Co(II) and Cd(II) substitute for Zn(II) in the zinc finger derived from the DNA repair protein XPA, demonstrating a variety of potential mechanisms of toxicity
Co(II) and Cd(II) substitute for Zn(II) in the zinc finger derived from the DNA repair protein XPA, demonstrating a variety of potential mechanisms of toxicity
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DOI：
10.1021/tx049842s
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发表时间：
2004-11-01
影响因子：
4.1
通讯作者：
Bal, W
中科院分区：
文献类型：
--
作者：
Kopera, E;Schwerdtle, T;Bal, W
XPA是DNA修复的核苷酸切除修复（NER）途径的蛋白质复合物的关键成员之一。XPA的CCCC锌指结构域参与与其他NER蛋白的相互作用。为了研究XPA抑制的可能的分子机制，我们先前研究了Zn（II）和Ni（II）与合成的37个氨基酸肽（XPAzf）AcDYVICEECGKEFMDSYLMNHFDLPTCDNCRDADDKHKam的相互作用，所述肽代表XPA锌指序列（Bal，W.，Schwerdtle，T.，和Hartwig，A.（2003）镍攻击DNA修复蛋白XPA锌指的机制。毒理学化学研究16，242-248）。在这项工作中，我们扩展了这些研究的其他致癌金属离子，钴（II）和镉（II）。结合常数和复杂的几何形状，确定使用LTV-vis和CD光谱，和氧化损伤的XPAzf进行了研究与HPLC。在50 mM磷酸盐缓冲液（pH 7.4）中测定的Co（II）和Cd（II）的条件结合常数分别为10（7.4+/-0.4）和10（12.8+/-10.5），得到的结合常数比Zn（II）/Co（II）为100，Zn（II）/Cd（II）为0.001，这是迄今为止报道的锌指的最低值。Co（II）离子与XPAzf的硫形成四面体络合物，其与天然锌指是同构的。Cd（II）络合物的结构稍差。的Zn（II）-饱和XPAzf的氧化H2 O2的存在下，Co（II）的加速，但这种效果的浓度分布表明形成一个活跃的Co（II）络合物外部的金属-硫中心。Cd（II）饱和的XPAzf对H2 O2的氧化非常耐受。总体而言，我们的研究结果表明，YPAzf可以在特定条件下进行Co（II）和Cd（II）的攻击。
XPA is one of the key members of the protein complex of the nucleotide excision repair (NER) pathway of DNA repair. The CCCC zinc finger domain of XPA is involved in the interactions with other NER proteins. To study the possible molecular mechanisms of XPA inhibition, we previously investigated Zn(II) and Ni(II) interactions with the synthetic 37 amino acid peptide (XPAzf), AcDYVICEECGKEFMDSYLMNHFDLPTCDNCRDADDKHKam, representing the XPA zinc finger sequence (Bal, W., Schwerdtle, T., and Hartwig, A. (2003) Mechanism of nickel assault on the zinc finger of DNA repair protein XPA. Chem. Res. Toxicol. 16, 242-248). In this work, we extended these studies on other carcinogenic metal ions, Co(II) and Cd(II). The binding constants and complex geometries were determined using LTV-vis and CD spectroscopies, and oxidative damage to XPAzf was studied with HPLC. The conditional binding constants determined for Co(II) and Cd(II) in 50 mM phosphate buffer, pH 7.4, are 10(7.4+/-0.4) and 10(12.8+/-10.5), respectively, yielding binding constant ratios Zn(Il)/Co(II) of 100 and Zn(Il)/Cd(II) of 0.001, which are the lowest values reported for zinc fingers so far. The Co(II) ion forms a tetrahedral complex with the sulfurs of XPAzf, which is isostructural with the native zinc finger. The Cd(II) complex is somewhat less structured. The oxidation of Zn(II)-saturated XPAzf by H2O2 is accelerated in the presence of Co(II), but the concentration profile of this effect indicates the formation of an active Co(II) complex external to the metal-sulfur center. The Cd(II)-saturated XPAzf is very resistant to oxidation by H2O2. Overall, our results indicate that YPAzf can undergo Co(II) and Cd(II) assault under specific conditions.