Evolution of mitochondria

Conserved motifs reveal details of ancestry and structure in the small TIM chaperones of the mitochondrial intermembrane space. Mol Biol Evol 24 1149-1160 Gray MW, Burger G, Lang BF (2001) The origin and early evolution of mitochondria. 

Iron-Sulfur Cluster Biosynthesis and the Evolution of Mitochondria... 

Fig. 7.2. The vast majority of mitochondrial proteins did not originate from the ancestral a-proteobacterial endosymbiont but from a variety of eukaryotic, eubacterial, and archaeal sources (Gabaldon and Huynen 2004 Esser et al. 2004 Timmis et al. 2004). The evolution of mitochondria was not only accompanied by a substantial loss of superfluous genes, but also by the transfer of many a-proteobacterial genes into the nucleus. As a consequence, many a-proteobacterial proteins were retargeted to other cellular compartments. Consequently, mitochondria and peroxisomes possess a similar fraction of proteins of a-proteobacterial proteins (Gabaldon et al. 2006), whereas up to 80% of the mitochondrial proteome can be made up from proteins that have various non-a-proteobacterial origins. (Modified from Gabaldon and Huynen 2004)...

Fig. 10.5. Evolution of mitochondria and anaerobic organelles. Two possible scenarios for the evolution of diverse mitochondrial-derived organelles, (a) The aerobic and anaerobic metabolic pathways were present in the mitochondrial ancestor, followed by differential loss of functions in different extant eukaryote lineages, (b) The mitochondrial ancestor contained enzymes for aerobic metabolism, and the origin of anaerobes occurred via the acquisition of enzymes of anaerobic metabolism by lateral gene transfer (LGT). The order of gains and losses is unknown and the order depicted in the diagram is arbitrary...

The genetic code of mitochondria is not the same as the universal code, which has implications for the evolution of mitochondria. Human mitochondria contain a set of tRNA molecules that are not found elsewhere in the... 

Hjy Chloroplasts contain their own DNA and the machinery for replicat-I ing and expressing it. However, chloroplasts are not autonomous they also contain many proteins encoded by nuclear DNA. How did the intriguing relation between the cell and its chloroplasts develop We now believe that, in a manner analogous to the evolution of mitochondria (p. 504), chloroplasts are the result of endosymbiotic events in which a photosynthetic... 

In contrast to common usage, the distinction between photosynthetic and respiratory Rieske proteins does not seem to make sense. The mitochondrial Rieske protein is closely related to that of photosynthetic purple bacteria, which represent the endosymbiotic ancestors of mitochondria (for a review, see also (99)). Moreover, during its evolution Rieske s protein appears to have existed prior to photosynthesis (100, 101), and the photosynthetic chain was probably built around a preexisting cytochrome be complex (99). The evolution of Rieske proteins from photosynthetic electron transport chains is therefore intricately intertwined with that of respiration, and a discussion of the photosynthetic representatives necessarily has to include excursions into nonphotosynthetic systems. 

This essay was written in an attempt to explain our overview of primary cell walls and to reach consensus on the nomenclature of primary cell wall polysaccharides. We present evidence supporting the hypothesis that cellulose, xyloglucan, arabinoxylan, homogalacturonan, RG-I, and RG-II are the six polysaccharides common to all primary cell walls of higher plants. In many cells, these six polysaccharides account for all or nearly all of the primary wall polysaccharides. Like the physically interacting proteins that constitute the electron transport machinery of mitochondria, the structures of the six patently ubiquitous polysaccharides of primary cell walls have been conserved during evolution. Indeed, we hypothesize that the common set of six structural polysaccharides of primary cell walls have been structurally... 

Dolezal P, Likic V, Tachezy J, Lithgow T (2006) Evolution of the molecular machines for protein import into mitochondria. Science 313 314-318 Doolittle WF (1980) Revolutionary concepts in evolutionary cell biology. Trends Biochem Sci 5 146-149... 

It has been hypothesized that the process of inventing a protein import machine for mitochondria would have been so intricate and critical that it is unlikely to have occurred more than once (CavaUer-Smith 1987). By extension, similarities found between mitosomal and hydrogenosomal and mitochondrial protein import have been presented as strong support that all these organelles use common components for import, and are therefore one and the same. These observations have prompted a number of experimental and bioinformatics studies to shed light on the constitution and evolution of the protein import machineries of hydrogenosomes and mitosomes. 

While in unicellular eukaryotes the mitochondria were shown to play a central role in cellular FeS cluster assembly, metazoan ISC machinery might not be exclusively localized to mitochondria. It has been found that key ISC components, including IscS, IscU, Nfu, and frataxin, are located in the cytosol and nucleus as well as in mitochondria, and their participation in de novo FeS cluster synthesis outside of mitochondria was suggested (Tong and Rouault 2000, 2006). It would be interesting to investigate at which step of eukaryote evolution the transfer of ISC machinery to other cell compartments occurred and to clarify its extramitochondrial function. 

Dolezal P, Likic V, Tachezy J, Lithgow T (2006) Evolution of the molecular machines for protein import into mitochondria. Science 313 314-318 Dong J-S, Lai R, Nielsen K, Fekete CA, Qiu H-F, Hinnebusch AG (2004) The essential ATP-binding cassette protein Rlil functions in translation by promoting preinitiation complex assembly. J Biol Chem 274 42157-42168 Ellis JE, Setchell KD, Kaneshiro ES (1994) Detection of ubiquinone in parasitic and free-living protozoa, including species devoid of mitochondria. Mol Biochem Parasitol 65 213-224... 

The existence of mitochondrial DNA, ribosomes, and tRNAs supports the hypothesis of the endosymbiotic origin of mitochondria (see Fig. 1-36), which holds that the first organisms capable of aerobic metabolism, including respiration-linked ATP production, were prokaryotes. Primitive eukaryotes that lived anaerobically (by fermentation) acquired the ability to carry out oxidative phosphorylation when they established a symbiotic relationship with bacteria living in their cytosol. After much evolution and the movement of many bacterial genes into the nucleus of the host eukaryote, the endosymbiotic bacteria eventually became mitochondria. 

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