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Pherotype Polymorphism in Streptococcus pneumoniae Has No Obvious Effects on Population Structure and Recombination
Eric L Miller1,2, Benjamin A Evans1,3, Omar E Cornejo4
1School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, United Kingdom.
Genome Biology and Evolution
|October 10, 2017
Summary
Competence stimulating peptide (CSP) pherotypes in Streptococcus pneumoniae do not restrict genetic exchange. Recombination occurs readily between strains with different pherotypes, suggesting CSP diversity doesn't drive population structure.
Area of Science:
- Microbiology
- Genetics
- Evolutionary Biology
Background:
- Streptococcus pneumoniae natural transformation is regulated by competence stimulating peptide (CSP) signaling.
- Two dominant CSP pherotypes exist, influencing genetic exchange, but their role in population structure is debated.
Purpose of the Study:
- To investigate the role of CSP pherotypes in mediating genetic exchange within and between Streptococcus pneumoniae populations.
- To determine if pherotypes promote or restrict recombination and if they contribute to population differentiation.
Main Methods:
- Bioinformatic analysis of 4,089 Streptococcus pneumoniae genomes.
- Estimation of recombination frequencies within and between different CSP pherotypes.
Main Results:
- Extensive recombination was observed between pneumococcal populations, irrespective of pherotype.
- Marginally higher rates of genetic exchange occurred between strains with different pherotypes compared to those with the same pherotype.
- CSP pherotype variation did not appear to be a primary driver of population differentiation.
Conclusions:
- Pneumococcal pherotypes do not restrict genetic exchange and may slightly facilitate it.
- The observed effects of pherotypes on recombination are marginal, suggesting other factors drive CSP polymorphism.
- CSP balanced polymorphism does not causally underlie pneumococcal population differentiation.