SarZ negatively regulates the lipase activity in Staphylococcus epidermidis

S. epidermidis plays a crucial role in maintaining the skin immunity barrier. However, when host immunity is compromised, it can also lead to skin infections and bloodstream infections. Staphylococcal lipases contribute to bacterial growth, detoxification, and immune evasion, while their esterification capabilities also give them potential biotechnological applications. S. epidermidis secretes at least two lipases, GehC and GehD, which are indirectly regulated by the global regulators Agr and SarA. SarZ, a transcription factor of the SarA family, regulates the expression of various exoproteins, but its role in regulation of lipase synthesis remains unknown. A sarZ gene knockout strain of S epidermidis previously constructed was utilized in this study. First, lipase activity was found to be significantly elevated in the sarZ mutant relative to the wild-type strain, as determined by both the olive oil agar plate assay and the p-nitrophenol assay. Subsequently, qRT-PCR experiments revealed that SarZ controls the transcription of gehC and gehD divergently. Furthermore, EMSA experiments demonstrated that the recombinant SarZ protein can directly bind to the promoter regions of gehC and gehD . These findings demonstrate that SarZ negatively regulates lipase activity by directly modulating expression of lipase genes, providing a basis for further understanding the regulatory mechanism of lipase production in S. epidermidis .