Mechanistic Studies of the Hsp70 Chaperone System

Hsp70 伴侣系统的机理研究

• 批准号: 7637482
• 负责人: Eugene Guy Maes
• 金额: $ 2.75万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7637482
• 关键词: ATP Hydrolysis; ATPase Domain; Amyloid; Antigen Presentation; Apoptosis; Binding; Biochemical; Cell physiology; Cells; Clinical; Complex; Fluorescence Resonance Energy Transfer; Generations; Heat Stress Disorders; Heat-Shock Proteins 70; Hydrolysis; Inflammation; Ischemia; Knowledge; Life; Macromolecular Complexes; Molecular Chaperones; Molecular Conformation; Nerve Degeneration; Nervous system structure; Neurodegenerative Disorders; Nucleotides; Organism; Play; Prevention; Process; Protein Family; Protein translocation; Proteins; Reaction; Reactive Oxygen Species; Recycling; Regulation; Research Design; Resistance; Role; Staging; Stress; Structure; Synaptic Vesicles; System; Testing; Time; Toxin; analog; cancer cell; free radical oxygen; interest; intermolecular interaction; mutant; neuron loss; novel; overexpression; protein aggregation; protein complex; protein folding; protein transport; research study; stressor

DESCRIPTION (provided by applicant): The Hsp70 protein family is a diverse and ubiquitous group of molecular chaperones. There are multiple representatives of the Hsp70 family in all living organisms. Their cellular roles include assistance in protein folding, protein targeting and translocation, the assembly and disassembly of macromolecular complexes, protein transport to appropriate cellular regions, and the delivery of proteins to a proteolytic system for their disposal. The roles of Hsp70s in the prevention of protein aggregation, the refolding of denatured proteins, and the disposal of irreversibly damaged proteins are cytoprotective. Within the nervous system, Hsp70s assist in the prevention of neurodegeneration which results from amyloid aggregates, as well as play a fundamental role in synaptic vesicle recycling. Overexpression of Hsp70s protects cells against the damaging effects of a variety of stressors (i.e. inflammation, ischemia, and free radical oxygen species). Consequently, there is considerable interest in elucidating their mechanism. The basic features of the Hsp70 cycle has been known for some time. ATP binding to the ATPase domain of the Hsp70 induces an allosteric change in the protein substrate binding domain, resulting in the release of substrate, thus setting the stage for the binding of a new substrate molecule. ATP hydrolysis, and the subsequent release of Pi, results in the formation of a stable ADP*Hsp70*substrate complex. The energy released from ATP hydrolysis can be harnessed to drive protein translocation and macromolecular complex remodeling reactions. The multiple steps involved in the Hsp70 cycle are regulated by cochaperones that increase the rate of ATP hydrolysis and deliver various substrates to the Hsp70, or increase the rate ofADP/ATP exchange. However, the precise mechanisms of these processes, chiefly the allosteric mechanism, remain elusive. To alleviate these deficiencies in our understanding, I will characterize the structures of an Hsp70 in distinct, allosteric states. Both mutational and biochemical experiments will be used to investigate the observed intermolecular interactions and mechanistic hypotheses inferred from inspection of these structures.

描述（由申请人提供）：Hsp70蛋白家族是一组多样且普遍存在的分子伴侣蛋白。Hsp70家族在所有生物体中都有多个代表。它们在细胞中的作用包括协助蛋白质折叠，蛋白质靶向和易位，大分子复合物的组装和拆卸，蛋白质运输到适当的细胞区域，以及将蛋白质递送到蛋白质水解系统以进行处理。hsp70在防止蛋白质聚集、变性蛋白质的再折叠和处理不可逆损伤蛋白质方面的作用具有细胞保护作用。在神经系统中，hsp70有助于预防淀粉样蛋白聚集引起的神经变性，并在突触囊泡循环中发挥基本作用。hsp70的过表达保护细胞免受各种应激源（如炎症、缺血和自由基氧）的损伤作用。因此，有相当大的兴趣阐明其机制。Hsp70周期的基本特征已经为人所知有一段时间了。ATP结合到Hsp70的ATP酶结构域，诱导蛋白质底物结合结构域发生变构变化，导致底物释放，从而为新的底物分子的结合奠定了基础。ATP水解，以及随后Pi的释放，导致形成稳定的ADP*Hsp70*底物络合物。ATP水解释放的能量可以用来驱动蛋白质易位和大分子复合物重塑反应。Hsp70循环中涉及的多个步骤由cochaperones调节，这些cochaperones增加ATP水解的速率，并将各种底物传递给Hsp70，或增加adp /ATP交换的速率。然而，这些过程的确切机制，主要是变构机制，仍然是难以捉摸的。为了减轻我们在理解上的这些缺陷，我将在不同的变构状态下描述Hsp70的结构。突变和生化实验将用于研究观察到的分子间相互作用和从检查这些结构推断出的机制假设。