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首页> 外文期刊>Biochemistry >The ferric uptake regulation (Fur) repressor is a zinc metalloprotein.
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The ferric uptake regulation (Fur) repressor is a zinc metalloprotein.

机译：铁摄取调节（Fur）阻遏物是锌金属蛋白。

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The Fur protein regulates the expression of a wide variety of iron-responsive genes; however, the interaction of this repressor with its cognate metal ion remains controversial. The iron-bound form of Fur has proved difficult to obtain, and conflicting results have been published using Mn(II) as a probe for in vitro DNA-binding studies. We report here that the purified protein contains tightly bound zinc and propose that Zn(II) is bound to the protein in vivo. Upon purification, Fur retains ca. 2.1 mol of Zn(II)/mol of Fur monomer (Zn2Fur). One zinc is easily removed by treatment of Zn2Fur with zinc chelating agents, resulting in Zn1Fur with ca. 0.9 mol of Zn(II)/mol of protein. The remaining zinc in Zn1Fur can only be removed under denaturing conditions to yield apo-Fur with ca. 0.1 mol of Zn(II)/mol of protein. Our results suggest that many literature descriptions of purified Fur protein do not correspond to the apo-protein, but to Zn1Fur or Zn2Fur. Dissociation constants (Kd) of protein-DNA complexes are ca. 20 nM for both Zn2Fur and Zn1Fur as determined by electrophoretic mobility shift assays and DNase I footprinting assays. The two metalated forms, however, show qualitative differences in the footprinting assays while apo-Fur does not bind specifically to the operator. The existence of these Zn(II) binding sites in Fur may resolve some discrepancies in the literature and have implications concerning Zur, a Fur homologue in E. coli that regulates zinc-responsive genes.
机译：Fur蛋白可调节多种铁反应基因的表达。然而，该阻遏物与其同源金属离子的相互作用仍然存在争议。事实证明，铁结合形式的Fur很难获得，并且使用Mn（II）作为体外DNA结合研究的探针已经发表了相互矛盾的结果。我们在这里报告纯化的蛋白质包含紧密结合的锌，并建议Zn（II）在体内与蛋白质结合。纯化后，毛皮保留约。 2.1摩尔的Zn（II）/摩尔的Fur单体（Zn2Fur）。通过用锌螯合剂处理Zn2Fur可以很容易地除去一种锌，导致Zn1Fur的摩尔比约为1。 0.9摩尔的Zn（II）/每摩尔蛋白质。只能在变性条件下去除Zn1Fur中剩余的锌，以得到大约a.Fur的apo-Fur。 0.1摩尔Zn（II）/每摩尔蛋白质。我们的结果表明，许多有关纯化的Fur蛋白的文献描述与脱辅基蛋白并不相对应，而与Zn1Fur或Zn2Fur相对应。蛋白质-DNA复合物的解离常数（Kd）为ca。 Zn2Fur和Zn1Fur的电泳电泳迁移率测定和DNase I足迹测定法均为20 nM。但是，这两种金属化形式在足迹分析中显示出质的差异，而载脂蛋白-Fur并没有与操作者特异性结合。 Fur中这些Zn（II）结合位点的存在可能会解决文献中的一些差异，并可能涉及Zur（一种在大肠杆菌中调节锌敏感基因的Fur同源物）。

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