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A Visual Assay to Monitor T6SS-mediated Bacterial Competition
08:45

A Visual Assay to Monitor T6SS-mediated Bacterial Competition

Published on: March 20, 2013

16.0K

A type VI secretion system delivers a cell wall amidase to target bacterial competitors

Tietao Wang1, Zhaoyu Hu2, Xiao Du1

  • 1Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, China.

Molecular Microbiology
|April 13, 2020
PubMed

Insights

Pseudomonas aeruginosa uses its type VI secretion system to deliver the AmpDh3 protease to prey bacteria, causing cell wall hydrolysis and death. A self-protection protein, PA0808, prevents self-lysis, conferring a competitive advantage.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Molecular Biology

Background:

  • Pseudomonas aeruginosa possesses three zinc proteases (AmpD, AmpDh2, AmpDh3) involved in cell wall turnover.
  • AmpD is cytoplasmic and linked to muropeptide recycling and antibiotic resistance.
  • AmpDh2 is a periplasmic enzyme, while another paralog is membrane-anchored.

Purpose of the Study:

  • To investigate the role of AmpDh3 in bacterial competition.
  • To determine the mechanism by which P. aeruginosa delivers AmpDh3 to prey bacteria.
  • To identify mechanisms of self-protection against AmpDh3.

Main Methods:

  • Utilized the type VI secretion system locus II (H2-T6SS) for delivery.
  • Observed AmpDh3 hydrolysis of prey bacterial cell walls.
  • Identified PA0808 as a self-protective protein.

Main Results:

  • P. aeruginosa delivers AmpDh3 to the periplasm of prey bacteria via H2-T6SS.
  • AmpDh3 hydrolyzes prey peptidoglycan, leading to bacterial killing.
  • PA0808 protects P. aeruginosa from AmpDh3-mediated lysis.
  • AmpDh3-PA0808 homologs are widespread in Gram-negative bacteria.

Conclusions:

  • The H2-T6SS-mediated delivery of AmpDh3 provides a growth advantage to P. aeruginosa in competition.
  • The AmpDh3-PA0808 system represents an evolutionary advantage for bacterial interactions.
  • This mechanism highlights a novel strategy for bacterial warfare and survival.
Keywords:
bacterial competitioncell wall degradationpeptidoglycan hydrolasetype 6 secretion system

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