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Crystal structures of Clostridium thermocellum xyloglucanase, XGH74A, reveal the structural basis for xyloglucan recognition and degradation

TitleCrystal structures of Clostridium thermocellum xyloglucanase, XGH74A, reveal the structural basis for xyloglucan recognition and degradation
Publication TypeJournal Article
Year of Publication2006
AuthorsMartinez-Fleites, C, Guerreiro, CIPD, Baumann, MJ, Taylor, EJ, Prates, JAM, Ferreira, LMA, Fontes, CMGA, Brumer, H, Davies, GJ
JournalJOURNAL OF BIOLOGICAL CHEMISTRY
Volume281
Pagination24922-24933
Date PublishedAUG 25
Type of ArticleArticle
ISSN0021-9258
Abstract

The enzymatic degradation of the plant cell wall is central both to the natural carbon cycle and, increasingly, to environmentally friendly routes to biomass conversion, including the production of biofuels. The plant cell wall is a complex composite of cellulose microfibrils embedded in diverse polysaccharides collectively termed hemicelluloses. Xyloglucan is one such polysaccharide whose hydrolysis is catalyzed by diverse xyloglucanases. Here we present the structure of the Clostridium thermocellum xyloglucanase Xgh74A in both apo and ligand-complexed forms. The structures, in combination with mutagenesis data on the catalytic residues and the kinetics and specificity of xyloglucan hydrolysis reveal a complex subsite specificity accommodating seventeen monosaccharide moieties of the multibranched substrate in an open substrate binding terrain.

DOI10.1074/jbc.M603583200