Figure 3. The NsrR-regulated STM1808 and ygbA genes are important for S. Typhimurium growth under nitrosative stress.

Overnight cultures of S. Typhimurium 14028s were inoculated to a cell density of 4 × 10⁷ cfu/ml followed by addition of the NO· donor Sper/NO, and growth monitored for 25 h at 37°C. Strains carrying mutations in individual genes belonging to the NsrR regulon were compared to wild-type (WT, black) for growth in LB + 5mM Sper/NO. A. hmp (red) and STM1808 (light blue). B. ytfE (green) and ygbA (light purple). C. hcp (orange) and yeaR (dark purple). Double mutant strains containing mutations in hmp and additional NsrR-regulated genes were compared to WT (black) and hmp (red) for growth in LB + 3mM Sper/NO. D. hmp STM1808 (light blue circles). E. hmp ytfE (green circles) and hmp ygbA (light purple circles). F. hmp hcp (orange circles) and hmp yeaR (dark purple circles). Triple mutant strains containing mutations in nsrR, hmp and additional NsrR-regulated genes were compared to WT (black), hmp (red) and nsrR hmp (red squares) for growth in LB + 3mM Sper/NO. G. nsrR hmp STM1808 (light blue squares). H. nsrR hmp ytfE (green squares) and nsrR hmp ygbA (light purple squares). I. nsrR hmp hcp (orange squares) and nsrR hmp yeaR (dark purple squares).