Transient idling of posttermination ribosomes ready to reinitiate protein synthesis
Transient idling of posttermination ribosomes ready to reinitiate protein synthesis
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DOI：
10.1016/j.biochi.2004.08.006
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发表时间：
2004-12-01
期刊：
影响因子：
3.9
通讯作者：
Nakamura, Y
中科院分区：
文献类型：
--
作者：
Karamyshev, AL;Karamysheva, ZN;Nakamura, Y
蛋白质合成过程中核糖体在终止和起始之间的命运是非常基本的，但人们知之甚少。在这里，我们发现，当真实翻译在重新起始密码子上游七个密码子（我们称为“重新起始窗口”）上游的无义密码子处过早终止时，大肠杆菌中碱性磷酸酶基因的翻译重新起始发生在内部甲硫氨酸密码子处。改变终止密码子下游的阅读框并没有消除重新启动，而使上游起始密码子失活则消除了重新启动。此外，核糖体循环因子（RRF）的耗尽（与延伸因子G一起分解终止后核糖体）并不影响观察到的重新启动。这些发现表明，即使在重新启动窗口内没有 Shine-Dalgamo (SD) 序列的情况下，终止后核糖体也可以经历短暂的空闲状态，准备重新启动蛋白质合成，从而避免与 mRNA 脱离。 (C) 2004 年爱思唯尔 SAS。版权所有。
The fate of ribosomes between termination and initiation during protein synthesis is very basic, yet poorly understood. Here we found that translational reinitiation of the alkaline phosphatase gene occurs in Escherichia coli from an internal methionine codon when the authentic translation is prematurely terminated at a nonsense codon that is within seven codons upstream of the reinitiation codon (which we refer to as "reinitiation window"). Changing the reading frame downstream of the stop codon did not abolish the reinitiation, while inactivating the upstream initiation codon abolished the reinitiation. Moreover, depletion of the ribosome recycling factor (RRF), which disassembles posttermination ribosomes in conjunction with elongation factor G, did not influence the observed reinitiation. These findings suggest that post-termination ribosomes can undergo a transient idling state ready to reinitiate protein synthesis even in the absence of the Shine-Dalgamo (SD) sequence within the reinitiation window by evading disengagement from the mRNA. (C) 2004 Elsevier SAS. All rights reserved.