STRUCTURAL STUDIES OF THE BACTERIAL TRANSCRIPTION FACTOR

双组分信号系统在细菌中非常常见，但 也发生在真核生物中。信号通过磷酸转移发生 从激酶到“接收器”蛋白质，引发构象变化， 导致改变与其他蛋白质的相互作用以传播信号。 研究人员将研究细菌转录因子NtrC， 在磷酸化后经历自缔合，与σ 54相互作用 聚合酶和ATP水解，导致转录。理解这一 一个相对简单的系统将为理解更复杂的系统提供基础 真核生物的信号传导过程，也可能导致方法， 中断特定的细菌信号传导过程。工作目标 这里提出的是确定细菌转录的结构， 因子NtrC及其结构域，以了解其分子基础 因此，分子信号的一般过程 转导具体目标是：（1）确定高分辨率结构 的BeF 3激活接收域，并了解差异和 在激活时相对于其它接收器域的变化的相似性; (2)表达和纯化野生型序列DNA结合结构域，和 确定与增强子DNA序列结合的二聚体的结构， 以及试图理解连接到相邻的连接器的作用 （3）构建和筛选用于表达ATP酶的中心结构域的构建体， 结构测定（包括来自嗜热菌的那些），并确定 该结构域在不同核苷酸连接状态下的结构;（4） 检查连接接收器和中心的通信螺旋的作用 域，并广泛分析接收器和 （5）用凝胶位移、荧光和免疫荧光检测完整的NtrC， EPR方法跟踪激活，组装和核苷酸 水解，并表达聚合酶的sigma 54亚基，以开始 探索其与NtrC的互动。

Two component signaling systems are very common in bacteria, but also occur in eukaryotes. The signaling occurs through transfer of a phosphate from a kinase to a "receiver" protein, initiating a conformational change, leading to altered interactions with other proteins to propagate the signal. The investigators will study the bacterial transcription factor NtrC, which upon phosphorylation undergoes self-association, interaction with sigma54 polymerase and ATP hydrolysis, leading to transcription. Understanding this relatively simple system will provide a basis for understanding more complex eukaryotic signaling processes, and could also lead to approaches for interrupting specific bacterial signaling processes. The goal of the work proposed here is to determine the structures of the bacterial transcription factor NtrC, and domains of it, to gain an understanding of the molecular basis for its activity, and thereby the general processes for molecular signal transduction. Specific aims are to: (1) determine a high resolution structure of the BeF3- activated receiver domain, and to understand differences and similarities in changes upon activation with respect to other receiver domains; (2) to express and purify the wild type sequence DNA binding domain, and determine the structure of this dimer bound to an enhancer DNA sequence, as well as trying to understand the role of the linker connecting to the adjacent domain; (3) to make and screen constructs of the central ATPase domain for structure determination (including those from a thermophile), and determine the structures of this domain in different nucleotide ligation states; (4) to examine the role of the communication helix linking the receiver and central domains, and to analyze broadly the interactions between the receiver and central domains; (5) to examine intact NtrC with gel shift, fluorescence and EPR approaches to track changes upon activation, assembly and nucleotide hydrolysis, and to express the sigma54 subunit of polymerase to start to explore its interactions with NtrC.