Greater binding affinity of trivalent antimony to a CCCH zinc finger domain compared to a CCHC domain of kinetoplastid proteins
Greater binding affinity of trivalent antimony to a CCCH zinc finger domain compared to a CCHC domain of kinetoplastid proteins
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DOI：
10.1039/c2mt00176d
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发表时间：
2012-01-01
期刊：
影响因子：
3.4
通讯作者：
Demicheli, Cynthia
中科院分区：
文献类型：
--
作者：
Frezard, Frederic;Silva, Heveline;Demicheli, Cynthia
最近有报道，Sb-III与Zn-II竞争其与HIV-1 NCp 7蛋白的CCHC锌指结构域的结合，这表明锌指蛋白可能是基于锑的药物的分子靶点。在这里，锑-III与CCCH锌指结构域，这被认为是在动质体原生动物的生物学中发挥至关重要的作用，相互作用的特点是第一次。从动质体蛋白和两个不同的CCHC型锌指肽CCCH型肽之间的Sb-III的结合特性进行了比较。1的形成：1利用圆二色性、紫外吸收、荧光光谱和ESI-MS证实了来自不同肽的Zn-肽和Sb-肽复合物。在pH 6和7下用SbCl 3进行Zn-肽复合物的滴定，利用肽的固有荧光。的肽的差分光谱特性允许不同的肽之间的竞争实验的结合Zn-II。本研究确定，Sb-III比CCHC更有效地从CCCH肽中置换Zn-II，这是由于Sb-CCCH络合物的稳定性更高（与Sb-CCHC络合物相比）和Zn-CCCH络合物的稳定性更低（与Zn-CCHC络合物相比）。比较不同氨基酸序列的CCHC型肽与Sb-Ⅲ或Zn-Ⅱ的结合特性，支持了不仅保守的锌指基序，而且非保守氨基酸序列决定Sb-Ⅲ和Zn-Ⅱ的结合亲和力的模型。这些数据表明，锑-III与CCCH型锌指蛋白的相互作用可能会调节，甚至介导，锑药物的药理作用。
It has been reported recently that Sb-III competes with Zn-II for its binding to the CCHC zinc finger domain of the HIV-1 NCp7 protein, suggesting that zinc finger proteins may be molecular targets for antimony-based drugs. Here, the interaction of Sb-III with a CCCH zinc finger domain, which is considered to play a crucial role in the biology of kinetoplastid protozoa, has been characterized for the first time. The binding characteristics of Sb-III were compared between a CCCH-type peptide derived from a kinetoplastid protein and two different CCHC-type zinc finger peptides. The formation of 1 : 1 Zn-peptide and Sb-peptide complexes from the different peptides was demonstrated using circular dichroism, UV absorption, fluorescence spectroscopies and ESI-MS. Titration of the Zn-peptide complexes with SbCl3 was performed at pH 6 and 7, exploiting the intrinsic fluorescence of the peptides. The differential spectral characteristics of the peptides allowed for competition experiments between the different peptides for binding of Zn-II. The present study establishes that Sb-III more effectively displaces Zn-II from the CCCH peptide than CCHC ones, as a result of both the greater stability of the Sb-CCCH complex (compared to Sb-CCHC complexes) and the lower stability of the Zn-CCCH complex (compared to Zn-CCHC complexes). Comparison of the binding characteristics of Sb-III or Zn-II between the CCHC-type peptides with different amino acid sequences supports the model that not only the conserved zinc finger motif, but also the sequence of non-conserved amino acids determines the binding affinity of Sb-III and Zn-II. These data suggest that the interaction of Sb-III with CCCH-type zinc finger proteins may modulate, or even mediate, the pharmacological action of antimonial drugs.