Inhibition of Mucin-Type O-Glycosylation through Metabolic Processing and Incorporation of N-Thioglycolyl-d-galactosamine Peracetate (Ac5GalNTGc)

Mucin-type O-glycans form one of the most abundant and complex post-translational modifications (PTM) on cell surface proteins that govern adhesion, migration, and trafficking of hematopoietic cells. Development of targeted approaches to probe functions of O-glycans is at an early stage. Among several approaches, small molecules with unique chemical functional groups that could modulate glycan biosynthesis form a critical tool. Herein, we show that metabolism of peracetyl N-acyl-d-galactosamine derivatives carrying an N-thioglycolyl (Ac5GalNTGc, 1) moiety—but not N-glycolyl (Ac5GalNGc, 2) and N-acetyl (Ac4GalNAc, 3)—through the N-acetyl-d-galactosamine (GalNAc) salvage pathway induced abrogation of MAL-II and PNA epitopes in Jurkat cells. Mass spectrometry of permethylated O-glycans from Jurkat cells confirmed the presence of significant amounts of elaborated O-glycans (sialyl-T and disialyl-T) which were inhibited upon treatment with 1. O-Glycosylation of CD43, a cell surface antigen rich in O-glycans, w...