Evolution of a transfer RNA gene through a point mutation in the anticodon
Evolution of a transfer RNA gene through a point mutation in the anticodon
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DOI：
10.1126/science.279.5357.1665
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发表时间：
1998-03-13
期刊：
影响因子：
56.9
通讯作者：
Abelson, J
中科院分区：
文献类型：
--
作者：
Saks, ME;Sampson, JR;Abelson, J
转移RNA （tRNA）多基因家族由20个氨基酸接受基团组成，其中许多包含同位受体。向tRNA库添加同位受体对于建立遗传密码至关重要，但同位受体的起源仍未得到很大程度的探索。一个称为“tRNA基因募集”的tRNA进化模型被制定。该模型的测试表明，当表达一个具有点突变的tRNA(Arg)，其反密码子从UCU变为UGU（苏氨酸）时，一个必需tRNA(UGU)（Thr）基因失活，而另一个tRNA（Arg）的反密码子从UCU变为UGU（苏氨酸），则使该tRNA（Arg）能够存活。体外氨基酰化实验证实了“招募”的tRNA（Arg）在苏氨酸密码子上插入苏氨酸，表明其特异性已从精氨酸转变为苏氨酸，因此，这种招募模式可能解释了一些tRNA基因的进化。
The transfer RNA (tRNA) multigene family comprises 20 amino acid-accepting groups, many of which contain isoacceptors, The addition of isoacceptors to the tRNA repertoire was critical to establishing the genetic code, yet the origin of isoacceptors remains largely unexplored, A model of tRNA evolution, termed "tRNA gene recruitment," was formulated. It proposes that a tRNA gene can be recruited from one isoaccepting group to another by a point mutation that concurrently changes tRNA amino acid identity and messenger RNA coupling capacity, A test of the model showed that an Escherichia coli strain, in which the essential tRNA(UGU)(Thr), gene was inactivated, was rendered viable when a tRNA(Arg) with a point mutation that changed its anticodon from UCU to UGU (threonine) was expressed, Insertion of threonine at threonine codons by the "recruited" tRNA(Arg) was corroborated by in vitro aminoacylation assays showing that its specificity had been changed from arginine to threonine, Therefore, the recruitment model may account for the evolution of some tRNA genes.