SmpB triggers GTP hydrolysis of elongation factor Tu on ribosomes by compensating for the lack of codon-anticodon interaction during trans- translation initiation
SmpB triggers GTP hydrolysis of elongation factor Tu on ribosomes by compensating for the lack of codon-anticodon interaction during trans- translation initiation
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DOI：
10.1074/jbc.m512165200
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发表时间：
2006-06-09
影响因子：
4.8
通讯作者：
Ueda, Takuya
中科院分区：
文献类型：
--
作者：
Shimizu, Yoshihiro;Ueda, Takuya
细菌tmRNA通过反式翻译过程拯救由于缺陷mRNA而停滞的核糖体。虽然进入的带电的转移信使RNA（tmRNA）进入核糖体进行的延伸因子（EF-Tu）的情况下，并在EF-Tu和抗生素kirromycin的存在下，EF-Tu的参与反式翻译起始的证据被发现。通过使用仅由tRNA样结构域组成的tmRNA变体获得的聚丙氨酸合成系统显示，它完全依赖于SmpB的存在，并通过EF-Tu和EF-G大大增强。实际上，EF-Tu的核糖体依赖性GTdR活性通过添加SmpB和tmRNA而被刺激，但独立于模板mRNA，表明SmpB补偿了反式翻译起始的第一步期间密码子-反密码子相互作用的缺乏。基于这些结果，我们建议，SmpB结构模仿tRNA的反密码子臂和electiveGTP水解EF-Tu后，在核糖体的A位点的tRNA住宿。
Bacterial tmRNA rescues ribosomes that stall because of defective mRNAs via the trans-translation process. Although entry of the charged transfer messenger RNA ( tmRNA) into the ribosome proceeded in the absence of elongation factor (EF-Tu) and in the presence of EF-Tu and the antibiotic kirromycin, evidence was found for the involvement of EF-Tu in trans-translation initiation. The polyalanine synthesis system attained by using a tmRNA variant consisting of only the tRNA-like domain revealed that it was completely dependent on the presence of SmpB and greatly enhanced by EF-Tu and EF-G. Actually, ribosome-dependent GTPase activity of EF-Tu was stimulated by the addition of SmpB and tmRNA but independently of template mRNA, demonstrating that SmpB compensates for the lack of codon-anticodon interaction during the first step of the trans-translation initiation. Based on these results, we suggest that SmpB structurally mimics the anticodon arm of tRNA and elicits GTP hydrolysis of EF-Tu upon tmRNA accommodation in the A site of the ribosome.