1fr8
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CRYSTAL STRUCTURE OF THE BOVINE BETA 1,4 GALACTOSYLTRANSFERASE (B4GALT1) CATALYTIC DOMAIN COMPLEXED WITH URIDINE DIPHOSPHOGALACTOSE
OverviewOverview
beta1,4-galactosyltransferase T1 (beta4Gal-T1, EC 2.4.1.90/38), a Golgi, resident membrane-bound enzyme, transfers galactose from uridine, diphosphogalactose to the terminal beta-N-acetylglucosamine residues, forming the poly-N-acetyllactosamine core structures present in, glycoproteins and glycosphingolipids. In mammals, beta4Gal-T1 binds to, alpha-lactalbumin, a protein that is structurally homologous to lyzozyme, to produce lactose. beta4Gal-T1 is a member of a large family of, homologous beta4galactosyltransferases that use different types of, glycoproteins and glycolipids as substrates. Here we solved and refined, the crystal structures of recombinant bovine beta4Gal-T1 to 2.4 A, resolution in the presence and absence of the substrate uridine, diphosphogalactose. The crystal structure of the bovine substrate-free, beta4Gal-T1 catalytic domain showed a new fold consisting of a single, conical domain with a large open pocket at its base. In the, substrate-bound complex, the pocket encompassed residues interacting with, uridine diphosphogalactose. The structure of the complex contained clear, regions of electron density for the uridine diphosphate portion of the, substrate, where its beta-phosphate group was stabilized by, hydrogen-bonding contacts with conserved residues including the, Asp252ValAsp254 motif. These results help the interpretation of engineered, beta4Gal-T1 point mutations. They suggest a mechanism possibly involved in, galactose transfer and enable identification of the critical amino acids, involved in alpha-lactalbumin interactions.
About this StructureAbout this Structure
1FR8 is a Single protein structure of sequence from Bos taurus with GDU as ligand. Active as Beta-N-acetylglucosaminylglycopeptide beta-1,4-galactosyltransferase, with EC number 2.4.1.38 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of the bovine beta4galactosyltransferase catalytic domain and its complex with uridine diphosphogalactose., Gastinel LN, Cambillau C, Bourne Y, EMBO J. 1999 Jul 1;18(13):3546-57. PMID:10393171
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