Hydrogen Sulfide and Reactive Sulfur Species Impact Proteome <i>S</i>‑Sulfhydration and Global Virulence Regulation in <i>Staphylococcus aureus</i>

Hydrogen sulfide (H<sub>2</sub>S) is thought to protect bacteria from oxidative stress, but a comprehensive understanding of its function in bacteria is largely unexplored. In this study, we show that the human pathogen <i>Staphylococcus aureus</i> (<i>S. aureus</i>) harbors significant effector molecules of H<sub>2</sub>S signaling, reactive sulfur species (RSS), as low molecular weight persulfides of bacillithiol, coenzyme A, and cysteine, and significant inorganic polysulfide species. We find that proteome <i>S</i>-sulfhydration, a post-translational modification (PTM) in H<sub>2</sub>S signaling, is widespread in <i>S. aureus</i>. RSS levels modulate the expression of secreted virulence factors and the cytotoxicity of the secretome, consistent with an <i>S</i>-sulfhydration-dependent inhibition of DNA binding by MgrA, a global virulence regulator. Two previously uncharacterized thioredoxin-like proteins, denoted TrxP and TrxQ, are <i>S</i>-sulfhydrated in sulfide-stressed cells and are capable of reducing protein hydrodisulfides, suggesting that this PTM is potentially regulatory in <i>S. aureus</i>. In conclusion, our results reveal that <i>S. aureus</i> harbors a pool of proteome- and metabolite-derived RSS capable of impacting protein activities and gene regulation and that H<sub>2</sub>S signaling can be sensed by global regulators to affect the expression of virulence factors.