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A Visual Assay to Monitor T6SS-mediated Bacterial Competition
Published on: March 20, 2013
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Type 6 secretion system-mediated immunity to type 4 secretion system-mediated gene transfer
Brian T Ho1, Marek Basler, John J Mekalanos
1Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.
Science (New York, N.Y.)
|October 12, 2013
Summary
Pseudomonas aeruginosa mounts a lethal type VI secretion system (T6SS) attack against donor cells. This response, triggered by mating pair formation (Mpf) systems, may prevent the acquisition of foreign DNA.
Area of Science:
- Microbiology
- Bacterial genetics
- Cellular communication
Background:
- Gram-negative bacteria utilize the type VI secretion system (T6SS) for interbacterial antagonism.
- The Pseudomonas aeruginosa H1-locus T6SS is known to activate in response to external T6SS attacks.
Purpose of the Study:
- To investigate the triggers for Pseudomonas aeruginosa's H1-locus T6SS counterattack.
- To determine if the mating pair formation (Mpf) system of conjugative plasmids induces T6SS activity.
Main Methods:
- Genetic disruption of Mpf system components in plasmid RP4.
- Assessing T6SS activity in Pseudomonas aeruginosa recipient cells.
- Induction of T6SS by polymyxin B.
Main Results:
- The Pseudomonas aeruginosa T6SS counterattack is induced by the Mpf system of IncPα conjugative plasmid RP4.
- T6SS induction requires Mpf structural genes, not DNA transfer components.
- Membrane-perturbing agents like polymyxin B also induce T6SS activity.
Conclusions:
- Conjugative plasmids can trigger "donor-directed T6SS attacks" in recipient bacteria.
- This T6SS response is linked to membrane perturbation sites caused by Mpf.
- The T6SS may function to block the uptake of foreign DNA during conjugation.
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