Clark K L, Larsen P B, Wang X, Chang C
Department of Cell Biology and Molecular Genetics, H. J. Patterson Hall, University of Maryland, College Park, MD 20742, USA.
Proc Natl Acad Sci U S A. 1998 Apr 28;95(9):5401-6. doi: 10.1073/pnas.95.9.5401.
In Arabidopsis thaliana, signal transduction of the hormone ethylene involves at least two receptors, ETR1 and ERS, both of which are members of the two-component histidine protein kinase family that is prevalent in prokaryotes. The pathway also contains a negative regulator of ethylene responses, CTR1, which closely resembles members of the Raf protein kinase family. CTR1 is thought to act at or downstream of ETR1 and ERS based on double mutant analysis; however, the signaling mechanisms leading from ethylene perception to the regulation of CTR1 are unknown. By using the yeast two-hybrid assay, we detected a specific interaction between the CTR1 amino-terminal domain and the predicted histidine kinase domain of ETR1 and ERS. We subsequently verified these interactions by using an in vitro protein association assay(s). In addition, we determined that the amino-terminal domain of CTR1 can associate with the predicted receiver domain of ETR1 in vitro. Based on deletion analysis, the portion of CTR1 that interacts with ETR1 roughly aligns with the regulatory region of Raf kinases. These physical associations support the genetic evidence that CTR1 acts in the pathway of ETR1 and ERS and suggest that these interactions could be involved in the regulation of CTR1 activity.
在拟南芥中，激素乙烯的信号转导涉及至少两种受体，即ETR1和ERS，它们都是原核生物中普遍存在的双组分组氨酸蛋白激酶家族的成员。该信号通路还包含乙烯反应的负调控因子CTR1，它与Raf蛋白激酶家族的成员非常相似。基于双突变分析，CTR1被认为在ETR1和ERS的作用位点或下游起作用；然而，从乙烯感知到CTR1调控的信号传导机制尚不清楚。通过酵母双杂交试验，我们检测到CTR1氨基末端结构域与ETR1和ERS预测的组氨酸激酶结构域之间存在特异性相互作用。随后，我们通过体外蛋白质结合试验验证了这些相互作用。此外，我们还确定CTR1的氨基末端结构域在体外可与ETR1预测的受体结构域结合。基于缺失分析，CTR1中与ETR1相互作用的部分大致与Raf激酶的调控区域对齐。这些物理相互作用支持了CTR1在ETR1和ERS信号通路中起作用的遗传学证据，并表明这些相互作用可能参与了CTR1活性的调控。
