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Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling
Published on: June 25, 2015
Capsule expression regulated by a two-component signal transduction system in Streptococcus iniae.
Shelly Bolotin1, Jeffrey D Fuller, Darrin J Bast
1Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
FEMS Immunology and Medical Microbiology
|June 1, 2007
Summary
Streptococcus iniae capsule production is regulated by the sivS/R two-component system (TCS). This TCS is crucial for evading phagocytosis and maintaining cell shape, impacting virulence.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Streptococcus iniae is an important fish and human pathogen.
- Bacterial capsule production is often linked to virulence.
- Understanding virulence factors is key to controlling infections.
Purpose of the Study:
- To identify genes regulating Streptococcus iniae capsule production.
- To investigate the role of a novel two-component system (TCS), sivS/R, in virulence.
- To elucidate the function of sivS/R in capsule expression and bacterial evasion of host defenses.
Main Methods:
- Tn917 transposon mutagenesis to identify capsule-associated genes.
- Construction of a sivS/R deletion-insertion mutant.
- Real-time PCR to assess capsule operon transcription.
- Whole human blood killing assays to evaluate phagocytosis resistance.
- Transmission electron microscopy to examine cell morphology and exopolysaccharide presence.
Main Results:
- A mutant with transposon insertion in the sivS/R TCS was identified.
- The sivS/R mutant showed significantly reduced transcription of the capsule operon gene, cpsA.
- The mutant was susceptible to phagocytosis by human blood, unlike the parent strain.
- Electron microscopy revealed loss of exopolysaccharide and aberrant cell morphology in the mutant.
Conclusions:
- The sivS/R TCS regulates Streptococcus iniae capsule expression at the transcriptional level.
- Capsule production mediated by sivS/R is essential for evading phagocytosis.
- The sivS/R system influences bacterial cell integrity and morphology, impacting virulence.
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