STRUCTURE/STABILITY OF AN EXTREME THERMOPHILE PROTEIN

极端嗜热蛋白质的结构/稳定性

• 批准号: 6180472
• 负责人: JOHN W SHRIVER
• 金额: $ 20.4万
• 依托单位: SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6180472
• 关键词: Archaea; DNA binding protein; X ray crystallography; bacterial proteins; calorimetry; chemical models; circular dichroism; hydrogen bond; intermolecular interaction; nuclear magnetic resonance spectroscopy; protein denaturation; protein folding; protein structure; site directed mutagenesis; structural biology; thermodynamics; thermophilic organism; thermostability

This project is designed to characterize the structural thermodynamics of a DNA binding protein from the hyperthermophile Sulfolobus. The emphasis is on both stability and function. Proteins from hyperthermophiles are of interest in protein engineering and biotechnology since they are designed for both folding and functioning at high temperature (via 80 to 110 degrees C). Little is known about the structures of hyperthermophile proteins, and even less is known about the thermodynamics of both their folding and function. The 7 kD chromatin proteins Sac7d and Sso7d are two of the few hyperthermophile proteins studied to date which unfold reversibly, permitting detailed thermodynamic studies. They also provide a simple model system for studies of the thermodynamics of non-specific DNA-binding using proteins that are designed for that purpose. Current ideas on the thermodynamics of nonspecific protein-DNA interactions are largely based on studies of sequence-specific proteins binding to non-consensus sequences. The first determination of the free energy of stabilization of a hyperthermophile protein was performed in the initial phase of this project using recombinant Sac7d. This work will now be extended to the native protein along with an extensive study of the folding thermodynamics with site-directed mutagenesis. Of particular interest will be a characterization and thermodynamic study of a post-translational modification, possibly lysine methylation, which increases the Sac7d stability. The importance of this modification, surface ionic interactions, ion binding, and core packing will be investigated by a combination of site-directed mutagenesis, NMR, chemical denaturation, and scanning and titration calorimetry. Sac7d and Sso7d bind double-stranded DNA non-specifically as monomers. This is an especially simple system for detailed structural thermodynamic studies of individual interactions and the thermodynamics of nonspecific binding. The importance of both ionic and nonionic interactions in DNA binding will be investigated by scanning and titration calorimetry, binding measurements using fluorescence and circular dichroism, and site-specific mutagenesis. Information gained from this project will contribute to our ability to design and control protein stability and protein-DNA interactions with potential applications in medicine and biotechnology.

该项目旨在表征结构热力学 来自超嗜热菌硫化叶菌的 DNA 结合蛋白。重点 兼顾稳定性和功能。来自超级嗜热菌的蛋白质是 自设计以来就对蛋白质工程和生物技术感兴趣 用于高温折叠和功能（通过 80 至 110 度 C）。人们对超嗜热蛋白的结构知之甚少， 关于它们的折叠和折叠的热力学知之甚少。 功能。 7 kD 染色质蛋白 Sac7d 和 Sso7d 是少数几个中的两个 迄今为止研究的超嗜热蛋白可逆地展开， 允许进行详细的热力学研究。 他们还提供了一个简单的 用于研究非特异性 DNA 结合热力学的模型系统 使用为此目的而设计的蛋白质。目前的想法 非特异性蛋白质-DNA 相互作用的热力学很大程度上基于 与非共有序列结合的序列特异性蛋白的研究 序列。 首次测定稳定自由能 超嗜热蛋白在该项目的初始阶段进行 使用重组 Sac7d。这项工作现在将扩展到本地 蛋白质以及折叠热力学的广泛研究 定点诱变。特别令人感兴趣的是 翻译后的表征和热力学研究 修饰，可能是赖氨酸甲基化，这会增加 Sac7d 稳定。这种修饰的重要性，表面离子相互作用， 离子结合和核心堆积将通过组合进行研究 定点突变、核磁共振、化学变性、扫描和 滴定量热法。 Sac7d 和 Sso7d 作为单体非特异性结合双链 DNA。这 是一个特别简单的详细结构热力学系统 个体相互作用和非特异性热力学的研究 绑定。 DNA 中离子和非离子相互作用的重要性 将通过扫描和滴定量热法研究结合 使用荧光和圆二色性以及位点特异性进行测量 诱变。 从这个项目中获得的信息将有助于我们的能力 设计和控制蛋白质稳定性以及蛋白质-DNA 相互作用 在医学和生物技术方面的潜在应用。