Send to

Choose Destination
Glycobiology. 2013 May;23(5):536-45. doi: 10.1093/glycob/cwt001. Epub 2013 Jan 8.

Structure-based mutagenic analysis of mechanism and substrate specificity in mammalian glycosyltransferases: porcine ST3Gal-I.

Author information

Department of Chemistry, University of British Columbia, Vancouver, BC, Canada.


Sialyltransferases (STs) play essential roles in signaling and in the cellular recognition processes of mammalian cells by selectively installing cell-surface sialic acids in an appropriate manner both temporally and organ-specifically. The availability of the first three-dimensional structure of a mammalian (GT29) sialyltransferase has, for the first time, allowed quantitative structure/function analyses to be performed, thereby providing reliable insights into the roles of key active site amino acids. Kinetic analyses of mutants of ST3Gal-I, in conjunction with structural studies, have confirmed the mechanistic roles of His302 and His319 as general acid and base catalysts, respectively, and have quantitated other interactions with the cytosine monophosphate-N-acetyl β-neuraminic acid donor substrate. The contributions of side chains that provide key interactions with the acceptor substrate, defining its specificity, have also been quantitated. Particularly important transition-state interactions of 2.5 and 2.7 kcal mol(-1) are found between the acceptor axial 4-hydroxyl and the conserved side chains of Gln108 and Tyr269, respectively. These results provide a basis for the engineering of mammalian STs to accommodate non-natural substrate analogs that should prove valuable as chemical biological probes of sialyltransferase function.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Silverchair Information Systems
Loading ...
Support Center