FlavonoidC‐Glycosyltransferases: Function, Evolutionary Relationship, Catalytic Mechanism and Protein Engineering

Abstract C ‐glycosylflavonoids are polyphenolic phytochemicals that are ubiquitously distributed in the plant kingdom and confer a wealth of health‐promoting benefits to human body. These compounds harbor one or more sugar moieties that are attached to various regions of the flavonoid scaffold through rigid C–C glycosidic bonds. The diverse structures of C ‐glycosylflavonoids are granted by the prominent reactions of flavonoid C ‐glycosyltransferases (CGTs). This review gives an extensive overview of CGTs that are involved in the biosynthesis of C ‐glycosylflavonoids, focusing on their evolutionary relationship and substrate specificity. Furthermore, structural insights into the catalytic mechanism and protein engineering of flavonoid CGTs are summarized. This review provides an important guidance for identification of novel flavonoid CGTs, biosynthesis of C ‐glycosylflavonoids, and elucidation of the function‐structure relationship of flavonoid CGTs.