RstA, a two-component response regulator, plays important roles in multiple virulence-associated processes in enterohemorrhagic Escherichia coli O157:H7

Background Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) causes bloody diarrhea and hemolytic-uremic syndrome. EHEC O157 encounters varied microenvironments during infection, and can efficiently adapt to these using the two-component system (TCS). Recently, a functional TCS, RstAB, has been implicated in the regulation of virulence of several bacterial pathogens. However, the regulatory function of RstAB in EHEC O157 is poorly understood. This study aimed at providing insights into the global effects of RstA on gene expression in EHEC O157. Results In the present study, we analyzed gene expression differences between the EHEC O157 wild-type strain and a Delta rstA mutant using RNA-seq technology. Genes with differential expression in the Delta rstA mutant compared to that in the wild-type strain were identified and grouped into clusters of orthologous categories. RstA promoted EHEC O157 LEE gene expression, adhesion in vitro, and colonization in vivo by indirect regulation. We also found that RstA could bind directly to the promoter region of hdeA and yeaI to enhance acid tolerance and decrease biofilm formation by modulating the concentration of c-di-GMP. Conclusions In summary, the RstAB TCS in EHEC O157 plays a major role in the regulation of virulence, acid tolerance, and biofilm formation. We clarified the regulatory function of RstA, providing an insight into mechanisms that may be potential drug targets for treatment of EHEC O157-related infections.

背景 肠出血性大肠杆菌O157:H7（EHEC O157）可导致血性腹泻和溶血性尿毒综合征。EHEC O157在感染过程中会遇到不同的微环境，并能利用双组分系统（TCS）有效地适应这些环境。最近，一种功能性的双组分系统RstAB被认为与几种细菌病原体的毒力调控有关。然而，RstAB在EHEC O157中的调控功能尚不清楚。本研究旨在深入了解RstA对EHEC O157基因表达的全局影响。 结果 在本研究中，我们利用RNA - seq技术分析了EHEC O157野生型菌株和ΔrstA突变体之间的基因表达差异。鉴定出了ΔrstA突变体与野生型菌株相比差异表达的基因，并将其归类到直系同源类别簇中。RstA通过间接调控促进了EHEC O157 LEE基因表达、体外黏附和体内定植。我们还发现RstA可直接结合到hdeA和yeaI的启动子区域，通过调节环二鸟苷酸（c - di - GMP）的浓度来增强耐酸性并减少生物膜形成。 结论 总之，EHEC O157中的RstAB双组分系统在毒力调控、耐酸性和生物膜形成方面起着重要作用。我们阐明了RstA的调控功能，为可能成为治疗EHEC O157相关感染的潜在药物靶点的机制提供了见解。