3OTK image
Entry Detail
PDB ID:
3OTK
Keywords:
Title:
Structure and mechanisim of core 2 beta1,6-n-acetylglucosaminyltransferase: a Metal-ion independent gt-a glycosyltransferase
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2010-09-13
Release Date:
2011-09-14
Method Details:
Experimental Method:
Resolution:
2.30 Å
R-Value Free:
0.21
R-Value Work:
0.16
R-Value Observed:
0.16
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-N-acetylglucosaminyltransferase
Mutations:C217S
Chain IDs:A, B, C, D
Chain Length:391
Number of Molecules:4
Biological Source:Mus musculus
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
ASN C ASN GLYCOSYLATION SITE
Primary Citation
Structural and mechanistic characterization of leukocyte-type core 2 beta 1,6-N-acetylglucosaminyltransferase: a metal-ion-independent GT-A glycosyltransferase.
J.Mol.Biol. 414 798 811 (2011)
PMID: 22056345 DOI: 10.1016/j.jmb.2011.10.039

Abstact

Leukocyte-type core 2 β1,6-N-acetylglucosaminyltransferase (C2GnT-L) is an inverting, metal-ion-independent glycosyltransferase that catalyzes the formation of mucin-type core 2 O-glycans. C2GnT-L belongs to the GT-A fold, yet it lacks the metal ion binding DXD motif characteristic of other nucleoside disphosphate GT-A fold glycosyltransferases. To shed light on the basis for its metal ion independence, we have solved the X-ray crystal structure (2.3 Å resolution) of a mutant form of C2GnT-L (C217S) in complex with the nucleotide sugar product UDP and, using site-directed mutagenesis, examined the roles of R378 and K401 in both substrate binding and catalysis. The structure shows that C2GnT-L exists in an "open" conformation and a "closed" conformation and that, in the latter, R378 and K401 interact with the β-phosphate moiety of the bound UDP. The two conformations are likely to be important in catalysis, but the conformational changes that lead to their interconversion do not resemble the nucleotide-sugar-mediated loop ordering observed in other GT-A glycosyltransferases. R378 and K401 were found to be important in substrate binding and/or catalysis, an observation consistent with the suggestion that they serve the same role played by metal ion in all of the other GT-A glycosyltransferases studied to date. Notably, R378 and K401 appear to function in a manner similar to that of the arginine and lysine residues contained in the RX(4-5)K motif found in the retaining GT-B glycosyltransferases.

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