2016-01-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/671245摘要：大腸桿菌異化代謝活化子是個眾所皆知的轉錄活化子，藉由細胞中環單磷酸腺甘的濃度來調控幾百個轉錄單位。異化代謝活化子能提供研究結構及轉錄機制的經典模式系統，也比其他的轉錄活化調控著更幾近完成的機制說明。環單磷酸腺甘能引發異化代謝活化子的異位轉變，能將其由“關”的狀態，只能跟脫氧核糖核酸以非特異性的微弱方式結合，轉至“開的”狀態，而能跟脫氧核糖核酸以特異性地強力方式結合。異化代謝活化子與環單磷酸腺甘結合後能跟促進子附近的脫氧核糖核酸序列以特異性地強力方式結合，而造成跟核糖核酸相互影響能進一步調控轉錄活化。這個計劃的主要目標是利用異化代謝活化子作為模型系統能回答異位調控及轉錄活化的基本問題。我們將接合結構、動力學及熱力學的方法用於（1）決定第一類及第二類倚賴異化代謝活化子的促進子複合體;（2）決定整個異化代謝活化子傳遞的轉錄起始聚合體。<br> Abstract: Escherichia coli catabolite activator protein (CAP) is a transcriptional activator known to regulate hundreds of transcription units by responding to fluctuations of the cellular concentration of cAMP. CAP has provided a classic model system for structural and mechanistic studies of transcription activation. Mechanistic descriptions of transcription activation, developed for CAP, are more nearly complete than descriptions of any other examples of transcription activation. cAMP elicits an allosteric transition that switches CAP from the “off” state, which binds DNA weakly and nonspecifically, to the “on” state, which binds DNA strongly and specifically. In the cAMP-bound state, CAP binds to DNA sites located in or adjacent to target promoters resulting in modulation of interactions of RNA polymerase. The main objectives of this project are to use CAP as a model system to address fundamental questions regarding allosteric regulation and transcriptional activation. An integrated structural, dynamic, and thermodynamic approach will be used to (1) determine the solution structure of the class I and class II CAP-dependent promoter subassemblies and (2) determine the structural basis for the assembly of the entire CAP-mediated transcription initiation complex.蛋白質結構protein structure