Gene conversion maintains nonfunctional transposable elements in an obligate mutualistic endosymbiont.
Long-term bacterial endosymbionts typically exhibit reduced genomes, lack genes encoding recombination functions and transposable elements, such as insertion sequences (ISs). In sharp contrast, I found that ISs constitute 2.4% of the genome of the obligate mutualistic endosymbiont Wolbachia wBm. Although no IS copy is transpositionally functional, I show that ISs persist in wBm because of frequent recombinational gene conversion (GC) homogenizing homologous IS sequences. These results not only indicate that there exists a functional recombination molecular machinery in wBm, but they also suggest that, by slowing down the rate of IS degradation and loss, GC may represent a major force influencing reductive evolution in wBm.
Université de Poitiers, CNRS UMR 6556 Ecologie, Evolution, Symbiose, Poitiers, France. richard.cordaux@univ-poitiers.fr
Richard
R
Cordaux
D000818:Animals; D004251:DNA Transposable Elements; D005785:Gene Conversion; D009348:Nematoda / Q000382:microbiology* / Q000502:physiology; D013559:Symbiosis; D020577:Wolbachia / Q000235:genetics* / Q000502:physiology
D004251:DNA Transposable Elements