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首页> 外文期刊>Infection and immunity >Characterization of the Effect of the Histidine Kinase CovS on Response Regulator Phosphorylation in Group A Streptococcus
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Characterization of the Effect of the Histidine Kinase CovS on Response Regulator Phosphorylation in Group A Streptococcus

机译:组氨酸激酶CovS对A组链球菌应答调节剂磷酸化的影响的表征。

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Two-component gene regulatory systems (TCSs) are a major mechanism by which bacteria respond to environmental stimuli and thus are critical to infectivity. For example, the control of virulence regulator/sensor kinase (CovRS) TCS is central to the virulence of the major human pathogen group A Streptococcus (GAS). Here, we used a combination of quantitative in vivo phosphorylation assays, isoallelic strains that varied by only a single amino acid in CovS, and transcriptome analyses to characterize the impact of CovS on CovR phosphorylation and GAS global gene expression. We discovered that CovS primarily serves to phosphorylate CovR, thereby resulting in the repression of virulence factor-encoding genes. However, a GAS strain selectively deficient in CovS phosphatase activity had a distinct transcriptome relative to that of its parental strain, indicating that both CovS kinase and phosphatase activities influence the CovR phosphorylation status. Surprisingly, compared to a serotype M3 strain, serotype M1 GAS strains had high levels of phosphorylated CovR, low transcript levels of CovR-repressed genes, and strikingly different responses to environmental cues. Moreover, the inactivation of CovS in the serotype M1 background resulted in a greater decrease in phosphorylated CovR levels and a greater increase in the transcript levels of CovR-repressed genes than did CovS inactivation in a serotype M3 strain. These data clarify the influence of CovS on the CovR phosphorylation status and provide insight into why serotype M1 GAS strains have high rates of spontaneous mutations in covS during invasive GAS infection, thus providing a link between TCS molecular function and the epidemiology of deadly bacterial infections.
机译:两成分基因调节系统(TCS)是细菌对环境刺激做出反应的主要机制,因此对感染性至关重要。例如,毒力调节剂/传感器激酶(CovRS)TCS的控制对于主要人类病原体A链球菌(GAS)的毒力至关重要。在这里,我们结合使用了定量体内磷酸化测定,仅在CovS中仅一个氨基酸变化的等位基因菌株,以及转录组分析,以表征CovS对CovR磷酸化和GAS全局基因表达的影响。我们发现CovS主要用于磷酸化CovR,从而导致抑制毒力因子编码基因。然而,相对于其亲本菌株而言,选择性缺乏CovS磷酸酶活性的GAS菌株具有独特的转录组,表明CovS激酶和磷酸酶活性均影响CovR磷酸化状态。出乎意料的是,与血清型M3菌株相比,血清型M1 GAS菌株具有高水平的磷酸化CovR,低水平的CovR抑制基因转录本,以及对环境提示的反应截然不同。此外,与血清型M3菌株中的CovS灭活相比,血清型M1背景中CovS的灭活导致磷酸化CovR水平的降低幅度更大,并且CovR抑制基因的转录水平的提高幅度更大。这些数据阐明了CovS对CovR磷酸化状态的影响,并提供了洞察力,以了解为什么血清型M1 GAS菌株在侵袭性GAS感染期间在covS中具有高自发突变率,从而在TCS分子功能与致命细菌感染的流行病学之间建立联系。

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