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Publikationen - Molekulare Signalverarbeitung

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Publikation

Wasternack, C.; Hause, B.; OPDA-Ile – a new JA-Ile-independent signal? Plant Signal Behav. 11, e1253646, (2016) DOI: 10.1080/15592324.2016.1253646

Expression takes place for most of the jasmonic acid (JA)-induced genes in a COI1-dependent manner via perception of its conjugate JA-Ile in the SCFCOI1-JAZ co-receptor complex. There are, however, numerous genes and processes, which are preferentially induced COI1-independently by the precursor of JA, 12-oxo-phytodienoic acid (OPDA). After recent identification of the Ile-conjugate of OPDA, OPDA-Ile, biological activity of this compound could be unequivocally proven in terms of gene expression. Any interference of OPDA, JA, or JA-Ile in OPDA-Ile-induced gene expression could be excluded by using different genetic background. The data suggest individual signaling properties of OPDA-Ile. Future studies for analysis of an SCFCOI1-JAZ co-receptor-independent route of signaling are proposed.
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.
Publikation

Wasternack, C.; Goetz, S.; Hellwege, A.; Forner, S.; Strnad, M.; Hause, B.; Another JA/COI1-independent role of OPDA detected in tomato embryo development Plant Signal Behav. 7, 1349-1353, (2012) DOI: 10.4161/psb.21551

Jasmonates (JAs) are ubiquitously occurring signaling compounds in plants formed in response to biotic and abiotic stress as well as in development. (+)-7-iso-jasmonoyl isoleucine, the bioactive JA, is involved in most JA-dependent processes mediated by the F-box protein COI1 in a proteasome-dependent manner. However, there is an increasing number of examples, where the precursor of JA biosynthesis, cis-(+)-12-oxophytodienoic acid (OPDA) is active in a JA/COI1-independent manner. Here, we discuss those OPDA-dependent processes, thereby giving emphasis on tomato embryo development. Recent data on seed coat-generated OPDA and its role in embryo development is discussed based on biochemical and genetic evidences.
Publikation

Bachmann, A.; Hause, B.; Maucher, H.; Garbe, E.; Vörös, K.; Weichert, H.; Wasternack, C.; Feussner, I.; Jasmonate-Induced Lipid Peroxidation in Barley Leaves Initiated by Distinct 13-LOX Forms of Chloroplasts Biol. Chem. 383, 1645-1657, (2002) DOI: 10.1515/BC.2002.185

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.
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.
Publikation

Feussner, I.; Hause, B.; Nellen, A.; Wasternack, C.; Kindl, H.; Lipid-body lipoxygenase is expressed in cotyledons during germination prior to other lipoxygenase forms Planta 198, 288-293, (1996) DOI: 10.1007/BF00206255

Lipid bodies are degraded during germination. Whereas some proteins, e.g. oleosins, are synthesized during the formation of lipid bodies of maturating seeds, a new set of proteins, including a specific form of lipoxygenase (LOX; EC 1.13.11.12), is detectable in lipid bodies during the stage of fat degradation in seed germination. In cotyledons of cucumber (Cucumis sativus L.) seedlings at day 4 of germination, the most conspicuous staining with anti-LOX antibodies was observed in the cytosol. At very early stages of germination, however, the LOX form present in large amounts and synthesized preferentially was the lipid-body LOX. This was demonstrated by immunocytochemical staining of cotyledons from 1-h and 24-h-old seedlings: the immunodecoration of sections of 24-h-old seedlings with anti-LOX antiserum showed label exclusively correlated with lipid bodies of around 3 μm in diameter. In accordance, the profile of LOX protein isolated from lipid bodies during various stages of germination showed a maximum at day 1. By measuring biosynthesis of the protein in vivo we demonstrated that the highest rates of synthesis of lipid-body LOX occurred at day 1 of germination. The early and selective appearance of a LOX form associated with lipid bodies at this stage of development is discussed.
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