Biosynthetic Mechanisms of a Unique Ribitol Phosphate-containing Glycan by FKRP, a Ribitol Phosphate Transferase

Abstract

We recently revealed that the muscular dystrophy-related O-mannosyl glycan of α-dystroglycan contains a tandem structure consisting of ribitol phosphate, a newly identified glycan constituent in mammals. This unique structure is formed by the ribitol phosphate transferases FKTN and FKRP. However, the synthetic mechanisms, in particular, the substrate recognition mechanism and catalytic machinery of these enzymes, are unknown. This review article initially outlines the synthetic mechanisms of O-mannosyl glycan of α-dystroglycan, illustrates the results of our recent structure-function analysis of FKRP, and finally introduces the latest findings regarding the mechanisms by which a ribitol phosphate is transferred to the glycan.