Xanthomonas campestris attenuates virulence by sensing light through a bacteriophytochrome photoreceptor
Xanthomonas campestris attenuates virulence by sensing light through a bacteriophytochrome photoreceptor
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DOI：
10.15252/embr.201541691
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发表时间：
2016-11-01
期刊：
影响因子：
7.7
通讯作者：
Malamud, Florencia
中科院分区：
文献类型：
--
作者：
Bonomi, Hernan R.;Toum, Laila;Malamud, Florencia
光敏色素构成在植物、藻类、真菌和原核生物（包括病原体）中发现的主要光感受器家族。在这里，我们报告说，黄单胞菌campestris pv。campestris（Xcc）编码一种功能性细菌光敏色素（XccBphP）。XccBphP具有N末端PAS 2-GAF-PHY感光结构域三联体和C末端PAS 9结构域作为其输出模块。我们的研究结果表明，照明XCC，植物感染之前，减弱其毒力的XccBphP依赖的方式。此外，在响应光，XccBphP下调黄原胶胞外多糖的生产和生物膜的形成，两个已知的Xcc毒力因子。此外，XccbphP无效突变体显示增强的毒力，类似于黑暗适应的Xcc文化。气孔孔径调节和胼胝质沉积，这两个完善的植物防御机制对细菌病原体，被推翻的XccbphP菌株。此外，RNA-Seq分析显示，远红光或XccBphP过表达产生全基因组转录变化，包括抑制几个Xcc毒力系统。我们的研究结果表明，Xcc通过XccBphP感知光，通过下调细菌毒力因子引起细菌毒力衰减。XccBphP在体外和体内对光的反应能力被保守的Cys 13残基上的突变所消除。这些结果提供了一种新的细菌光敏色素功能影响感染过程的证据。
Phytochromes constitute a major photoreceptor family found in plants, algae, fungi, and prokaryotes, including pathogens. Here, we report that Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot disease which affects cruciferous crops worldwide, codes for a functional bacteriophytochrome (XccBphP). XccBphP possesses an N-terminal PAS2-GAF-PHY photosensory domain triad and a C-terminal PAS9 domain as its output module. Our results show that illumination of Xcc, prior to plant infection, attenuates its virulence in an XccBphP-dependent manner. Moreover, in response to light, XccBphP downregulates xanthan exopolysaccharide production and biofilm formation, two known Xcc virulence factors. Furthermore, the XccbphP null mutant shows enhanced virulence, similar to that of dark-adapted Xcc cultures. Stomatal aperture regulation and callose deposition, both well-established plant defense mechanisms against bacterial pathogens, are overridden by the XccbphP strain. Additionally, an RNA-Seq analysis reveals that far-red light or XccBphP overexpression produces genomewide transcriptional changes, including the inhibition of several Xcc virulence systems. Our findings indicate that Xcc senses light through XccBphP, eliciting bacterial virulence attenuation via downregulation of bacterial virulence factors. The capacity of XccBphP to respond to light both in vitro and in vivo was abolished by a mutation on the conserved Cys13 residue. These results provide evidence for a novel bacteriophytochrome function affecting an infectious process.