| 1. |
- Andersson, Siv, et al.
(författare)
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On the origin of mitochondria: a genomics perspective.
- 2003
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2970. ; 358:1429, s. 165-177
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Tidskriftsartikel (refereegranskat)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 f-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 f-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.
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| 2. |
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| 3. |
- Kurland, Charles, et al.
(författare)
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Horizontal gene transfer: a critical view
- 2003
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 100:17, s. 9658-9662
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Forskningsöversikt (refereegranskat)abstract
- It has been suggested that horizontal gene transfer (HGT) is the "essence of phylogeny." In contrast, much data suggest that this is an exaggeration resulting in part from a reliance on inadequate methods to identify HGT events. In addition, the assumption that HGT is a ubiquitous influence throughout evolution is questionable. Instead, rampant global HGT is likely to have been relevant only to primitive genomes. In modern organisms we suggest that both the range and frequencies of HGT are constrained most often by selective barriers. As a consequence those HGT events that do occur most often have little influence on genome phylogeny. Although HGT does occur with important evolutionary consequences, classical Darwinian lineages seem to be the dominant mode of evolution for modern organisms.
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| 4. |
- Kurland, Charles, et al.
(författare)
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Origin and evolution of the mitochondrial proteome
- 2000
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Ingår i: Microbiology and Molecular Biology Reviews. - 1092-2172. ; 64:4, s. 786-786
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Tidskriftsartikel (refereegranskat)abstract
- The endosymbiotic theory for the origin of mitochondria requires substantial modification. The three identifiable ancestral sources to the proteome of mitochondria are proteins descended from the ancestral alpha -proteobacteria symbiont, proteins with no homology to bacterial orthologs, and diverse proteins with bacterial affinities not derived from alpha -proteobacteria. Random mutations in the form of deletions large and small seem to have eliminated nonessential genes from the endosymbiont-mitochondrial genome lineages. This process, together with the transfer of genes from the endosymbiont-mitochondrial genome to nuclei, has led to a marked reduction in the size of mitochondrial genomes. All proteins of bacterial descent that are encoded by nuclear genes were probably transferred by the same mechanism, involving the disintegration of mitochondria ol bacteria by the intracellular membranous vacuoles of cells to release nucleic acid fragments that transform the nuclear genome. This ongoing process has intermittently introduced bacterial genes to nuclear. genomes. The genomes of the last common ancestor of all organisms, in particular of mitochondria, encoded cytochrome oxidase homologues. There are no phylogenetic indications either in the mitochondrial proteome ol in the nuclear genomes that the initial or subsequent function of the ancestor to the mitochondria was anaerobic. In contrast there are indications that relatively advanced eukaryotes adapted to anaerobiosis by dismantling their mitochondria and refitting them as hydrogenosomes. Accordingly, a continuous history of aerobic respiration seems to have been the fate of most mitochondrial lineages. The initial phases of this history may have involved aerobic respiration by the symbiont functioning as a scavenger of toxic oxygen. The transition to mitochondria capable of active ATP export to the host cell seems to have required recruitment of eukaryotic ATP transport proteins from the nucleus. The identity of the ancestral host of the alpha -proteobacterial endosymbiont is unclear; but there is no indication that it was an autotroph. There are no indications of a specific alpha -proteobacterial origin to genes for glycolysis. In the absence of data to the contrary it is assumed that the ancestral host cell was a heterotroph.
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| 5. |
- Kurland, Charles
(författare)
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Something for everyone - Horizontal gene transfer in evolution
- 2000
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Ingår i: EMBO Reports. - : EMBO. - 1469-221X .- 1469-3178. ; 1:2, s. 92-95
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Tidskriftsartikel (refereegranskat)abstract
- Horizontal gene transfer (HGT) is a sensational topic largely because its exploitation to date has been primarily journalistic. Properly packaged it captures the attention of a sensitized lay public and peps up circulation. HGT provides technical challenges for academic scientists as well as market analysts. For fans of science fiction as well as for environmental pessimists, HGT is the stuff of doomsday prophecies. Interest in HGT might even be seen as a reasonable response to the recent acquisition of genome sequence data and the need to understand how genomes exchange sequences.
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