3I0E

Crystal structure of GTB C80S/C196S + H-antigen

Summary for 3I0E

• Entry DOI: 10.2210/pdb3i0e/pdb
• Related: 1LZ7 3I0C 3I0D 3I0F 3I0G 3I0H 3I0I 3I0J 3I0K 3I0L
• Descriptor: ABO glycosyltransferase, alpha-L-fucopyranose-(1-2)-hexyl beta-D-galactopyranoside (3 entities in total)
• Functional Keywords: gtb, glycosyltransferase, abo blood group, retaining, transferase
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 33831.84

Authors

Schuman, B.,Persson, M.,Landry, R.C.,Polakowski, R.,Weadge, J.T.,Seto, N.O.L.,Borisova, S.,Palcic, M.M.,Evans, S.V. (deposition date: 2009-06-25, release date: 2010-08-11, Last modification date: 2023-09-06)

Primary citation

Schuman, B.,Persson, M.,Landry, R.C.,Polakowski, R.,Weadge, J.T.,Seto, N.O.,Borisova, S.N.,Palcic, M.M.,Evans, S.V.
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
J.Mol.Biol., 402:399-411, 2010

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.

PubMed: 20655926
DOI: 10.1016/j.jmb.2010.07.036

Experimental method

X-RAY DIFFRACTION (1.81 Å)