BINDING PROTEINS FOR ACTIVE TRANSPORT AND CHEMOTAXIS

本申请的长期目标是研究结构和 几种周质结合或受体蛋白的功能。 这些 蛋白质是渗透冲击敏感活性物质的基本成分， 运输和趋化性。 将使用X射线晶体学 主要是为了实现这个目标。 这一目标是可能的，因为 已经获得了五种受体蛋白的单晶体， 阿拉伯糖-、D-半乳糖-、麦芽糖-、亮氨酸/异亮氨酸/缬氨酸-，和 硫酸盐结合蛋白。 此外，晶体结构的 阿拉伯糖结合蛋白已在2.4处解出。 决议和 对其他结合蛋白的分析已经在进行中。 相同的 技术将被用来详细确定立体化学的 配体结合这些结合蛋白。 伴随的构象变化 结合，假设是必不可少的易位和一个强制性的 趋化行为期间信号传递的第一步，可以是 通过这种分析，在dtail中阐明。 我们还将采用停流 快速混合和小角度X射线散射技术，以进一步研究 各种受体蛋白的配体状态。 本研究结果 将从一个主要的基础上了解分子的作用， 转运和趋化结合蛋白，两个重要的细胞 流程. 运输过程在地球的生命中起着至关重要的作用。 通过维持细胞内环境的相对恒定性 调节各种物质的进出， 代谢活动 此外，趋化性对于细胞的存活也很重要。 因为微生物与环境的相互作用在很大程度上取决于 对刺激做出反应的能力。 高等生物细胞的趋化性 对受精和生物防御机制很重要。 此外，本发明还 信息的单一处理和传输原理 细菌在许多感觉系统中是相似的。 因此，我们认为， 在一个相对简单的系统中详细了解这些过程 将允许在高等生物中评估类似的过程和原理。

The long-range goal of this application is to study the structure and function of several periplasmic binding or receptor proteins. These proteins are essential components of osmotic shock-sensitive active transport and chemotaxis in bacteria. X-ray crystallography will be used primarily to ahcieve this goal. This goal is imminently possible since we have obtained single crystals of five receptor proteins specific for arabinose-, D-galactose-, maltose-, leucine/isoleucine/valine-, and sulfate-binding proteins. Furthermore, the crystal structure of the arabinose-binding protein has been solved at 2.4. A resolution and the analysis of other binding proteins are already in progress. The same technique will be utilized to determine in detail the stereochemistry of ligand binding to these binding proteins. Conformational changes attendant to binding, postulated to be essential in translocation and an obligatory first step in transmission of signals during chemotactic behavior, can be elucidated in dtail by this analysis. We will also employ stopped-flow rapid mixing and small angle x-ray scattering techniques to further study the liganded state of the various receptor proteins. Results of this study will from a major basis for a molecular understanding of the role of binding proteins in transport and chemotaxis, two important cellular processes. Transport processes perform a vital function in the life of the cell by maintaining a relative constancy of the environment within the cell and regulating the entrance and exist of various substances necessary for metabolic activity. In addition, chemotaxis is important for the survival of the microorgnisms since interaction with the environment depends largely on the ability to respond to stimuli. Taxis of cells from higher organisms is important for fertilization and biological defense mechanisms. Further, the principle of single processing and transmission of information in bacteria is similar in a wide variety of sensory systems. Therefore, detailed understanding of these processes in a relatively simple system will allow evaluation of similar process and principles in higher organisms.