Substrate promiscuity catalyzed by an O-glycosyltransferase MrOGT2 from Metarhizium robertsii

Glycosides tremendously extend the wide spectrum of biological activities of flavonoids and phenolics, which are catalysed by the glycosyltransferases (GTs) in diverse plants, bacteria, and fungi. However, the glycosyltransferases identified from fungi are still limited. Herein, one novel O-glycosyltransferase of MrOGT2 from the entomopathogenic fungus Metarhizium robertsii was presented. MrOGT2 exhibited typical substrate promiscuity characteristics towards four uridine diphosphate (UDP) sugar donors and 17 sugar receptors including flavonols, flavanones, flavones, isoflavones, and phenolics five types of compounds. Molecular docking and site-directed mutagenesis revealed the key substrate binding sites in the binding pocket and possible conservative catalytic mechanism of the O-glycosyltransferase MrOGT2. Our research provides an advance in the knowledge of glycosyltransferase in fungi and contributes the application potential for the efficient biocatalyst of O-glycosylation to both agricultural and pharmaceutical industries.