High-resolution crystal structures and STD NMR mapping of human ABO(H) blood group glycosyltransferases in complex with trisaccharide reaction products suggest a molecular basis for product release.Gagnon, S.M.L., Legg, M.S.G., Sindhuwinata, N., Letts, J.A., Johal, A.R., Schuman, B., Borisova, S.N., Palcic, M.M., Peters, T., Evans, S.V.
(2017) Glycobiology 27: 966-977
- PubMed: 28575295
- DOI: 10.1093/glycob/cwx053
- Primary Citation of Related Structures:
- PubMed Abstract:
The human ABO(H) blood group A- and B-synthesizing glycosyltransferases GTA and GTB have been structurally characterized to high resolution in complex with their respective trisaccharide antigen products. These findings are particularly timely and re ...
The human ABO(H) blood group A- and B-synthesizing glycosyltransferases GTA and GTB have been structurally characterized to high resolution in complex with their respective trisaccharide antigen products. These findings are particularly timely and relevant given the dearth of glycosyltransferase structures collected in complex with their saccharide reaction products. GTA and GTB utilize the same acceptor substrates, oligosaccharides terminating with α-l-Fucp-(1→2)-β-d-Galp-OR (where R is a glycolipid or glycoprotein), but use distinct UDP donor sugars, UDP-N-acetylgalactosamine and UDP-galactose, to generate the blood group A (α-l-Fucp-(1→2)[α-d-GalNAcp-(1→3)]-β-d-Galp-OR) and blood group B (α-l-Fucp-(1→2)[α-d-Galp-(1→3)]-β-d-Galp-OR) determinant structures, respectively. Structures of GTA and GTB in complex with their respective trisaccharide products reveal a conflict between the transferred sugar monosaccharide and the β-phosphate of the UDP donor. Mapping of the binding epitopes by saturation transfer difference NMR measurements yielded data consistent with the X-ray structural results. Taken together these data suggest a mechanism of product release where monosaccharide transfer to the H-antigen acceptor induces active site disorder and ejection of the UDP leaving group prior to trisaccharide egress.
Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany.,Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.,Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6.