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Staphylococcus epidermidis uses the SrrAB regulatory system to modulate oxidative stress and intracellular survival in mouse macrophage cell line Ana-1

ABSTRACT: The two-component system (TCS) SrrAB responds to the oxidative stress in Staphylococcus epidermidis. To study its regulatory function in oxidative stress, a srrAB deletion mutant (∆srrAB) was constructed using S. epidermidis strain 1457 (SE1457) as the parent strain. Compared to SE1457, the viable cell counts of the ∆srrAB mutant significantly decreased in the post-stationary phase culture, coinciding with a sharp increase in ROS accumulation. The impaired growth of the ∆srrAB mutant was partially restored by shifting the culture from oxic to microaerobic conditions. Consistently, growth of the ∆srrAB mutant in TSB medium containing H2O2 was notably inhibited compared to parent strain SE1457, and the mutant showed significantly decreased resistance (100- to 1000-fold) to H2O2 and CHP in both oxic and microaerobic conditions, which was fully rescued by the addition of ROS inhibitor DIP. Furthermore, deletion of srrAB resulted in decreased intracellular survival in the Ana-1 macrophages due to intracellular ROS accumulation. Complementation of srrAB in the ∆srrAB mutant restored ROS resistance and intracellular survival to wild-type levels. RNA-seq analysis revealed that srrAB deletion affected the transcription levels of 610 genes, including those involved in oxidative stress, respiratory and energy metabolism, and transition ion homeostasis. These findings were corroborated by quantitative real-time reverse transcription-PCR (qRT-PCR). In the ∆srrAB mutant, expressions of ROS-scavenging genes katA, ahpC, scdA, serp1797 and serp0483 were downregulated compared to SE1457. Electrophoretic mobility shift assay further demonstrated that phosphorylated SrrA bound to the promoter regions of srrAB, katA, ahpC, scdA, serp1797 and serp0483 genes. This study elucidates that in S. epidermidis, SrrAB is the first TCS to sense and respond upon the oxidants, directly regulating transcription levels of the genes involved in ROS scavenging and ion homeostasis, thereby facilitating S. epidermidis detoxification of ROS and adaption to the commensal environment.

ORGANISM(S): Staphylococcus epidermidis RP62A

PROVIDER: GSE277473 | GEO | 2025/03/24

REPOSITORIES: GEO

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Staphylococcus epidermidis uses the SrrAB regulatory system to modulate oxidative stress and intracellular survival in mouse macrophage cell line Ana-1

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