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Evolution of DNA double-strand break repair by gene conversion: coevolution between a phage and a
Koji Yahara1, Ryota Horie, Ichizo Kobayashi
1Laboratory of Social Genome Sciences, Department of Medical Genome Sciences, Graduate School of Frontier Science and Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Genetics
|April 6, 2007
Summary
DNA repair evolved as a crucial factor in the origin of sex, driven by bacteriophage infections. Modeling antagonistic coevolution revealed repair allele evolution depends on the ratio of burst sizes under damage versus normal conditions.
Area of Science:
- Evolutionary Biology
- Molecular Biology
- Genetics
Background:
- Genome damage necessitates repair mechanisms.
- Bacteriophage DNA entering bacteria can trigger recombinational repair.
- Antagonistic coevolution between phages and bacteria drives genetic innovation.
Purpose of the Study:
- To model the coevolution of bacteriophages and bacteria concerning DNA repair.
- To investigate the evolutionary advantage of DNA repair in the context of phage-bacterial interactions.
- To determine the factors influencing the evolution of repair alleles in phage genomes.
Main Methods:
- Developed a mathematical model of antagonistic coevolution.
- Assigned fitness values to phage and bacterial genotypes based on infection probabilities and costs.
- Analyzed the conditions under which DNA repair alleles become evolutionarily advantageous.
Main Results:
- The evolution of the DNA repair allele is contingent on the ratio of burst sizes (b(1)/b(0)).
- This ratio reflects the impact of unrepaired double-strand breaks on host cell physiology.
- The evolutionary advantage of DNA repair was only apparent after incorporating this burst size ratio.
Conclusions:
- DNA repair plays a significant role in the evolutionary dynamics between phages and bacteria.
- The cost of unrepaired genome damage is a key driver for the evolution of repair mechanisms.
- Understanding these coevolutionary dynamics sheds light on the origin of sex and genome maintenance strategies.
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