Crystal structure and biological implications of a glycoside hydrolase family 55 β-1,3-glucanase from Chaetomium thermophilum

: Anastassios C. Papageorgiou, Jinyin Chen, Duochuan Li

: 2017/05/10 0

Publisher: ELSEVIER SCIENCE BV

: 2017

: BBA - Proteins and Proteomics

: 1865

: 8

: 1030

: 1038

: 9

: 1570-9639

: 0006-3002

DOI: https://doi.org/10.1016/j.bbapap.2017.05.002

Crystal structures of a beta-1,3-glucanase from the thermophilic fungus Chaetomium thermophilum were determined at 1.20 and 1.42A resolution in the free and glucose-bound form, respectively. This is the third structure of a family 55glycoside hydrolase (GH55) member and the second from a fungus. Based oncomparative structural studies and site-directed mutagenesis, Glu654 is proposedas the catalytic acid residue. The substrate binding cleft exhibits restrictedaccess on one side, rendering the enzyme as an exo-beta-1,3-glucanase asconfirmed also by thin layer chromatography experiments. A lack of stackinginteractions was found at the substrate binding cleft, suggesting thatinteractions at positions -1, +1 and +2 are sufficient to orientate thesubstrate. A binding pocket was identified that could explain binding of branchedlaminarin and accumulation of laminaritriose.CI - Copyright (c) 2017 Elsevier B.V. All rights reserved.