Oxaliplatin Binding to Human Copper Chaperone Atox1 and Protein Dimerization
Oxaliplatin Binding to Human Copper Chaperone Atox1 and Protein Dimerization
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DOI：
10.1021/acs.inorgchem.6b00750
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发表时间：
2016-07-04
影响因子：
4.6
通讯作者：
Natile, Giovanni
中科院分区：
文献类型：
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作者：
Belviso, Benny D.;Galliani, Angela;Natile, Giovanni
铜转运蛋白与细胞对铂类抗癌药物的反应有关。我们研究了伴侣Atox1与活化形式的奥沙利铂的反应，奥沙利铂是第三种获得全球批准的铂类药物。与含有单齿状胺的顺铂不同，奥沙利铂含有螯合的1,2-二氨基环己烷（DACH），它更能抵抗亲核试剂的位移。在溶液中，一个或两个{Pt(DACH)(2+)}片段结合到保守的Atox1的CXXC金属结合基序上；在后一种情况下，两个硫原子可能连接两个铂单元。在较长的反应时间下，形成二聚体，其组成为Atox1(2)中心点Pt-2(2+)，表明二胺配体完全丧失。这种二聚化过程伴随着蛋白质的部分展开。相反，旨在表征单体物种的结晶实验提供了类似于Boal和Rosenzweig在与顺铂进行的类似反应中已经获得的二聚体物种。然而，在后一种情况下，只有一个由两个Atox1链的CXXC基序的四个硫原子以四面体排列组成的pt结合位点（0.4占位），此外，我们还发现了一个涉及B链Cys41的次级pt结合位点（0.25占位）。此外，两个铂原子都失去了二胺。因此，在溶液中观察到的东西和在固态中形成的东西之间似乎没有什么关系。由于与其他金属离子（Cu+， Cd2+和Hg2+）获得的所有Atox1二聚体结构的四面体腔的完全占据是一个共同特征，我们提出在铂的情况下，其占据率仅为0.4，其余的腔被Cu+离子占据。实验证据支持后一种假设。我们的建议代表了Boal和Rosenzweig最初的建议（0.4 Pt占位率）和Shabalin等人提出的对原始晶体学数据的重新解释（1 Cu占位率）之间的交汇点，可以适用于其他情况。
Copper trafficking proteins have been implicated in the cellular response to platinum anticancer drugs. We investigated the reaction of the chaperone Atox1 with an activated form of oxaliplatin, the third platinum drug to reach worldwide approval. Unlike cisplatin, which contains mono dentate ammines, oxaliplatin contains chelated 1,2-diaminocyclohexane (DACH), which is more resistant to displacement by nucleophiles. In solution, one or two {Pt(DACH)(2+)} moieties bind to the conserved CXXC metal-binding motif of Atox1; in the latter case the two sulfur atoms likely bridging the two platinum units. At longer reaction times, a dimeric species is formed whose composition, Atox1(2)center dot Pt-2(2+), indicates complete loss of the diamine ligands. Such a dimerization process is accompanied by partial unfolding of the protein. Crystallization experiments aiming at the characterization of the monomeric species have afforded, instead, a dimeric species resembling that already obtained by Boal and Rosenzweig in a similar reaction performed with cisplatin. However, while in the latter case there was only one Pt-binding site (0.4 occupancy) made of four sulfur atoms of the CXXC motifs of the two Atox1 chains in a tetrahedral arrangement, we found, in addition, a secondary Pt-binding site involving Cys41 of the B chain (0.25 occupancy). Moreover, both platinum atoms have lost their diamines. Thus, there appears to be little relationship between what is observed in solution and what is formed in the solid state. Since full occupancy of the tetrahedral cavity is a common feature of all Atox1 dimeric structures obtained with other metal ions (Cu+, Cd2+, and Hg2+), we propose that in the case of platinum, where the occupancy is only 0.4, the remaining cavities are occupied by Cu+ ions. Experimental evidence is reported in support of the latter hypothesis. Our proposal represents a meeting point between the initial proposal of Boal and Rosenzweig (0.4 Pt occupancy) and the reinterpretation of the original crystallographic data put forward by Shabalin et al. (1 Cu occupancy), and could apply to other cases.