The manganese-responsive transcriptional regulator MumR protects from oxidative stress.

is an emerging opportunistic pathogen that primarily infects critically ill patients in nosocomial settings. Because of its rapid acquisition of antibiotic resistance, infections caused by have become extremely difficult to treat, underlying the importance of identifying new antimicrobial targets for this pathogen. Manganese (Mn) is an essential nutrient metal required for a number of bacterial processes, including the response to oxidative stress. Here, we show that exogenous Mn can restore viability in the presence of reactive oxygen species (ROS). This restoration is not dependent on the high-affinity Nramp-family Mn transporter, MumT, as a Δ mutant is no more sensitive to hydrogen peroxide (HO) killing than wildtype However, , which encodes the transcriptional regulator of is critical for growth and survival in the presence of HO, suggesting that MumR regulates additional genes that contribute to HO resistance. RNA-sequencing revealed a role for in regulating the activity of a number of metabolic pathways, including two pathways, phenylacetate and gamma-aminobutyric acid catabolism, which were found to be important for resisting killing by HO Finally, Δ exhibited reduced fitness in a murine model of pneumonia, indicating that MumR-regulated gene products are crucial for protection against the host immune response. In summary, these results suggest that MumR facilitates resistance to the host immune response by activating a transcriptional program that is critical for surviving both Mn starvation and oxidative stress.