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Regulation of type VI secretion system during Burkholderia pseudomallei infection

Yahua Chen1, Jocelyn Wong, Guang Wen Sun

  • 1Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597.

Infection and Immunity
|June 15, 2011
PubMed

Insights

The study reveals how Burkholderia pseudomallei controls its secretion systems. VirAG and BprC are essential regulators for the type VI secretion system (T6SS-1) in both lab conditions and host infections.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Type III and type VI secretion systems (T3SSs and T6SSs) are key virulence factors in Gram-negative bacteria.
  • In Burkholderia pseudomallei, T3SS-3 and T6SS-1 contribute significantly to virulence in mammalian hosts.

Purpose of the Study:

  • To elucidate the regulatory cascade controlling T3SS-3 and T6SS-1 expression in Burkholderia pseudomallei.
  • To investigate the roles of BsaN, VirAG, and BprC in regulating T6SS-1.

Main Methods:

  • Analysis of gene expression under different growth conditions (in vitro vs. host cells).
  • Identification of transcriptional start sites regulated by VirAG and BprC.
  • Assessment of bacterial virulence in macrophages and mouse models using regulator mutants.

Main Results:

  • BsaN regulates T3SS-3 effectors and T6SS-1 regulators (VirAG, BprC).
  • T6SS-1 expression is BprC-dependent in vitro, but VirAG-dependent in host cells (except for tssAB operon, which is BprC-dependent).
  • VirAG and BprC directly control T6SS-1 gene expression and are critical for virulence in macrophages and mice.

Conclusions:

  • VirAG and BprC are indispensable regulators for T6SS-1 function and Burkholderia pseudomallei virulence.
  • The regulatory mechanism differs between in vitro and host cell environments, highlighting adaptive virulence strategies.

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