Pseudomonas syringae Two-Component Response Regulator RhpR Regulates Promoters Carrying an Inverted Repeat Element
Pseudomonas syringae Two-Component Response Regulator RhpR Regulates Promoters Carrying an Inverted Repeat Element
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DOI：
10.1094/mpmi-23-7-0927
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发表时间：
2010-07-01
影响因子：
3.5
通讯作者：
Tang, Xiaoyan
中科院分区：
文献类型：
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作者：
Deng, Xin;Lan, Lefu;Tang, Xiaoyan
在丁香假单胞菌中，双组分系统 RhpRS 被鉴定为编码 III 型分泌系统和 III 型效应蛋白（统称为 T3 基因）的基因的调节因子。在缺乏传感器激酶 RhpS 的情况下，反应调节剂 RhpR 以磷酸化依赖性方式抑制由 hrpRS、hrpL 和 T3 基因组成的 T3 基因调控级联的诱导。 RhpS 抑制 RhpR 的阻遏活性，RhpS 可能在 T3 基因诱导条件下充当磷酸酶。在这里，我们证明 RhpR 以磷酸化依赖性方式结合并诱导其自身的启动子。缺失和诱变分析揭示了 rhpR 启动子中的反向重复 (IR) 元件 GTATC-N-6-GATAC，可实现 RhpR 依赖性诱导。对丁香假单胞菌基因组中推定的 IR 元件进行计算搜索，并对启动子区域中具有推定的 IR 元件的基因进行 Northern 印迹分析，发现了 5 个上调基因和 2 个以 RhpR 依赖性方式下调的基因。对 RhpR 强烈诱导的两个基因进行了基因调控中 IR 元件活性的测定，并且在这两种情况下，IR 元件介导了 RhpR 依赖性基因诱导。染色质免疫沉淀测定表明，RhpR 结合含有假定 IR 元件的启动子，但不结合不含有 IR 元件的 hrpR 和 hrpL 启动子，这表明 RhpR 间接调节 hrpRS、hrpL 和 T3 基因的转录级联。
The two-component system RhpRS was identified in Pseudomonas syringae as a regulator of the genes encoding the type III secretion system and type III effector proteins (together called the T3 genes). In the absence of the sensor kinase RhpS, the response regulator RhpR represses the induction of the T3 gene regulatory cascade consisting of hrpRS, hrpL, and the T3 genes in a phosphorylation-dependent manner. The repressor activity of RhpR is inhibited by RhpS, which presumably acts as a phosphatase under the T3 gene inducing conditions. Here, we show that RhpR binds and induces its own promoter in a phosphorylation-dependent manner. Deletion and mutagenesis analyses revealed an inverted repeat (IR) element, GTATC-N-6-GATAC, in the rhpR promoter that confers the RhpR-dependent induction. Computational search of the P. syringae genomes for the putative IR elements and Northern blot analysis of the genes with a putative IR element in the promoter region uncovered five genes that were upregulated and two genes that were downregulated in an RhpR-dependent manner. Two genes that were strongly induced by RhpR were assayed for the IR element activity in gene regulation and, in both cases, the IR element mediated the RhpR-dependent gene induction. Chromatin immunoprecipitation assays indicated that RhpR binds the promoters containing a putative IR element but not the hrpR and hrpL promoters that do not have an IR element, suggesting that RhpR indirectly regulates the transcriptional cascade of hrpRS, hrpL, and the T3 genes.