The survival ability of Salmonella enterica serovar Enteritidis in antibacterial egg white is an important factor leading to Salmonella outbreaks through eggs and egg products. In this study, the role of the gene yoaE, encoding an inner membrane protein, in the survival of Salmonella Enteritidis in egg white, and its transcriptional regulation by CpxR were investigated. Quantitative reverse transcription-PCR (RT-qPCR) results showed that the yoaE gene expression was upregulated 35-fold after exposure to egg white for 4 h compared to that in M9FeS medium, and the deletion of yoaE (ΔyoaE) dramatically decreased the survival rate of bacteria in egg white to less than 1% of the wild type (WT) and the complementary strain at both 37 and 20°C, indicating that yoaE was essential for bacteria to survive in egg white. Furthermore, the ΔyoaE strain was sensitive to a 3-kDa ultrafiltration matrix of egg white because of its high pH and antimicrobial peptide components. Putative conserved binding sites for the envelope stress response regulator CpxR were found in the yoaE promoter region. In vivo, the RT-qPCR assay results showed that the upregulation of yoaE in a ΔcpxR strain in egg white was 1/5 that of the WT. In vitro, results from DNase I footprinting and electrophoretic mobility shift assays further demonstrated that CpxR could directly bind to the yoaE promoter region, and a specific CpxR binding sequence was identified. In conclusion, it was shown for the first time that CpxR positively regulated the transcription of yoaE, which was indispensable for survival of Salmonella Enteritidis in egg white.IMPORTANCE Salmonella enterica serovar Enteritidis is the predominant Salmonella serotype that causes human salmonellosis mainly through contaminated chicken eggs or egg products and has been a global public health threat. The spread and frequent outbreaks of this serotype through eggs correlate significantly with its exceptional survival in eggs, despite the antibacterial properties of egg white. Research on the survival mechanisms of S. Enteritidis in egg white will help develop effective strategies to control the contamination of eggs by this Salmonella serotype and help further elucidate the complex antibacterial mechanisms of egg white. This study revealed the importance of yoaE, a gene with unknown function, on the survival of S. Enteritidis in egg white, as well as its transcriptional regulation by CpxR. Our work provides the basis to reveal the mechanisms of survival of S. Enteritidis in egg white and the specific function of the yoaE gene.

中文翻译：

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受CpxR调控的yoaE基因在小肠沙门氏菌肠杆菌血清肠炎沙门氏菌的存活中的作用。

肠炎沙门氏菌肠炎沙门氏菌在抗菌蛋清中的存活能力是导致沙门氏菌通过鸡蛋和蛋制品暴发的重要因素。在这项研究中，研究了编码内膜蛋白的基因yoaE在肠炎沙门氏菌在蛋清中的存活及其通过CpxR的转录调控。定量逆转录-PCR（RT-qPCR）结果显示，与M9FeS培养基相比，暴露于蛋清4 h后yoaE基因表达上调了35倍，并且yoaE的缺失（ΔyoaE）大大降低了存活率将卵清中的细菌数量降至野生型（WT）的不足1％，并且在37和20°C时都检测到互补菌株，这表明yoaE对于细菌在卵中生存至关重要。此外，ΔyoaE菌株对蛋清的3 kDa超滤基质敏感，因为它具有较高的pH值和抗菌肽成分。在yoaE启动子区域发现了包膜应激反应调节因子CpxR的保守保守结合位点。在体内，RT-qPCR分析结果表明，蛋白中的ΔcpxR菌株中yoaE的上调是野生型的1/5。在体外，DNase I足迹和电泳迁移率变动分析的结果进一步证明CpxR可以直接结合到yoaE启动子区域，并鉴定出特定的CpxR结合序列。总之，这首次表明CpxR正调控yoaE的转录，这对于蛋清肠炎沙门氏菌的生存是必不可少的。重要信息肠炎沙门氏菌肠炎沙门氏菌是主要的沙门氏菌血清型，主要通过受污染的鸡蛋或蛋制品引起人沙门氏菌病，已成为全球公共卫生威胁。尽管蛋白具有抗菌特性，但这种血清型通过卵的传播和频繁爆发与其在卵中的异常存活密切相关。研究肠炎沙门氏菌在蛋清中的存活机制将有助于制定有效策略，以控制这种沙门氏菌血清型对鸡蛋的污染，并有助于进一步阐明蛋清的复杂抗菌机制。这项研究揭示了功能未知的基因yoaE对肠炎链球菌在蛋清中的存活及其CpxR的转录调控的重要性。