AR COBRE: PROTEIN TARGETING

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。信号识别粒子（SRPs）及其受体在生命的各个领域发挥作用。它们是一个复杂的蛋白质靶向系统的组成部分，该系统将新合成的蛋白质传递给存在于三种不同膜系统中的转运蛋白（蛋白质转位酶）；细菌的细胞质膜、内质网和叶绿体类囊体膜。人类SRP靶向/易位系统的故障与特发性炎性肌病、糖尿病和结肠癌有关。在细菌中，SRP的功能对细菌病原体的成功至关重要。SRP靶向的复杂性继续延缓了SRP如何靶向并将蛋白质转移到靶膜上的易位机制的详细机制模型。最近发现的叶绿体SRP独特的结构和功能特征为使用其他基于SRP的靶向模型不可用或不易应用的工具和分析来研究SRP靶向机制提供了前所未有的机会。在Henry的指导下，Goforth领导的跨学科团队将运用先进的蛋白质组学和蛋白质结构分析，结合更传统的分子和生化方法，以(1)确定SRP/受体/转位酶复合物组分之间的蛋白质相互作用，(2)确定SRP与受体和转位酶通信的关键蛋白质结构。(3)通过重建靶向/易位机制的每个步骤的分析确定特定蛋白质/蛋白质相互作用的功能。完成所提出的工作将提供对以下相互作用的理解：(i)靶向成分参与适当和可用的易位机制所需的相互作用，（ii）调节底物从SRP释放到易位酶，以及（iii）控制靶向成分从易位酶释放。我们的结果将广泛影响我们对蛋白质靶向和插入功能的分子机器的理解。此外，通过这种跨学科方法获得的见解将提供必要的比较信息，以确定基于srp的靶向的共同机制原则。尽管进化力量已经改变了SRP靶向/插入机制，使其在多种生物体和细胞环境中有效运作，但正是这些共同特征无疑确保了忠实的蛋白质靶向和插入。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Signal recognition particles (SRPs) and their receptors function in every domain of life. They are components of an elaborate protein targeting system that delivers newly synthesized proteins to transporters (protein translocases) present in three different membrane systems; the bacterial cytoplasmic membrane, the endoplasmic reticulum, and the chloroplast thylakoid membrane. Malfunction of the SRP targeting/translocation system in humans is implicated in idiopathic inflammatory myopathies, diabetes mellitus, and colon cancer. In bacteria, SRP function is central to the success of bacterial pathogens. Complexities of SRP targeting continue to slow a detailed mechanistic model for how SRP targets and transfers proteins to translocation machinery located in the target membrane. Unique structural and functional features of the more recently discovered chloroplast SRP provide an unprecedented opportunity to examine the SRP targeting mechanism using tools and assays not available or not easily applied to other SRP-based targeting models. A transdisciplinary team led by Goforth and under the mentorship of Henry will apply advanced proteomics and protein structure analysis with more traditional molecular and biochemical approaches in order to (1) identify protein interactions between components of a SRP/receptor/translocase complex, (2) determine the structure of proteins critical for SRP to communicate with receptor and translocase, and (3) determine the function of specific protein/protein interactions in assays that reconstitute each step of the targeting/translocation mechanism. Completion of the proposed work will provide understanding of interactions that (i) are needed for targeting components to engage appropriate and available translocation machinery, (ii) regulate substrate release from SRP to the translocase, and (iii) control release of targeting components from the translocase. Our resulsts will broadly impact our understanding of the molecular machines that function in protein targeting and insertion. Moreover, insight gained through this transdisciplinary approach will provide needed comparative information to identify common mechanistic principals of SRP-based targeting. It is these common features that undoubtedly ensure faithful protein targeting and insertion despite evolutionary forces that have altered the SRP targeting/insertion machinery for efficient operation in a diverse array of organisms and cellular environments.