Crystal structure of GTB C80S/C196S/C209S unliganded

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.168 

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Cysteine-to-serine mutants dramatically reorder the active site of human ABO(H) blood group B glycosyltransferase without affecting activity: structural insights into cooperative substrate binding

Schuman, B.Persson, M.Landry, R.C.Polakowski, R.Weadge, J.T.Seto, N.O.Borisova, S.N.Palcic, M.M.Evans, S.V.

(2010) J Mol Biol 402: 399-411

  • DOI: https://doi.org/10.1016/j.jmb.2010.07.036
  • Primary Citation of Related Structures:  
    3I0C, 3I0D, 3I0H, 3I0I

  • PubMed Abstract: 

    A common feature in the structures of GT-A-fold-type glycosyltransferases is a mobile polypeptide loop that has been observed to participate in substrate recognition and enclose the active site upon substrate binding. This is the case for the human ABO(H) blood group B glycosyltransferase GTB, where amino acid residues 177-195 display significantly higher levels of disorder in the unliganded state than in the fully liganded state. Structural studies of mutant enzymes GTB/C80S/C196S and GTB/C80S/C196S/C209S at resolutions ranging from 1.93 to 1.40 A display the opposite trend, where the unliganded structures show nearly complete ordering of the mobile loop residues that is lost upon substrate binding. In the liganded states of the mutant structures, while the UDP moiety of the donor molecule is observed to bind in the expected location, the galactose moiety is observed to bind in a conformation significantly different from that observed for the wild-type chimeric structures. Although this would be expected to impede catalytic turnover, the kinetics of the transfer reaction are largely unaffected. These structures demonstrate that the enzymes bind the donor in a conformation more similar to the dominant solution rotamer and facilitate its gyration into the catalytically competent form. Further, by preventing active-site closure, these structures provide a basis for recently observed cooperativity in substrate binding. Finally, the mutation of C80S introduces a fully occupied UDP binding site at the enzyme dimer interface that is observed to be dependent on the binding of H antigen acceptor analog.

  • Organizational Affiliation

    Department of Biochemistry and Microbiology, University of Victoria, PO Box 3800, STN CSC, Petch Building, Victoria, BC, Canada V8W 3P6.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ABO glycosyltransferase287Homo sapiensMutation(s): 3 
Gene Names: GTB
UniProt & NIH Common Fund Data Resources
Find proteins for P16442 (Homo sapiens)
Explore P16442 
Go to UniProtKB:  P16442
PHAROS:  P16442
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP16442
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.165 
  • R-Value Observed: 0.168 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 51.875α = 90
b = 149.782β = 90
c = 79.365γ = 90
Software Package:
Software NamePurpose
d*TREKdata scaling
PDB_EXTRACTdata extraction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-08-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2021-10-13
    Changes: Database references
  • Version 1.3: 2023-09-06
    Changes: Data collection, Refinement description