title: Phylogenomic analysis of Odyssella thessalonicensis fortifies the common origin of Rickettsiales, Pelagibacter ubique and Reclimonas americana mitochondrion.
abstract: BACKGROUND
  The evolution of the Alphaproteobacteria and origin of the mitochondria are topics of considerable debate. Most studies have placed the mitochondria ancestor within the Rickettsiales order. Ten years ago, the bacterium Odyssella thessalonicensis was isolated from Acanthamoeba spp., and the 16S rDNA phylogeny placed it within the Rickettsiales. Recently, the whole genome of O. thessalonicensis has been sequenced, and 16S rDNA phylogeny and more robust and accurate phylogenomic analyses have been performed with 65 highly conserved proteins.
  
  
  RESULTS
  The results suggested that the O. thessalonicensis emerged between the Rickettsiales and other Alphaproteobacteria. The mitochondrial proteins of the Reclinomonas americana have been used to locate the phylogenetic position of the mitochondrion ancestor within the Alphaproteobacteria tree. Using the K tree score method, nine mitochondrion-encoded proteins, whose phylogenies were congruent with the Alphaproteobacteria phylogenomic tree, have been selected and concatenated for Bayesian and Maximum Likelihood phylogenies. The Reclinomonas americana mitochondrion is a sister taxon to the free-living bacteria Candidatus Pelagibacter ubique, and together, they form a clade that is deeply rooted in the Rickettsiales clade.
  
  
  CONCLUSIONS
  The Reclinomonas americana mitochondrion phylogenomic study confirmed that mitochondria emerged deeply in the Rickettsiales clade and that they are closely related to Candidatus Pelagibacter ubique.
authors.affiliation: Unité de Recherche en Maladies Infectieuses Tropicales Emergentes, CNRS-IRD UMR 6236, Faculté de la Médecine, Université de la Méditerranée, Marseille, France.
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Georgiades
authors.forename: Mohammed-Amine
authors.initials: MA
authors.lastname: Madoui
authors.forename: Phuong
authors.initials: P
authors.lastname: Le
authors.forename: Catherine
authors.initials: C
authors.lastname: Robert
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
mesh_terms: D020561:Alphaproteobacteria / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D019143:Evolution, Molecular; D023281:Genomics; D008928:Mitochondria / Q000235:genetics*; D010802:Phylogeny
chemical_list: D004269:DNA, Bacterial; D004272:DNA, Mitochondrial