生理胆盐小分子对沙门氏菌 phoP 表达的抑制作用。
Repression of Salmonella enterica phoP expression by small molecules from physiological bile.
机构信息
Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
出版信息
J Bacteriol. 2012 May;194(9):2286-96. doi: 10.1128/JB.00104-12. Epub 2012 Feb 24.
Infection with Salmonella enterica serovar Typhi in humans causes the life-threatening disease typhoid fever. In the laboratory, typhoid fever can be modeled through the inoculation of susceptible mice with Salmonella enterica serovar Typhimurium. Using this murine model, we previously characterized the interactions between Salmonella Typhimurium and host cells in the gallbladder and showed that this pathogen can successfully invade gallbladder epithelial cells and proliferate. Additionally, we showed that Salmonella Typhimurium can use bile phospholipids to grow at high rates. These abilities are likely important for quick colonization of the gallbladder during typhoid fever and further pathogen dissemination through fecal shedding. To further characterize the interactions between Salmonella and the gallbladder environment, we compared the transcriptomes of Salmonella cultures grown in LB broth or physiological murine bile. Our data showed that many genes involved in bacterial central metabolism are affected by bile, with the citric acid cycle being repressed and alternative respiratory systems being activated. Additionally, our study revealed a new aspect of Salmonella interactions with bile through the identification of the global regulator phoP as a bile-responsive gene. Repression of phoP expression could also be achieved using physiological, but not commercial, bovine bile. The biological activity does not involve PhoPQ sensing of a bile component and is not caused by bile acids, the most abundant organic components of bile. Bioactivity-guided purification allowed the identification of a subset of small molecules from bile that can elicit full activity; however, a single compound with phoP inhibitory activity could not be isolated, suggesting that multiple molecules may act in synergy to achieve this effect. Due to the critical role of phoP in Salmonella virulence, further studies in this area will likely reveal aspects of the interaction between Salmonella and bile that are relevant to disease.
人类感染沙门氏菌伤寒血清型会导致威胁生命的伤寒病。在实验室中,可以通过向易感小鼠接种沙门氏菌伤寒血清型 Typhimurium 来模拟伤寒病。使用这种鼠模型,我们之前描述了沙门氏菌 Typhimurium 与胆囊中宿主细胞的相互作用,并表明该病原体可以成功入侵胆囊上皮细胞并增殖。此外,我们还表明,沙门氏菌 Typhimurium 可以利用胆汁磷脂以高速生长。这些能力对于在伤寒病期间快速定殖胆囊以及通过粪便脱落进一步传播病原体可能很重要。为了进一步描述沙门氏菌与胆囊环境之间的相互作用,我们比较了在 LB 肉汤或生理小鼠胆汁中生长的沙门氏菌培养物的转录组。我们的数据表明,许多参与细菌中心代谢的基因受到胆汁的影响,柠檬酸循环受到抑制,替代呼吸系统被激活。此外,我们的研究通过鉴定全局调控因子 phoP 作为胆汁反应基因,揭示了沙门氏菌与胆汁相互作用的一个新方面。使用生理但不是商业牛胆汁也可以抑制 phoP 表达。这种生物活性不涉及 PhoPQ 对胆汁成分的感应,也不是由胆汁中最丰富的有机成分胆汁酸引起的。基于生物活性的纯化允许从胆汁中鉴定出一组可以产生全部活性的小分子;然而,不能分离出具有 phoP 抑制活性的单一化合物,这表明多种分子可能协同作用以达到这种效果。由于 phoP 在沙门氏菌毒力中的关键作用,该领域的进一步研究可能会揭示沙门氏菌与胆汁相互作用的相关方面与疾病有关。