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Structure of the catalytic core module of the module of the Chaetomium thermophilum family GH6 cellobiohydrolase Cel6A

DOI: 10.1107/S0907444912016496 DOI Help
PMID: 22868752 PMID Help

Authors: Andrew J. Thompson (University of York, U.K.) , Tia Heu (Novozymes Inc. USA.) , Tarana Shaghasi (Novozymes Inc. USA.) , Romil Benyamino (Novozymes Inc. USA.) , Aubrey Jones (Novozymes Inc. USA.) , Esben P. Friis (Novozymes Inc. USA.) , Keith S. Wilson (University of York, U.K.) , Gideon J. Davies (University of York, U.K.)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Crystallographica Section D Biological Crystallography , VOL 68 (8) , PAGES 875 - 882

State: Published (Approved)
Published: August 2012
Diamond Proposal Number(s): 1221

Abstract: Cellulases, including cellobiohydrolases and endoglucanases, are important enzymes involved in the breakdown of the polysaccharide cellulose. These catalysts have found widescale industrial applications, particularly in the paper and textile industries, and are now finding use in `second-generation' conversion of biomass to biofuels. Despite this considerable biotechnological application, and undoubted future potential, uncertainty remains as to the exact reaction mechanism of the inverting cellulases found in the GH6 family of carbohydrate-active enzymes. In order to gain additional understanding as to how these societally beneficial biocatalysts function, the crystal structure of a GH6 cellobiohydrolase from Chaetomium thermophilum, CtCel6A, has been solved. This structure reveals a distorted α/β-barrel fold comprising a buried tunnel-like active site quite typical of Cel6A enzymes. Analysis of an enzyme–product complex (cellobiose in the −3 and −2 subsites and cellotetraose in subsites +1 to +4) supports the hypothesis that this group of enzymes act via an atypical single-displacement mechanism. Of particular note in this analysis is an active-centre metal ion, Li+, the position of which matches the position of the positively charged anomeric carbon of the oxocarbenium-ion-like transition state

Journal Keywords: Amino; Biofuels; Biomass; Carbohydrate; Catalytic; Cellobiose; Cellulose; Cellulose; Chaetomium; Computational; Crystallography; X-Ray; Ethanol; Fungal; Hydrolysis; Ions; Models; Chemical; Models; Statistical; Protein; Sequence; Amino Acid

Subject Areas: Biology and Bio-materials

Instruments: I04-1-Macromolecular Crystallography (fixed wavelength)

Added On: 26/09/2012 13:53

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