Functional characterization of steroid hydroxylase CYP106A1 derived from Bacillus megaterium

In this study, we examined the catalytic activity of CYP106A1 from the Bacillus megaterium American Type Culture Collection 14581 strain. The CYP106A1 gene was cloned from B. megaterium, heterologously expressed in Escherichia coli, and purified. Potential electron partners and possible bacterial CYP106A1 substrates were identified by examining the oxidative activity toward a set of steroids in the presence of several reductase systems. The activities of CYP106A1 in a reconstituted system could not be achieved using rat NADPH-P450 reductase or a putidaredoxin reductase–putidaredoxin pair. However, the spinach redox proteins, a ferredoxin reductase–ferredoxin pair, were found to be efficient redox partners for CYP106A1. CYP106A1 catalyzes the hydroxylation of a set of steroids including testosterone, progesterone, 17α-hydroxyprogesterone, 11-deoxycorticosterone, corticosterone, and 11-deoxycortisol to produce monohydroxylated products as the major metabolites. These results suggest that CYP106A1 would be useful for the bioconversion of steroid hormones to hydroxylated products that can be used for industrial applications.