Phylogenomic Analysis of Odyssella thessalonicensis Fortifies the Common Origin of Rickettsiales, Pelagibacter ubique and Reclimonas americana Mitochondrion

Abstract

BackgroundThe 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.Methodology/Principal FindingsThe 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/SignificanceThe Reclinomonas americana mitochondrion phylogenomic study confirmed that mitochondria emerged deeply in the Rickettsiales clade and that they are closely related to Candidatus Pelagibacter ubique.

“Candidatus Finniella” (Rickettsiales, Alphaproteobacteria), Novel Endosymbionts of Viridiraptorid Amoeboflagellates (Cercozoa, Rhizaria)

“…Paracaedibacteraceae," and clade C/N were absent or poorly represented (e.g., only "Ca. Odyssella thessalonicensis"), preventing clear conclusions about the interrelationships of these lineages and the monophyly of the Rickettsiales sensu lato (44)(45)(46)(47)(48). Recently, phylogenetic analyses and gene order patterns of newly generated genomic data from additional orphan Rickettsiales (Caedibacter acanthamoebae, two strains of "Ca.…”

The Pre-Endosymbiont Hypothesis: A New Perspective on the Origin and Evolution of Mitochondria

“…However, there is currently no consensus in the literature as towhether mitochondria branch within or as sister to either of the two Rickettsiales families, oroutside of Rickettsiales altogether. Several newly identified free-living a-proteobacteria have recently been considered candidates for the title of "closest mitochondrial relative" (Brindefalk et al 2011;Georgiades et al 2011;Viklund et al 2012), but methodological issues complicate phylogenetic tree reconstructions (Thrash et al 2011;Rodrí-guez-Ezpeleta and Embley 2012), and thus the jury is still out on this point. † We do not know the evolutionary origin of most of the mitochondrial proteome (i.e., the NPC).…”

Protein and DNA Modifications: Evolutionary Imprints of Bacterial Biochemical Diversification and Geochemistry on the Provenance of Eukaryotic Epigenetics

“…4). Importantly, some of these endosymbionts like Odyssella are phylogenetically close to the alphaproteobacterial progenitor of the mitochondrion (Georgiades et al 2011), suggesting that the latter might have been an important player in the acquisition of such domains by the stem eukaryote . Prokaryotic metabolites are often synthesized via serial enzymatic modifications from amino acid or short peptide precursors (e.g., b-lactam antibiotics from tripeptides) (Walsh 2003).…”