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Published on: February 19, 2019
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Rsp activates expression of the Cnt system in Staphylococcus aureus
1Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, Boston, MA, 02114-2696, USA. lvinue-santolalla@mgh.harvard.edu.
BMC Microbiology
|October 29, 2020
Summary
Rsp protein activates the cnt operon in Staphylococcus aureus, essential for metal import and virulence. This regulation occurs independently of iron levels and known repressors Fur and Zur, suggesting a role in maintaining basal metal scavenging capabilities.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Pathogenesis
Background:
- The Cnt system is vital for essential metal import in Staphylococcus aureus under metal-limiting conditions.
- This system also contributes to the virulence of S. aureus.
Purpose of the Study:
- To identify regulators of efflux pumps in S. aureus.
- To investigate the role of Rsp in regulating the cnt operon.
- To understand the interplay between Rsp, Fur, and Zur in cnt operon regulation.
Main Methods:
- Phage-based ultra-high-density transposon library screening.
- Quantitative Reverse Transcription PCR (RT-qPCR) to measure gene expression.
- Construction and analysis of single and double mutants (rsp, fur, zur).
- Electrophoretic Mobility Shift Assay (EMSA) to assess direct DNA binding.
Main Results:
- Rsp acts as an activator of the cnt operon, with a two-fold decrease in expression observed in the rsp mutant.
- Rsp-mediated activation of the cnt operon occurs under both low and high iron conditions.
- While Fur and Zur repress cnt gene expression, Rsp activation is not abolished in their absence, indicating independent or cooperative regulation.
- Purified Rsp directly binds to the promoter regions of cntK and cntA genes.
Conclusions:
- Rsp activation of the cnt operon may maintain basal staphylopine levels for metal scavenging.
- This regulation complements the metal-dependent control exerted by Fur and Zur.
- Rsp plays a significant role in S. aureus metal homeostasis and potentially virulence.
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