Advances toward mapping the full extent of protein site-specific O-GalNAc glycosylation that better reflects underlying glycomic complexity

• Published in: Current opinion in structural biology 2019-06, Vol.56, p.146-154
• Main Author: Khoo, Kay-Hooi
• Format: Article
• Language: English
• ISSN: 0959-440X; 1879-033X
• DOI: 10.1016/j.sbi.2019.02.007

[Display omitted] •Site-specific O-GalNAc glycosylation of Ser/Thr rich domain still defies high sensitivity and precision mass spectrometry-based analysis.•Specific endoprotease cleavages directed at O-GalNAc glycosylated sites facilitate definitive O-glycoproteomic mapping.•Glycomic analysis of released O-GalNAc glycans is needed to determine the full extent of complexity and to better delineate isomeric structures. Recent advances in mass spectrometry has empowered unbiased global analysis of site-specific O-GalNAc glycosylation. Despite thousands of sites being identified, significant technical hurdles remain, particularly in the delineation of fully extended, larger O-GalNAc glycans on heavily O-glycosylated mucin domain. Current approaches require simplification of the O-GalNAc glycans either by genetic means or glycosidase treatments to allow unambiguous sequencing of the derived O-glycopeptides. In contrast, a full mapping of the O-GalNAc glycomic complexity still necessitates a detailed analysis of the released glycans. Chromatographic resolution and multistage fragmentation coupled with judicious choice of chemical derivatization are key to increase the analytical precision and glycomic coverage depth, which should be duly considered along with attainable sensitivity and throughput for meaningful glycobiology applications.