12-Oxophytodienoate reductase 3 (OPR3) is the isoenzyme involved in jasmonate biosynthesis.
In addition to OPR1 and OPR2, two isoenzymes of 12-oxophytodienoate reductase, a third isoform (OPR3) has recently been identified in Arabidopsis thaliana (L.) Heynh. The expression of the OPR3 gene is induced not only by a variety of stimuli, such as touch, wind, wounding, UV-light and application of detergent, but also by brassinosteroids. The three enzymes were expressed in a functional form in Escherichia coli, and OPR2 was additionally expressed in insect cell cultures and overexpressed in A. thaliana. Substrate conversion was analyzed using a stereospecific assay. The results show that OPR3 effectively converts the natural (9S,13S)-12-oxophytodienoic acid [Km = 35 microM, Vmax 53.7 nkat (mg protein)-1] to the corresponding 3-2(2'(Z)-pentenyl) cyclopentane-1-octanoic acid (OPC-8:0) stereoisomer while OPR1 and OPR2 convert (9S,13S)-12-oxophytodienoic acid with greatly reduced efficiency compared to OPR3. Thus, OPR3 is the isoenzyme relevant for jasmonate biosynthesis.
Schaller
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Lehrstuhl für Pflanzenphysiologie, Ruhr-Universität, Bochum, Germany.
Biesgen
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Müssig
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Altmann
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Weiler
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D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism*; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D054883:Oxylipins; D010937:Plant Growth Regulators / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D003517:Cyclopentanes; D007527:Isoenzymes; D054883:Oxylipins; D010937:Plant Growth Regulators; C011006:jasmonic acid; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C106360:12-oxophytodienoate reductase