RPAP3 provides a flexible scaffold for coupling HSP90 to the human R2TP co-chaperone complex

Nat Commun. 2018 Apr 16;9(1):1501. doi: 10.1038/s41467-018-03942-1.

Abstract

The R2TP/Prefoldin-like co-chaperone, in concert with HSP90, facilitates assembly and cellular stability of RNA polymerase II, and complexes of PI3-kinase-like kinases such as mTOR. However, the mechanism by which this occurs is poorly understood. Here we use cryo-EM and biochemical studies on the human R2TP core (RUVBL1-RUVBL2-RPAP3-PIH1D1) which reveal the distinctive role of RPAP3, distinguishing metazoan R2TP from the smaller yeast equivalent. RPAP3 spans both faces of a single RUVBL ring, providing an extended scaffold that recruits clients and provides a flexible tether for HSP90. A 3.6 Å cryo-EM structure reveals direct interaction of a C-terminal domain of RPAP3 and the ATPase domain of RUVBL2, necessary for human R2TP assembly but absent from yeast. The mobile TPR domains of RPAP3 map to the opposite face of the ring, associating with PIH1D1, which mediates client protein recruitment. Thus, RPAP3 provides a flexible platform for bringing HSP90 into proximity with diverse client proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATPases Associated with Diverse Cellular Activities / chemistry*
  • ATPases Associated with Diverse Cellular Activities / genetics
  • ATPases Associated with Diverse Cellular Activities / metabolism
  • Amino Acid Sequence
  • Animals
  • Apoptosis Regulatory Proteins / chemistry*
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • Binding Sites
  • Carrier Proteins / chemistry*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cloning, Molecular
  • Cryoelectron Microscopy
  • DNA Helicases / chemistry*
  • DNA Helicases / genetics
  • DNA Helicases / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression
  • Genetic Vectors / chemistry
  • Genetic Vectors / metabolism
  • HSP90 Heat-Shock Proteins / chemistry*
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism
  • Humans
  • Models, Molecular
  • Molecular Chaperones / chemistry*
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Protein Binding
  • Protein Conformation, alpha-Helical
  • Protein Conformation, beta-Strand
  • Protein Interaction Domains and Motifs
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism

Substances

  • Apoptosis Regulatory Proteins
  • Carrier Proteins
  • HSP90 Heat-Shock Proteins
  • Molecular Chaperones
  • PIH1D1 protein, human
  • RPAP3 protein, human
  • Recombinant Proteins
  • prefoldin
  • ATPases Associated with Diverse Cellular Activities
  • DNA Helicases
  • RUVBL1 protein, human
  • RUVBL2 protein, human