1k4v
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1.53 A Crystal Structure of the Beta-Galactoside-alpha-1,3-galactosyltransferase in Complex with UDP
OverviewOverview
UDP-galactose:beta-galactosyl alpha-1,3-galactosyltransferase (alpha3GT), catalyzes the transfer of galactose from UDP-alpha-d-galactose into an, alpha-1,3 linkage with beta-galactosyl groups in glycoconjugates. The, enzyme is expressed in many mammalian species but is absent from humans, apes, and old world monkeys as a result of the mutational inactivation of, the gene; in humans, a large fraction of natural antibodies are directed, against its product, the alpha-galactose epitope. alpha3GT is a member of, a family of metal-dependent retaining glycosyltransferases including the, histo-blood group A and B synthases. A crystal structure of the catalytic, domain of alpha3GT was recently reported (Gastinel, L. N., Bignon, C., Misra, A. K., Hindsgaul, O., Shaper, J. H., and Joziasse, D. H. (2001), EMBO J. 20, 638-649). However, because of the limited resolution (2.3 A), and high mobility of the atoms (as indicated by high B-factors) this, structure (form I) does not provide a clear depiction of the catalytic, site of the enzyme. Here we report a new, highly ordered structure for the, catalytic domain of alpha3GT at 1.53-A resolution (form II). This provides, a more accurate picture of the details of the catalytic site that includes, a bound UDP molecule and a Mn(2+) cofactor. Significantly, in the new, structure, the C-terminal segment (residues 358-368) adopts a very, different, highly structured conformation and appears to form part of the, active site. The properties of an Arg-365 to Lys mutant indicate that this, region is important for catalysis, possibly reflecting its role in a donor, substrate-induced conformational change.
About this StructureAbout this Structure
1K4V is a Single protein structure of sequence from Bos taurus with MN, UDP and GOL as ligands. Active as N-acetyllactosaminide 3-alpha-galactosyltransferase, with EC number 2.4.1.87 Full crystallographic information is available from OCA.
ReferenceReference
Structure of UDP complex of UDP-galactose:beta-galactoside-alpha -1,3-galactosyltransferase at 1.53-A resolution reveals a conformational change in the catalytically important C terminus., Boix E, Swaminathan GJ, Zhang Y, Natesh R, Brew K, Acharya KR, J Biol Chem. 2001 Dec 21;276(51):48608-14. Epub 2001 Oct 9. PMID:11592969
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