3OTK

Structure and mechanisim of core 2 beta1,6-n-acetylglucosaminyltransferase: a Metal-ion independent gt-a glycosyltransferase

Summary for 3OTK

• Entry DOI: 10.2210/pdb3otk/pdb
• Descriptor: Beta-1,3-galactosyl-O-glycosyl-glycoprotein beta-1,6-N-acetylglucosaminyltransferase, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[alpha-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose, HEPTANE-1,2,3-TRIOL, ... (7 entities in total)
• Functional Keywords: glycosyltransferase, golgi, transferase
• Biological source: Mus musculus (mouse)
• Cellular location: Golgi apparatus membrane; Single-pass type II membrane protein: Q09324
• Total number of polymer chains: 4
• Total formula weight: 185200.41

Authors

Pak, J.E.,Rini, J.M. (deposition date: 2010-09-13, release date: 2011-09-14, Last modification date: 2024-11-20)

Primary citation

Pak, J.E.,Satkunarajah, M.,Seetharaman, J.,Rini, J.M.
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

PubMed Abstract: 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.

PubMed: 22056345
DOI: 10.1016/j.jmb.2011.10.039

Experimental method

X-RAY DIFFRACTION (2.3 Å)