CpxAR of Actinobacillus pleuropneumoniae Contributes to Heat Stress Response by Repressing Expression of Type IV Pilus Gene apfA.
CpxAR of Actinobacillus pleuropneumoniae Contributes to Heat Stress Response by Repressing Expression of Type IV Pilus Gene apfA.
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DOI：
10.1128/spectrum.02523-22
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发表时间：
2022-12-21
影响因子：
3.7
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中科院分区：
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猪的急性胸膜肺炎是由胸膜肺炎放线杆菌引起的，其特征是持续高热。发烧为许多细菌创造了一个不利的环境，导致细菌增殖减少;然而，大多数致病细菌可以耐受更高的温度。CpxAR是一种双组分调节系统，在革兰氏阴性菌中普遍存在，其感测并响应于主要与周质中的蛋白质错误折叠相关的包膜改变。我们先前的研究表明CpxAR是必要的最佳生长条件下热应激胸膜肺炎放线杆菌。在这里，我们发现IV型菌毛蛋白基因apfA的突变挽救了热应激下cpxAR缺失菌株的生长缺陷。RNA测序（RNA-seq）分析显示，在42°C下生长的ΔcpxAR菌株中有265个基因差异表达，包括参与IV型菌毛生物合成的基因。我们还证明了直接结合的CpxR蛋白的启动子的apf操纵子的电泳迁移率变动分析和确定的结合位点的DNA酶I足迹分析。总之，我们的结果揭示了CpxAR在A.胸膜肺炎通过直接抑制ApfA的表达来抵抗热应激。重要性热是病原体的危险信号，特别是那些感染哺乳动物宿主的病原体，发热表明感染。然而，一些细菌已经进化出精致的机制来在热应激下生存。研究热应激的抗性机制对了解热应激的发病机制具有重要意义。胸膜肺炎在感染的急性期。我们的研究表明CpxAR在A.胸膜肺炎通过直接抑制IV型菌毛蛋白ApfA的表达来抵抗热应激。
Acute pleuropneumonia in swine, caused by Actinobacillus pleuropneumoniae, is characterized by a high and sustained fever. Fever creates an adverse environment for many bacteria, leading to reduced bacterial proliferation; however, most pathogenic bacteria can tolerate higher temperatures. CpxAR is a two-component regulation system, ubiquitous among Gram-negative bacteria, which senses and responds to envelope alterations that are mostly associated with protein misfolding in the periplasm. Our previous study showed that CpxAR is necessary for the optimal growth of Actinobacillus pleuropneumoniae under heat stress. Here, we showed that mutation of the type IV pilin gene apfA rescued the growth defect of the cpxAR deletion strain under heat stress. RNA sequencing (RNA-seq) analyses revealed that 265 genes were differentially expressed in the ΔcpxAR strains grown at 42°C, including genes involved in type IV pilus biosynthesis. We also demonstrated direct binding of the CpxR protein to the promoter of the apf operon by an electrophoretic mobility shift assay and identified the binding site by a DNase I footprinting assay. In conclusion, our results revealed the important role of CpxAR in A. pleuropneumoniae resistance to heat stress by directly suppressing the expression of ApfA. IMPORTANCE Heat acts as a danger signal for pathogens, especially those infecting mammalian hosts in whom fever indicates infection. However, some bacteria have evolved exquisite mechanisms to survive under heat stress. Studying the mechanism of resistance to heat stress is crucial to understanding the pathogenesis of A. pleuropneumoniae during the acute stage of infection. Our study revealed that CpxAR plays an important role in A. pleuropneumoniae resistance to heat stress by directly suppressing expression of the type IV pilin protein ApfA.