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首页> 外文期刊>Biochemistry >Redox Sensing by PecS from the Plant Pathogen Pectobacterium atrosepticum and Its Effect on Gene Expression and the Conformation of PecS-Bound Promoter DNA
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Redox Sensing by PecS from the Plant Pathogen Pectobacterium atrosepticum and Its Effect on Gene Expression and the Conformation of PecS-Bound Promoter DNA

机译：PECS从植物病原体植物膜腹膜内渗透腺氧化还原感测及其对基因表达的影响及肽结合促进剂DNA的作用

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摘要

The plant pathogen Pectobacterium atrosepticum encounters a stressful environment when it colonizes the plant apoplast. Chief among the stressors are the reactive oxygen species (ROS) that are produced by the host as a first line of defense. Bacterial transcription factors in turn use these signals as cues to upregulate expression of virulence-associated genes. We have previously shown that the transcription factor PecS from P. atrosepticum binds the promoters that drive expression of pecS and pecM, which encodes an efflux pump, to repress gene expression. We show here that addition of oxidant relieves repression in vivo and in vitro. While reduced PecS distorts promoter DNA on binding, oxidized PecS does not, as evidenced by DNaseI footprinting. PecS oxidation is reversible, as shown by an oxidant-dependent quenching of the intrinsic tryptophan fluorescence that is completely reversed upon addition of a reducing agent. Cysteine 45 positioned at the PecS dimer interface is the redox sensor. Reduced PecS-C45A causes less DNA distortion on binding compared to wild-type PecS; addition of an oxidant has no effect on binding, and PecS-C45A cannot repress gene expression. Our data suggest that reduced PecS distorts its cognate DNA on binding, perhaps inducing a conformation in which promoter elements are suboptimally aligned for RNA polymerase binding, resulting in transcriptional repression. In contrast, oxidized PecS binds promoter DNA such that RNA polymerase may successfully compete with PecS for binding, allowing gene expression. This mode of regulation would facilitate induction of the PecS regulon when the bacteria encounter host-derived ROS in the plant apoplast.
机译：植物病原体植物膜腹膜内腹膜内腹膜内肌腱在植物灌注植物殖民殖民地时遇到压力环境。压力源之间的主要源性是由宿主作为第一道防线生产的反应性氧物种（ROS）。细菌转录因子反过来使用这些信号作为提示来上调毒力相关基因的表达。我们先前已经表明，来自P.Atrosepticum的转录因子PECs结合了驱动PEC和PECM的表达的启动子，该促进剂编码泵浦泵，以抑制基因表达。我们在这里展示了氧化剂的添加缓解体内和体外镇压。虽然降低的PECS扭曲了促进剂DNA的结合，但是氧化的PEC不通过DNASEI足迹证明。 PECS氧化是可逆的，如在加入还原剂上完全反转的本质色氨酸荧光的氧化剂依赖性猝灭所示。位于PECS二聚体界面处的半胱氨酸45是氧化还原传感器。与野生型PECs相比，减少的PECS-C45A导致较少的DNA畸变与结合相比;添加氧化剂对结合没有影响，并且PECS-C45A不能抑制基因表达。我们的数据表明，降低的PECs对其结合的同源DNA扭曲，可能诱导启动子元素依赖于RNA聚合酶结合的构象，导致转录抑制。相反，氧化的PECs结合启动子DNA，使得RNA聚合酶可以成功地与PEC竞争结合，允许基因表达。这种调节模式将促进PECS调节件当细菌在植物血晶杆中遇到宿主的ROS时。

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  • 来源
    《Biochemistry》 |2019年第21期|共12页
  • 作者

    Deochand Dinesh K.; Pande Anuja; Meariman Jacob K.; Grove Anne;

  • 作者单位

    Louisiana State Univ Dept Biol Sci Baton Rouge LA 70803 USA;

    Louisiana State Univ Dept Biol Sci Baton Rouge LA 70803 USA;

    Louisiana State Univ Dept Biol Sci Baton Rouge LA 70803 USA;

    Louisiana State Univ Dept Biol Sci Baton Rouge LA 70803 USA;

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  • 正文语种 eng
  • 中图分类 生物化学;
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