Cloning and identification of a novel steroid 11α-hydroxylase gene from Absidia coerulea

Steroid 11-hydroxylation by filamentous fungi is a major route for industrial scale production of key intermediates in the synthesis of steroid drugs. Although it is well established that enzymes involved in fungal hydroxylation of steroids are cytochrome P450s (CYP), few fungal steroid hydroxylase genes have been identified. In this study, we identified a novel 11α-hydroxylase gene CYP5311B1 from Absidia coerulea AS3.65 by a combination of transcriptome sequencing, real-time qRT-PCR and heterologous expression in Pichia pastoris. The full-length open reading frame (ORF) of CYP5311B1 is predicted to encode a CYP protein of 527 amino acids whose expression in Pichia cells was confirmed by western blot. In addition, the major hydroxylation product was characterized by HPLC and 2D NMR. CYP5311B1 was highly induced by steroid substrate at the transcriptional level. The cloning and identification of an 11α-hydroxylase gene from A. coerulea should aid in a better understanding of the structural basis underlying regio- and stereoselectivity, and substrate specificity of fungal steroid 11α-hydroxylases, thus facilitating the engineering of more efficient steroid hydroxylases for industrial applications.