Regulatory Requirements for Staphylococcus aureus Nitric Oxide Resistance

The ability of Staphylococcus aureus to resist host innate immunity augments the severity and pervasiveness of its pathogenesis. Nitric oxide (NO center dot) is an innate immune radical that is critical for the efficient clearance of a wide range of microbial pathogens. Exposure of microbes to NO center dot typically results in growth inhibition and induction of stress regulons. S. aureus, however, induces a metabolic state in response to NO center dot that allows for continued replication and precludes stress regulon induction. The regulatory factors mediating this distinctive response remain largely undefined. Here, we employ a targeted transposon screen and tran-scriptomics to identify and characterize five regulons essential for NO center dot resistance in S. aureus: three virulence regulons not formerly associated with NO center dot resistance, SarA, CodY, and Rot, as well as two regulons with established roles, Fur and SrrAB. We provide new insights into the contributions of Fur and SrrAB during NO center dot stress and show that the S. aureus Delta sarA mutant, the most sensitive of the newly identified mutants, exhibits metabolic dysfunction and widespread transcriptional dysregulation following NO center dot exposure. Altogether, our results broadly characterize the regulatory requirements for NO center dot resistance in S. aureus and suggest an intriguing overlap between the regulation of NO center dot resistance and virulence in this well-adapted human pathogen. IMPORTANCE The prolific human pathogen Staphylococcus aureus is uniquely capable of resisting the antimicrobial radical nitric oxide (NO center dot), a crucial component of the innate immune response. However, a complete understanding of how S. aureus regulates an effective response to NO center dot is lacking. Here, we implicate three central virulence regulators, SarA, CodY, and Rot, as major players in the S. aureus NO center dot response. Additionally, we elaborate on the contribution of two regulators, SrrAB and Fur, already known to play a crucial role in S. aureus NO center dot resistance. Our study sheds light on a unique facet of S. aureus pathogenicity and demonstrates that the transcriptional response of S. aureus to NO center dot is highly pleiotropic and intrinsically tied to metabolism and virulence regulation.