Crystal Structure of a Mycoestrogen-Detoxifying Lactonase from Rhinocladiella mackenziei: Molecular Insight into ZHD Substrate Selectivity

Development of potent biocatalysts for enzymatic detoxification of estrogenic mycotoxin zearalenone (ZEN) and its more toxic derivative α-zearalenol (α-ZOL) is of great interest. Here, we report the crystal structures of a ZEN-hydrolyzing enzyme from Rhinocladiella mackenziei (RmZHD), including substrate complexes. A molecular mechanism for the distinct activity of RmZHD in hydrolyzing the structurally similar ZEN and α-ZOL is then proposed. In addition, structure-based engineering to modify the substrate-binding pocket and improve the RmZHD activity toward α-ZOL is presented. These results expand our scope in understanding the catalytic mechanism of ZHD-family enzymes and are of vital importance in further industrial applications.