Minimal translation of the tmRNA tag-coding region is required for ribosome release
Minimal translation of the tmRNA tag-coding region is required for ribosome release
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DOI：
10.1016/j.bbrc.2007.03.142
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发表时间：
2007-05-25
影响因子：
3.1
通讯作者：
O'Connor, Michael
中科院分区：
文献类型：
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作者：
O'Connor, Michael
细菌中的反式翻译系统促进停滞的核糖体的再循环，并靶向不完整的肽用于蛋白质水解。在大肠杆菌中，在正常实验室条件下，反式翻译功能的丧失对生长几乎没有影响。tRNA缺陷突变体的微妙表型之一是不能接种某些λ imm（P22）酶。这种表型依赖于反式翻译系统的核糖体再循环功能，但不依赖于其蛋白水解靶向活性。这里描述的实验表明，tRNA翻译tmRNA开放阅读框的第一个（恢复）密码子对于核糖体再循环是必要的和充分的。虽然多种有义密码子可以取代天然存在的GCA丙氨酸密码子作为恢复密码子，但AAA和AAG赖氨酸密码子都是非功能性恢复密码子。这些结果表明，tmRNA在释放停滞的核糖体中的主要功能是提供终止密码子，从而促进终止和随后的核糖体再循环。(c)2007年爱思唯尔公司All rights reserved.
The trans-translation system in bacteria promotes recycling of stalled ribosomes and targets incomplete peptides for proteolysis. In Escherichia coli, loss of trans-translation function has little effect on growth under normal laboratory conditions. Among the subtle phenotypes of tmRNA-deficient mutants is the inability to plate certain lambda imm(P22) phages. This phenotype is dependent on the ribosome recycling functions of the trans-translation system but is independent of its proteolysis-targeting activity. The experiments described here show that translation of the first (resume) codon of the tmRNA open reading frame by a tRNA is both necessary and sufficient for ribosome recycling. While a variety of sense codons can replace the naturally-occurring GCA alanine codon as the resume codon, both AAA and AAG lysine codons are non-functional resume codons. These results suggest that the main function of tmRNA in releasing stalled ribosomes is to supply a stop codon and so facilitate termination and subsequent ribosome recycling. (c) 2007 Elsevier Inc. All rights reserved.