Does Mitochondrial DNA Evolution in Metazoa Drive the Origin of New Mitochondrial Proteins?
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Does Mitochondrial DNA Evolution in Metazoa Drive the Origin of New Mitochondrial Proteins?
S. L. van Esveld, M. A. Huynen
DOI : 10.1002/iub.1940
Most eukaryotic cells contain mitochondria with a genome that evolved from their α-proteobacterial ancestor. In the course of eukaryotic evolution, the mitochondrial genome underwent a dramatic reduction in size, caused by the loss and translocation of genes. This required adjustments in mitochondrial gene expression mechanisms and resulted in a complex collaborative system of mitochondrially encoded transfer RNAs and ribosomal RNAs with nuclear encoded proteins to express the mitochondrial encoded oxidative phosphorylation (OXPHOS) proteins.
It is tentative to argue that this co-evolution is driven by the mtDNA, given the relatively high rate at which it accumulates mutations in Metazoa (88), but evolutionary arguments are often rooted in wishful thinking. To make a more convincing argument we would have to observe such co-evolution in other parallel evolutionary lineages with a high accumulation of slightly deleterious mutations. Furthermore, even though we mapped the coevolution of the mitochondrial genome and the origin of new mitochondrial proteins by narrowing down events in both using phylogenetic analyses, we still face a chicken and egg problem: we do not know whether the origin of a new, nuclear encoded
mitochondrial protein allowed the change in the mitochondrial genome, or whether a change in the mitochondrial genome provided the selective advantage for the maintenance of a new mitochondrial protein.
the reason why only Metazoa need these new proteins remains unclear. At the very least, the coincidence of the arrival of new mitochondrial proteins with changes in the mtDNA can provide hypotheses about the functions of those proteins and therewith drive experimental tests.
Common Design 