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Epithelial Cell Infection Analyses with Shigella
Published on: February 9, 2024
Reduced selection leads to accelerated gene loss in Shigella
Ruth Hershberg1, Hua Tang, Dmitri A Petrov
1Department of Biological Sciences, Stanford University, Serra Mall, Stanford, CA 94305, USA. ruthersh@stanford.edu
Genome Biology
|August 10, 2007
Summary
Facultative pathogenic bacteria, Shigella, exhibit accelerated gene loss compared to pathogenic Escherichia coli. This increased gene loss in Shigella is linked to a genome-wide reduction in the effectiveness of purifying selection.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genomics
Background:
- Obligate pathogens lose more genes than facultative pathogens, and facultative pathogens lose more genes than free-living bacteria.
- Increased gene loss in obligate pathogens is hypothesized to stem from reduced purifying selection effectiveness.
- Causes of accelerated gene loss in facultative pathogens remain less explored.
Purpose of the Study:
- To investigate the rate of gene loss in facultative pathogenic bacteria, specifically comparing pathogenic Escherichia coli and Shigella.
- To determine the role of selection effectiveness in driving gene loss differences between these bacterial groups.
Main Methods:
- Comparative genomic analysis of pathogenic Escherichia coli and Shigella strains.
- Assessment of gene loss rates across bacterial genomes.
- Evaluation of the effectiveness of purifying selection genome-wide.
Main Results:
- Shigella strains demonstrate a significantly accelerated rate of gene loss compared to pathogenic Escherichia coli.
- A genome-wide reduction in the effectiveness of selection was identified as a contributing factor to accelerated gene loss in Shigella.
- Differences in selection effectiveness correlate with observed differences in gene loss rates among facultative pathogens.
Conclusions:
- Niche-limited Shigella strains exhibit a markedly higher gene loss rate than closely related pathogenic Escherichia coli.
- Reduced effectiveness of purifying selection contributes to the accelerated gene loss observed in Shigella.
- Bacterial lifestyle and pathogenicity influence selection effectiveness, thereby impacting gene loss rates.
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