The cellulosome: an exocellular, multiprotein complex specialized in cellulose degradation

Crit Rev Biochem Mol Biol. 1996 Jun;31(3):201-36. doi: 10.3109/10409239609106584.

Abstract

Clostridium thermocellum produces a highly active cellulase system that consists of a high-M(r) multienzyme complex termed cellulosome. Hydrolytic components of the cellulosome are organized around a large, noncatalytic glycoprotein termed CipA that acts both as a scaffolding component and a cellulose-binding factor. Catalytic subunits of the cellulosome bear conserved, noncatalytic subdomains, termed dockerin domains, which bind to receptor domains of CipA, termed cohesin domains. CipA includes nine cohesin domains, a cellulose-binding domain, and a specialized dockerin domain. Proteins of the cell envelope carrying cohesin domains that specifically bind the dockerin domain of CipA have been identified. These proteins may mediate anchoring of the cellulosomes to the cell surface. Cellulase complexes similar to the cellulosome of C. thermocellum are produced by several cellulolytic clostridia. High-M(r) multienzyme complexes have also been identified in anaerobic rumen fungi. The architecture of the fungal complexes also seems to rely on the interaction of conserved, noncatalytic docking domains with a scaffolding component. However, the sequence of the fungal docking domains bears no resemblance to the clostridial dockerin domains, suggesting that the fungal and clostridial complexes arose independently.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism
  • Bacterial Proteins / physiology*
  • Binding Sites
  • Cell Membrane / metabolism
  • Cellulase / metabolism
  • Cellulose / metabolism*
  • Clostridium / chemistry
  • Clostridium / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism
  • Models, Molecular
  • Multienzyme Complexes / chemistry
  • Multienzyme Complexes / metabolism*
  • Multienzyme Complexes / ultrastructure
  • Protein Conformation

Substances

  • Bacterial Proteins
  • CipA protein, Clostridium
  • Membrane Proteins
  • Multienzyme Complexes
  • Cellulose
  • Cellulase