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A Visual Assay to Monitor T6SS-mediated Bacterial Competition
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Published on: March 20, 2013

Separate inputs modulate phosphorylation-dependent and -independent type VI secretion activation.

Julie M Silverman1, Laura S Austin, FoSheng Hsu

  • 1Department of Microbiology, University of Washington, Seattle, WA 98195, USA.

Molecular Microbiology
|October 25, 2011
PubMed
Summary
This summary is machine-generated.

Pseudomonas aeruginosa uses the H1-T6SS secretion system for inter-bacterial protein delivery. Two distinct regulatory pathways, TagF and TPP, control this system, with surface growth activating H1-T6SS exclusively via TPP.

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Area of Science:

  • Microbiology
  • Bacterial Secretion Systems
  • Cellular Communication

Background:

  • The type VI secretion system (T6SS) in Pseudomonas aeruginosa is crucial for delivering effector proteins to other bacterial cells.
  • Efficient delivery requires precise temporal and spatial control, with export typically repressed under planktonic conditions.

Purpose of the Study:

  • To elucidate the regulatory pathways governing the H1-T6SS in Pseudomonas aeruginosa.
  • To identify mechanisms that ensure efficient and controlled secretion of effector proteins.

Main Methods:

  • Investigated the role of TagF, a T6S-associated protein, as a posttranslational repressor.
  • Analyzed the previously identified threonine phosphorylation pathway (TPP).
  • Examined effector output levels and genetic requirements under different regulatory conditions, including surface growth.

Main Results:

  • Identified TagF as a posttranslational repressor of the H1-T6SS.
  • Both TagF derepression and TPP stimulation lead to secretory ATPase recruitment but result in different effector outputs.
  • Surface growth was identified as a specific cue activating H1-T6SS exclusively through the TPP.

Conclusions:

  • Two distinct pathways, TagF-mediated posttranslational regulation and TPP, control H1-T6SS activity.
  • The TPP pathway is specifically activated by surface growth, ensuring secretion during cell-contact conditions.
  • This coordinated regulation prevents wasteful effector release by linking secretion to specific environmental cues and growth conditions.