Molecular Mechanism of Protein Targeting by the Signal Recognition Particle

信号识别粒子靶向蛋白质的分子机制

• 批准号: 7923876
• 负责人: Shu-ou Shan
• 金额: $ 30.94万
• 依托单位: CALIFORNIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-28 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7923876
• 关键词: Affect; Binding; Biochemical; Biological Assay; Cell membrane; Cells; Collection; Complex; Coupled; Cues; DNA Sequence Rearrangement; Data; Endoplasmic Reticulum; Event; Fluorescence; GTP Binding; Goals; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Hydrolysis; Individual; Investigation; Kinetics; Knowledge; Lead; Life; Membrane; Membrane Proteins; Molecular; Monitor; Nature; Pathology; Pathway interactions; Peptide Signal Sequences; Phospholipids; Physiology; Process; Protein Region; Proteins; Reaction; Reagent; Regulation; Relative (related person); Reporting; Research; Ribosomes; Role; Series; Signal Recognition Particle; Signal Transduction; Staging; Surface; Testing; Time; Work; analog; base; driving force; improved; insight; molecular rearrangement; molecular recognition; mutant; receptor; research study; secretory protein; tool

DESCRIPTION (provided by applicant): Proper localization of proteins is crucial to all cells. The signal recognition particle (SRP) and its receptor (SR) constitute the major cellular machinery that delivers newly synthesized proteins to the eukaryotic endoplasmic reticulum membrane, or the bacterial plasma membrane. This process is regulated by two homologous GTPases in the SRP and SR that directly interact with one another, making it particularly exciting for mechanistic investigations. Though past work has defined the components of the targeting pathway, the molecular mechanism of this process remains unclear. Our general goal is to decipher, at a biochemical and biophysical level, the intricate inner workings of this universally conserved targeting machine. Our specific goal is to understand the mechanism by which the SRP and SR GTPases use their cycles of GTP binding and hydrolysis to provide spatial and temporal coordination of the protein targeting reaction. To this end, three specific aims are envisioned: (1) We will define and characterize the dynamics and conformational intermediates during SRP-SR complex formation and their reciprocal GTPase activation; (2) We will define whether, when and how other components of the protein targeting pathway - the ribosome, the signal sequence, and the membrane translocation channel - modulate the conformational changes of SRP and SR during their binding and activation cycle; (3) We will use the array of mutant GTPases and GTP analogues to perturb specific conformational steps in the GTPase cycle of SRP and SR, and test how these perturbations affect the recognition, delivery and unloading of cargo protein during the protein targeting reaction. These experiments will allow us to define the precise role of each GTP binding and hydrolysis event in providing the driving force or improving the fidelity of the protein targeting reaction. Ultimately, these studies will not only advance our understanding of the process of protein localization within the cell, but also provide new insights into the general principles of molecular recognition and regulation at a very fundamental level. The proposed research is of a most basic nature, and will contribute profoundly to our general understanding of physiology and pathology of all living cells at the molecular level.

描述（由申请人提供）：蛋白质的正确定位对所有细胞都至关重要。信号识别颗粒（SRP）及其受体（SR）是将新合成的蛋白质传递到真核细胞内质网膜或细菌质膜的主要细胞机制。这一过程由SRP和SR中的两个同源GTP酶调节，它们直接相互作用，使其对机制研究特别令人兴奋。虽然过去的工作已经确定了靶向途径的组成部分，但这一过程的分子机制仍不清楚。我们的总体目标是在生物化学和生物物理水平上破译这个普遍保守的靶向机器的复杂内部运作。我们的具体目标是了解SRP和SR GTP酶使用其GTP结合和水解循环来提供蛋白质靶向反应的空间和时间协调的机制。 为此，我们设想了三个具体的目标：（1）我们将定义和表征SRP-SR复合物形成过程中的动力学和构象中间体及其相互的GT3激活;（2）我们将定义蛋白质靶向途径的其他组分-核糖体，信号序列，膜转运通道调节SRP和SR结合和活化过程中的构象变化;（3）我们将使用突变型GTP酶和GTP类似物的阵列来扰动SRP和SR的GTP酶循环中的特定构象步骤，并测试这些扰动如何影响识别，在蛋白质靶向反应期间货物蛋白的递送和卸载。这些实验将使我们能够定义每个GTP结合和水解事件在提供驱动力或提高蛋白质靶向反应的保真度中的精确作用。 最终，这些研究不仅将推进我们对细胞内蛋白质定位过程的理解，而且还将在非常基础的水平上为分子识别和调控的一般原理提供新的见解。拟议的研究是一个最基本的性质，并将有助于我们在分子水平上对所有活细胞的生理学和病理学的一般理解。