A substrate-binding-state mimic of H2O2-dependent cytochrome P450 produced by one-point mutagenesis and peroxygenation of non-native substrates

Abstract

A substrate-binding-state mimic of H₂O₂-dependent cytochrome P450 that is able to catalyze monooxygenation of non-native substrates was constructed by one-point mutagenesis of P450_SPα (CYP152B1). P450_SPα, a long-alkyl-chain fatty acid hydroxylase, lacks any general acid–base residue around the heme. The carboxylate group of a fatty acid is thus indispensable for the generation of active species using H₂O₂. We prepared an A245E mutant to mimic a substrate-binding state by placing a carboxylate group at the active site. The active site structure of the A245E mutant is similar to that of the fatty-acid-bound state of P450_SPα and catalyzes styrene oxidation at a rate of 280 min⁻¹ (k_cat), whereas the wild-type enzyme does not show any catalytic activity. More importantly, the same mutation, i.e. the mutation of the highly conserved threonine in P450s to glutamic acid, was also effective in introducing peroxygenase activity into P450BM3, P450_cam, and CYP119. These results indicate that a variety of peroxygenases based on P450s can be constructed by one-point mutagenesis.