The RPAP3-Cterminal domain identifies R2TP-like quaternary chaperones

Nat Commun. 2018 May 29;9(1):2093. doi: 10.1038/s41467-018-04431-1.

Abstract

R2TP is an HSP90 co-chaperone that assembles important macro-molecular machineries. It is composed of an RPAP3-PIH1D1 heterodimer, which binds the two essential AAA+ATPases RUVBL1/RUVBL2. Here, we resolve the structure of the conserved C-terminal domain of RPAP3, and we show that it directly binds RUVBL1/RUVBL2 hexamers. The human genome encodes two other proteins bearing RPAP3-C-terminal-like domains and three containing PIH-like domains. Systematic interaction analyses show that one RPAP3-like protein, SPAG1, binds PIH1D2 and RUVBL1/2 to form an R2TP-like complex termed R2SP. This co-chaperone is enriched in testis and among 68 of the potential clients identified, some are expressed in testis and others are ubiquitous. One substrate is liprin-α2, which organizes large signaling complexes. Remarkably, R2SP is required for liprin-α2 expression and for the assembly of liprin-α2 complexes, indicating that R2SP functions in quaternary protein folding. Effects are stronger at 32 °C, suggesting that R2SP could help compensating the lower temperate of testis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATPases Associated with Diverse Cellular Activities / metabolism*
  • Adaptor Proteins, Signal Transducing / metabolism
  • Antigens, Surface / metabolism
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line
  • DNA Helicases / metabolism*
  • GTP-Binding Proteins / metabolism
  • HEK293 Cells
  • HSP90 Heat-Shock Proteins / metabolism*
  • HeLa Cells
  • Humans
  • Male
  • Membrane Proteins / metabolism
  • Molecular Chaperones / metabolism*
  • Protein Binding
  • Protein Folding
  • Protein Structure, Secondary
  • Signal Transduction
  • Testis / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Antigens, Surface
  • Apoptosis Regulatory Proteins
  • Carrier Proteins
  • HSP90 Heat-Shock Proteins
  • Membrane Proteins
  • Molecular Chaperones
  • PIH1D1 protein, human
  • PPFIA2 protein, human
  • RPAP3 protein, human
  • GTP-Binding Proteins
  • SPAG1 protein, human
  • ATPases Associated with Diverse Cellular Activities
  • DNA Helicases
  • RUVBL1 protein, human
  • RUVBL2 protein, human