Gene conversion maintains nonfunctional transposable elements in an obligate mutualistic endosymbiont
1Université de Poitiers, CNRS UMR 6556 Ecologie, Evolution, Symbiose, Poitiers, France. richard.cordaux@univ-poitiers.fr
Molecular Biology and Evolution
|May 6, 2009
Summary
Obligate endosymbionts usually lose insertion sequences (ISs). However, Wolbachia wBm retains ISs due to frequent gene conversion (GC), which homogenizes IS sequences and influences reductive evolution.
Area of Science:
- Microbiology
- Genomics
- Evolutionary Biology
Background:
- Long-term bacterial endosymbionts often display genome reduction.
- These endosymbionts typically lack recombination genes and transposable elements like insertion sequences (ISs).
Purpose of the Study:
- To investigate the persistence of insertion sequences (ISs) in the obligate mutualistic endosymbiont Wolbachia wBm.
- To understand the mechanisms maintaining ISs despite their lack of transpositional activity.
Main Methods:
- Genomic analysis of Wolbachia wBm.
- Investigation of sequence homogenization mechanisms.
Main Results:
- Insertion sequences (ISs) constitute 2.4% of the Wolbachia wBm genome.
- No IS copy in wBm is transpositionally functional.
- ISs persist in wBm due to frequent homologous recombination via gene conversion (GC).
Conclusions:
- Wolbachia wBm possesses a functional recombination molecular machinery.
- Gene conversion (GC) slows IS degradation and loss, potentially driving reductive evolution in wBm.
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