A Novel Human-Infection-Derived Bacterium Provides Insights into the Evolutionary Origins of Mutualistic Insect-Bacterial Symbioses

作者：Clayton Adam L^*; Oakeson Kelly F; Gutin Maria; Pontes Arthur; Dunn Diane M; von Niederhausern Andrew C; Weiss Robert B; Fisher Mark; Dale Colin

来源：PLoS Genetics, 2012, 8(11): e1002990.

DOI：10.1371/journal.pgen.1002990

Despite extensive study, little is known about the origins of the mutualistic bacterial endosymbionts that inhabit approximately 10% of the world's insects. In this study, we characterized a novel opportunistic human pathogen, designated "strain HS," and found that it is a close relative of the insect endosymbiont Sodalis glossinidius. Our results indicate that ancestral relatives of strain HS have served as progenitors for the independent descent of Sodalis-allied endosymbionts found in several insect hosts. Comparative analyses indicate that the gene inventories of the insect endosymbionts were independently derived from a common ancestral template through a combination of irreversible degenerative changes. Our results provide compelling support for the notion that mutualists evolve from pathogenic progenitors. They also elucidate the role of degenerative evolutionary processes in shaping the gene inventories of symbiotic bacteria at a very early stage in these mutualistic associations.

• 出版日期2012-11