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Characterization of the type III secretion associated low calcium response genes of Vibrio parahaemolyticus

Darren Sarty1, Noel T Baker, Euan L Thomson

  • 1Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.

Canadian Journal of Microbiology
|November 14, 2012
PubMed

Insights

Researchers optimized a secretion assay for Vibrio parahaemolyticus type III secretion system 1 (T3SS-1). This method identified new T3SS-1 substrates and implicated low calcium response genes in cytotoxicity.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogen Research

Background:

  • Vibrio parahaemolyticus is a major cause of bacterial gastroenteritis.
  • Type III secretion systems (T3SS-1 and T3SS-2) are key virulence factors, secreting effector proteins.
  • Many predicted T3SS-1 substrates remain uncharacterized due to detection challenges.

Purpose of the Study:

  • To develop and optimize a reliable secretion assay for V. parahaemolyticus T3SS-1.
  • To identify novel T3SS-1 secreted proteins.
  • To investigate the role of low calcium response genes in T3SS-1 secretion and cytotoxicity.

Main Methods:

  • Development and optimization of a V. parahaemolyticus T3SS-1 secretion assay.
  • Utilizing proteomic approaches to identify secreted proteins.
  • Generating isogenic mutants in putative low calcium response genes.

Main Results:

  • Optimized assay conditions require magnesium and low calcium for T3SS-1 substrate secretion.
  • Proteomics identified known and novel V. parahaemolyticus secreted effectors.
  • Mutants in low calcium response genes showed altered secretion and reduced host-cell cytotoxicity.

Conclusions:

  • The developed secretion assay enables reliable detection of T3SS-1 substrates.
  • New V. parahaemolyticus T3SS-1 substrates were identified.
  • Low calcium response genes play a role in T3SS-1 mediated virulence and cytotoxicity.

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