Replication Protein A Dynamics in DNA Metabolism

Replication Protein A (RPA) is the principal single-stranded DNA (ssDNA)-binding complex in eukaryotic cells, orchestrating fundamental processes of DNA replication, repair and recombination. As a heterotrimer, RPA coats exposed ssDNA at replication forks and sites of damage, protecting the strand from nucleolytic attack while serving as a dynamic platform for the recruitment of downstream factors. Rather than binding statically, RPA exhibits a spectrum of modes ranging from tightly packed “protection” states to looser “action” states that allow access to recombinases and polymerases. This dynamic behaviour is modulated by inter-subunit communication, local protein concentrations and post-translational modifications such as phosphorylation and acetylation. Recent work has also revealed that RPA can undergo macromolecular phase separation, forming transient condensates that enrich ssDNA and associated factors at telomeres and stressed forks. Together, these emerging insights depict RPA not merely as a passive ssDNA clamp but as a highly regulated, multifunctional nexus that adapts its binding affinity, spatial organisation and interaction network to meet the changing demands of genome maintenance.

Research from Nature Portfolio

Studies using single-molecule imaging have uncovered how multiple RPA molecules organise along long ssDNA tracts. A low-complexity ssDNA curtain approach combined with non-equilibrium modelling delineated a three-step sequence by which RPA shifts from a densely protective mode to a more open state, enabling mediator proteins to expose DNA for recombinase loading. This work highlighted the ability of partner factors to tune RPA spacing and ssDNA accessibility.
Investigations into the biophysical properties of RPA have demonstrated that purified heterotrimers form liquid-like condensates in vitro, selectively incorporating ssDNA into dynamic droplets. Condensation depends on the intrinsically disordered region of the RPA2 subunit and is regulated by multi-site phosphorylation. Functionally, these condensates have been linked to telomere clustering and integrity, suggesting a role in organising ssDNA transactions within nuclear microenvironments.
Foundational structural studies using cryo-electron microscopy and fluorescence resonance energy transfer have produced a detailed model of RPA assembly on ssDNA. High-resolution reconstructions revealed how the four DNA-binding domains of RPA70 undergo coordinated rearrangements during cooperative loading. Phosphorylation at key serine residues was shown to modulate these conformational transitions, providing a structural basis for RPA’s switching between binding modes.

Replication Protein A Dynamics in DNA Metabolism publication trend

The graph below shows the total number of articles in replication protein a dynamics in dna metabolism across all publications each year (not limited to Nature Index journals).

Technical terms

Replication Protein A (RPA): Heterotrimeric complex that binds single-stranded DNA to protect it and recruit repair or replication factors.

Single-stranded DNA (ssDNA): DNA consisting of a single nucleotide strand, generated transiently during replication and repair.

Phase separation: Process by which biomolecules demix to form concentrated liquid-like condensates within the cell.

Replication fork: The Y-shaped structure formed when parental DNA is unwound and newly synthesised strands are extended.

Acetylation: Addition of an acetyl group to lysine residues in proteins, modulating their binding and localisation.

Phosphorylation: Covalent attachment of phosphate groups to amino acids, regulating protein activity and interactions.

Replisome: Multi-protein assembly that carries out DNA unwinding and synthesis at replication forks.

References

1. ssDNA accessibility of Rad51 is regulated by orchestrating multiple RPA dynamics. Nature Communications (2023).
2. Phase separation properties of RPA combine high-affinity ssDNA binding with dynamic condensate functions at telomeres. Nature Structural & Molecular Biology (2023).
3. A structural and dynamic model for the assembly of Replication Protein A on single-stranded DNA. Nature Communications (2018).
4. Proper RPA acetylation promotes accurate DNA replication and repair. Nucleic Acids Research (2023).
5. Replisome Proximal Protein Associations and Dynamic Proteomic Changes at Stalled Replication Forks. Molecular & Cellular Proteomics (2024).
6. NRF2 promotes radiation resistance by cooperating with TOPBP1 to activate the ATR-CHK1 signaling pathway. Theranostics (2024).