Edwardsiella piscicida is a notorious pathogen infecting diverse kinds of fish and causes substantial economic losses in the global aquaculture industries. The EsrA-EsrB two-component system plays a critical role in the regulation of virulence genes expression, including type III and type VI secretion systems (T3/T6SSs). In this study, the putative regulators of esrB were screened by the transposon insertion sequencing (TIS) technology. As a result, MviN, a lipid II flippase, was identified as a modulator to upregulate esrB and downstream T3/T6SS gene expression in the earlier growth phases while downregulate esrB at the later stages. Complement or overexpression of the mviN restored the esrB as well as T3/T6SS expression in the ΔmviN mutant strain. Moreover, MviN also mediated the regulation of environmental osmotic pressure on the expression of esrB. MviN was also found to significantly influence the in vivo colonization of E. piscicida in turbot. Collectively, this study enhanced our understanding of pathogenesis and virulence regulatory network of E. piscicida.

爱德华氏菌是一种臭名昭著的病原体，可感染多种鱼类，并在全球水产养殖业中造成重大经济损失。EsrA-EsrB两组分系统在毒力基因表达的调节中起关键作用，包括III型和VI型分泌系统（T3 / T6SSs）。在这项研究中，通过转座子插入测序（TIS）技术筛选了esrB的假定调控因子。结果，脂质体II脂酶MviN被鉴定为在早期生长期上调esrB和下游T3 / T6SS基因表达的调节剂，而在后期则下调esrB。mviN的互补或过表达恢复了esrB以及ΔmviN突变菌株中的T3 / T6SS表达。此外，MviN还介导环境渗透压对esrB表达的调节。还发现MviN显着影响大菱t中大肠杆菌的体内定殖。总体而言，这项研究增强了我们对大肠埃希氏菌的发病机理和毒力调控网络的理解。