Kinetics of Stop Codon Recognition by Release Factor 1
Kinetics of Stop Codon Recognition by Release Factor 1
复制标题
DOI：
10.1021/bi901577d
复制
发表时间：
2009-12-01
期刊：
影响因子：
2.9
通讯作者：
Joseph, Simpson
中科院分区：
文献类型：
--
作者：
Hetrick, Byron;Lee, Kristin;Joseph, Simpson
1类释放因子对终止密码子的识别是蛋白质合成终止阶段的基本步骤。由于过早终止对细胞来说是昂贵的，释放因子必须有效地区分终止密码子和有义密码子。为了了解终止密码子和正义密码子之间的歧视机制，我们开发了一种新的，预稳态动力学测定来监测RF1与核糖体的相互作用。我们的研究结果表明，RF1协会与类似的协会速率常数与核糖体编程终止或正义密码子。然而，RF1从有义密码子的解离比从终止密码子的解离快3个数量级。有趣的是，RF1对用不同有义密码子编程的核糖体的亲和力与肽释放中的缺陷无关。因此，通过解离速率的增加和肽释放速率的降低来实现对有义密码子的区分。这些结果表明，正义密码子抑制RF1稳定结合核糖体和催化肽释放所必需的构象变化。
Recognition of stop codons by class 1 release factors is a fundamental step in the termination phase of protein synthesis. Since premature termination is costly to the cell, release factors have to efficiently discriminate between stop and sense codons. To understand the mechanism of discrimination between stop and sense codons, we developed a new, pre-steady state kinetic assay to monitor the interaction of RF1 with the ribosome. Our results show that RF1 associates with similar association rate constants with ribosomes programmed with stop or sense codons. However, dissociation of RF1 from sense codons is as much as 3 orders of magnitude faster than from stop codons. Interestingly, the affinity of RF1 for ribosomes programmed with different sense codons does not correlate with the defects in peptide release. Thus, discrimination against sense codons is achieved with both an increase in the dissociation rates and a decrease in the rate of peptide release. These results suggest that sense codons inhibit conformational changes necessary for RF1 to stably bind to the ribosome and catalyze peptide release.