title: Modulation of cellulosome composition in Clostridium cellulolyticum: adaptation to the polysaccharide environment revealed by proteomic and carbohydrate-active enzyme analyses.
abstract: Clostridium cellulolyticum is a model mesophilic anaerobic bacterium that efficiently degrades plant cell walls. The recent genome release offers the opportunity to analyse its complete degradation system. A total of 148 putative carbohydrate-active enzymes were identified, and their modular structures and activities were predicted. Among them, 62 dockerin-containing proteins bear catalytic modules from numerous carbohydrate-active enzymes' families and whose diversity reflects the chemical and structural complexity of the plant carbohydrate. The composition of the cellulosomes produced by C. cellulolyticum upon growth on different substrates (cellulose, xylan, and wheat straw) was investigated by LC MS/MS. The majority of the proteins encoded by the cip-cel operon, essential for cellulose degradation, were detected in all cellulosome preparations. In the presence of wheat straw, the natural and most complex of the substrates studied, additional proteins predicted to be involved in hemicellulose degradation were produced. A 32-kb gene cluster encodes the majority of these proteins, all harbouring carbohydrate-binding module 6 or carbohydrate-binding module 22 xylan-binding modules along dockerins. This newly identified xyl-doc gene cluster, specialised in hemicellulose degradation, comes in addition of the cip-cel operon for plant cell wall degradation. Hydrolysis efficiencies determined on the different substrates corroborates the finding that cellulosome composition is adapted to the growth substrate.
authors.affiliation: Laboratoire de Chimie Bactérienne, IFR88-CNRS, Marseille, France.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Blouzard
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Coutinho
authors.forename: Henri-Pierre
authors.initials: HP
authors.lastname: Fierobe
authors.forename: Bernard
authors.initials: B
authors.lastname: Henrissat
authors.forename: Sabrina
authors.initials: S
authors.lastname: Lignon
authors.forename: Chantal
authors.initials: C
authors.lastname: Tardif
authors.forename: Sandrine
authors.initials: S
authors.lastname: Pagès
authors.forename: Pascale
authors.initials: P
authors.lastname: de Philip
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050260:Carbohydrate Metabolism / Q000235:genetics; D044603:Cellulosomes / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D046973:Ruminiclostridium cellulolyticum / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D011134:Polysaccharides / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D011134:Polysaccharides