Cytosolic Ni(II) sensor in cyanobacterium: nickel detection follows nickel affinity across four families of metal sensors.
Cytosolic Ni(II) sensor in cyanobacterium: nickel detection follows nickel affinity across four families of metal sensors.
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DOI：
10.1074/jbc.m111.338301
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发表时间：
2012-04-06
期刊：
影响因子：
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通讯作者：
Robinson NJ
中科院分区：
文献类型：
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作者：
Foster AW;Patterson CJ;Pernil R;Hess CR;Robinson NJ
背景：CsoR/RcnR样蛋白InrS的功能尚不清楚。结果：InrS和CsoR金属配合物具有相似的光谱，但InrS对镍不敏感。结论：InrS检测细胞溶质镍的KD比细胞的其他金属传感器更紧密。重要性：InrS可用于优化氢化酶Ni（II）的供应，这项研究表明金属特异性如何成为一组金属传感器的共享功能。集胞藻PCC 6803的外膜和内膜的过剩Ni（II）的流出是由Nrs系统介导的，该系统受周质Ni（II）的传感器NrsS的控制。在这里，我们表明，产品的ORF sll 0176，它编码的CsoR/RcnR-样蛋白，现在指定为InrS（内部镍响应传感器），抑制nrsD（NrsD推断流出镍（II）通过内膜）从一个隐蔽的启动子之间的最后两个ORF的nrs操纵子。新发现的nrsD启动子的转录本积累响应镍或钴，但不铜，和重组InrS形式的具体，镍（II）抑制复合物与nrsD启动子区域。Ni（II）-和Cu（I）-InrS的金属依赖性差异光谱与Cu（I）-感测CsoR相似，与Ni（II）/Co（II）-感测RcnR不同，与主要配位球切换金属选择性之外的因素一致。与螯合剂mag-fura-2、次氮基三乙酸、EDTA和EGTA的竞争估计，InrS最紧密位点的KD Ni（II）为2.05（±1.5）× 10−14 m，而其他类型的细胞金属传感器的KD Ni（II）较弱：Zn（II）辅阻遏物Zur、Co（II）激活剂CoaR和Zn（II）去阻遏物ZiaR。Ni（II）向InrS的转移发生在添加到每个其他传感器的Ni（II）形式时。InrS结合Ni（II）足够紧密，以在低于其他传感器的KD Ni（II）的浓度下解抑制Ni（II）输出。
Background: The function of CsoR/RcnR-like protein InrS was unknown. Results: InrS and CsoR metal complexes have similar spectra, but InrS senses nickel not copper. Conclusion: InrS detects cytosolic nickel with tighter KD than the other metal sensors of the cell. Significance: InrS might be exploited to optimize hydrogenase Ni(II) supply, and this study shows how metal specificity can be a shared function of a set of metal sensors. Efflux of surplus Ni(II) across the outer and inner membranes of Synechocystis PCC 6803 is mediated by the Nrs system under the control of a sensor of periplasmic Ni(II), NrsS. Here, we show that the product of ORF sll0176, which encodes a CsoR/RcnR-like protein now designated InrS (for internal nickel-responsive sensor), represses nrsD (NrsD is deduced to efflux Ni(II) across the inner membrane) from a cryptic promoter between the final two ORFs in the nrs operon. Transcripts initiated from the newly identified nrsD promoter accumulate in response to nickel or cobalt but not copper, and recombinant InrS forms specific, Ni(II)-inhibited complexes with the nrsD promoter region. Metal-dependent difference spectra of Ni(II)- and Cu(I)-InrS are similar to Cu(I)-sensing CsoR and dissimilar to Ni(II)/Co(II)-sensing RcnR, consistent with factors beyond the primary coordination sphere switching metal selectivity. Competition with chelators mag-fura-2, nitrilotriacetic acid, EDTA, and EGTA estimate KD Ni(II) for the tightest site of InrS as 2.05 (±1.5) × 10−14 m, and weaker KD Ni(II) for the cells' metal sensors of other types: Zn(II) co-repressor Zur, Co(II) activator CoaR, and Zn(II) derepressor ZiaR. Ni(II) transfer to InrS occurs upon addition to Ni(II) forms of each other sensor. InrS binds Ni(II) sufficiently tightly to derepress Ni(II) export at concentrations below KD Ni(II) of the other sensors.