渗透调节周质葡聚糖对小肠结肠炎耶尔森菌多型性表型的影响及其分子机制

Yersinia enterocolitica is a food-borne invasive enteric pathogen, which is the most common bacteriological cause of food poisoning and gastrointestinal disease. The fast response to environmental changes plays a key role in the transmission and pathogenesis of Y. enterocolitica. Two-component regulatory systems (TCSs) are the predominant form of signal transduction used by bacteria to respond to environmental stimuli. Although several TCSs have been described in Y. enterocolitica, the regulatory interactions between these systems are still unclear. Recent studies suggested several new insights on the biological roles of the osmoregulated periplasmic glucans (OPGs) in Proteobacteria. It is indicated that the OPGs take part in environmental perception, modulate pleiotropic phenotype and indirectly regulate genes involved in virulence through TCSs in several Enterobacteriaceae pathogens. Y. enterocolitica belongs to the family Enterobacteriaceae and our pretest studies detected the OPGs accumulation in its periplasm. It could be speculated that OPGs in Y. enterocolitica might be involved in the regulatory interactions between different TCSs and play an important role in environmental responses. To prove the hypothesis, the pleiotropic phenotype effects of OPGs on Y. enterocolitica and its molecular mechanisms will be investigated in this study. An OPG mutant Y. enterocolitica strain lack of OPG synthesis will be constructed. With the wild-type and OPG mutant strains, the pleiotropic effects of OPGs on various transmission and virulence-related phenotypes of Y. enterocolitica will be studied, and the comparative proteomic analysis will be conducted to reveal the molecular mechanisms of OPGs in the signal transduction and regulation of Y. enterocolitica. This research will offer a new start to explore how Y. enterocolitica responses to environmental changes, and shed light on the biological role of OPGs. Taking OPGs as the targets for new antimicrobial molecules, this study could be also served as a theoretical basis for the development of new food safety strategies or new drugs to prevent and control Y. enterocolitica infections.

快速环境应答能力是决定小肠结肠炎耶尔森菌（Yersinia enterocolitica）流行性和致病性的关键因素。尽管在Y. enterocolitica中已发现多个参与环境应答的双组分调节系统，但不同系统间的协作机制尚不清楚。本项目从整体性环境应答角度出发，根据渗透调节周质葡聚糖（OPGs）研究的新发现，探索Y. enterocolitica中OPGs环境应答机制。项目拟通过比较野生株和OPGs缺失突变株在流行性或致病性关键表型上的差异，研究OPGs对Y. enterocolitica多型性表型的影响；通过比较蛋白质组分析，探索OPGs参与Y. enterocolitica信号转导和代谢调控的分子机制。本项目为Y. enterocolitica环境应答机制的研究提供了新思路，有助于完善对OPGs生物学功能的认识，亦可为食品微生物安全控制、感染预防与治疗新方案的开发提供理论依据。

快速环境应答能力是决定小肠结肠炎耶尔森菌 (Yersinia enterocolitica) 流行性和致病性的关键因素。渗透调节周质葡聚糖 (OPGs) 是γ-变形菌门病原菌重要的环境信号分子，本研究探讨了OPGs对小肠结肠炎耶尔森菌多型性表型的影响，并对OPGs的分子调控机制进行了探索。通过比较野生株、OPGs缺失株和OPGs回补株在生长、运动性、生物被膜形成以及抗生素耐受性这些表型特征上的差异，评价OPGs对Y. enterocolitica多型性表型的影响。近期研究显示，OPGs可能通过调节细菌双组分系统——Rcs系统的活性来参与细胞的信号转导，从而调控多型性表型。Rcs系统是存在于许多肠杆菌科细菌中重要的信号转导系统，该系统能整合环境信号，调节基因表达并改变细菌的生理行为。本研究在OPGs缺失的基础上分别敲除Rcs系统关键基因rcsF、rcsC和rcsB，构建双突变菌株，阻断Rcs磷酸传递功能，并结合比较菌株在这些致病表型及相关靶基因的表达水平上的变化，证实Y. enterocolitica Rcs系统对OPGs缺失的响应。最后通过比较转录组学分析发现Rcs系统负调控Y. enterocolitica的趋化性、鞭毛形成以及对Caco-2细胞的侵染力。本项目揭示了Y. enterocolitica OPGs的部分生物学功能以及联同Rcs系统调节Y. enterocolitica致病表型的潜在分子机制。该研究为Y. enterocolitica环境应答的研究提出了新思路，亦可为该菌的控制、预防及治疗方案的开发提供理论依据。