Structural characterization of human RPA70N association with DNA damage response proteins

The heterotrimeric Replication protein A (RPA) is the ubiquitous eukaryotic single-stranded DNA (ssDNA) binding protein and participates in nearly all aspects of DNA metabolism, especially DNA damage response. The N-terminal OB domain of the RPA70 subunit (RPA70N) is a major protein-protein interaction element for RPA. Previous crystallography studies of RPA70N with p53, DNA2 and PrimPol fragments revealed that RPA70N binds to amphipathic peptides that mimics ssDNA. NMR chemical-shift studies also provided valuable information of RPA70N residues interacting with target sequences. However, it is still not clear how RPA70N recognizes and distinguishes such a diverse group of proteins. Here we present high resolution crystal structures of RPA70N in complex with peptides from HelB, ATRIP, RMI1, WRN and BLM. The structures showed that in addition to the ssDNA mimicry mode of interaction, RPA70N employs multiple ways to bind its partners, some of which may serve to increase the avidity of RPA70N binding.