Fluorescent glycan fingerprinting of SARS2 spike proteins

• Published in: Scientific reports 2021-10, Vol.11 (1), p.20428-20428, Article 20428
• Main Authors: Wu, Zhengliang L., Ertelt, James M.
• Format: Article
• Language: English
• Subjects: 631/45/221; 631/45/72/1202; Carbocyanines - chemistry; Coronaviruses; COVID-19; COVID-19 - virology; Economic impact; Electrophoresis; Electrophoresis, Polyacrylamide Gel; Electrophoretic mobility; Fluorescent Dyes - chemistry; Fucose - analogs & derivatives; Gel electrophoresis; Glycoproteins; Glycosylation; Humanities and Social Sciences; Humans; multidisciplinary; N-Acetylneuraminic Acid - analogs & derivatives; Optical Imaging; Pandemics; Peptide mapping; Peptides; Polysaccharides; Polysaccharides - analysis; Post-translation; Proteins; SARS-CoV-2 - chemistry; Science; Science (multidisciplinary); Severe acute respiratory syndrome coronavirus 2; Sodium lauryl sulfate; Spike Glycoprotein, Coronavirus - chemistry; Trypsin
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-98919-4

Glycosylation is the most common post-translational modification and has myriad of biological functions. However, glycan analysis has always been a challenge. Here, we would like to present new techniques for glycan fingerprinting based on enzymatic fluorescent labeling and gel electrophoresis. The method is illustrated on SARS2 spike (S) glycoproteins. SARS2, a novel coronavirus and the causative agent of the COVID-19 pandemic, has had significant social and economic impacts since the end of 2019. To obtain the N-glycan fingerprint of an S protein, glycans released from the protein are first labeled through enzymatic incorporation of fluorophore-conjugated sialic acid or fucose, then separated by SDS-PAGE, and finally visualized with a fluorescent imager. To identify the labeled glycans of a fingerprint, glycan standards and glycan ladders are enzymatically generated and run alongside the samples as references. By comparing the mobility of a labeled glycan to that of a glycan standard, the identity of glycans maybe determined. O-glycans can also be fingerprinted. Due to the lack of an enzyme for broad O-glycan release, O-glycans on the S protein can be labeled with fluorescent sialic acid and digested with trypsin to obtain labeled glycan peptides that are then separated by gel electrophoresis. Glycan fingerprinting could serve as a quick method for globally assessing the glycosylation of a specific glycoprotein.