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首页> 外文期刊>Journal of bacteriology >Crystal Structure of the Staphylococcus aureus pI258 CadC Cd(II)/Pb(II)/Zn(II)-Responsive Repressor
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Crystal Structure of the Staphylococcus aureus pI258 CadC Cd(II)/Pb(II)/Zn(II)-Responsive Repressor

机译:金黄色葡萄球菌pI258 CadC Cd(II)/ Pb(II)/ Zn(II)响应阻遏物的晶体结构

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The Staphylococcus aureus plasmid pI258 cadCA operon encodes a P-type ATPase, CadA, that confers resistance to the heavy metals Cd(II), Zn(II), and Pb(II). Expression of this heavy-metal efflux pump is regulated by CadC, a homodimeric repressor that dissociates from the cad operator/promoter upon binding of Cd(II), Pb(II), or Zn(II). CadC is a member of the ArsR/SmtB family of metalloregulatory proteins. Here we report the X-ray crystal structure of CadC at 1.9 ? resolution. The dimensions of the protein dimer are approximately 30 ? by 40 ? by 70 ?. Each monomer contains six α-helices and a three-stranded β-sheet. Helices 4 and 5 form a classic helix-turn-helix motif that is the putative DNA binding region. The α1 helix of one monomer crosses the dimer to approach the α4 helix of the other monomer, consistent with the previous proposal that these two regulatory metal binding sites for the inducer cadmium or lead are each formed by Cys-7 and Cys-11 from the N terminus of one monomer and Cys-58 and Cys-60 of the other monomer. Two nonregulatory metal binding sites containing zinc are formed between the two antiparallel α6 helices at the dimerization interface. This is the first reported three-dimensional structure of a member of the ArsR/SmtB family with regulatory metal binding sites at the DNA binding domain and the first structure of a transcription repressor that responds to the heavy metals Cd(II) and Pb(II).
机译:金黄色葡萄球菌质粒pI258 cadCA 操纵子编码一个P型ATPase CadA,赋予对重金属Cd(II),Zn(II)和Pb( II)。该重金属外排泵的表达受CadC调控,CadC是一种同二聚体阻遏物,在Cd(II),Pb(II)或Zn(II)结合后从 cad 操纵子/启动子解离。 CadC是金属调控蛋白ArsR / SmtB家族的成员。在这里,我们报告CadC的X射线晶体结构为1.9?解析度。蛋白质二聚体的尺寸约为30?减40?乘70?。每个单体包含六个α-螺旋和一个三链β-折叠。螺旋4和5形成经典的螺旋-转-螺旋基序,其是推定的DNA结合区。一种单体的α1螺旋穿过二聚体以接近另一种单体的α4螺旋,这与先前的建议一致,即诱导剂镉或铅的这两个调节金属结合位点分别由Cys-7和Cys-11从一个单体的N末端,另一单体的Cys-58和Cys-60。在二聚化界面处的两个反平行的α6螺旋之间形成了两个含锌的非调节性金属结合位点。这是ArsR / SmtB家族成员中第一个报道的三维结构,该结构在DNA结合结构域具有调节性金属结合位点,并且是转录抑制剂的第一个结构,其对重金属Cd(II)和Pb(II )。

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