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Type VI secretion systems of pathogenic and commensal bacteria mediate niche occupancy in the gut

Antonio Serapio-Palacios1, Sarah E Woodward1, Stefanie L Vogt1

  • 1Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology and Immunology, University of British Columbia, BC V6T 1Z3, Canada.

Cell Reports
|April 27, 2022
PubMed

Insights

The type VI secretion system (T6SS) is crucial for bacterial competition in the gut. Pathogens like Citrobacter rodentium use T6SS to attack rivals, while commensal bacteria use it for defense.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Host-Microbe Interactions

Background:

  • The type VI secretion system (T6SS) is a protein-targeting nanomachine found in many Gram-negative bacteria.
  • While T6SS is known for inter-bacterial competition, its role in vivo during infection is not well understood.

Purpose of the Study:

  • To investigate the role of T6SS in the colonization of Citrobacter rodentium in the murine gut.
  • To identify T6SS effectors involved in bacterial competition within the gut environment.

Main Methods:

  • Utilized Citrobacter rodentium as a model pathogen for studying bacterial infection in vivo.
  • Investigated the function of T6SS-1 in C. rodentium colonization and identified VgrG1 as a T6SS effector.
  • Assessed the role of T6SS in commensal E. coli Mt1B1 in counteracting pathogen colonization.

Main Results:

  • Citrobacter rodentium possesses two functional T6SSs, with T6SS-1 essential for colonizing the murine gastrointestinal tract.
  • VgrG1 was identified as a toxic T6SS effector of C. rodentium, inhibiting E. coli growth.
  • Commensal E. coli Mt1B1 utilizes its own T6SSs to resist C. rodentium colonization.

Conclusions:

  • T6SS is a critical weapon in bacterial warfare within the gut ecosystem.
  • Both pathogenic and commensal bacteria leverage T6SS to compete for ecological niches.
  • T6SS plays a significant role in shaping the gut microbiota composition during infection.
Keywords:
CP: MicrobiologyCitrobacter rodentiumEnterobacteriaceaeEscherichia coliT6SS effectorattaching and effacing pathogencompetitive exclusioninter-bacterial competitiontype VI secretion system

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