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- Title
X‐ray crystal structure of rabbit N‐acetylglucosaminyltransferase I: catalytic mechanism and a new protein superfamily.
- Authors
Ünligil, Uluĝ M.; Zhou, Sihong; Yuwaraj, Sivashankary; Sarkar, Mohan; Schachter, Harry; Rini, James M.
- Abstract
N‐acetylglucosaminyltransferase I (GnT I) serves as the gateway from oligomannose to hybrid and complex N‐glycans and plays a critical role in mammalian development and possibly all metazoans. We have determined the X‐ray crystal structure of the catalytic fragment of GnT I in the absence and presence of bound UDP‐GlcNAc/Mn2+ at 1.5 and 1.8 Å resolution, respectively. The structures identify residues critical for substrate binding and catalysis and provide evidence for similarity, at the mechanistic level, to the deglycosylation step of retaining β‐glycosidases. The structuring of a 13 residue loop, resulting from UDP‐GlcNAc/Mn2+ binding, provides an explanation for the ordered sequential 'Bi Bi' kinetics shown by GnT I. Analysis reveals a domain shared with Bacillus subtilis glycosyltransferase SpsA, bovine β‐1,4‐galactosyl transferase 1 and Escherichia coliN‐acetylglucosamine‐1‐phosphate uridyltransferase. The low sequence identity, conserved fold and related functional features shown by this domain define a superfamily whose members probably share a common ancestor. Sequence analysis and protein threading show that the domain is represented in proteins from several glycosyltransferase families.
- Subjects
CRYSTAL structure; X-rays; BACILLUS subtilis; BIOCHEMICAL substrates; RABBITS
- Publication
EMBO Journal, 2000, Vol 19, Issue 20, p5269
- ISSN
0261-4189
- Publication type
Article
- DOI
10.1093/emboj/19.20.5269