A newly described cellulosomal cellobiohydrolase, CelO, from Clostridium thermocellum: investigation of the exo-mode of hydrolysis, and binding capacity to crystalline cellulose

Microbiology (Reading). 2002 Jan;148(Pt 1):247-255. doi: 10.1099/00221287-148-1-247.

Abstract

The sequence of the celO gene from Clostridium thermocellum F7 was determined. The gene product, cellulase CelO (Ct-Cel5F), had a modular structure consisting of a carbohydrate-binding module of the CBM3 family and a catalytic domain of the glycosyl hydrolase family 5. The presence of the dockerin module indicated that the enzyme was a component of the cellulosome complex. The thermostable recombinant gene product was active on cellodextrins, barley beta-glucan, carboxymethylcellulose and insoluble cellulose. Cellobiose was the only product released from amorphic and crystalline cellulose, cellotetraose and higher cello-oligosaccharides, identifying CelO as a cellobiohydrolase. The cleavage pattern of p-nitrophenyl beta-D-cellotetraoside, blockage of the hydrolysis of NaBH(4)-reduced cellopentaose and the reduction in substrate viscosity suggested activity from the reducing end in a processive mode after making random cuts. Binding to insoluble, i.e. amorphous, and crystalline cellulose was mediated by the carbohydrate-binding module CBM3b, with a preference for the crystalline substrate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cellobiose / metabolism
  • Cellulase / chemistry
  • Cellulase / genetics*
  • Cellulase / metabolism*
  • Cellulose / metabolism*
  • Cellulose 1,4-beta-Cellobiosidase
  • Clostridium / enzymology*
  • Clostridium / genetics
  • Crystallization
  • Hydrolysis
  • Molecular Sequence Data
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Analysis, DNA
  • Substrate Specificity

Substances

  • Recombinant Proteins
  • Cellobiose
  • Cellulose
  • Cellulase
  • Cellulose 1,4-beta-Cellobiosidase

Associated data

  • GENBANK/AJ275975