The LysR-Type Transcriptional Regulator CrgA Negatively Regulates the Flagellar Master Regulator flhDC in Ralstonia solanacearum GMI1000
The LysR-Type Transcriptional Regulator CrgA Negatively Regulates the Flagellar Master Regulator flhDC in Ralstonia solanacearum GMI1000
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DOI：
10.1128/jb.00419-20
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发表时间：
2020-10
影响因子：
3.2
通讯作者：
Xiaojing Fan;Zhiwen Zhao;Tingyan Sun;Wei Rou;Cai-Ping Gui;T. Saleem;Xuxu Zhao;Xianyuan Xu;Tao Zhuo;Xun Hu;Huasong Zou
中科院分区：
文献类型：
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作者：
Xiaojing Fan;Zhiwen Zhao;Tingyan Sun;Wei Rou;Cai-Ping Gui;T. Saleem;Xuxu Zhao;Xianyuan Xu;Tao Zhuo;Xun Hu;Huasong Zou
青枯雷尔氏菌是一种广泛分布的土传植物病原菌，可引起多种植物的青枯病。运动性是R.青枯菌，因为它允许这种病原体有效地入侵和定殖宿主植物。In R.青枯菌运动缺陷型菌株的致病性受多种毒力因子的共同调控。在这项研究中，我们确定了一个新的LysR型转录调节因子（LTTR），CrgA，负调节运动。当用土壤浸泡接种法引入病原菌时，相应基因的突变导致番茄植株上枯萎症状的早熟出现。本研究表明，R.青枯菌运动比以前认为的更复杂，并增强了我们对青枯菌鞭毛调节的理解。青枯菌属摘要青枯雷尔氏菌是一种重要的植物病原菌，其入侵和定殖依赖于其细胞运动，而细胞运动受多种因素控制。在这里，我们报告说，LysR型转录调节因子CrgA（RS_RS16695）抑制细胞运动在R。青枯菌GMI 1000。CrgA具有LysR型转录调节因子的共同特征，并且含有N-末端螺旋-转角-螺旋基序以及C-末端LysR底物结合结构域。crgA的缺失导致增强的游泳环和增加的flhDC转录。此外，ΔcrgA突变体具有比野生型GMI 1000更多的极鞭毛，并且表现出更高的鞭毛蛋白基因fliC表达。尽管有这些改变，ΔcrgA突变体在培养中没有可检测到的生长缺陷。酵母单杂交和电泳迁移率变动测定显示CrgA直接与flhDC启动子相互作用。在crgA启动子控制下表达β-葡萄糖醛酸酶（GUS）报告基因表明crgA转录依赖于细胞密度。用crgA突变体浸土接种番茄（Solanum lycopersicum L.）CV.红杨李）植株的发病早于用野生型GMI 1000接种，但导致较低的病害严重度。我们的结论是R.青枯菌调节剂CrgA抑制flhDC表达，并因此影响fliC的表达以调节细胞运动性，从而调节宿主植物中的疾病发展。青枯雷尔氏菌（Ralstonia solanacearum）是一种广泛分布的土传植物病原体，可在多种植物上引起细菌性枯萎病。运动性是R.青枯菌，因为它允许这种病原体有效地入侵和定殖宿主植物。In R.青枯菌运动缺陷型菌株的致病性受多种毒力因子的共同调控。在这项研究中，我们确定了一个新的LysR型转录调节因子（LTTR），CrgA，负调节运动。当用土壤浸泡接种法引入病原菌时，相应基因的突变导致番茄植株上枯萎症状的早熟出现。本研究表明，R.青枯菌运动比以前认为的更复杂，并增强了我们对青枯菌鞭毛调节的理解。青枯菌属
Ralstonia solanacearum is a widely distributed soilborne plant pathogen that causes bacterial wilt disease on diverse plant species. Motility is a critical virulence attribute of R. solanacearum because it allows this pathogen to efficiently invade and colonize host plants. In R. solanacearum, motility-defective strains are markedly affected in pathogenicity, which is coregulated with multiple virulence factors. In this study, we identified a new LysR-type transcriptional regulator (LTTR), CrgA, that negatively regulates motility. The mutation of the corresponding gene leads to the precocious appearance of wilt symptoms on tomato plants when the pathogen is introduced using soil-soaking inoculation. This study indicates that the regulation of R. solanacearum motility is more complex than previously thought and enhances our understanding of flagellum regulation in R. solanacearum. ABSTRACT The invasion and colonization of host plants by the destructive pathogen Ralstonia solanacearum rely on its cell motility, which is controlled by multiple factors. Here, we report that the LysR-type transcriptional regulator CrgA (RS_RS16695) represses cell motility in R. solanacearum GMI1000. CrgA possesses common features of a LysR-type transcriptional regulator and contains an N-terminal helix-turn-helix motif as well as a C-terminal LysR substrate-binding domain. Deletion of crgA results in an enhanced swim ring and increased transcription of flhDC. In addition, the ΔcrgA mutant possesses more polar flagella than wild-type GMI1000 and exhibits higher expression of the flagellin gene fliC. Despite these alterations, the ΔcrgA mutant did not have a detectable growth defect in culture. Yeast one-hybrid and electrophoretic mobility shift assays revealed that CrgA interacts directly with the flhDC promoter. Expressing the β-glucuronidase (GUS) reporter under the control of the crgA promoter showed that crgA transcription is dependent on cell density. Soil-soaking inoculation with the crgA mutant caused wilt symptoms on tomato (Solanum lycopersicum L. cv. Hong yangli) plants earlier than inoculation with the wild-type GMI1000 but resulted in lower disease severity. We conclude that the R. solanacearum regulator CrgA represses flhDC expression and consequently affects the expression of fliC to modulate cell motility, thereby conditioning disease development in host plants. IMPORTANCE Ralstonia solanacearum is a widely distributed soilborne plant pathogen that causes bacterial wilt disease on diverse plant species. Motility is a critical virulence attribute of R. solanacearum because it allows this pathogen to efficiently invade and colonize host plants. In R. solanacearum, motility-defective strains are markedly affected in pathogenicity, which is coregulated with multiple virulence factors. In this study, we identified a new LysR-type transcriptional regulator (LTTR), CrgA, that negatively regulates motility. The mutation of the corresponding gene leads to the precocious appearance of wilt symptoms on tomato plants when the pathogen is introduced using soil-soaking inoculation. This study indicates that the regulation of R. solanacearum motility is more complex than previously thought and enhances our understanding of flagellum regulation in R. solanacearum.