Rtt105 regulates RPA function by configurationally stapling the flexible domains

Nat Commun. 2022 Sep 2;13(1):5152. doi: 10.1038/s41467-022-32860-6.


Replication Protein A (RPA) is a heterotrimeric complex that binds to single-stranded DNA (ssDNA) and recruits over three dozen RPA-interacting proteins to coordinate multiple aspects of DNA metabolism including DNA replication, repair, and recombination. Rtt105 is a molecular chaperone that regulates nuclear localization of RPA. Here, we show that Rtt105 binds to multiple DNA binding and protein-interaction domains of RPA and configurationally staples the complex. In the absence of ssDNA, Rtt105 inhibits RPA binding to Rad52, thus preventing spurious binding to RPA-interacting proteins. When ssDNA is available, Rtt105 promotes formation of high-density RPA nucleoprotein filaments and dissociates during this process. Free Rtt105 further stabilizes the RPA-ssDNA filaments by inhibiting the facilitated exchange activity of RPA. Collectively, our data suggest that Rtt105 sequesters free RPA in the nucleus to prevent untimely binding to RPA-interacting proteins, while stabilizing RPA-ssDNA filaments at DNA lesion sites.

MeSH terms

  • DNA Replication
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism
  • Protein Binding
  • RNA-Binding Proteins / chemistry
  • RNA-Binding Proteins / metabolism*
  • Recombination, Genetic
  • Replication Protein A / chemistry
  • Replication Protein A / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae* / metabolism


  • DNA, Single-Stranded
  • RFA1 protein, S cerevisiae
  • RNA-Binding Proteins
  • RTT105 protein, S cerevisiae
  • Replication Protein A
  • Saccharomyces cerevisiae Proteins