Suzuki T, Imamura A, Ueguchi C, Mizuno T
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Japan.
Plant Cell Physiol. 1998 Dec;39(12):1258-68. doi: 10.1093/oxfordjournals.pcp.a029329.
His to Asp phosphorelay signal transduction mechanisms involve three types of widespread signaling components: a sensor His-kinase, a response regulator, and a histidine-containing phosphotransfer (HPt) domain. In Arabidopsis, several sensor His-kinases have recently been discovered (e.g., ETR1 and CKI1) through extensive genetic studies. Furthermore, a recent search for response regulators in this higher plant revealed that it possesses a group of response regulators (ARR-series), each of which exhibits the phospho-accepting receiver function. However, no signal transducer containing the HPt domain has been reported. Here we identify three distinct Arabidopsis genes (AHP1 to AHP3), each encoding a signal transducer containing a HPt domain. Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. It was demonstrated that AHP1 exhibits in vivo ability to complement a mutational lesion of the yeast YPD1 gene, encoding a typical HPt domain involved in an osmosensing signal transduction. It was also demonstrated that AHPs can interact in vitro with ARRs through the His-Asp phosphotransfer reaction. It was thus suggested that the uncovered sensors-AHPs-ARRs lineups may play important roles in propagating environmental stimuli through the multistep His-Asp phosphorelay in Arabidopsis.
组氨酸 - 天冬氨酸磷酸化信号转导机制涉及三种广泛存在的信号组分：一种传感组氨酸激酶、一种反应调节蛋白和一个含组氨酸的磷酸转移（HPt）结构域。在拟南芥中，通过广泛的遗传学研究，最近发现了几种传感组氨酸激酶（例如，ETR1和CKI1）。此外，最近在这种高等植物中对反应调节蛋白的搜索表明，它拥有一组反应调节蛋白（ARR系列），每个反应调节蛋白都具有磷酸接纳受体功能。然而，尚未报道含有HPt结构域的信号转导蛋白。在此，我们鉴定出三个不同的拟南芥基因（AHP1至AHP3），每个基因编码一个含有HPt结构域的信号转导蛋白。通过使用大肠杆菌和酵母组氨酸 - 天冬氨酸磷酸化系统，获得了体内和体外证据，表明每个AHP都可以作为具有活性组氨酸位点的磷酸传递HPt结构域发挥作用。已证明AHP1在体内具有互补酵母YPD1基因突变损伤的能力，YPD1基因编码参与渗透感应信号转导的典型HPt结构域。还证明了AHP可以在体外通过组氨酸 - 天冬氨酸磷酸转移反应与ARR相互作用。因此，有人提出，新发现的传感器 - AHP - ARR组合可能在拟南芥中通过多步骤组氨酸 - 天冬氨酸磷酸化传递环境刺激方面发挥重要作用。
