Structural basis of the nickel response in Helicobacter pylori:: Crystal structures of HpNikR in Apo and nickel-bound states
Structural basis of the nickel response in Helicobacter pylori:: Crystal structures of HpNikR in Apo and nickel-bound states
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DOI：
10.1016/j.jmb.2006.06.058
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发表时间：
2006-08-25
影响因子：
5.6
通讯作者：
Terradot, Laurent
中科院分区：
文献类型：
--
作者：
Dian, Cyril;Schauer, Kristine;Terradot, Laurent
人类胃中幽门螺杆菌的存活严重依赖于镍的可用性和使用，镍是重要的毒力决定因素脲酶的绝对辅助因子。镍响应性基因调控是由HpNikR介导的，HpNikR是一种属于带状-螺旋-螺旋转录调控家族的蛋白质。与它的同源物不同，HpNikR在酸适应级联中既是抑制因子又是激活因子。我们报道了全长HpNikR无镍构象的晶体结构和在不同条件下获得的两种镍结合结构：Ni1-HpNikR和Ni2-HpNikR。Apo-HpNikR表现出与其细菌同源物相同的全局折叠，尽管具有不寻常的封闭反式构象和不对称的四元排列。在镍的存在下，Ni1-HpNikR的结构有两个不同的侧面，一面显示出与已知nikr类似的镍结合，另一面反映出中间态。使用较短的镍暴露获得的Ni2-HpNikR结构提供了镍掺入的另一个快照。总之，这三种结构使我们能够确定镍在HpNikR中的路径，并揭示四聚结构域和dna结合结构域之间的协同作用。利用参与镍内化的HpnikR残基的点突变进行的实验证实，这些残基对体内HpnikR功能至关重要，(c) 2006 Elsevier Ltd。版权所有。
The survival of Helicobacter pylori in the human stomach critically relies on the availability and use of nickel, an absolute cofactor of the important virulence determinant urease. Nickel-responsive gene regulation is mediated by HpNikR, a protein belonging to the ribbon-helix-helix family of transcriptional regulators. Unlike its homologues, HpNikR acts as both a repressor and an activator within an acid adaptation cascade. We report the crystal structure of the full-length HpNikR in a nickel-free conformation and two nickel-bound structures obtained in different conditions: Ni1-HpNikR and Ni2-HpNikR. Apo-HpNikR shows the same global fold as its bacterial homologues although with an unusual closed trans-conformation and asymmetrical quaternary arrangement. The structure of Ni1-HpNikR in the presence of nickel has two different sides, one showing nickel binding similar to that of known NikRs and the other reflecting an intermediate state. The structure of Ni2-HpNikR obtained using a shorter exposure to nickel provides another snapshot of the nickel incorporation. Altogether, the three structures have allowed us to determine the route for nickel within HpNikR and reveal the cooperativity between the tetramerization domain and the DNA-binding domain. Experiments using point mutations of HpnikR residues involved in nickel internalisation confirm that these residues are critical for HpNikR functions in vivo, (c) 2006 Elsevier Ltd. All rights reserved.