Old Yellow Enzyme from Brevibacillus nitrificans functions as 12- oxo -phytodienoic acid reductase in planta

Old Yellow Enzymes (OYEs) are a widely distributed family of ene -reductases that were first described in a Saccharomyces cerevisiae ferment. In plants, cis -12- oxo -phytodienoic acid ( cis -OPDA) reductase (OPR) is the best studied OYE. In Arabidopsis thaliana , the peroxisomal AtOPR3 was characterized as the major OPDA reductase, which generates 3- oxo -2-(2-pentenyl)-cyclopentane-1-octanoic acid in the jasmonic acid (JA) biosynthesis. In Atopr3 lines, only small amounts of JA are detectable after wounding. Here, we describe an OPR-like enzyme (named BnOPR) from the gram-positive Brevibacillus nitrificans . The sequence was identified in an early version of the Physcomitrium patens genome and is assumed to be a contamination by a bacterium growing in association with P. patens . In complementation experiments with an Atopr3 line, we demonstrate that expression of BnOPR, fused with a peroxisomal targeting signal, rescues the male infertile phenotype and increases JA and JA-Ile levels. The catalytic parameters of BnOPR were determined for a set of substrates, including cis -OPDA and prednisone. Interestingly, B. nitrificans, B. brevis , and Paenibacillus physcomitrellae were shown to have a positive effect on P. patens growth.