Chitobiose phosphorylase from Vibrio proteolyticus, a member of glycosyl transferase family 36, has a clan GH-L-like (alpha/alpha)(6) barrel fold

• Published in: Structure (London) Vol. 12; no. 6; pp. 937 - 947
• Main Authors: Hidaka, Masafumi, Honda, Yuji, Kitaoka, Motomitsu, Nirasawa, Satoru, Hayashi, Kiyoshi, Wakagi, Takayoshi, Shoun, Hirofumi, Fushinobu, Shinya
• Format: Journal Article
• Language: English
• Published: United States 01.06.2004
• Subjects: Amino Acid Sequence; Bacterial Proteins; Binding Sites; Carbohydrates - chemistry; Crystallography, X-Ray; Dimerization; Glucan 1,4-alpha-Glucosidase - chemistry; Glucosyltransferases - chemistry; Glycoside Hydrolases - chemistry; Glycosyltransferases - chemistry; Models, Molecular; Molecular Sequence Data; N-Acetylglucosaminyltransferases - chemistry; Protein Binding; Protein Conformation; Protein Folding; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Software; Substrate Specificity; Sulfates - chemistry; Vibrio - enzymology
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2004.03.027

Vibrio proteolyticus chitobiose phosphorylase (ChBP) belongs to glycosyl transferase family 36 (GT-36), and catalyzes the reversible phosphorolysis of chitobiose into alpha-GlcNAc-1-phosphate and GlcNAc with inversion of the anomeric configuration. As the first known structures of a GT-36 enzyme, we determined the crystal structure of ChBP in a ternary complex with GlcNAc and SO(4). It is also the first structures of an inverting phosphorolytic enzyme in a complex with a sugar and a sulfate ion, and reveals a pseudo-ternary complex structure of enzyme-sugar-phosphate. ChBP comprises a beta sandwich domain and an (alpha/alpha)(6) barrel domain, constituting a distinctive structure among GT families. Instead, it shows significant structural similarity with glycoside hydrolase (GH) enzymes, glucoamylases (GH-15), and maltose phosphorylase (GH-65) in clan GH-L. The structural similarity reported here, together with distant sequence similarities between ChBP and GHs, led to the reclassification of family GT-36 into a novel GH family, namely GH-94.