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Bordetella BcrH1 and BcrH2 Are Specific Chaperones for the Pore-Forming Complex
Yuya Kishino1, Toshinobu Ogawa1, Hiroko Sato1
1Laboratory of Bacterial Infection, Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
Microbiology and Immunology
|December 8, 2025
Summary
Bordetella type III secretion system proteins BcrH1 and BcrH2 are crucial chaperones. They maintain the stability of virulence proteins BopB and BopD, impacting infection establishment and host cell toxicity.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Bordetella utilizes a type III secretion system (T3SS) to deliver virulence proteins essential for infection.
- The T3SS components in Bordetella are encoded within the bsc region, including the bcrH1 and bcrH2 genes.
Purpose of the Study:
- To investigate the functional roles of BcrH1 and BcrH2 proteins within the Bordetella T3SS.
- To determine if BcrH1 and BcrH2 are involved in the stability or secretion of key T3SS effectors.
Main Methods:
- Generation of BcrH1-deficient and BcrH2-deficient Bordetella strains.
- Analysis of type III secreted proteins BopB and BopD levels in whole cell fractions.
- Assessment of hemolytic activity and host cell toxicity.
- Immunoprecipitation assays using anti-BcrH1 and anti-BcrH2 antibodies.
Main Results:
- Deficiency in BcrH1 or BcrH2 led to reduced levels of BopB and BopD, respectively.
- BcrH1 and BcrH2 deficient strains exhibited significantly lower hemolytic activity and cell toxicity compared to wild-type.
- BopB and BopD were co-precipitated with BcrH1 and BcrH2, respectively.
Conclusions:
- BcrH1 and BcrH2 function as specific chaperones for Bordetella virulence proteins BopB and BopD.
- These chaperones are essential for maintaining the stability of BopB and BopD, thereby influencing T3SS function and virulence.
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