Role of Molecular Chaperones in Stress Response and Disease

分子伴侣在应激反应和疾病中的作用

• 批准号: 9474648
• 负责人: Ursula H. Jakob
• 金额: $ 68.56万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9474648
• 关键词: Acids; Amyloid; Amyloidosis; Bacteria; Biochemical; Blood; Cells; Disease; Dissociation; Enterobacteriaceae; Eukaryota; Exposure to; Goals; Host Defense; Hypochlorous Acid; Insecta; Leishmania infantum; Mammals; Microbial Biofilms; Mitochondria; Molecular Chaperones; Molecular Conformation; Mutation; Neurodegenerative Disorders; Neurons; Organism; Oxidation-Reduction; Parasites; Parkinson Disease; Pathway interactions; Physiological; Play; Polymers; Polyphosphates; Polyps; Process; Proteins; Research; Resistance; Resolution; Role; Site; Stomach; Stress; Suggestion; System; Temperature; Testing; Time; Toxic effect; Work; Yeasts; acid stress; amyloid formation; analog; antimicrobial; beta pleated sheet; biological adaptation to stress; disulfide bond; flexibility; improved; novel; pathogenic bacteria; protein folding; protein protein interaction; proteotoxicity; scaffold; thermostability; tool

Many organisms regularly encounter fast-acting, highly proteotoxic stress conditions, including exposure to the physiological antimicrobial hypochlorous acid (HOCl), highly elevated temperatures or acid stress. To survive these stress conditions, they employ a class of ATP-independent, stress specific chaperones, whose posttranslational activation is tailored towards the stress conditions that require their chaperone functions. Our lab investigates four of these stress-specific chaperones; Hsp33, which is activated by oxidative disulfide bond formation to protect bacteria and eukaryotic parasites against HOCl, which is commonly produced by cells of the innate host defense; Get3, a redox-regulated Hsp33 analogue that protects yeast and likely other eukaryotes against oxidative protein damage; HdeA, which is rapidly activated by acid-induced dissociation and protects enteric bacteria against acid-stress encountered in the mammalian stomach; and mitochondrial Prdx2 from Leishmania infantum, which is a temperature-regulated chaperone that protects parasites against the sudden temperature shift as they transit from insects to warm-blooded mammals. All four of these proteins are chaperone-inactive and stably folded under non-stress conditions but are activated following very rapid, stress-induced conformational rearrangements, converting them into proteins with extensive regions of intrinsic disorder. We will now combine mutational, biochemical and high-resolution structural tools to elucidate the precise working mechanism of these proteins, testing the hypothesis that stress-induced unfolding serves to generate novel, highly flexible protein-protein interaction sites. These studies have the potential to open up a completely new perspective in chaperone research, protein folding and stress response pathways. In a separate line of research, we discovered that polyphosphate (polyP), which is a universally conserved, very abundant and ubiquitously distributed polymer, works as a highly effective protein-stabilizing scaffold. This demonstrates that protein chaperones are not the only cellular solution to deal with proteotoxic stress conditions. We found that polyP increases the thermostability of proteins by stabilizing them in a predominantly β-sheet conformation. This finding helps to explain how polyP confers resistance to stress conditions that cause protein unfolding. At the same time, it also explains how polyP acts to accelerate processes such as bacterial biofilm formation, which depend on the stabilization of amyloid-like proteins in a fibril-forming cross-β-sheet conformation. We recently realized that polyP equally accelerates fibril formation of disease-associated amyloids. This activity appears to reduce the amount of toxic oligomers and, most importantly, protects neurons against amyloid toxicity. We will now further investigate this exciting suggestion that polyP is a physiologically important cytoprotective modifier of amyloidogenic processes, and might play a role in Parkinson's disease and potentially other neurodegenerative diseases associated with amyloid formation.

许多生物体经常遇到快速作用的高蛋白毒性应激条件，包括暴露于 生理抗微生物次氯酸（HOCl）、高度升高的温度或酸胁迫。生存 在这些应激条件下，它们采用一类ATP-非依赖性的应激特异性分子伴侣，其 翻译后激活是针对需要其伴侣蛋白功能的应激条件而定制的。我们 一个实验室研究了其中四种应激特异性分子伴侣：Hsp 33，它被氧化二硫键激活 形成保护细菌和真核寄生虫免受HOCl，HOCl通常由细胞产生， 先天宿主防御; Get 3，一种氧化还原调节的Hsp 33类似物，可保护酵母和其他可能的宿主。 抗氧化蛋白损伤的真核生物; HdeA，可通过酸诱导解离快速激活 并保护肠道细菌免受哺乳动物胃中遇到的酸应激; Prdx 2来自婴儿利什曼原虫，这是一种温度调节的伴侣蛋白，可保护寄生虫免受 从昆虫转变为温血哺乳动物时温度的突然变化。这四种蛋白质 在非应激条件下是无伴侣活性的和稳定折叠的， 应激诱导的构象重排，将其转化为具有广泛的内在结构区域的蛋白质。 disorder.我们现在将结合联合收割机突变，生化和高分辨率结构工具来阐明 这些蛋白质的精确工作机制，测试假设，应力诱导的展开服务于 产生新的、高度灵活的蛋白质-蛋白质相互作用位点。这些研究有可能开辟一个 在分子伴侣研究、蛋白质折叠和应激反应途径方面的全新视角。中 我们发现，聚磷酸盐（polyP），这是一个普遍保守的，非常 丰富和无处不在的聚合物，作为一种高效的蛋白质稳定支架。这 表明蛋白伴侣不是处理蛋白毒性应激的唯一细胞解决方案 条件我们发现polyP通过将蛋白质稳定在一个合适的温度来增加蛋白质的热稳定性。 主要是β折叠构象。这一发现有助于解释polyP如何赋予抗压力能力 导致蛋白质解折叠的条件。同时，它还解释了polyP如何加速 过程，如细菌生物膜的形成，这取决于淀粉样蛋白的稳定性， 纤维形成交叉β-折叠构象。我们最近意识到，聚P同样加速了纤维的形成。 疾病相关的淀粉样蛋白这种活性似乎减少了有毒低聚物的量， 重要的是，保护神经元免受淀粉样蛋白毒性。我们现在将进一步研究这个令人兴奋的建议 聚P是淀粉样蛋白形成过程中生理学上重要的细胞保护性修饰剂， 在帕金森病和其他可能与淀粉样蛋白相关的神经退行性疾病中的作用 阵