Citrate and Metal Efflux by IceT

描述(申请人提供)：鼠伤寒沙门氏菌是一种典型的肠道病原体。像许多病原体一样，鼠伤寒沙门氏菌需要铁才能在环境和宿主中生存。然而，当宿主防御破坏含有铁的细菌蛋白质时，细胞内的游离铁起到了产生自由基的催化剂的作用。ICET是主要促进剂超家族中的一种应激诱导转运蛋白，在整个肠杆菌科中都是保守的。它在鼠伤寒沙门氏菌中的表达导致铁和柠檬酸盐的外流，从而保护细菌免受各种压力和抗生素的伤害。这项建议的目的是进一步表征这种细菌胁迫抗性的内在机制，并了解其在鼠伤寒沙门氏菌毒力中的作用。这将通过鉴定ICET转运的特定底物和阐明转运的化学成分，检测ICET蛋白的结构-功能关系，以及鉴定ICET的同源物YieO来实现，该同源物也存在于鼠伤寒沙门氏菌中，可能在对宿主防御和抗生素的内在抵抗力中发挥补充作用。实验将在体外、培养和小鼠感染模型中进行。这些研究将深入了解主要促进剂超家族中两个具有代表性的成员的功能，以及细菌代谢调节在抗逆性中所起的作用。

DESCRIPTION (provided by applicant): Salmonella enterica serovar Typhimurium (S. Typhimurium) is a model enteric pathogen. Like many pathogens, S. Typhimurium requires iron for survival both in the environment and in the host. However, when host defenses damage iron containing bacterial proteins, intracellular free iron acts as a catalyst for production of free radicals. IceT is a stress-induced transporter in the major facilitator superfamily that is conserved throughout the Enterobacteriaceae. Its expression in S. Typhimurium leads to efflux of iron and citrate, which protects the bacteria from a variety of stresses and antibiotics. The goal of this proposal is to further characterize this intrinsic mechanism of bacterial stress resistance and understand its role in S. Typhimurium virulence. This will be accomplished by characterizing the specific substrates transported by IceT and elucidating the chemistry of transport, examining structure-function relationships in the IceT protein, and characterizing a homologue of IceT, YieO, that is also found in S. Typhimurium and may play a complementary role in intrinsic resistance to host defenses and antibiotics. Experiments will be conducted in vitro, in culture, and in a murine model of infection. These studies will provide insight into the function of two representative members of the major facilitator superfamily and the role regulation of bacterial metabolism plays in resistance to stress.