METAL BINDING DOMAINS IN METALLOREGULATORY PROTEINS

这个项目的目标是确定金属结合部位的结构，这些金属结合部位形成转录抑制物的诱导物结合域，调控质粒编码的细菌耐药性。与许多药物和抗生素耐药一样，砷(Ars)和镉(Cad)抗性操纵子编码As(III)/Sb(III)或Pb(II)/Cd(II)/Zn(II)的转运ATPase。ArsR和CADC抑制子是两个小的同源金属调控蛋白，负责金属调控的Ars和cad操纵子的基因表达。将确定每个诱导子结合结构域所需的残基。此外，在Ars操纵子中还有第二个AS(III)/Sb(III)反应的阻遏因子ARSD，它与任何已知的金属结合蛋白都不具有同源性。ArsR和ARSD形成了一个调节电路，既可以感知环境中低浓度的金属，也可以感知高浓度的环境金属。将测定与ARSD结合的As(III)/Sb(III)所涉及的残留量。铜(COPA)抗性基因编码一个铜(I)转运型P型ATPase。COPA的表达受铜或银的调控。推测的COPR调节蛋白将被鉴定和鉴定。我们的研究将定义新的金属结合基序类别。这可能是更普遍的适用性，因为几乎所有与运输相关的耐药性都是转录调控的，而且调控蛋白的药物结合基序在很大程度上是未知的。因此，这些外排泵基因的抑制子为研究传播性细菌抗生素耐药性的调控提供了很好的模型系统。

The goal of this project is determination of the structure of the metal binding sites that form the inducer binding domains of transcriptional repressors that regulate plasmid-encoded bacterial resistances. In common with many drug and antibiotic resistances, the arsenical (ars) and cadmium (cad) resistance operons encode transport ATPases for the extrusion of As(III)/Sb(III) or Pb(II)/Cd(II)/Zn(II). The ArsR and CadC repressors are two small homologous metalloregulatory proteins responsible for metal-regulated gene expression of the ars and cad operons. Residues required for each inducer binding domain will be determined. In addition, in ars operons there is a second As(III)/Sb(III)-responsive repressor, ArsD, which does not exhibit homology to any known metal binding protein. ArsR and ArsD form a regulatory circuit that senses both low and high concentrations of environmental metalloid. The residues involved in As(III)/Sb(III) binding to ArsD will be determined. Finally, the copper (copA) resistance gene encodes a Cu(I)-translocating P-type ATPase. Expression of copA is regulated by copper or silver. The putative CopR regulatory protein will be identified and characterized. Our studies will define new classes of metal binding motifs. This may be more general applicability, since nearly all transport-related drug resistances are transcriptionally regulated, and the drug binding motifs of the regulatory proteins are largely unknown. Thus the repressors of the genes for these efflux pumps provide good model systems for the study of regulation of transmissible bacterial antibiotic resistances.