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Acidic pH is required for the functional assembly of the type III secretion system encoded by Salmonella

Catherine Rappl1, Jörg Deiwick, Michael Hensel

  • 1Lehrstuhl für Bakteriologie, Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität München, Munich, Germany.

FEMS Microbiology Letters
|October 14, 2003
PubMed

Insights

Acidic conditions increase Salmonella enterica

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogenesis

Background:

  • Salmonella enterica utilizes two type III secretion systems (T3SS) for host cell interaction.
  • The Salmonella pathogenicity island 2 (SPI2)-encoded T3SS is crucial for intracellular replication and survival within phagocytes.

Purpose of the Study:

  • To investigate how acidic pH affects the protein levels and assembly of the SPI2 T3SS in Salmonella.
  • To understand the role of environmental stimuli in modulating T3SS function for effector protein translocation.

Main Methods:

  • Analysis of T3SS subunit protein levels and subcellular localization under varying pH conditions (acidic vs. neutral).
  • Assessment of SsaC protein oligomerization and its correlation with secretion.
  • Investigating the impact of environmental stimuli on SPI2 gene expression and T3SS assembly.

Main Results:

  • Acidic pH elevated SsaC protein levels without altering operon expression.
  • Acidic pH induced SsaC subunit oligomerization, forming a functional secretin pore.
  • Environmental stimuli, similar to the intraphagosomal habitat, influence SPI2 gene expression.

Conclusions:

  • Acidic pH modulates the assembly of a functional SPI2 T3SS in Salmonella.
  • Environmental cues regulate both the expression and assembly of the SPI2 T3SS for effective pathogenesis.
  • This study proposes a mechanism by which Salmonella adapts its secretion machinery to the host environment.

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