Functional Expression and Construction of a Self‐Sufficient Cytochrome P450 Chimera for Efficient Steroidal C14α Hydroxylation in Escherichia coli

C14-functionalized steroids enabled diverse biological activities in anti-gonadotropin and anticancer therapy. However, access to C14-functionalized steroids was impeded by the deficiency of chemical synthetic methods. Recently, several membrane-bound fungal cytochrome P450s (CYPs) have been identified with steroid C14α-hydroxylation activity. However, the lack of efficient heterologous overexpression strategy hampered their further characterization and molecular engineering. In the present study, sequences of fungi-derived CYP genes encoding putative 14α-hydroxylase were selected and bioinformatically analyzed. Substitution of the N-terminal hydrophobic helix by a soluble maltose binding protein tag significantly enhanced the soluble expression level in Escherichia coli. A novel CYP originated from Bipolaris oryzae was discovered with high steroidal C14α-hydroxylation activity when coupled with the redox partner CPR