Evolution of eukaryotic translation elongation and termination factors: Variations of evolutionary rate and genetic code deviations
Evolution of eukaryotic translation elongation and termination factors: Variations of evolutionary rate and genetic code deviations
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DOI：
10.1093/oxfordjournals.molbev.a004071
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发表时间：
2002-02-01
影响因子：
10.7
通讯作者：
Philippe, H
中科院分区：
文献类型：
--
作者：
Moreira, D;Kervestin, S;Philippe, H
翻译是由核糖体和几个相关的蛋白质因子通过三个连续的步骤进行的：起始、延伸和终止。终止仍然是其中最不被理解的，部分原因是所涉及因素的非普遍性。为了深入了解真核生物翻译终止的进化，我们比较了释放因子eRF1和eRF3与延伸因子EF-1α和EF-2的系统发育，特别是纤毛虫。我们的结果表明，这四种翻译蛋白经历了不同的进化模式。这在EF-1α、EF-2和eRF1纤毛虫序列中尤为明显。纤毛虫在EF-2的系统发育树上显示为单系，而在EF-1α和eRF1的系统发育树上不是。这似乎主要是由于纤毛虫EF-1α和eRF1序列进化速度加快而产生的系统发育重建伪影(长枝吸引)所致。与纤毛虫中发现的高度分化的肌动蛋白的相互作用，或者相反，相互作用的丧失，可以解释EF-1α序列进化速度的加快。在纤毛虫eRF1序列中，它们异常高的进化速度可能与在不同纤毛虫中发现的遗传密码使用的偏差有关。这些偏差涉及放宽(甚至取消)eRF1对一个或两个终止密码子的识别。为了实现这一点，eRF1的结构变化是必要的，这可能会影响其进化速度。真核生物的翻译似乎遵循了一种镶嵌进化，其不同的成分受到不同的选择压力的支配。然而，相关分析表明，在不同翻译蛋白表现出的不一致之下，与其他未参与翻译的蛋白质相比，当它们疲惫时，它们的协同进化仍然明显。
Translation is carried out by the ribosome and several associated protein factors through three consecutive steps: initiation, elongation, and termination. Termination remains the least understood of them, partly because of the nonuniversality of the factors involved. To get some insights on the evolution of eukaryotic translation termination, we have compared the phylogeny of the release factors eRF1 and eRF3 to that of the elongation factors EF-1alpha and EF-2, with special focus on ciliates. Our results show that these four translation proteins have experienced different modes of evolution. This is especially evident for the EF-1alpha, EF-2, and eRF1 ciliate sequences. Ciliates appear as monophyletic in the EF-2 phylogenetic tree but not in the EF-1alpha and eRF1 phylogenetic trees. This seems to be mainly because of phylogeny reconstruction artifacts (the long-branch attraction) produced by the acceleration of evolutionary rate of ciliate EF-1alpha and eRF1 sequences. Interaction with the highly divergent actin found in ciliates, or on the contrary, loss of interaction, could explain the acceleration of the evolutionary rate of the EF-1alpha sequences. In the case of ciliate eRF1 sequences, their unusually high evolutionary rate may be related to the deviations in the genetic code usage found in diverse ciliates. These deviations involve a relaxation (or even abolition) of the recognition of one or two stop codons by eRF1. To achieve this, structural changes in eRF1 are needed, and this may affect its evolutionary rate. Eukaryotic translation seems to have followed a mosaic evolution, with its different elements governed by different selective pressures. However, a correlation analysis shows that, beneath the disagreement shown by the different translation proteins, their concerted evolution can still be made apparent when they tire compared with other proteins that are not involved in translation.