Title
Crystal structure of the catalytic unit of GH 87-type α-1,3-glucanase Agl-KA from Bacillus circulans
Author
Shigekazu Yano, Wasana Suyotha, Natsuki Oguro, Takashi Matsui, Shota Shiga, Takafumi Itoh, Takao Hibi, Yoshikazu Tanaka, Mamoru Wakayama, Koki Makabe
Year
2019
Journal
Scientific Reports
Abstract
Glycoside hydrolase (GH) 87-type α-1,3-glucanase hydrolyses the α-1,3-glucoside linkages of α-1,3-glucan, which is found in fungal cell walls and extracellular polysaccharides produced by oral Streptococci. In this study, we report on the molecular structure of the catalytic unit of GH 87-type α-1,3-glucanase, Agl-KA, from Bacillus circulans, as determined by x-ray crystallography at a resolution of 1.82 Å. The catalytic unit constitutes a complex structure of two tandemly connected domains—the N-terminal galactose-binding-like domain and the C-terminal right-handed β-helix domain. While the β-helix domain is widely found among polysaccharide-processing enzymes, complex formation with the galactose-binding-like domain was observed for the first time. Biochemical assays showed that Asp1067, Asp1090 and Asp1091 are important for catalysis, and these residues are indeed located at the putative substrate-binding cleft, which forms a closed end and explains the product specificity.
Full Article
Instrument
J-820
Keywords
Circular dichroism, Secondary structure, Biochemistry