Figure 1.
Key time points in mitochondria evolution.
Time point A represents pre-mitochondria, the last common ancestor of mitochondria and alphaproteobacteria. Time point B represents proto-mitochondria, the last common ancestor of all contemporary mitochondria. Time point C represents the origin of mitochondria.
Figure 2.
Reconstructed metabolism of proto-mitochondria.
Black solid lines represent genes identified only in our reconstruction. Dotted lines represent missing genes in an otherwise complete pathway in our reconstruction. Red solid lines represent genes also present in Gabaldon et al. 2007.
Figure 3.
Function breakdown of reconstructed metabolisms of mitochondria ancestors.
Within each class, from left to right are 1) the reconstructed proto-mitochondria in our study, 2) the reconstructed proto-mitochondria by Gabaldon et al. 2007, 3) the reconstructed pre-mitochondria in our study, 4) human mitochondrial proteome.
Table 1.
Comparison between proto-mitochondrial reconstructions of this study and Gabaldon et al. 2007.
Table 2.
List of mitochondria-derived nuclear genes involved in eukaryotic lipid metabolism.
Figure 4.
A species tree of alphaproteobacteria and mitochondria.
The Bayesian consensus tree was based on concatenated protein sequences of 55 mitochondrial and nuclear genes. The tree was rooted using 8 beta- and gammaproteobacteria as the outgroup, as described in the methods. Asterisks indicate 5 newly sequenced Rickettsiales species. The posterior probability support values of the internal nodes are greater than 0.9 unless as indicated in the tree. Branches of several lineages are shortened for display purpose. The distribution of ATP/ADP translocase, flagella genes, cbb3 cytochrome oxidase and bd-quinol cytochrome oxidase in Rickettsiales and mitochondria is displayed besides the lineages.
Figure 5.
Reconstructed metabolism of pre-mitochondria.
Black solid lines represent genes identified in our reconstruction while dotted lines represent missing genes in an otherwise complete pathway. Red lines represent genes present in proto-mitochondria in Figure 2.
Figure 6.
The synteny of flagellar genes.
Holosporaceae, Candidatus Midichloriaceae, and free-living alphaproteobacteria representatives are highlighted in green, red and black respectively. Each arrow represents a gene in the cluster. Genome rearrangements are shown as dotted lines between two genes, with the distance between them shown above the lines. Because of the incomplete nature of some genome assemblies, the exact distance between two genes could not be determined. In this case, a minimum distance was estimated as the sum of distances of each gene to the end of the contig it was located in. For the same reason, the orientation of some genes could not be determined (indicated by asterisks below the genes).