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.[1]References
- 12-Oxophytodienoate reductase 3 (OPR3) is the isoenzyme involved in jasmonate biosynthesis. Schaller, F., Biesgen, C., Müssig, C., Altmann, T., Weiler, E.W. Planta (2000) [Pubmed]
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