Signal Transduction by Histidine Kinases and their Response Regulators

组氨酸激酶是真核生物Ser/Thr和Tyr蛋白激酶的细菌对应物，所有组氨酸激酶都是真核生物的蛋白激酶。 其作为细胞响应和适应外界环境所需的信号转换器 信号（应力）。典型的细菌组氨酸激酶（不包括涉及 趋化性）是跨膜信号转导子，其调节其细胞的磷酸化状态。 自身的同源反应调节因子，其功能主要是转录因子。这反过来 调节（激活或抑制）适应压力所需的特定基因。在 与Ser/Thr和Tyr蛋白激酶不同， 在信号转导过程中通过组氨酸激酶转化为应答调节剂。因此 组氨酸激酶反应调节系统被称为“双组分His-Asp 磷酸化信号转导系统”。其中，来自埃希氏菌的EnvZ-OmpR系统 CO//是最广泛研究的系统之一。EnvZ是一种对组氨酸敏感的组氨酸激酶， 其胞质激酶结构域的NMR三维结构已被 测定在目标1中，我们将继续对周质受体结构域进行结构研究 和胞质接头结构域来理解细胞的整体三维结构。 膜中的EnvZ二聚体。我们还将构建EnvZ和 Tar，一种趋化性Asp传感器，以获得对精确分子机制的机理见解 通过信号输入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6个OmpR-P结合位点的结合模式 启动子，以证明一个名为“驰振模型”的模型预测的初步结果。我们将 并分析了ompF和ompC外膜孔蛋白的相互调控机制 在转录水平上通过OmpR-P和在翻译水平上通过两个反义寡核苷酸来表达基因。 RNA、micF和micC RNA。

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.