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Publikationen - Molekulare Signalverarbeitung

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Publikation

Feussner, I.; Wasternack, C. Lipoxygenase catalyzed oxygenation of lipids Fett/Lipid 100, 146-152, (1998)

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Publikation

Miersch, O.; Wasternack, C. Octadecanoid and jasmonate signaling in tomato leaves (<EM>Lycopersicon esculentum</EM> Mill.): Endogenous jasmonates do not induce jasmonate biosynthesis Biol. Chem. 381, 715-722, (2000)

Jasmonates and their precursors, the octadecanoids, are signals in stress-induced alteration of gene expression. Several mRNAs coding for enzymes of jasmonic acid (JA) biosynthesis are up-regulated upon JA treatment or endogenous rise of JA level. Here we inspected the positive feed back of endogenous JA on JA formation as well as its beta-oxidation steps. JA responsive gene expression was recorded in terms of proteinase inhibitor2 (pin2) mRNA accumulation. JA formed upon treatment of tomato (Lycopersicon esculentum cv. Moneymaker) leaves with JA derivatives carrying different length of the carboxylic acid side chain was quantified by gas chromatography-mass spectrometry (GC-MS). The data reveal that beta-oxidation of the side chain occurs up to a butyric acid moiety. The amount of JA formed from side-chain modified JA derivatives, correlated with pin2-mRNA accumulation. JA derivatives with a carboxylic side chain of 3, 5 or 7 carbon atoms were unable to form JA and to express on pin2, whereas even numbered derivatives were active. After treatment of tomato leaves with (10-2H)-(-)-12-oxophytoenoic acid, (4-2H)-(-)-JA and its methyl ester were formed and could be quantified separately from the endogenously unlabeled JA pool by GC-MS analysis via isotopic discrimination. The level of 8 nmol per g f.w. JA and its methyl ester originated exclusively from labeled 12-oxophytoenic acid. This and further data indicate that endogenous synthesis of the JA precursor 12-oxophytodienoic acid as well as of JA and its methyl ester are not induced in tomato leaves, suggesting that positive feedback in JA biosynthesis does not function in vivo.
Publikation

Schilling, S.; Manhart, S.; Hoffmann, T.; Ludwig, H.-H.; Wasternack, C.; Demuth, H.-U. Substrate specificity of glutaminyl cyclases from plants and animals Biol. Chem. 384, 1583-1592, (2003)

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Publikation

Abel, S.; Savchenko, T.; Levy, M. Genome-wide comparative analysis of the <em>IQD</em> gene families in <em>Arabidopsis thaliana</em> and Oryza sativa BMC Evolutionary Biology 5, 72 (1-25), (2005)

We identified and analyzed 33 and 29 IQD1-like genes in Arabidopsis thaliana and Oryza sativa, respectively. The encoded IQD proteins contain a plant-specific domain of 67 conserved amino acid residues, referred to as the IQ67 domain, which is characterized by a unique and repetitive arrangement of three different calmodulin recruitment motifs, known as the IQ, 1-5-10, and 1-8-14 motifs. We demonstrated calmodulin binding for IQD20, the smallest IQD protein in Arabidopsis, which consists of a C-terminal IQ67 domain and a short N-terminal extension. A striking feature of IQD proteins is the high isoelectric point (~10.3) and frequency of serine residues (~11%). We compared the Arabidopsis and rice IQD gene families in terms of gene structure, chromosome location, predicted protein properties and motifs, phylogenetic relationships, and evolutionary history. The existence of an IQD-like gene in bryophytes suggests that IQD proteins are an ancient family of calmodulin-binding proteins and arose during the early evolution of land plants. Comparative phylogenetic analyses indicate that the major IQD gene lineages originated before the monocot-eudicot divergence. The extant IQD loci in Arabidopsis primarily resulted from segmental duplication and reflect preferential retention of paralogous genes, which is characteristic for proteins with regulatory functions. Interaction of IQD1 and IQD20 with calmodulin and the presence of predicted calmodulin binding sites in all IQD family members suggest that IQD proteins are a new class of calmodulin targets. The basic isoelectric point of IQD proteins and their frequently predicted nuclear localization suggest that IQD proteins link calcium signaling pathways to the regulation of gene expression. Our comparative genomics analysis of IQD genes and encoded proteins in two model plant species provides the first step towards the functional dissection of this emerging family of putative calmodulin targets.
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