A new zinc-protein coordination site in intracellular metal trafficking: Solution structure of the Apo and Zn(II) forms of ZntA(46-118)
A new zinc-protein coordination site in intracellular metal trafficking: Solution structure of the Apo and Zn(II) forms of ZntA(46-118)
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DOI：
10.1016/s0022-2836(02)01007-0
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发表时间：
2002-11-08
影响因子：
5.6
通讯作者：
O'Halloran, TV
中科院分区：
文献类型：
--
作者：
Banci, L;Bertini, L;O'Halloran, TV
锌，金属离子的功能，在各种各样的催化和金属蛋白的结构位点，在这里示出采取一种新的协调环境中的大肠杆菌转运蛋白ZntA。ZntA蛋白是P型ATP酶，其将锌从细胞质中泵出并进入周质。它对Zn（II）具有生理选择性，并与细胞中的金属调节蛋白一起发挥作用，以将锌配额保持在严格的限度内。然而，N-末端胞质结构域包含与酵母Cu（I）金属伴侣Atx 1高度同源的区域。为了研究该区域的结构如何影响其功能，已从基因中克隆出含有残基46-118的该片段并过表达。我们在这里报告的解决方案的结构，这一片段确定的NMR。已测定了apo和Zn（II）-ZntA（46-118）结构。它含有一个以前未知的锌蛋白配位位点，包括两个半胱氨酸残基Cys 59和Cys 62，以及一个羧酸残基Asp 58。该位点的溶剂可及性也非常高，这一特征越来越成为重金属离子转运蛋白结构域的特征。Asp 58在ZntA金属离子结合位点的参与可能在调节Zn（II）/Pb（II）/Cd（II）的相对亲和力和金属交换速率方面发挥重要作用，与其他P型ATP酶相比，其对Cu（I）或Ag（I）具有选择性。(C)2002爱思唯尔科技有限公司版权所有。
Zinc, a metal ion that functions in a wide variety of catalytic and structural sites in metalloproteins, is shown here to adopt a novel coordination environment in the Escherichia coli transport protein ZntA. The ZntA protein is a P-type ATPase that pumps zinc out of the cytoplasm and into the periplasm. It is physiologically selective for Zn(II) and functions with metalloregulatory proteins in the cell to keep the zinc quota within strict limits. Yet, the N-terminal cytoplasmic domain contains a region that is highly homologous to the yeast Cu(I) metallochaperone Atx1. To investigate how the structure of this region may influence its function, this fragment, containing residues 46-118, has been cloned out of the gene and overexpressed. We report here the solution structure of this fragment as determined by NMR. Both the apo and Zn(II)-ZntA(46-118) structures have been determined. It contains a previously unknown protein coordination site for zinc that includes two cysteine residues, Cys59 and Cys62, and a carboxylate residue, Asp58. The solvent accessibility of this site is also remarkably high, a feature that increasingly appears to be a characteristic of domains of heavy metal ion transport proteins. The participation of Asp58 in this ZntA metal ion binding site may play an important role in modulating the relative affinities and metal exchange rates for Zn(II)/Pb(II)/Cd(II) as compared with other P-type ATPases, which are selective for Cu(I) or Ag(I). (C) 2002 Elsevier Science Ltd. All rights reserved.