On the origin of mitochondria: a genomics perspective

Abstract

The availability of complete genome sequence data from both bacteria and eukaryotes provides information about the contribution of bacterial genes to the origin and evolution of mitochondria. Phylogenetic analyses based on genes located in the mitochondrial genome indicate that these genes originated from within the a-proteobacteria. A number of ancestral bacterial genes have also been transferred from the mitochondrial to the nuclear genome, as evidenced by the presence of orthologous genes in the mitochondrial genome in some species and in the nuclear genome of other species. However, a multitude of mitochondrial proteins encoded in the nucleus display no homology to bacterial proteins, indicating that these originated within the eukaryotic cell subsequent to the acquisition of the endosymbiont. An analysis of the expression patterns of yeast nuclear genes coding for mitochondrial proteins has shown that genes predicted to be of eukaryotic origin are mainly translated on polysomes that are free in the cytosol whereas those of putative bacterial origin are translated on polysomes attached to the mitochondrion. The strong relationship with a-proteobacterial genes observed for some mitochondrial genes, combined with the lack of such a relationship for others, indicates that the modern mitochondrial proteome is the product of both reductive and expansive processes.

Dual targeting of the protein disulfide isomerase RB60 to the chloroplast and the endoplasmic reticulum

“…This evolutionary path of organellar proteins might be more prevalent than previously expected, because comparison of proteomes of Arabidopsis chloroplast and of cyanobacterium suggested that only Ϸ35% of chloroplast proteins originated from the cyanobacterium genome (44). Likewise, studies of the mitochondrial proteome indicate that its evolution included recruitment of ␣-proteobacterial gene products as well (45). It seems that RB60 gained its chloroplast function in addition to its role in the ER.…”

On the Evolution of the tRNA-Dependent Amidotransferases, GatCAB and GatDE

“…38 The Pet112 family forms a group with the α-Proteobacteria, with a specific relationship with the Rickettsia, this result indicates Pet112 is not a component of the nuclear line of decent but is of mitochondrial origin. 39,40 The function of Pet112, the mitochondrial GatB-like protein, in eukaryotes such as S. cerevisae is unresolved. Our alignment of Pet112 with GatB and GatE shows conservation of the kinase active site (Supplemental Fig.…”

Tumor metabolism, cancer cell transporters, and microenvironmental resistance

“…MCT-1 is expressed on the plasma membrane of the cell 54 . According to the endosymbiotic theory, mitochondria originated from bacteria that were engulfed by the plasma membrane [55][56][57] . Therefore, it is not surprising that MCT-1 is localized at both the mitochondrial and peroxisomal membranes (while evolution peroxisomes originated from mitochondria) 58,59 .…”