmed mutant lines that showed severely impaired growth on medium containing DNA as the only source of phosphorus, but which recovered on medium containing soluble inorganic phosphate. Characterization of nine such mutant lines demonstrated an inability to utilize either DNA or RNA. One mutant line, psr1 (phosphate starvation response), had significantly reduced activities of phosphate-starvation-inducible isoforms of ribonuclease and acid phosphatase under phosphate-limiting conditions. The data suggest that a subset of the selected mutations impairs the expression of more than one phosphate-starvation-inducible enzyme required for utilization of exogenous nucleic acids, and may thus affect regulatory components of a Pi starvation response pathway in higher plants.
Bücher und Buchkapitel

Feussner, I.; Balkenhohl, T. J.; Porzel, A.; Kühn, H.; Wasternack, C.; Structural Elucidation of Oxygenated Triacylglycerols in Cucumber and Sunflower Cotyledons 57-58, (1998)

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Publikation

Görschen, E.; Dunaeva, M.; Hause, B.; Reeh, I.; Wasternack, C.; Parthier, B.; Expression of the ribosome-inactivating protein JIP60 from barley in transgenic tobacco leads to an abnormal phenotype and alterations on the level of translation Planta 202, 470-478, (1997) DOI: 10.1007/s004250050151

In this paper we report the in-planta activity of the ribosome-inactivating protein JIP60, a 60-kDa jasmonate-induced protein from barley (Hordeum vulgare L.), in transgenic tobacco (Nicotiana tabacum L.) plants. All plants expressing the complete JIP60 cDNA under the control of the cauliflower mosaic virus (CaMV) 35S promoter exhibited conspicuous and similar phenotypic alterations, such as slower growth, shorter internodes, lanceolate leaves, reduced root development, and premature senescence of leaves. Microscopic inspection of developing leaves showed a loss of residual meristems and higher degree of vacuolation of mesophyll cells as compared to the wild type. When probed with an antiserum which was immunoreactive against both the N- and the C-terminal half of JIP60, a polypeptide with a molecular mass of about 30 kDa, most probably a processed JIP60 product, could be detected. Phenotypic alterations could be correlated with the differences in the detectable amount of the JIP60 mRNA and processed JIP60 protein. The protein biosynthesis of the transformants was characterized by an increased polysome/monosome ratio but a decreased in-vivo translation activity. These findings suggest that JIP60 perturbs the translation machinery in planta. An immunohistological analysis using the JIP60 antiserum indicated that the immunoreactive polypeptide(s) are located mainly in the nucleus of transgenic tobacco leaf cells and to a minor extent in the cytoplasm.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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