Heterohexameric ring arrangement of the eukaryotic proteasomal ATPases: implications for proteasome structure and assembly

Mol Cell. 2010 May 14;38(3):393-403. doi: 10.1016/j.molcel.2010.02.035.

Abstract

The proteasome has a paramount role in eukaryotic cell regulation. It consists of a proteolytic core particle (CP) bound to one or two regulatory particles (RPs). Each RP is believed to include six different AAA+ ATPases in a heterohexameric ring that binds the CP while unfolding and translocating substrates into the core. No atomic-resolution RP structures are available. Guided by crystal structures of related homohexameric prokaryotic ATPases, we use disulfide engineering to show that the eukaryotic ATPases form a ring with the arrangement Rpt1-Rpt2-Rpt6-Rpt3-Rpt4-Rpt5 in fully assembled proteasomes. The arrangement is consistent with known assembly intermediates. This quaternary organization clarifies the functional overlap of specific RP assembly chaperones and led us to identify a potential RP assembly intermediate that includes four ATPases (Rpt6-Rpt3-Rpt4-Rpt5) and their cognate chaperones (Rpn14, Nas6, and Nas2). Finally, the ATPase ring structure casts light on alternative RP structural models and the mechanism of RP action.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / chemistry*
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism
  • Cysteine / chemistry
  • Disulfides / chemistry
  • Fungal Proteins / chemistry*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Models, Molecular
  • Molecular Chaperones / chemistry
  • Multiprotein Complexes
  • Mutation
  • Proteasome Endopeptidase Complex / chemistry*
  • Proteasome Endopeptidase Complex / genetics
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Engineering
  • Protein Multimerization
  • Protein Structure, Quaternary
  • Structure-Activity Relationship
  • Yeasts / enzymology*
  • Yeasts / genetics

Substances

  • Disulfides
  • Fungal Proteins
  • Molecular Chaperones
  • Multiprotein Complexes
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease
  • Adenosine Triphosphatases
  • Cysteine