A Evolution of ­macromolecular import pathways in mitochondria, hydrogenosomes and mitosomes. Philos Trans R Soc Lond B Biol Sci

Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia.
Philosophical Transactions of The Royal Society B Biological Sciences (Impact Factor: 7.06). 03/2010; 365(1541):799-817. DOI: 10.1098/rstb.2009.0167
Source: PubMed


All eukaryotes require mitochondria for survival and growth. The origin of mitochondria can be traced down to a single endosymbiotic event between two probably prokaryotic organisms. Subsequent evolution has left mitochondria a collection of heterogeneous organelle variants. Most of these variants have retained their own genome and translation system. In hydrogenosomes and mitosomes, however, the entire genome was lost. All types of mitochondria import most of their proteome from the cytosol, irrespective of whether they have a genome or not. Moreover, in most eukaryotes, a variable number of tRNAs that are required for mitochondrial translation are also imported. Thus, import of macromolecules, both proteins and tRNA, is essential for mitochondrial biogenesis. Here, we review what is known about the evolutionary history of the two processes using a recently revised eukaryotic phylogeny as a framework. We discuss how the processes of protein import and tRNA import relate to each other in an evolutionary context.

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    • "Fu et al. GBE 2008; Lithgow and Schneider 2010). In addition, mismatches were identified in the first 1–3 bp of the amino acid acceptor stem in 8 of the 11 remaining Acrasis tRNAs (fig. "
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    • "The core components and mechanisms involved in mitochondrial protein import and assembly were established in the earliest eukaryotes with ancient origins of many components of the protein import apparatus (Albrecht et al., 2010; Delage et al., 2011; Hewitt et al., 2011). This is evidenced by the presence of many core and central components, such as the translocase of the outer membrane (TOM), sorting and assembly machinery (SAM), and the translocases of the inner membrane (TIM), in stramenophiles and hydrosomes (Lithgow and Schneider, 2010; Delage et al., 2011; Hewitt et al., 2011; Heinz and Lithgow, 2013). These ancient fundamental transporters originating from bacterial ancestors, exhibit a high level of conservation across the eukaryotic kingdoms from unicellular eukaryotes to plants, present in nearly all systems studied to date (Liu et al., 2011). "
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    • "The proto-mitochondrion at the origin of present-day mitochondria likely expressed the full set of mt tRNA genes of the ancestral endosymbiotic a proteobacterium. In contrast to this ancient situation, most mt genomes have now lost at least a few tRNA genes (Fig. 2) [24] [27]. From the examples presented in the figure, a few conclusions can be drawn. "
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