|HUANG, XIAOZHEN - Shanghai Jiaotong University|
|HU, MENGJUN - Shanghai Jiaotong University|
|ZHOU, XIUJUAN - Shanghai Jiaotong University|
|SHI, CHUNLEI - Shanghai Jiaotong University|
|SHI, XIANMING - Shanghai Jiaotong University|
Submitted to: mSphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2019
Publication Date: 1/8/2020
Citation: Huang, X., Hu, M., Zhou, X., Liu, Y., Shi, C., Shi, X. 2020. The role of yoaE gene regulated by CpxR in the survival ability of Salmonella Enterica serovar Enteritidis in antibacterial egg white. mSphere. https://doi.org/10.1128/mSphere.00638-19. https://doi.org/10.1128/mSphere.00638-19.
Interpretive Summary: Salmonella is one of the major foodborne pathogens with many different types of Salmonella referred to as serotypes or serovars. Most of the Salmonella serotypes are human pathogens. One serotype within Salmonella group Enteritidis is known as S. Enteritidis, which is also highly pathogenic to humans, causing outbreaks through egg products. It is important to understand how this pathogen grows in eggs and cause illness. One gene that is critical for survival was identified in S. Enteritidis, and S. Enteritidis strains lacking this gene was created and analyzed to determine their function. Results demonstrated that this gene contributed to various functions, including survival. Furthermore, we also found that this gene was controlled by a protein regulator named CpxR. The information obtained from this work can be used to develop strategies for control Salmonella in egg products, therefore, reduce the potential outbreaks caused by Salmonella.
Technical Abstract: The survival ability of Salmonella Enteritidis in antibacterial egg white is an important factor leading to Salmonella outbreaks through eggs and egg products. In this study, the role of inner membrane protein gene yoaE in the survival ability of Salmonella Enteritidis in egg white, and its transcriptional regulation mechanism by CpxR were investigated. RT-qPCR results showed that the yoaE gene expression was up-regulated 35-fold after exposure to egg white for 4 h compared with that in M9FeS; and deletion of yoaE ('yoaE) dramatically decreased the survival rate of bacteria in egg white to less than 1% of WT and complementary strain at both 37 deg C and 20 deg C, indicating that yoaE was essential for bacteria to survive in egg white. Furthermore, 'yoaE strain was sensitive to the 3 kilodalton (KDa) ultrafiltration matrix of egg white because of its high pH and antimicrobial peptides components. Putative conserved binding sites of envelope stress response regulator CpxR was found in the yaoE promoter region. In vivo, RT-qPCR assay results showed that the up-regulation of yoaE in the 'cpxR strain in egg white was 1/4 that of WT. In vitro, results from DNase' foot-printing and electrophoretic mobility shift assay (EMSA) further demonstrated that CpxR protein could directly bind to the yoaE promoter region, and specific CpxR binding sequence was identified. In conclusion, it was shown for the first time that CpxR positively regulated the transcription of yaoE gene, which was indispensable for survival of Salmonella Enteritidis in egg white and its ultrafiltration matrix.