2aec: Difference between revisions

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Crystal Structure of Human M340H-Beta1,4-Galactosyltransferase-I (M340H-B4GAL-T1) in Complex with GlcNAc-beta1,2-Man-alpha1,6-Man-beta-OR

OverviewOverview

beta-1,4-Galactosyltransferase-I (beta4Gal-T1) transfers galactose from UDP-galactose to N-acetylglucosamine (GlcNAc) residues of the branched N-linked oligosaccharide chains of glycoproteins. In an N-linked biantennary oligosaccharide chain, one antenna is attached to the 3-hydroxyl-(1,3-arm), and the other to the 6-hydroxyl-(1,6-arm) group of mannose, which is beta-1,4-linked to an N-linked chitobiose, attached to the aspargine residue of a protein. For a better understanding of the branch specificity of beta4Gal-T1 towards the GlcNAc residues of N-glycans, we have carried out kinetic and crystallographic studies with the wild-type human beta4Gal-T1 (h-beta4Gal-T1) and the mutant Met340His-beta4Gal-T1 (h-M340H-beta4Gal-T1) in complex with a GlcNAc-containing pentasaccharide and several GlcNAc-containing trisaccharides present in N-glycans. The oligosaccharides used were: pentasaccharide GlcNAcbeta1,2-Manalpha1,6 (GlcNAcbeta1,2-Manalpha1,3)Man; the 1,6-arm trisaccharide, GlcNAcbeta1,2-Manalpha1,6-Manbeta-OR (1,2-1,6-arm); the 1,3-arm trisaccharides, GlcNAcbeta1,2-Manalpha1,3-Manbeta-OR (1,2-1,3-arm) and GlcNAcbeta1,4-Manalpha1,3-Manbeta-OR (1,4-1,3-arm); and the trisaccharide GlcNAcbeta1,4-GlcNAcbeta1,4-GlcNAc (chitotriose). With the wild-type h-beta4Gal-T1, the K(m) of 1,2-1,6-arm is approximately tenfold lower than for 1,2-1,3-arm and 1,4-1,3-arm, and 22-fold lower than for chitotriose. Crystal structures of h-M340H-beta4Gal-T1 in complex with the pentasaccharide and various trisaccharides at 1.9-2.0A resolution showed that beta4Gal-T1 is in a closed conformation with the oligosaccharide bound to the enzyme, and the 1,2-1,6-arm trisaccharide makes the maximum number of interactions with the enzyme, which is in concurrence with the lowest K(m) for the trisaccharide. Present studies suggest that beta4Gal-T1 interacts preferentially with the 1,2-1,6-arm trisaccharide rather than with the 1,2-1,3-arm or 1,4-1,3-arm of a bi- or tri-antennary oligosaccharide chain of N-glycan.

About this StructureAbout this Structure

2AEC is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

ReferenceReference

Oligosaccharide preferences of beta1,4-galactosyltransferase-I: crystal structures of Met340His mutant of human beta1,4-galactosyltransferase-I with a pentasaccharide and trisaccharides of the N-glycan moiety., Ramasamy V, Ramakrishnan B, Boeggeman E, Ratner DM, Seeberger PH, Qasba PK, J Mol Biol. 2005 Oct 14;353(1):53-67. PMID:16157350 Page seeded by OCA on Sat May 3 18:56:21 2008

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OCA

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 [[Image:2aec.gif|left|200px]]
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 '''Crystal Structure of Human M340H-Beta1,4-Galactosyltransferase-I (M340H-B4GAL-T1) in Complex with GlcNAc-beta1,2-Man-alpha1,6-Man-beta-OR'''
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 [[Category: Ratner, D M.]]
 [[Category: Seeberger, P H.]]
-[[Category: beta1,4-galactosyltransferase-i]]
+[[Category: Beta1,4-galactosyltransferase-i]]
-[[Category: closed conformation]]
+[[Category: Closed conformation]]
-[[Category: mutant]]
+[[Category: Mutant]]
-[[Category: trisaccharide]]
+[[Category: Trisaccharide]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 18:56:21 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 01:51:27 2008''