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抗西格玛因子 RsbW 在艰难梭菌应激反应、持久性和感染中的调控作用。

Regulatory Role of Anti-Sigma Factor RsbW in Clostridioides difficile Stress Response, Persistence, and Infection.

机构信息

Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom.

Instituto Gulbenkian de Ciência, Oeiras, Portugal.

出版信息

J Bacteriol. 2023 May 25;205(5):e0046622. doi: 10.1128/jb.00466-22. Epub 2023 Apr 26.

Abstract

The anaerobic pathogen Clostridioides difficile, which is a primary cause of antibiotic-associated diarrhea, faces a variety of stresses in the environment and in the mammalian gut. To cope with these stresses, alternative sigma factor B (σ) is employed to modulate gene transcription, and σ is regulated by an anti-sigma factor, RsbW. To understand the role of RsbW in C. difficile physiology, a mutant (Δ), in which σ is assumed to be "always on," was generated. Δ did not show fitness defects in the absence of stress but tolerated acidic environments and detoxified reactive oxygen and nitrogen species better compared to the parental strain. Δ was defective in spore and biofilm formation, but it displayed increased adhesion to human gut epithelia and was less virulent in a Galleria mellonella infection model. A transcriptomic analysis to understand the unique phenotype of Δ showed changes in expression of genes associated with stress responses, virulence, sporulation, phage, and several σ-controlled regulators, including the pleiotropic regulator sinRR'. While these profiles were distinct to Δ, changes in some σ-controlled stress-associated genes were similar to those reported in the absence of σ. Further analysis of Δ showed unexpected lower intracellular levels of σ, suggesting an additional post-translational control mechanism for σ in the absence of stress. Our study provides insight into the regulatory role of RsbW and the complexity of regulatory networks mediating stress responses in C. difficile. Pathogens like Clostridioides difficile face a range of stresses in the environment and within the host. Alternative transcriptional factors like sigma factor B (σ) enable the bacterium to respond quickly to different stresses. Anti-sigma factors like RsbW control sigma factors and therefore the activation of genes via these pathways. Some of these transcriptional control systems provide C. difficile with the ability to tolerate and detoxify harmful compounds. Here, we investigate the role of RsbW in C. difficile physiology. We demonstrate distinctive phenotypes for a mutant in growth, persistence, and virulence and suggest alternate σ control mechanisms in C. difficile. Understanding C. difficile responses to external stress is key to designing better strategies to combat this highly resilient bacterial pathogen.

摘要

产芽孢梭菌艰难梭菌是一种主要的抗生素相关性腹泻病原体,它在环境中和哺乳动物肠道中面临多种压力。为了应对这些压力,替代σ因子 B(σ)被用来调节基因转录,而 σ 则受到抗σ因子 RsbW 的调节。为了了解 RsbW 在艰难梭菌生理学中的作用,我们生成了一个突变体(Δ),假设该突变体中的 σ 因子“总是开启”。在没有压力的情况下,Δ 没有表现出适应性缺陷,但与亲本菌株相比,它能更好地耐受酸性环境并解毒活性氧和氮物种。Δ 在孢子和生物膜形成方面存在缺陷,但它对人肠道上皮的黏附能力增强,在大蜡螟感染模型中的毒力降低。为了了解 Δ 的独特表型,我们进行了转录组分析,结果显示与应激反应、毒力、孢子形成、噬菌体以及几个 σ 调控因子相关的基因表达发生了变化,包括多效调控因子 sinRR'。虽然这些表型在 Δ 中是独特的,但一些 σ 调控的应激相关基因的变化与没有 σ 时报告的变化相似。对 Δ 的进一步分析表明,其细胞内 σ 的水平出人意料地降低,这表明在没有应激的情况下,σ 存在额外的翻译后调控机制。我们的研究提供了关于 RsbW 的调节作用以及调节网络复杂性的见解,这些调节网络介导了艰难梭菌中的应激反应。像艰难梭菌这样的病原体在环境中和宿主内面临着一系列的压力。像 σ 因子 B(σ)这样的替代转录因子使细菌能够快速应对不同的压力。像 RsbW 这样的抗σ因子控制 σ 因子,从而通过这些途径激活基因。这些转录调控系统中的一些使艰难梭菌能够耐受和解毒有害化合物。在这里,我们研究了 RsbW 在艰难梭菌生理学中的作用。我们证明了一个突变体在生长、持续存在和毒力方面的独特表型,并提出了艰难梭菌中替代 σ 调控机制的假设。了解艰难梭菌对外界应激的反应是设计更好的策略来对抗这种高度弹性的细菌病原体的关键。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/716f/10210984/dd1608776f19/jb.00466-22-f001.jpg

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