Translational standby sites: How ribosomes may deal with the rapid folding kinetics of mRNA
Translational standby sites: How ribosomes may deal with the rapid folding kinetics of mRNA
复制标题
DOI：
10.1016/s0022-2836(03)00809-x
复制
发表时间：
2003-08-22
影响因子：
5.6
通讯作者：
van Duin, J
中科院分区：
文献类型：
--
作者：
de Smit, MH;van Duin, J
我们以前已经表明，在大肠杆菌中的翻译起始位点的稳定碱基配对可以通过与核糖体的结合竞争来抑制翻译。当碱基配对不太强时，这种竞争被核糖体赢得，导致从结构化核糖体结合位点（RBS）的有效翻译。我们现在重新检查这些结果的光的RNA折叠动力学，并发现，在此期间，折叠RBS是开放的窗口通常是太短，从细胞质中招募30 S核糖体亚基。我们认为，为了实现有效的表达，30 S亚基必须已经与mRNA接触，而这仍然是折叠的，转移到地方，只要结构打开。该结构侧翼的单链区域可构成备用位点，30 S亚基可非特异性地附着于该备用位点。我们提出了一个稳态动力学模型的翻译起始的早期步骤，并使用此来检查备用绑定的各个定量方面。动力学模型提供了一个解释，为什么早期的平衡竞争模型预测难以置信的高30 S-mRNA的亲和力。因为所有的RNA都具有某种程度的结构，所以备用结合可能是翻译起始的一般特征。(C)2003 Elsevier Ltd.保留所有权利。
We have previously shown that stable base-pairing at a translational initiation site in Escherichia coli can inhibit translation by competing with the binding of ribosomes. When the base-pairing is not too strong, this competition is won by the ribosomes, resulting in efficient translation from a structured ribosome binding site (RBS). We now re-examine these results in the light of RNA folding kinetics and find that the window during which a folded RBS is open is generally much too short to recruit a 30 S ribosomal subunit from the cytoplasm. We argue that to achieve efficient expression, a 30 S subunit must already be in contact with the mRNA while this is still folded, to shift into place as soon as the structure opens. Single-stranded regions flanking the structure may constitute a standby site, to which the 30 S subunit can attach non-specifically. We propose a steady-state kinetic model for the early steps of translational initiation and use this to examine various quantitative aspects of standby binding. The kinetic model provides an explanation of why the earlier equilibrium competition model predicted implausibly high 30 S-mRNA affinities. Because all RNA is structured to some degree, standby binding is probably a general feature of translational initiation. (C) 2003 Elsevier Ltd. All rights reserved.