FIG 3.
Impacts of NrfA, SO_0039, Hcp, and NnrS on NO resistance and removal. (A) Promoter activity measurement of PnrfA, PSO0039, Phcp, PnnrS, and Pfre by an integrated lacZ reporter in cells grown under indicated conditions. Cells of mid-log-phase cultures were pelleted, processed, and subjected to a β-galactosidase activity assay. O2, aerobic growth fumarate; +NO, containing 400 μM DETA-NONOate; TMAO, 30 mM; +NO2−, 5 mM nitrite. (B) Effects of NrfA on NO-induced growth inhibition. Growth of WT and ΔnrfA strains in LB containing 0.4 mM DETA-NONOate was compared. Expression of nrfA (ΔnrfA/pnrfA) was driven by Ptac promoter with 1 mM IPTG, resulting in at least 15× induction compared to the chromosomal copy in the WT as calibrated previously. (C) Effects of NrfA on NO consumption. Data are shown as means± SEMs from at least three experiments.