Neisseria gonorrhoeae DNA recombination and repair enzymes protect against oxidative damage caused by hydrogen peroxide

The strict human pathogen Neisseria gonorrhoeae is exposed to oxidative damage during infection. N. gonorrhoeae has many defenses that have been demonstrated to counteract oxidative damage. However, recN is the only DNA repair and recombination gene upregulated in response to hydrogen peroxide (H2O2) by microarray analysis and subsequently shown to be important for oxidative damage protection. We therefore tested the importance of RecA and DNA recombination and repair enzymes in conferring resistance to H2O2 damage. recA mutants, as well as RecBCD (recB, recC, and recD) and Recf-like pathway mutants (recJ, recO, and recQ), all showed decreased resistance to H2O2. Holliday junction processing mutants (ruvA, ruvC, and recG) showed decreased resistance to H2O2 resistance as well. Finally, we show that RecA protein levels did not increase as a result of H2O2 treatment. We propose that RecA, recombinational DNA repair, and branch migration are all important for H2O2 resistance in N. gonorrhoeae but that constitutive levels of these enzymes are sufficient for providing protection against oxidative damage by H2O2.