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Publikationen - Molekulare Signalverarbeitung

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Publikation

Schneider, K.; Kienow, L.; Schmelzer, E.; Colby, T.; Bartsch, M.; Miersch, O.; Wasternack, C.; Kombrink, E.; Stuible, H.-P. A new type of peroxisomal acyl-coenzyme A synthetase from <EM>Arabidopsis thaliana</EM> has the catalytic capacity of activate biosynthetic precursors of jasmonic acid J. Biol. Chem. 280, 13962-13972, (2005)

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Publikation

Wasternack, C. Jasmonates - Introductory remarks on biosynthesis and diversity in action J. Plant Growth Reg. 23, 167-169, (2004)

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Publikation

Gidda, K.S.; Miersch, O.; Schmidt, J.; Wasternack, C.; Varin, L. Biochemical and molecular characterization of a hydroxy-jasmonate sulfotransferase from Arabidopsis thaliana J. Biol. Chem. 278, 17895-17900, (2003) DOI: 10.1074/jbc.M211943200

12-Hydroxyjasmonate, also known as tuberonic acid, was first isolated from Solanum tuberosum and was shown to have tuber-inducing properties. It is derived from the ubiquitously occurring jasmonic acid, an important signaling molecule mediating diverse developmental processes and plant defense responses. We report here that the gene AtST2a from Arabidopsis thaliana encodes a hydroxyjasmonate sulfotransferase. The recombinant AtST2a protein was found to exhibit strict specificity for 11- and 12-hydroxyjasmonate with Km values of 50 and 10 µM, respectively. Furthermore, 12-hydroxyjasmonate and its sulfonated derivative are shown to be naturally occurring in A. thaliana. The exogenous application of methyljasmonate to A. thaliana plants led to increased levels of both metabolites, whereas treatment with 12-hydroxyjasmonate led to increased level of 12-hydroxyjasmonate sulfate without affecting the endogenous level of jasmonic acid. AtST2a expression was found to be induced following treatment with methyljasmonate and 12-hydroxyjasmonate. In contrast, the expression of the methyljasmonate-responsive gene Thi2.1, a marker gene in plant defense responses, is not induced upon treatment with 12-hydroxyjasmonate indicating the existence of independent signaling pathways responding to jasmonic acid and 12-hydroxyjasmonic acid. Taken together, the results suggest that the hydroxylation and sulfonation reactions might be components of a pathway that inactivates excess jasmonic acid in plants. Alternatively, the function of AtST2a might be to control the biological activity of 12-hydroxyjasmonic acid.
Publikation

Schilling, S.; Niestroj, A.J.; Rahfeld, J.-U.; Hoffmann, T.; Wermann, M.; Zunkel, K.; Wasternack, C.; Demuth, H.-U. Identification of human glutaminyl cyclase as a metalloenzyme - Potent inhibition by imidazole derivatives and heterocyclic chelators J. Biol. Chem. 278, 49773-49779, (2003)

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Publikation

Ziegler, J.; Stenzel, I.; Hause, B.; Maucher, H.; Miersch, O.; Hamberg, M.; Grimm, M.; Ganal, M.; Wasternack, C. Molecular cloning of allene oxide cyclase: The enzyme establishing the stereochemistry of octadecanoids and jasmonates J. Biol. Chem. 275, 19132-19138, (2000) DOI: 10.1074/jbc.M002133200

Allene oxide cyclase (AOC) catalyses the stereospecific cyclisation of an unstable allene oxide to 9(S),13(S)-12-oxo-10,15(Z)-phytodienoic acid, the ultimate precursor of jasmonic acid. This enzyme has previously been purified, and two identical N-terminal peptides were found suggesting AOC to be a homodimeric protein. Furthermore, the native protein was N-terminal processed. Using degenerate primers, a PCR fragment could be generated from tomato, which was further used to isolate a full length cDNA clone of 1kb coding for a protein with 245 amino acids with a molecular mass of 26 kDa. Whereas expression of the whole coding region failed to detect AOC activity, a 5-'truncated protein showed high activity, suggesting that additional amino acids impair the enzymatic function. Steric analysis of the 12-oxo-phytodienoic acid formed by the recombinant AOC revealed exclusive (>99%) formation of the 9(S),13(S) enantiomer. Exclusive formation of this enantiomer was also found in wounded tomato leaves. Southern analysis and genetic mapping revealed the existence of a single gene for AOC located on chromosome 2 of tomato. Inspection of the N-terminus revealed the presence of a chloroplastic transit peptide, and the location of AOC protein in that compartment could be shown by immunohistochemical methods. Concomitant with the jasmonate levels, the accumulation of AOC mRNA was transiently induced after wounding of tomato leaves.
Publikation

Feussner, I.; Balkenhohl, T.J.; Porzel, A.; Kühn, H.; Wasternack, C. Structural elucidation of oxygenated storage lipids in cucumber cotyledons. Implication of lipid body lipoxygenase in lipid mobilization during germination J. Biol. Chem. 272, 21635-21641, (1997)

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