Identification of CYP106A2 as a Regioselective Allylic Bacterial Diterpene Hydroxylase

The cytochrome P450 monooxygenase CYP106A2 from Bacillus megaterium ATCC 13368 catalyzes hydroxylations of a variety of 3-oxo-Δ ⁴-steroids such as progesterone and deoxycorticosterone (DOC), mainly in the 15β-position. We combined a high-throughput screening and a rational approach for identifying new substrates of CYP106A2. The diterpene resin acid abietic acid was found to be a substrate and was docked into the active site of a CYP106A2 homology model to provide further inside into the structural basis of the regioselectivity of hydroxylation. The products of the hydroxylation reaction were analyzed by HPLC and the V _max and K _m values were calculated. The corresponding reaction products were analyzed by NMR spectroscopy and identified as 12α- and 12β-hydroxyabietic acid. CYP106A2 was therefore identified as the first reported bacterial cytochrome P450 diterpene hydroxylase. Furthermore, an effective whole-cell catalyst for the selective allylic 12α- and 12β-hydroxylation was applied to produce the hydroxylated products. Bacterial allylic hydroxylation: CYP106A2 has been identified as the first reported bacterial cytochrome P450 diterpene hydroxylase. It is able to carry out a one-step regioselective allylic hydroxylation of the diterpene abietic acid. An effective whole-cell catalyst for the selective allylic 12α- and 12β-hydroxylation was developed.