2GAK

X-ray crystal structure of murine leukocyte-type Core 2 b1,6-N-acetylglucosaminyltransferase (C2GnT-L)

Summary for 2GAK

• Entry DOI: 10.2210/pdb2gak/pdb
• Related: 2GAM
• Descriptor: beta-1,6-N-acetylglucosaminyltransferase, 2-acetamido-2-deoxy-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: glycoprotein, cis-peptide, dimer, transferase
• Biological source: Mus musculus (house mouse)
• Cellular location: Golgi apparatus membrane; Single-pass type II membrane protein: Q09324
• Total number of polymer chains: 2
• Total formula weight: 91082.28

Authors

Pak, J.E.,Rini, J.M. (deposition date: 2006-03-09, release date: 2006-07-11, Last modification date: 2024-10-30)

Primary citation

Pak, J.E.,Arnoux, P.,Zhou, S.,Sivarajah, P.,Satkunarajah, M.,Xing, X.,Rini, J.M.
X-ray Crystal Structure of Leukocyte Type Core 2 beta1,6-N-Acetylglucosaminyltransferase: Evidence for a covergence of metal ion independent glycosyltransferase mechanism.
J.Biol.Chem., 281:26693-26701, 2006

PubMed Abstract: 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.

PubMed: 16829524
DOI: 10.1074/jbc.M603534200

Experimental method

X-RAY DIFFRACTION (2 Å)