In this study, a new cytochrome P450 enzyme, namely, CYP68J5_Fusarium graminearum (CYP68J5_fg), was identified from Fusarium graminearum via a combination of transcriptome sequencing and heterologous expression in Saccharomyces cerevisiae. The biotransformation of progesterone by whole-cells of S. cerevisiae expressing CYP68J5_fg revealed that the CYP68J5_fg possessed steroidal 12β- and 15α-hydroxylase activities. To the best of our knowledge, this is the first time that a fungal P450 enzyme with 12β-hydroxylase activity has been identified. This advance offers opportunities to boost the efficiency and selectivity of the CYP68J5_fg hydroxylating system and thus shows great potential for further applications of this enzyme for the synthesis of steroid drugs. IMPORTANCE Regioselective and stereoselective hydroxylation is of vital importance in the functionalization of steroids, which remains challenging in organic synthesis. In particular, the C12-hydroxy steroids play a significant role in the synthesis of many important steroidal drugs. In this study, a novel fungal P450 enzyme with 12β-hydroxylation activity was identified, and it shows different substrate specificity and regioselectivity, compared to the bacterial and fungal steroidal hydroxylases that are known to date. This lays the foundation for the creation of effective biocatalysts for the process of 12β-hydroxylation, although further understanding of the molecular structural basis of this fungal P450 is needed to facilitate the engineering of this enzyme for industrial applications.
Keywords: 12β-hydroxylase; cytochrome P450; steroid hydroxylation.