σE controlled regulation of porin OmpU in Vibrio cholerae,Molecular Microbiology

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σE controlled regulation of porin OmpU in Vibrio cholerae
Molecular Microbiology ( IF 2.6 ) Pub Date : 2020-12-16 , DOI: 10.1111/mmi.14669
Nina Pennetzdorfer ₁ , Thomas Höfler ₁ , Martina Wölflingseder ₁ , Sarah Tutz ₁ , Stefan Schild _{1,

2,

3} , Joachim Reidl _{1,

2,

3}

Affiliation

Bile resistance is essential for enteric pathogens, as exemplified by Vibrio cholerae, the causative agent of cholera. The outer membrane porin OmpU confers bacterial survival and colonization advantages in the presence of host-derived antimicrobial peptides as well as bile. Expression of ompU is controlled by the virulence regulator ToxR. rpoE knockouts are accompanied by suppressor mutations causing ompU downregulation. Therefore, OmpU constitutes an intersection of the ToxR regulon and the σ^E-pathway in V. cholerae. To understand the mechanism by which the sigma factor σ^E regulates OmpU synthesis, we performed transcription studies using ompU reporter fusions and immunoblot analysis. Our data revealed an increase in ompU promoter activity in ΔrpoE strains, as well as in a ΔompU background, indicating a negative feedback regulation circuit of ompU expression. This regulation seems necessary, since elevated lethality rates of ΔrpoE strains occur upon ompU overexpression. Manipulation of OmpU’s C-terminal portion revealed its relevance for protein stability and potency of σ^E release. Furthermore, ΔrpoE strains are still capable of elevating OmpU levels under membrane stress conditions triggered by the bile salt sodium deoxycholate. This study provides new details about the impact of σ^E on ompU regulation, which is critical to the pathogen’s intestinal survival.

中文翻译：

σE 调控霍乱弧菌孔蛋白 OmpU

胆汁抵抗对于肠道病原体至关重要，例如霍乱弧菌，霍乱的病原体。在宿主来源的抗菌肽和胆汁存在的情况下，外膜孔蛋白 OmpU 赋予细菌存活和定植优势。ompU 的表达受毒力调节剂 ToxR 控制。rpoE敲除伴随着导致ompU下调的抑制突变。因此，OmpU 构成了 ToxR 调节子和V 中的 σ ^E通路的交集。霍乱。理解 sigma 因子 σ ^E的机制调节 OmpU 合成，我们使用ompU报告基因融合和免疫印迹分析进行了转录研究。我们的数据显示Δ rpoE菌株以及 Δ ompU背景中ompU启动子活性的增加，表明ompU表达的负反馈调节回路。这种调节似乎是必要的，因为在ompU过表达时会出现Δ rpoE菌株的高致死率。OmpU 的 C 端部分的操作揭示了它与蛋白质稳定性和 σ ^E释放效力的相关性。此外，ΔrpoE在由胆汁盐脱氧胆酸钠引发的膜应激条件下，菌株仍然能够提高 OmpU 水平。这项研究提供了有关 σ ^E对ompU调节影响的新细节，这对病原体的肠道存活至关重要。

更新日期：2020-12-16

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