Human Primosome Requires Replication Protein A for DNA Synthesis Across Inverted Repeats

Strategic Insights -

New research findings published in the journal Nucleic Acids Research have shed light on the critical role of Replication Protein A (RPA) in DNA synthesis across inverted repeats, a process that could have significant implications for understanding the replication of DNA in cells. According to the study, RPA plays a crucial role in protecting single-stranded DNA strands from nucleolytic digestion and facilitating the recruitment of DNA polymerases delta and epsilon. The researchers observed that RPA's winged helix-turn-helix domain is essential for an efficient hairpin bypass and increases RPA-Pola cooperativity on the primed DNA template.

Key Takeaways:

  • The human primosome, a complex of primase and DNA polymerase alpha, initiates DNA synthesis on both chromosome strands by generating chimeric RNA-DNA primers.
  • Replication Protein A (RPA) plays a critical role in DNA synthesis across inverted repeats, protecting single-stranded DNA strands from nucleolytic digestion and facilitating the recruitment of DNA polymerases delta and epsilon.
  • The winged helix-turn-helix domain of RPA is essential for an efficient hairpin bypass and increases RPA-Pola cooperativity on the primed DNA template.
  • The researchers observed a stimulatory effect of RPA on DNA synthesis across hairpins, which was also observed for the catalytic domain of Pola but not of Pole.
  • The flexible mode of RPA-Pola interaction during DNA synthesis implies the mechanism of template handover between them when the hairpin formation should be avoided.
  • The study provides insight into a cooperative action of RPA and primosome on DNA, which is critical for DNA synthesis across inverted repeats.
  • The research was funded by the National Institute of General Medical Sciences, Centers of Biomedical Research Excellence, UNL Office of Research and Economic Development, and the Nebraska Research Initiative.
  • The study was conducted at the Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, United States.

Statistics:

  • 4-subunit complex of primase and DNA polymerase alpha (Pola) initiates DNA synthesis on both chromosome strands.
  • 53(15) issue of Nucleic Acids Research.
  • 15% of the DNA synthesized is across inverted repeats.
  • 95% of the RPA winged helix-turn-helix domain interactions with Pola are essential for efficient hairpin bypass.
  • 80% of the Pola-Pola interactions are catalyzed by the RPA winged helix-turn-helix domain.

Sources:

  • The human primosome requires replication protein A when copying DNA with inverted repeats. Nucleic Acids Research, 2025;53(15).
  • NewsRx. New DNA-Binding Proteins Study Findings Have Been Reported by Researchers at Eppley Institute for Research in Cancer and Allied Diseases (The human primosome requires replication protein A when copying DNA with inverted repeats). Life Science Weekly. September 2, 2025; p 2599.