Extremely thermophilic translation system in the common ancestor commonote: ancestral mutants of Glycyl-tRNA synthetase from the extreme thermophile Thermus thermophilus.
Extremely thermophilic translation system in the common ancestor commonote: ancestral mutants of Glycyl-tRNA synthetase from the extreme thermophile Thermus thermophilus.
复制标题
共同祖先commonote中的极端嗜热翻译系统：来自极端嗜热菌嗜热栖热菌的甘氨酰-tRNA合成酶的祖先突变体。
DOI：
10.1016/j.jmb.2007.04.001
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发表时间：
2007
影响因子：
5.6
通讯作者：
A. Yamagishi
中科院分区：
文献类型：
--
作者：
H. Shimizu;S. Yokobori;T. Ohkuri;T. Yokogawa;K. Nishikawa;A. Yamagishi
根据16 S和18 SrRNA的系统发育分析，提出所有生物的共同祖先（丛毛藻属）是极端嗜热的。我们以前已经测试了这一假设，使用酶与祖先的残基，推断分子系统发育分析。参与代谢系统的祖先突变酶显示出比野生型酶更高的热稳定性，与超嗜热菌共同祖先假说一致。在这里，我们已经扩展了实验，包括翻译系统的酶，甘氨酰-tRNA合成酶（GlyRS）。翻译系统通常显示与rRNA树相似的系统发育树。因此，这棵树很可能代表了生物体的进化路线。构建了α 2型GlyRS的最大似然树。从这个分析的祖先序列的GlyRS推导和个别或对祖先残基被引入到嗜热栖热菌GlyRS。在大肠杆菌中表达祖先突变体，纯化并测量活性。通过CD（圆二色性）测量评估八种突变蛋白的热稳定性。6个突变体显示出比野生型酶更高的热稳定性，7个突变体在70 °C下显示出比野生型酶更高的活性，这表明在共同祖先Commonote中存在极端嗜热的翻译系统。
Based on phylogenetic analysis of 16 S and 18 S rRNAs, the common ancestor of all organisms (Commonote) was proposed to be hyperthermophilic. We have previously tested this hypothesis using enzymes with ancestral residues that are inferred by molecular phylogenetic analysis. The ancestral mutant enzymes involved in metabolic systems show higher thermal stability than wild-type enzymes, consistent with the hyperthermophile common ancestor hypothesis. Here, we have extended the experiments to include an enzyme of the translation system, glycyl-tRNA synthetase (GlyRS). The translation system often shows a phylogenetic tree that is similar to the rRNA tree. Thus, it is likely that the tree represents the evolutionary route of the organisms. The maximum-likelihood tree of α2type GlyRS was constructed. From this analysis the ancestral sequence of GlyRS was deduced and individual or pairs of ancestral residues were introduced into Thermus thermophilus GlyRS. The ancestral mutants were expressed in Escherichia coli, purified and activity measured. The thermostability of eight mutated proteins was evaluated by CD (circular dichroism) measurements. Six mutants showed higher thermostability than wild-type enzyme and seven mutants showed higher activity than wild-type enzyme at 70 °C, suggesting an extremely thermophilic translation system in the common ancestor Commonote.