Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, USA.
Mol Biol Evol. 2013 Feb;30(2):310-4. doi: 10.1093/molbev/mss228. Epub 2012 Sep 19.
Rapid evolution of mitochondrial DNA (mtDNA) places intrinsic selective pressures on many nuclear genes involved in mitochondrial functions. Mitochondrial ribosomes, for example, are composed of mtDNA-encoded ribosomal RNAs (rRNAs) and a set of more than 60 nuclear-encoded ribosomal proteins (mRP) distinct from the cytosolic RPs (cRP). We hypothesized that the rapid divergence of mt-rRNA would result in rapid evolution of mRPs relative to cRPs, which respond to slowly evolving nuclear-encoded rRNA. In comparisons of rates of nonsynonymous and synonymous substitutions between a pair of divergent populations of the copepod Tigriopus californicus, we found that mRPs showed elevated levels of amino acid changes relative to cRPs. This pattern was equally strong at the interspecific level, between three pairs of sister species (Nasonia vitripennis vs. N. longicornis, Drosophila melanogaster vs. D. simulans, and Saccharomyces cerevisae vs. S. paradoxus). This high rate of mRP evolution may result in intergenomic incompatibilities between taxonomic lineages, and such incompatibilities could lead to dysfunction of mitochondrial ribosomes and the loss of fitness observed among interpopulation hybrids in T. californicus and interspecific hybrids in other species.
线粒体 DNA（mtDNA）的快速进化对许多参与线粒体功能的核基因施加了内在的选择压力。例如，线粒体核糖体由 mtDNA 编码的核糖体 RNA（rRNA）和一套与细胞质核糖体蛋白（cRP）不同的超过 60 种核编码核糖体蛋白（mRP）组成。我们假设 mt-rRNA 的快速分化会导致 mRP 相对于 cRP 的快速进化，而 cRP 则响应于缓慢进化的核编码 rRNA。在对加利福尼亚桡足类动物（Tigriopus californicus）的一对分化种群之间的非同义替换和同义替换率进行比较时，我们发现 mRP 相对于 cRP 表现出更高水平的氨基酸变化。这种模式在种间水平上同样强烈，在三个姐妹种对之间（Nasonia vitripennis 与 N. longicornis、Drosophila melanogaster 与 D. simulans 以及 Saccharomyces cerevisae 与 S. paradoxus）也是如此。这种 mRP 进化的高速度可能导致分类群之间的基因组间不兼容性，这种不兼容性可能导致线粒体核糖体功能失调，并导致加利福尼亚桡足类动物的种群间杂种和其他物种的种间杂种中观察到的适应性丧失。
