A SALMONELLA PROTEIN THAT IS REQUIRED FOR RESISTANCE TO ANTIMICROBIAL PEPTIDES AND TRANSPORT OF POTASSIUM
A SALMONELLA PROTEIN THAT IS REQUIRED FOR RESISTANCE TO ANTIMICROBIAL PEPTIDES AND TRANSPORT OF POTASSIUM
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DOI：
10.1002/j.1460-2075.1994.tb06712.x
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发表时间：
1994-09-01
期刊：
影响因子：
11.4
通讯作者：
GROISMAN, EA
中科院分区：
文献类型：
--
作者：
PARRALOPEZ, C;LIN, R;GROISMAN, EA
入侵病原体在宿主组织内增殖的能力需要具有抵抗多种宿主防御分子的杀伤作用的能力。兼性细胞内寄生虫鼠伤寒沙门氏菌的 sap 突变体对抗菌肽表现出超敏反应，不能在体外巨噬细胞内存活，并且在体内对小鼠毒力减弱。我们对 sapG 基因座进行了分子遗传学分析，结果表明它编码的产物与 NAD(+) 结合蛋白 TrkA 99% 相同，TrkA 是大肠杆菌中低亲和力 K+ 摄取系统的一个组成部分。 SapG 与参与 K+ 转运的其他大肠杆菌蛋白具有相似性，包括 KefC（一种谷胱甘肽调节的外排蛋白）和 Kch（一种类似于真核 Ki 通道蛋白的假定转运蛋白）。在高 K+ 和低 K+ 存在的情况下，sapG 突变体都会被抗菌肽鱼精蛋白杀死，这表明鱼精蛋白过敏不是由于 K+ 饥饿所致。 sapG 和 sapJ 或 sapABCDF 操纵子突变的菌株与 sapG 单突变体一样敏感，表明这些位点编码的蛋白质参与相同的抗性途径。 SapG 可能调节 SapABCDF 和 SapJ 的活性，以介导肽和钾的转运。
The ability of invading pathogens to proliferate within host tissues requires the capacity to resist the killing effects of a wide variety of host defense molecules. sap mutants of the facultative intracellular parasite Salmonella typhimurium exhibit hypersensitivity to antimicrobial peptides, cannot survive within macrophages in vitro and are attenuated for mouse virulence in vivo. We conducted a molecular genetic analysis of the sapG locus and showed that it encodes a product that is 99% identical to the NAD(+) binding protein TrkA, a component of a low-affinity K+ uptake system in Escherichia coli. SapG exhibits similarity with other E.coli proteins implicated in K+ transport including KefC, a glutathione-regulated efflux protein, and Kch, a putative transporter similar to eukaryotic Ki channel proteins. sapG mutants were killed by the antimicrobial peptide protamine in the presence of both high and low K+, indicating that protamine hypersensitivity is not due to K+ starvation. Strains with mutations in sapG and either sapJ or the sapABCDF operon were as susceptible as sapG single mutants, suggesting that the proteins encoded by these loci participate in the same resistance pathway. SapG may modulate the activities of SapABCDF and SapJ to mediate the transport of peptides and potassium.