Physical interaction between replication protein A (RPA) and MRN: Involvement of RPA2 phosphorylation and the N-terminus of RPA1

Greg G. Oakley, Kristin Tillison, Stephen A. Opiyo, Jason G. Glanzer, Jeffrey M. Horn, Steve M. Patrick

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Replication protein A (RPA) is a heterotrimeric protein consisting of RPA1, RPA2, and RPA3 subunits that binds to single-stranded DNA (ssDNA) with high affinity. The response to replication stress requires the recruitment of RPA and the MRE11-RAD50-NBS1 (MRN) complex. RPA bound to ssDNA stabilizes stalled replication forks by recruiting checkpoint proteins involved in fork stabilization. MRN can bind DNA structures encountered at stalled or collapsed replication forks, such as ssDNA-double-stranded DNA (dsDNA) junctions or breaks, and promote the restart of DNA replication. Here, we demonstrate that RPA2 phosphorylation regulates the assembly of DNA damage-induced RPA andMRNfoci. Using purified proteins, we observe a direct interaction between RPA with both NBS1 andMRE11. By utilizing RPA bound to ssDNA, we demonstrate that substituting RPA with phosphorylated RPA or a phosphomimetic weakens the interaction with the MRN complex. Also, the N-terminus of RPA1 is a critical component of the RPAMRNprotein-protein interaction. Deletion of the N-terminal oligonucleotide-oligosaccharide binding fold (OB-fold) of RPA1 abrogates interactions of RPA with MRN and individual proteins of the MRN complex. Further identification of residues critical for MRN binding in the N-terminus of RPA1 shows that substitution of Arg31 and Arg41 with alanines disrupts the RPA-MRN interaction and alters cell cycle progression in response to DNA damage. Thus, the N-terminus of RPA1 and phosphorylation of RPA2 regulate RPA-MRN interactions and are important in the response to DNA damage.

Original languageEnglish (US)
Pages (from-to)7473-7481
Number of pages9
Issue number31
StatePublished - Aug 11 2009

ASJC Scopus subject areas

  • Biochemistry


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