MOLECULAR BASES OF COMMON TWO-COMPONENT PHOSPHORELAY SIGNAL TRANSDUCTION IN BOTH PROKAYOTIC AND EUKAYOTIC MICROORGANISMS

His-激酶是His→Asp磷酸化信号转导的核心分子。然而，在某些情况下，另一种常见的含组氨酸的磷酸转移结构域（或因子）在顺序的His→Asp→His→Asp信号转导事件中起着至关重要的作用，通常称为“多步His→Asp磷酸化接力”。在这篇综述中，讨论了HPt结构域的特征，特别提到了大肠杆菌ArcB杂交his激酶，它包含了第一个发现的HPt结构域。在大肠杆菌生理学中，这种特殊的his激酶参与了复杂的转录调节网络，使大肠杆菌细胞能够对各种有氧和厌氧生长条件作出反应。对广泛存在的HPt域的一般看法也进行了讨论。正如本文简要概述的那样，一个多步骤的His→Asp磷酸化传递机制发挥了一个比以前认为的更复杂的任务，其中一个常见的HPt结构域与经典的两个组分，His激酶和反应调节因子协同作用。在目前的原核生物和真核生物数据库中，可以预测有许多HPt结构域的实例，并且它们的数量正在迅速增长。然而，它们的生物学（或生理学）作用实际上是未知的，除了这里提到的情况。由于His→Asp磷接力信号系统在原核生物和真核生物中都是如此普遍和全球性，因此通过采用新发展的后测序方法，如DNA微阵列和蛋白质组分析，它们是探索的最佳范例

A His-kinases is a central player of a His→Asp phosphorelay signal transduction. In some case, however, another common histidine-containing phosphotransfer domain (or factor) plays a crucial role in a sequential His→Asp→His→Asp signaling event that is generally referred to as "multistep His→Asp phosphorelay". In this review, characteristic features of the HPt domain are discussed with special reference to the Escherichia coli ArcB hybrid His-kinase that contains the first discovered HPt domain. In E.coli physiology, this particular His-kinase is involved in the complex transcriptional regulatory network that allows E.coli cells to respond to various aerobic and anaerobic growth conditions. General views as to the widespread HPt domains are also discussed. As briefly overviewed here, a multistep His→Asp phosphorelay mechanism exerts a more sophisticated task than thought previously, in which a common HPt domains acts in concert with the classical two components, His-kinases and response regulators. Numerous instances of HPt domains can be predicted to occur in the current databases both for prokaryotes and eukaryotes, and their numbers are growing very rapidly. Nevertheless, their biological (or physiological) roles are virtually unknown, except the cases mentioned here. Since His→Asp phosphorelay signaling systems are so common and global both in prokaryotes and eukaryotes, they are the best paradigms of choice to explore through taking the newly developing post-sequencing approaches, such as DNA micro-array and proteome analyses