1o0r

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Revision as of 20:35, 20 November 2007

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spinqualitylabelsall models 1o0r, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of the catalytic domain of bovine beta1,4-galactosyltransferase complex with UDP-galactose

Overview

The crystal structure of the catalytic domain of bovine, beta1,4-galactosyltransferase (Gal-T1) co-crystallized with UDP-Gal and, MnCl(2) has been solved at 2.8 A resolution. The structure not only, identifies galactose, the donor sugar binding site in Gal-T1, but also, reveals an oligosaccharide acceptor binding site. The galactose moiety of, UDP-Gal is found deep inside the catalytic pocket, interacting with, Asp252, Gly292, Gly315, Glu317 and Asp318 residues. Compared to the native, crystal structure reported earlier, the present UDP-Gal bound structure, exhibits a large conformational change in residues 345-365 and a change in, the side-chain orientation of Trp314. Thus, the binding of UDP-Gal induces, a conformational change in Gal-T1, which not only creates the acceptor, binding pocket for N-acetylglucosamine (GlcNAc) but also establishes the, binding site for an extended sugar acceptor. The presence of a binding, site that accommodates an extended sugar offers an explanation for the, observation that an oligosaccharide with GlcNAc at the non-reducing end, serves as a better acceptor than the monosaccharide, GlcNAc. Modeling, studies using oligosaccharide acceptors indicate that a pentasaccharide, such as N-glycans with GlcNAc at their non-reducing ends, fits the site, best. A sequence comparison of the human Gal-T family members indicates, that although the binding site for the GlcNAc residue is highly conserved, the site that binds the extended sugar exhibits large variations. This is, an indication that different Gal-T family members prefer different types, of glycan acceptors with GlcNAc at their non-reducing ends.

About this Structure

1O0R is a Single protein structure of sequence from Bos taurus with GDU, MN, SO4, MES and DIO as ligands. This structure superseeds the now removed PDB entry 1KYB. Active as N-acetyllactosamine synthase, with EC number 2.4.1.90 Full crystallographic information is available from OCA.

Reference

Crystal structure of beta1,4-galactosyltransferase complex with UDP-Gal reveals an oligosaccharide acceptor binding site., Ramakrishnan B, Balaji PV, Qasba PK, J Mol Biol. 2002 Apr 26;318(2):491-502. PMID:12051854

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