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Activation of the RcsC/YojN/RcsB phosphorelay system attenuates Salmonella virulence

Chakib Mouslim1, Mónica Delgado, Eduardo A Groisman

  • 1Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8230, St Louis, MO 63110, USA.

Molecular Microbiology
|October 8, 2004
PubMed

Insights

Salmonella virulence is reduced when the RcsC/YojN/RcsB system is constantly active due to an rcsC mutation. Suppressing this system is crucial for bacterial pathogens to effectively infect hosts.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Bacterial pathogens regulate virulence factor expression based on host environment.
  • Genes detrimental to infection are often suppressed during pathogen colonization.
  • The RcsC/YojN/RcsB system's role in virulence regulation is not fully understood.

Purpose of the Study:

  • To investigate the role of the RcsC/YojN/RcsB system in Salmonella virulence.
  • To identify genes whose expression is suppressed during infection and their impact on pathogenesis.

Main Methods:

  • Generating and analyzing Salmonella rcsC constitutive mutants.
  • Assessing bacterial virulence phenotypes, including invasion, survival, and host protection.
  • Investigating the genetic dependencies of virulence attenuation, including rcsB and rcsA.

Main Results:

  • Constitutive activation of the RcsC/YojN/RcsB system via an rcsC mutation significantly attenuated Salmonella virulence.
  • Restoration of virulence by mutating the rcsB gene confirmed the role of RcsB-regulated genes.
  • Virulence defects included reduced macrophage phagocytosis, impaired invasion, and decreased intracellular survival.
  • The colanic acid capsule synthesis operon (cps) was implicated in the virulence attenuation phenotype.

Conclusions:

  • Suppression of specific RcsB-regulated genes is essential for Salmonella virulence.
  • Aberrant activation of the RcsC/YojN/RcsB system hinders bacterial infection by upregulating detrimental factors.
  • Pathogen success requires downregulating gene products that interfere with virulence functions.

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