An Allosteric Interaction Network Promotes Conformation State-Dependent Eviction of the Nas6 Assembly Chaperone from Nascent 26S Proteasomes

Cell Rep. 2019 Jan 8;26(2):483-495.e5. doi: 10.1016/j.celrep.2018.12.042.

Abstract

The 26S proteasome is the central ATP-dependent protease in eukaryotes and is essential for organismal health. Proteasome assembly is mediated by several dedicated, evolutionarily conserved chaperone proteins. These chaperones associate transiently with assembly intermediates but are absent from mature proteasomes. Chaperone eviction upon completion of proteasome assembly is necessary for normal proteasome function, but how they are released remains unresolved. Here, we demonstrate that the Nas6 assembly chaperone, homolog of the human oncogene gankyrin, is evicted from nascent proteasomes during completion of assembly via a conformation-specific allosteric interaction of the Rpn5 subunit with the proteasomal ATPase ring. Subsequent ATP binding by the ATPase subunit Rpt3 promotes conformational remodeling of the ATPase ring that evicts Nas6 from the nascent proteasome. Our study demonstrates how assembly-coupled allosteric signals promote chaperone eviction and provides a framework for understanding the eviction of other chaperones from this biomedically important molecular machine.

Keywords: Nas6; assembly; gankyrin; macromolecular complex; oncogene; proteasome; proteolysis; ubiquitin.

Publication types

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

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Allosteric Regulation
  • Allosteric Site*
  • Proteasome Endopeptidase Complex / chemistry
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Binding
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism*

Substances

  • NAS6 protein, S cerevisiae
  • Rpn5 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphate
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease