PprA Protein Inhibits DNA Strand Exchange and ATP Hydrolysis of RecA and Regulates the Recombination in Gamma-Irradiated Cells.

DrRecA and PprA proteins function are crucial for the extraordinary resistance to γ-radiation and DNA strand break repair in . DrRecA mediated homologous recombination help in DNA strand break repair and cell survival, while the PprA protein confers radio-resistance its roles in DNA repair, genome maintenance, and cell division. Genetically and genes interact and constitute an epistatic group however, the mechanism underlying their functional interaction is not clear. Here, we showed the physical and functional interaction of DrRecA and PprA protein both and inside the cells. The absence of the gene increases the recombination frequency in gamma-irradiated cells and genomic instability in cells growing under normal conditions. PprA negatively regulates the DrRecA functions by inhibiting DrRecA mediated DNA strand exchange and ATPase function . Furthermore, it is shown that the inhibitory effect of PprA on DrRecA catalyzed DNA strand exchange was not due to sequestration of homologous dsDNA and was dependent on PprA oligomerization and DNA binding property. Together, results suggest that PprA is a new member of recombination mediator proteins (RMPs), and able to regulate the DrRecA function in γ-irradiated cells by protecting the genome from hyper-recombination and associated negative effects.