2gam
|
X-ray crystal structure of murine leukocyte-type Core 2 b1,6-N-acetylglucosaminyltransferase (C2GnT-L) in complex with Galb1,3GalNAc
OverviewOverview
Leukocyte type core 2 beta1,6-N-acetylglucosaminyltransferase (C2GnT-L) is, a key enzyme in the biosynthesis of branched O-glycans. It is an, inverting, metal ion-independent family 14 glycosyltransferase that, catalyzes the formation of the core 2 O-glycan, (Galbeta1-3[GlcNAcbeta1-6]GalNAc-O-Ser/Thr) from its donor and acceptor, substrates, UDP-GlcNAc and the core 1 O-glycan, (Galbeta1-3GalNAc-O-Ser/Thr), respectively. Reported here are the x-ray, crystal structures of murine C2GnT-L in the absence and presence of the, acceptor substrate Galbeta1-3GalNAc at 2.0 and 2.7A resolution, respectively. C2GnT-L was found to possess the GT-A fold; however, it, lacks the characteristic metal ion binding DXD motif. The Galbeta1-3GalNAc, complex defines the determinants of acceptor substrate binding and shows, that Glu-320 corresponds to the structurally conserved catalytic base, found in other inverting GT-A fold glycosyltransferases. Comparison of the, C2GnT-L structure with that of other GT-A fold glycosyltransferases, further suggests that Arg-378 and Lys-401 serve to electrostatically, stabilize the nucleoside diphosphate leaving group, a role normally played, by metal ion in GT-A structures. The use of basic amino acid side chains, in this way is strikingly similar to that seen in a number of metal, ion-independent GT-B fold glycosyltransferases and suggests a convergence, of catalytic mechanism shared by both GT-A and GT-B fold, glycosyltransferases.
About this StructureAbout this Structure
2GAM is a Single protein structure of sequence from Mus musculus. Active as Beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-N- acetylglucosaminyltransferase, with EC number 2.4.1.102 Full crystallographic information is available from OCA.
ReferenceReference
X-ray crystal structure of leukocyte type core 2 beta1,6-N-acetylglucosaminyltransferase. Evidence for a convergence of metal ion-independent glycosyltransferase mechanism., Pak JE, Arnoux P, Zhou S, Sivarajah P, Satkunarajah M, Xing X, Rini JM, J Biol Chem. 2006 Sep 8;281(36):26693-701. Epub 2006 Jul 7. PMID:16829524
Page seeded by OCA on Wed Nov 21 11:04:59 2007