Discovery of antiphage systems in the lactococcal plasmidome
Andriana Grafakou1, Cas Mosterd1, Matthias H Beck1
1School of Microbiology & APC Microbiome Ireland, University College Cork, Cork T12 YT20, Ireland.
Nucleic Acids Research
|August 9, 2024
Summary
Researchers discovered seven novel antiphage systems in lactococci plasmids, enhancing bacterial defense mechanisms. These systems, acting post-injection, offer broad phage resistance and are widespread in bacteria.
Area of Science:
- Microbiology
- Bacteriology
- Genetics
Background:
- Lactococci were historically significant for discovering plasmid-borne phage defense systems.
- Recent interest in novel antiphage systems in lactic acid bacteria is driven by 'defense islands' in other bacteria.
Purpose of the Study:
- To identify and characterize novel antiphage systems in lactococcal plasmids.
- To investigate the prevalence and mechanisms of these defense systems.
Main Methods:
- Systematic screening of 321 plasmid sequences from 53 lactococcal strains.
- Evaluation of 198 candidate antiphage systems.
- Structure and domain prediction for mechanism insights.
Main Results:
- Discovery of seven novel antiphage systems and identification of five known systems.
- All identified systems provide resistance against common lactococcal phages.
- Most systems function as abortive infection mechanisms, acting post-DNA injection.
Conclusions:
- Lactococcal plasmids are a valuable source of undiscovered antiphage systems.
- Novel systems identified are widespread among bacterial species.
- Understanding these systems aids in developing new phage resistance strategies.
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