Metabolism of phenolic compounds catalyzed by Tomato CYP736A61

Abstract

Cytochrome P450s (CYPs) regulate plant growth and stress responses by producing diverse primary and secondary metabolites. However, the function of many plant CYPs remains unknown because, despite their structural similarity, predicting the enzymatic activity of CYPs is difficult. In this study, one member of the CYP736A subfamily (CYP736A61) from tomatoes was isolated and characterized its enzymatic functions. CYP736A61 was successfully expressed in Escherichia coli through co-expression with molecular chaperones. The purified CYP736A61 showed hydroxylation activity toward 7-ethoxycoumarin, producing 7-hydroxycoumarin or 3-hydroxy 7-ethoxycoumarin. Further substrate screening revealed that dihydrochalcone and stilbene derivates (resveratrol and polydatin) are the substrates of CYP736A61. CYP736A61 also mediated the hydroxylation of resveratrol and polydatin, albeit with low activity. Importantly, CYP736A61 mediated the cleavage of resveratrol and polydatin as well as pinostilbene and pterostilbene. Interestingly, CY736A61 also converted phloretin to naringenin chalcone. These results suggest that CYP736A61 is a novel CYP enzyme with stilbene cleavage activity.

Keywords: CYP736A; Cytochrome P450; plant; stilbene; tomato.