Differential Substrate Specificity of Group I and Group II Chaperonins in the Archaeon Methanosarcina Mazei

Mol Microbiol. 2009 Dec;74(5):1152-68. doi: 10.1111/j.1365-2958.2009.06924.x. Epub 2009 Oct 15.


Chaperonins are macromolecular machines that assist in protein folding. The archaeon Methanosarcina mazei has acquired numerous bacterial genes by horizontal gene transfer. As a result, both the bacterial group I chaperonin, GroEL, and the archaeal group II chaperonin, thermosome, coexist. A proteome-wide analysis of chaperonin interactors was performed to determine the differential substrate specificity of GroEL and thermosome. At least 13% of soluble M. mazei proteins interact with chaperonins, with the two systems having partially overlapping substrate sets. Remarkably, chaperonin selectivity is independent of phylogenetic origin and is determined by distinct structural and biochemical features of proteins. GroEL prefers well-conserved proteins with complex alpha/beta domains. In contrast, thermosome substrates comprise a group of faster-evolving proteins and contain a much wider range of different domain folds, including small all-alpha and all-beta modules, and a greater number of large multidomain proteins. Thus, the group II chaperonins may have facilitated the evolution of the highly complex proteomes characteristic of eukaryotic cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Archaeal Proteins / analysis
  • Archaeal Proteins / chemistry
  • Archaeal Proteins / genetics
  • Archaeal Proteins / metabolism*
  • Chaperonin 60 / genetics
  • Chaperonin 60 / metabolism
  • Eukaryotic Cells / metabolism
  • Group I Chaperonins / chemistry
  • Group I Chaperonins / genetics
  • Group I Chaperonins / metabolism*
  • Group II Chaperonins / chemistry
  • Group II Chaperonins / genetics
  • Group II Chaperonins / metabolism*
  • Methanosarcina / genetics
  • Methanosarcina / metabolism*
  • Models, Molecular
  • Phylogeny
  • Protein Binding / genetics
  • Protein Folding
  • Proteome / analysis
  • Substrate Specificity
  • Thermosomes / chemistry
  • Thermosomes / genetics
  • Thermosomes / metabolism


  • Archaeal Proteins
  • Chaperonin 60
  • Proteome
  • Adenosine Triphosphate
  • Group I Chaperonins
  • Group II Chaperonins
  • Thermosomes