Interplay between the Signal Recognition Particle and Trigger Factor at the Ribos

描述（由申请人提供）：细胞竭尽全力确保蛋白质的适当生物合成。在翻译过程中，核糖体与多种因子如修饰酶、分子伴侣和靶向复合物结合，以保证最终产物是活性的、正确折叠的并正确定位于适当的细胞位置。如果没有这些因素，细胞将充满无活性，错误折叠，聚集和/或不正确分配的蛋白质。这种情况可能导致细胞的功能障碍和死亡，导致许多毁灭性的疾病。已经进行了许多研究来了解核糖体与这些分子机器的相互作用;然而，这些研究都没有研究核糖体如何处理和与多个复合物通信。在这个提议中，我们建议研究翻译核糖体与两个核糖体相关因子的相互作用，以确保适当的生物合成：信号识别颗粒（SRP）和触发因子（TF）。SRP是一种普遍保守的靶向机制，负责将膜蛋白和分泌蛋白递送至质膜或内质网。另一方面，TF是一种细菌伴侣，有助于胞质和周质蛋白的折叠。SRP和TF已被证明可以同时结合到核糖体上，然而，新出现的蛋白质如何通过SRP途径或TF途径的分子基础仍然不清楚。我建议：（1）测试SRP和TF是否以及如何竞争结合到核糖体新生链复合物（RNC）;（2）确定SRP受体的募集是否有助于排除TF;（3）测试新生链的进一步延伸是否有利于TF相互作用并将SRP从核糖体中移除。总的来说，这些实验的结果将提供一个全面的和定量的分子机制，“决策”是如何实现的核糖体，并将作为一个重要的框架，以了解其他核糖体相关的分子机制的相互作用。 公共卫生相关性：在翻译蛋白质时，核糖体与多种细胞因子相互作用，以确保其最终产物是活性的，正确折叠并正确定位在细胞中。在这个提议中，我们建议研究两个核糖体相关复合物的相互作用：信号识别颗粒和触发因子。实验结果将有助于我们进一步了解核糖体如何处理这些分子机制，并确定蛋白质生物合成如何实现的重要概念。

DESCRIPTION (provided by applicant): A cell goes to great lengths to ensure the proper biogenesis of proteins. During translation, the ribosome associates with multiple factors such as modification enzymes, chaperones and targeting complexes to guarantee that the final product is active, properly folded and correctly localized to the appropriate cellular location. Without these factors, the cell will be filled inactive, misfolded, aggregated and/or incorrectly allocated proteins. Such a scenario can result in the cell's malfunction and death, leading to many devastating diseases. Many studies have been carried out to understand the interaction of the ribosome with these molecular machineries; however, none of these studies look at how the ribosome handles and communicates with multiple complexes. In this proposal, we propose to study the interaction of a translating ribosome with two ribosome-associated factors that ensure proper biogenesis: the signal recognition particle (SRP) and the trigger factor (TF). SRP is a universally conserved targeting machinery and is responsible for delivering membrane and secretory proteins to the plasma membrane or to the endoplasmic reticulum. On the other hand, TF is a bacterial chaperone that aids in the folding of cytosolic and periplasmic proteins. SRP and TF have been shown to simultaneously bind to the ribosome, however, the molecular basis of how newly emerging proteins is funneled to either the SRP pathway or the TF pathway remains unclear. I propose to (1) test whether and how SRP and TF compete for binding to ribosome nascent chain complexes (RNCs); (2) determine if the recruitment of the SRP receptor helps exclude TF; and (3) test whether further elongation of the nascent chain favors TF interaction and removes SRP from the ribosome. Overall, the results of these proposed experiments will provide a comprehensive and quantitative molecular mechanism of how 'decision-making' is achieved by the ribosome and will serve as an important framework to understand the interplay of other ribosome- associated molecular machineries. PUBLIC HEALTH RELEVANCE: Upon translation of the protein, the ribosome interacts with multiple cellular factors to ensure that its final product is active, properly folded and correctly localized in the cell. In this proposal, we propose to study the interplay of two ribosome-associated complexes: the signal recognition particle and trigger factor. Results from the proposed experiments will help further our understanding of how the ribosome handles these molecular machineries and determine important concepts of how protein biogenesis is achieved.