Dynamics of reductive genome evolution in mitochondria and obligate intracellular microbes.
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Issue Date
2007-02
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Show full item recordAbstract
Reductive evolution in mitochondria and obligate intracellular microbes has led to a significant reduction in their genome size and guanine plus cytosine content (GC). We show that genome shrinkage during reductive evolution in prokaryotes follows an exponential decay pattern and provide a method to predict the extent of this decay on an evolutionary timescale. We validated predictions by comparison with estimated extents of genome reduction known to have occurred in mitochondria and Buchnera aphidicola, through comparative genomics and by drawing on available fossil evidences. The model shows how the mitochondrial ancestor would have quickly shed most of its genome, shortly after its incorporation into the protoeukaryotic cell and prior to codivergence subsequent to the split of eukaryotic lineages. It also predicts that the primary rickettsial parasitic event would have occurred between 180 and 425 million years ago (MYA), an event of relatively recent evolutionary origin considering the fact that Rickettsia and mitochondria evolved from a common alphaproteobacterial ancestor. This suggests that the symbiotic events of Rickettsia and mitochondria originated at different time points. Moreover, our model results predict that the ancestor of Wigglesworthia glossinidia brevipalpis, dated around the time of origin of its symbiotic association with the tsetse fly (50-100 MYA), was likely to have been an endosymbiont itself, thus supporting an earlier proposition that Wigglesworthia, which is currently a maternally inherited primary endosymbiont, evolved from a secondary endosymbiont.Citation
Dynamics of reductive genome evolution in mitochondria and obligate intracellular microbes. 2007, 24 (2):449-56 Mol. Biol. Evol.Affiliation
Department of Environmental Microbiology, Helmholtz Center for Infection Research, Braunschweig, Germany.Journal
Molecular biology and evolutionPubMed ID
17108184Type
ArticleLanguage
enISSN
0737-4038ae974a485f413a2113503eed53cd6c53
10.1093/molbev/msl174
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