Abstract
Despite a conserved set of core mitochondrial functions, animal mitochondrial proteomes show a large variation in size. We analyzed putative mechanisms behind and functional significance of this variation by performing comparative analysis of the experimentally-verified mitochondrial proteomes of four bilaterian animals (human, mouse, Caenorhabditis elegans, and Drosophila melanogaster) and two non-animal outgroups (Acanthamoeba castellanii and Saccharomyces cerevisiae). We found that of several factors affecting mitochondrial proteome size, evolution of novel mitochondrial proteins in mammals and loss of ancestral proteins in protostomes were the main contributors. Interestingly, the gain and loss of the N-terminal mitochondrial targeting signal was not a major factor in the proteome size evolution.
Highlights
Mitochondria, membrane-bound organelles present in most eukaryotic organisms, are involved in a number of cellular processes, including oxidative phosphorylation, Fe/S cluster biosynthesis, amino-acid and lipid metabolism, and apoptosis [1, 2]
We identified 45 and 68 proteins from C. elegans and D. melanogaster, which were present in Category I OGs and possessed a Mitochondrial Targeting Signals (MTS), but were not annotated as mt-proteins
Animal mt-proteomes vary with respect to size and content
Summary
Mitochondria, membrane-bound organelles present in most eukaryotic organisms, are involved in a number of cellular processes, including oxidative phosphorylation, Fe/S cluster biosynthesis, amino-acid and lipid metabolism, and apoptosis [1, 2] These tasks typically require more than a thousand proteins, the vast majority of which are encoded in the nuclear genome and imported into organelle [3, 4, 5]. The latter include identification of targeting signals, homology search, co-expression analysis, and phylogenetic profiling Since all these techniques have their pros and cons [6], integrated approaches have been advocated and applied to elucidate some mt-proteomes, as in the case of human and mouse MitoCarta [7]. The number of experimentally determined mt-proteomes remains small
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