Signal Transduction by Histidine Kinases and their Response Regulators

组氨酸激酶是真核生物丝氨酸/苏氨酸和酪氨酸蛋白激酶的细菌对应物，它们都是 它们的功能是细胞响应和适应外部环境所需的信号转导 信号(重音)。典型的细菌性组氨酸激酶(不包括参与 趋化性)是调节其磷酸化状态的跨膜信号转导 拥有同源反应调节因子，其主要功能是转录因子。这又反过来 调节(激活或抑制)适应压力所需的特定基因。在……里面 与丝氨酸/苏氨酸和酪氨酸蛋白激酶不同，高能的磷酸基是由ATP传递的 在信号转导过程中通过组氨酸激酶传递给反应调节器。因此， 组氨酸激酶-反应调节系统被称为“双组分组氨酸-天冬氨酸 其中，Escherichia的EnvZ-OmpR系统 CO//是研究最广泛的系统之一。EnvZ是一种渗透压敏感的组氨酸激酶 并对其胞质激酶区的核磁共振三维结构进行了研究。 下定决心。在目标1中，我们将继续对周质受体结构域的研究。 和细胞质连接蛋白结构域，以理解 膜上有EnvZ二聚体。我们还将在EnvZ和EnvZ之间构建混合信号传感器 TAR，一种趋化性天冬氨酸传感器，可获得对精确分子机制的机械性见解 通过信号输入来调节组氨酸激酶的活性。在《目标2》中，我们将破译 磷酸化OmpR(OmpR-P)与OmpF中六个OmpR-P结合位点的结合方式 推动者验证了一个模型，该模型名为“驰骋模型”，从初步结果预测。我们会 还分析了OmpF和OMPC外膜穿孔的相互调节机制 OmpR-P转录水平和两种反义翻译水平的基因 RT-PCR检测MICF、MICF和MICC基因的表达。

Histidine kinases are the bacterial counterpart to eukaryotic Ser/Thr and Tyr protein kinases, all of which function as signal transducers required for cellular response and adaptation to external signals (stresses). Typically bacterial histidine kinases (excluding a histidine kinase involved in chemotaxis) are transmembrane signal transducers that regulate the phosphorylation state of their own cognate response regulators, which function mostly as transcription factors. This in turn regulates (activates or represses) a specific gene required for adaptation to the stresses. In contrast to Ser/Thr and Tyr protein kinases, a high-energy phosphoryl group is relayed from ATP through a histidine kinase to a response regulator during signal transduction. Therefore, the histidine kinase-response regulator systems are referred as "the two-component His-Asp phosphorelay signal transduction system". Of these, the EnvZ-OmpR system from Escherichia co// is one of the most extensively investigated systems. EnvZ is an osmo-sensing histidine kinase and the NMR three-dimensional structures of its cytoplasmic kinase domains have been determined. In Aim 1, we will continue the structural studies on the periplasmic receptor domain and the cytoplasmic linker domain to comprehend the global three-dimensional structure of the EnvZ dimer in the membrane. We will also construct hybrid signal transducers between EnvZ and Tar, a chemotaxis Asp sensor to obtain mechanistic insights into the precise molecular mechanism of regulation of the histidine kinase activity by a signal input. In Aim 2, we will decipher the precise mode of binding of phosphorylated OmpR (OmpR-P) to six OmpR-P binding sites in the ompF promoter to prove a model called "galloping model" predicted from the preliminary results. We will also analyze the reciprocal regulatory mechanism for the ompF and ompC outer membrane porin genes at the level of transcription by OmpR-P and at the level of translation by two antisense RNAs, micF and micC RNAs by RT-PCR.