THE ATP-COUPLED ARSENICAL PUMP OF ESCHERICHIA COLI

这项研究的总体目标是阐明分子 离子泵的机制，其基因是细菌的天然成分 第二，这一运输系统在 细菌对抗生素和有毒化合物的耐药性。临床部 抗性质粒R773携带砷抗性(Ars)操纵子， 产生对砷酸盐、亚砷酸盐和亚硫酸盐的抵抗力。《歌剧集》 编码具有ATP偶联功能的氧阴离子转运型ATPase 用于有毒氧离子的挤压泵。泵的催化亚单位 是ARSA蛋白，一种受亚砷酸盐刺激的ATPase。的具体目标 该项目涉及ARSA蛋白的结构-功能分析。在……里面 具体a)两个核苷酸结合位点内残基的作用 将通过分子遗传和生化方法进行检查；b) 将对四个半胱氨酸残基进行诱变，以检查它们在 催化；c)参与二聚化的结构域以及与 泵的其他部件将另行确定。 而质粒介导的抗生素和重金属耐药性是由于 对能量依赖的外排系统可能在自然界中广泛分布，阴离子 水泵似乎相当罕见。砷外排系统提供了一个很好的 传播性细菌抗生素研究的模型系统 阻力。编码ars系统的质粒还提供了一种细菌 哺乳动物细胞多药耐药研究模型。美国空军基地 ATPase在结构和功能上与P-糖蛋白相似， 在肿瘤细胞中产生多重耐药性的蛋白质。

The overall goals of this research are elucidation of the molecular mechanisms of an ion pump whose genes are natural components of a bacterial resistance plasmid, and second, the role of this transport system in bacterial resistance to antibiotics and toxic compounds. The clinical resistance plasmid R773 carries the arsenical resistance (ars)operon, which produces resistance to arsenate, arsenite, and antimonite. The operon encodes an oxyanion-translocating ATPase which functions as an ATP-coupled extrusion pump for the toxic oxyanions. The catalytic subunit of the pump is the ArsA protein, an arsenite-stimulated ATPase. The specific aims of the project involve a structure-function analysis of the ArsA protein. In particular a) the role of residues within the two nucleotide binding sites will be examined by molecular genetic and biochemical approaches; b) the four cysteine residues will be mutagenized to examine their role in catalysis; c) the domains involved in dimerization and interaction with the other components of the pump will be determined. While plasmid-mediated antibiotic and heavy metal resistances which are due to energy-dependent efflux systems may be wide spread in nature, anion pumps appear to be rather rare. The arsenical efflux system provide a good model system for the study of transmissible bacterial antibiotic resistances. The plasmid encoded ars system also provides a bacterial model for the study of multidrug resistance in mammalian cells. The Ars ATPase exhibits structural and functional similarity to the P-glycoprotein, the protein which produces multiple drug resistance in tumor cells.