Glycosyltransferase B in complex with 3-amino-acceptor analog inhibitor, and uridine diphosphate-galactose

Experimental Data Snapshot

  • Resolution: 1.55 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.242 

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The influence of an intramolecular hydrogen bond in differential recognition of inhibitory acceptor analogs by human ABO(H) blood group A and B glycosyltransferases

Nguyen, H.P.Seto, N.O.L.Cai, Y.Leinala, E.K.Borisova, S.N.Palcic, M.M.Evans, S.V.

(2003) J Biol Chem 278: 49191-49195

  • DOI: https://doi.org/10.1074/jbc.M308770200
  • Primary Citation of Related Structures:  
    1R7T, 1R7U, 1R7V, 1R7X, 1R7Y, 1R80, 1R81, 1R82

  • PubMed Abstract: 

    Human ABO(H) blood group glycosyltransferases GTA and GTB catalyze the final monosaccharide addition in the biosynthesis of the human A and B blood group antigens. GTA and GTB utilize a common acceptor, the H antigen disaccharide alpha-l-Fucp-(1-->2)-beta-d-Galp-OR, but different donors, where GTA transfers GalNAc from UDP-GalNAc and GTB transfers Gal from UDP-Gal. GTA and GTB are two of the most homologous enzymes known to transfer different donors and differ in only 4 amino acid residues, but one in particular (Leu/Met-266) has been shown to dominate the selection between donor sugars. The structures of the A and B glycosyltransferases have been determined to high resolution in complex with two inhibitory acceptor analogs alpha-l-Fucp(1-->2)-beta-d-(3-deoxy)-Galp-OR and alpha-l-Fucp-(1-->2)-beta-d-(3-amino)-Galp-OR, in which the 3-hydroxyl moiety of the Gal ring has been replaced by hydrogen or an amino group, respectively. Remarkably, although the 3-deoxy inhibitor occupies the same conformation and position observed for the native H antigen in GTA and GTB, the 3-amino analog is recognized differently by the two enzymes. The 3-amino substitution introduces a novel intramolecular hydrogen bond between O2' on Fuc and N3' on Gal, which alters the minimum-energy conformation of the inhibitor. In the absence of UDP, the 3-amino analog can be accommodated by either GTA or GTB with the l-Fuc residue partially occupying the vacant UDP binding site. However, in the presence of UDP, the analog is forced to abandon the intramolecular hydrogen bond, and the l-Fuc residue is shifted to a less ordered conformation. Further, the residue Leu/Met-266 that was thought important only in distinguishing between donor substrates is observed to interact differently with the 3-amino acceptor analog in GTA and GTB. These observations explain why the 3-deoxy analog acts as a competitive inhibitor of the glycosyltransferase reaction, whereas the 3-amino analog displays complex modes of inhibition.

  • Organizational Affiliation

    Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glycoprotein-fucosylgalactoside alpha-galactosyltransferase283Homo sapiensMutation(s): 0 
Find proteins for P16442 (Homo sapiens)
Explore P16442 
Go to UniProtKB:  P16442
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP16442
Sequence Annotations
  • Reference Sequence


Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
alpha-L-fucopyranose-(1-2)-octyl 3-amino-3-deoxy-beta-D-galactopyranoside
Glycosylation Resources
GlyTouCan:  G17197TN
GlyCosmos:  G17197TN
Experimental Data & Validation

Experimental Data

  • Resolution: 1.55 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.242 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 52.8α = 90
b = 150.4β = 90
c = 79.5γ = 90
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-02-10
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Structure summary
  • Version 2.1: 2022-12-21
    Changes: Database references, Structure summary
  • Version 2.2: 2024-05-29
    Changes: Data collection