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Bacteriophages benefit from mobilizing pathogenicity islands encoding immune systems against competitors
Alfred Fillol-Salom1, Jakob T Rostøl1, Adaeze D Ojiogu2
1MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK.
Cell
|August 19, 2022
Summary
Phage-inducible chromosomal islands (PICIs) carry diverse anti-phage systems. Helper phages mobilize these systems, providing broad immunity against phages and other mobile elements, shaping bacterial evolution.
Area of Science:
- Bacteriology
- Microbial Ecology
- Genetics
Background:
- Bacteria possess diverse, mobile anti-phage defense systems, but their variability and mobility mechanisms are poorly understood.
- Phage-inducible chromosomal islands (PICIs) are mobile genetic elements known to interact with phages.
Purpose of the Study:
- To investigate the role of PICIs in bacterial defense and horizontal gene transfer.
- To elucidate the mechanisms by which PICIs and their defense systems are mobilized and spread.
Main Methods:
- Analysis of PICI-encoded defense systems.
- Investigating the role of helper phages in PICI dissemination.
- Assessing the immunity conferred by PICI systems against various mobile genetic elements.
Main Results:
- PICIs harbor a wide array of defense mechanisms against phages.
- Helper phages can disseminate PICI-encoded defense systems within and between bacterial genera.
- These systems confer broad immunity, inhibiting not only phage replication but also plasmid and non-cognate PICI transfer.
- Phages mobilize PICI systems to compete with other mobile genetic elements.
Conclusions:
- PICIs are key mediators of bacterial anti-phage defense and horizontal gene transfer.
- Phages and PICIs engage in mutualistic interactions, driving bacterial community dynamics and evolution.
- Mobilization of PICIs by phages offers benefits to phages, PICIs, and bacteria, influencing microbial ecosystems.
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