Kienow, Lucie , Schneider, Katja , Bartsch, Michael , Miersch, Otto , Wasternack, Claus , Kombrink, Erich .
Functional analysis of a peroxisomal acyl-CoA synthetase protein family from Arabidopsis thaliana uncovers enzymes participating in jasmonic acid biosynthesis.
Arabidopsis thaliana contains a large number of genes that encode carboxylic acid-activating enzymes, including nine long-chain fatty acyl-CoA synthetases (LACS), four 4-coumarate:CoA ligases (4CL), and twenty-five 4CL-like proteins of unknown biochemical function. We systematically explored the function of these proteins by applying an extensive substrate screen to recombinant and affinity purified proteins. This analysis uncovered that activation of fatty acids of variable chain length is the common feature of all active members of this protein family, thereby defining a new group of fatty acyl-CoA synthetase, which is distinct from the known LACS family. Significantly, four family members also displayed high activity towards different biosynthetic precursors of jasmonic acid (JA), including 12-oxo-phytodienoic acid (OPDA), dinor-OPDA, 3-oxo-2(2’-[Z]-pentenyl)cyclopentane-1-octanoic acid (OPC-8), OPC-6 and OPC-4. The activation of these compounds to the corresponding CoA esters is a prerequisite for their conversion to JA by three rounds of beta-oxidation. Detailed analysis of in vitro properties uncovered significant differences in substrate specificity for individual enzymes. Thereby a specific OPC-8:CoA ligase was identified, which represents a missing link of JA biosynthesis. The in vivo function of OPC-8:CoA ligase was analyzed by transcript and jasmonate profiling of an Arabidopsis insertion mutant for the gene in comparison to wild-type plants. In addition, we established that OPC-8:CoA ligase is localized in peroxisomes and monitored the developmental, tissue-, and cell-type specific expression pattern and regulatory properties of the gene by analyzing promoter::GUS reporter lines. Collectively, the results demonstrate that OPC-8:CoA ligase catalyzes an essential step in JA biosynthesis by initiating the beta-oxidative chain shortening of its precursors.
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1 - Max Planck Institute for Plant Breeding Research, Department of Plant-Microbe Interactions
2 - Leibniz Institute of Plant Biochemistry, Department of Natural Product Biotechnology
3 - Max Planck Institute for Plant Breeding Research, Department of Plant-Microbe Interactions, Carl-von-Linné-Weg 10, Cologne, 50829, Germany
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM