Gu Y Q, Yang C, Thara V K, Zhou J, Martin G B
Boyce Thompson Institute for Plant Research, Ithaca, New York 14853-1801, USA.
Plant Cell. 2000 May;12(5):771-86. doi: 10.1105/tpc.12.5.771.
The tomato Pti4 gene encodes a transcription factor that was identified on the basis of its specific interaction with the product of the Pto disease resistance gene in a yeast two-hybrid system. We show here that the Pti4 protein specifically binds the GCC-box cis element, which is present in the promoter region of many pathogenesis-related (PR) genes. Expression of the Pti4 gene in tomato leaves was rapidly induced by ethylene and by infection with Pseudomonas syringae pv tomato, and this induction preceded expression of GCC-box-containing PR genes. Although salicylic acid also induced Pti4 gene expression, it did not induce GCC-box PR genes. Rather, salicylic acid antagonized ethylene-mediated expression of GCC-box PR genes. We demonstrate that the Pti4 protein is specifically phosphorylated by the Pto kinase and that this phosphorylation enhances binding of Pti4 to the GCC box. In addition, induced overexpression of Pto and Pti4 in tomato leaves resulted in a concomitant increase in GCC-box PR genes. Our results support a model in which phosphorylation of the Pti4 protein by the Pto kinase enhances the ability of Pti4 to activate expression of GCC-box PR genes in tomato.
番茄Pti4基因编码一种转录因子，该转录因子是在酵母双杂交系统中基于其与Pto抗病基因产物的特异性相互作用而被鉴定出来的。我们在此表明，Pti4蛋白特异性结合GCC盒顺式元件，该元件存在于许多病程相关（PR）基因的启动子区域。乙烯和丁香假单胞菌番茄致病变种感染可迅速诱导番茄叶片中Pti4基因的表达，且这种诱导作用先于含GCC盒的PR基因的表达。虽然水杨酸也能诱导Pti4基因表达，但它不能诱导含GCC盒的PR基因。相反，水杨酸拮抗乙烯介导的含GCC盒的PR基因的表达。我们证明Pti4蛋白被Pto激酶特异性磷酸化，且这种磷酸化增强了Pti4与GCC盒的结合。此外，在番茄叶片中诱导Pto和Pti4的过表达会导致含GCC盒的PR基因随之增加。我们的结果支持一种模型，即Pto激酶对Pti4蛋白的磷酸化增强了Pti4激活番茄中含GCC盒的PR基因表达的能力。
