School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom.
PLoS One. 2011;6(8):e23713. doi: 10.1371/journal.pone.0023713. Epub 2011 Aug 23.
The RpoE and CpxR regulated envelope stress responses are extremely important for Salmonella Typhimurium to cause infection in a range of hosts. Until now the role for BaeSR in both the Salmonella Typhimurium response to stress and its contribution to infection have not been fully elucidated. Here we demonstrate stationary phase growth, iron and sodium tungstate as novel inducers of the BaeRregulon, with BaeR critically required for Salmonella resistance to sodium tungstate. We show that functional overlap between the resistance nodulation-cell division (RND) multidrug transporters, MdtA, AcrD and AcrB exists for the waste disposal of tungstate from the cell. We also point to a role for enterobactinsiderophores in the protection of enteric organisms from tungstate, akin to the scenario in nitrogen fixing bacteria. Surprisingly, BaeR is the first envelope stress response pathway investigated in S. Typhimurium that is not required for murine typhoid in either ity(S) or ity(R) mouse backgrounds. BaeR is therefore either required for survival in larger mammals such as pigs or calves, an avian host such as chickens, or survival out with the host altogether where Salmonella and related enterics must survive in soil and water.
RpoE 和 CpxR 调节的包膜应激反应对于沙门氏菌 Typhimurium 在多种宿主中引起感染极为重要。到目前为止，BaeSR 在沙门氏菌 Typhimurium 对压力的反应及其对感染的贡献中的作用尚未完全阐明。在这里，我们证明了静止期生长、铁和钨酸钠是 BaeR 调控组的新型诱导物，BaeR 对于沙门氏菌抵抗钨酸钠至关重要。我们表明，抵抗结节-细胞分裂（RND）多药转运蛋白 MdtA、AcrD 和 AcrB 之间存在功能重叠，用于从细胞中排出钨酸盐。我们还指出，肠菌素类物质在保护肠道生物免受钨酸盐的侵害方面发挥作用，类似于固氮细菌的情况。令人惊讶的是，BaeR 是在 S. Typhimurium 中研究的第一个包膜应激反应途径，无论是在 ity(S) 还是 ity(R) 小鼠背景下，都不是鼠伤寒的必需途径。因此，BaeR 要么是在猪或小牛等大型哺乳动物中生存所必需的，要么是在禽类宿主如鸡中生存所必需的，要么是在宿主之外的环境中生存所必需的，在这种环境中，沙门氏菌和相关肠杆菌必须在土壤和水中生存。
