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Antimicrobial peptides activate the Vibrio cholerae sigmaE regulon through an OmpU-dependent signalling pathway

Jyoti Mathur1, Brigid M Davis, Matthew K Waldor

  • 1Program in Immunology, Tufts University and Howard Hughes Medical Institute, 136 Harrison Avenue, Boston, MA 02111, USA.

Molecular Microbiology
|December 22, 2006
PubMed

Insights

Vibrio cholerae outer membrane protein OmpU is crucial for resisting antimicrobial peptides (AP). OmpU and sigma(E) work together in a pathway that senses and responds to AP-induced membrane damage.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Cellular Biology

Background:

  • Vibrio cholerae, an enteric pathogen, faces attacks from host antimicrobial peptides (AP).
  • The outer membrane protein OmpU in V. cholerae provides resistance to certain APs, like polymyxin B and P2.
  • The alternative sigma factor sigma(E) is known to regulate stress responses in bacteria.

Purpose of the Study:

  • To investigate the role of sigma(E) in V. cholerae resistance to AP.
  • To elucidate the relationship between OmpU and sigma(E) in the context of AP resistance.
  • To understand the signaling pathway by which APs trigger resistance mechanisms.

Main Methods:

  • Genetic analysis of V. cholerae strains with mutations in OmpU and sigma(E).
  • Assessment of bacterial survival and stress response activation upon exposure to sublethal concentrations of APs.
  • Biochemical assays to study protein interactions and signaling cascades.

Main Results:

  • Sigma(E) plays a critical role in V. cholerae resistance to AP.
  • OmpU is essential for basal sigma(E) expression and its activation by APs.
  • AP exposure activates sigma(E) and the associated periplasmic stress response.
  • OmpU and the protease DegS are required for AP-induced sigma(E) activation.

Conclusions:

  • OmpU and sigma(E) function in the same pathway to confer resistance to antimicrobial peptides.
  • OmpU acts as a sensor, detecting membrane perturbations caused by APs.
  • This interaction initiates a DegS-dependent signaling cascade that activates sigma(E), leading to a stress response.

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