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Structural Snapshots of the Reaction Center of Family GT6 α1,3-Galactosyltransferase with Native Substrates. Insights into the Catalytic Mechanism of Retaining Glycosyltransferases

DOI: 10.1002/anie.201707922 DOI Help

Authors: Marcelo E. Guerin (CIC bioGUNE) , David Albesa-jove (CSIC) , Maria-angela Sainz-polo (CIC bioGUNE) , Alberto Marina (CSIC)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie International Edition

State: Published (Approved)
Published: September 2017
Diamond Proposal Number(s): 15304

Abstract: Glycosyltransferases (GTs) are a key family of enzymes that catalyses the synthesis of glycosidic bonds in all living organisms. The reaction involves the transfer of a glycosyl moiety and can proceed with retention or inversion of the anomeric configuration. To date, the elucidation of the catalytic mechanism of retaining GTs is of great controversy, particularly for those enzymes containing a putative nucleophilic residue in the active site, for which a double-displacement mechanism has been suggested. Here, we report native ternary complexes of the retaining α1,3-Galactosyltransferase (α3GalT) from Bos taurus - containing such a nucleophile in the active site - in a productive mode for catalysis, in the presence of its sugar donor UDP-Gal, the acceptor substrate lactose, and the divalent cation cofactor. This new experimental evidence supports a front-side substrate-assisted SNi-type reaction for α3GalT, and suggests a conserved common catalytic mechanism among retaining GTs.

Journal Keywords: enzyme catalysis; enzymes; glycosyltransferases; reaction mechanisms; structural biology

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I04-1-Macromolecular Crystallography (fixed wavelength) , I24-Microfocus Macromolecular Crystallography

Other Facilities: Soleil