NMR Study of Temperature-Dependent Single-Stranded DNA Binding Affinity of Human Replication Protein A

The replication protein A (RPA), is a heterotrimer with 70, 32 and 14 kDa subunits and plays a crucial role in DNA replication, recombination, and repair. The largest subunit, RPA70, binds to single-stranded DNA (ssDNA) and mediates interactions with many cellular and viral proteins. In this study, we performed nuclear magnetic resonance experiments on the complex of the DNA binding domain A of human RPA70 (RPA70A) with ssDNA, d(CCCCC), at various temperatures, to understand the temperature dependency of ssDNA binding affinity of RPA70A. Essential residues for ssDNA binding were conserved while less essential parts were changed with the temperature. Our results provide valuable insights into the molecular mechanism of the ssDNA binding of human RPA.