Selective charging of tRNA isoacceptors induced by amino-acid starvation
Selective charging of tRNA isoacceptors induced by amino-acid starvation
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DOI：
10.1038/sj.embor.7400341
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发表时间：
2005-02-01
期刊：
影响因子：
7.7
通讯作者：
Pan, T
中科院分区：
文献类型：
--
作者：
Dittmar, KA;Sorensen, MA;Pan, T
氨基酰化（带电）转移RNA同受体为同一氨基酸读取不同的信使RNA密码子。同受体的浓度及其带电部分是其密码子翻译速率的主要决定因素。最近的一个理论模型预测，氨基酸缺乏会导致“选择性充电”，其中一些tRNA同工受体的充电水平很低，而另一些则保持在较高水平。在这里，我们开发了一种微阵列来分析trna的带电部分，并测量了在亮氨酸、苏氨酸或精氨酸饥饿之前和期间所有大肠杆菌trna的带电情况。在饥饿之前，大多数trna都充满电。在饥饿过程中，当细胞缺乏同源氨基酸时，亮氨酸、苏氨酸或精氨酸家族的异受体表现出选择性充电，直接证实了理论预测。保留高电荷的同位受体读取的密码子可用于氨基酸饥饿期间必需的基因的有效翻译。选择性电荷可以解释不同蛋白质家族基因中密码子使用的异常模式。
Aminoacylated (charged) transfer RNA isoacceptors read different messenger RNA codons for the same amino acid. The concentration of an isoacceptor and its charged fraction are principal determinants of the translation rate of its codons. A recent theoretical model predicts that amino-acid starvation results in 'selective charging' where the charging levels of some tRNA isoacceptors will be low and those of others will remain high. Here, we developed a microarray for the analysis of charged fractions of tRNAs and measured charging for all Escherichia coli tRNAs before and during leucine, threonine or arginine starvation. Before starvation, most tRNAs were fully charged. During starvation, the isoacceptors in the leucine, threonine or arginine families showed selective charging when cells were starved for their cognate amino acid, directly confirming the theoretical prediction. Codons read by isoacceptors that retain high charging can be used for efficient translation of genes that are essential during amino-acid starvation. Selective charging can explain anomalous patterns of codon usage in the genes for different families of proteins.