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DNA-Binding Protein HU Coordinates Pathogenicity in Vibrio parahaemolyticus
Ngoc Quang Phan1, Takashi Uebanso2, Takaaki Shimohata1
1Department of Preventive Environment and Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.
Journal of Bacteriology
|July 8, 2015
Summary
Bacterial HU proteins regulate Vibrio parahaemolyticus virulence, specifically controlling type III secretion system 1 (T3SS1) gene expression and cytotoxicity independently of growth rate.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Nucleoid-associated protein HU is crucial for bacterial gene regulation, influencing growth, motility, metabolism, and virulence.
- Vibrio parahaemolyticus pathogenicity is linked to rapid growth and type III secretion system 1 (T3SS1)-mediated cytotoxicity.
- The specific role of HU in V. parahaemolyticus pathogenicity remained uncharacterized.
Purpose of the Study:
- To investigate the role of HU proteins (HUα and HUβ) in the pathogenicity of Vibrio parahaemolyticus.
- To determine whether HU influences bacterial growth rate, virulence factor expression, or cytotoxicity.
- To elucidate the relationship between HU-mediated regulation, bacterial growth, and virulence factor expression.
Main Methods:
- Construction and analysis of V. parahaemolyticus strains with single and double deletions of HU subunits (Δvp2911, Δvp0920, and ΔHUs [Δvp0920 Δvp2911]).
- Quantitative assessment of bacterial growth rates for wild-type and mutant strains.
- Measurement of T3SS1-related gene expression levels (exsA, exsD, vp1680, vp1671) using quantitative PCR.
- Evaluation of cytotoxicity against HeLa cells.
Main Results:
- Deletion of both HU subunits (ΔHUs strain) significantly reduced the growth rate compared to the wild type.
- The ΔHUs strain exhibited reduced expression of key T3SS1 genes and consequently decreased cytotoxicity to HeLa cells.
- Deleting the negative regulator exsD in the ΔHUs strain restored T3SS1 gene expression and cytotoxicity, but not the growth rate.
- These findings indicate that HU regulates T3SS1 gene expression and cytotoxicity independently of its effect on growth rate.
Conclusions:
- Bacterial HU proteins play a significant role in regulating Vibrio parahaemolyticus pathogenicity.
- HU controls the expression of virulence factors, specifically T3SS1, and bacterial cytotoxicity.
- This regulation occurs independently of the bacterial growth rate, highlighting a distinct mechanism of virulence control.
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