Krizek B A, Zawadzke L E, Berg J M
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218.
Protein Sci. 1993 Aug;2(8):1313-9. doi: 10.1002/pro.5560020814.
Most Cys2His2 zinc finger proteins contain tandem arrays of metal binding domains. The tandem nature of these arrays suggests that metal binding by these domains may not be independent but rather that metal binding may occur in a cooperative manner. This is especially true in light of the crystal structure of a three zinc finger array bound to DNA that revealed several types of interactions between domains. To address this question, peptides containing two tandem domains have been prepared. While metal binding studies do show that the two finger peptide has a metal ion affinity about threefold higher than that for a single domain peptide with the same sequence, additional studies reveal that this behavior is due to increased single site affinities in the context of the two domain peptide rather than to cooperativity. These studies indicate that domains of this type are independent of one another with regard to metal binding, at least in the absence of DNA. This observation has implications with regard to the question of whether the activities of proteins of this class might be modulated by available zinc concentrations.
大多数Cys2His2锌指蛋白含有串联排列的金属结合结构域。这些结构域的串联性质表明，这些结构域与金属的结合可能不是独立的，而是可能以协同方式发生。鉴于与DNA结合的三锌指阵列的晶体结构揭示了结构域之间的几种相互作用类型，情况尤其如此。为了解决这个问题，已经制备了含有两个串联结构域的肽。虽然金属结合研究确实表明，双指肽对金属离子的亲和力比具有相同序列的单结构域肽高约三倍，但进一步的研究表明，这种行为是由于在双结构域肽的背景下单位点亲和力增加，而不是由于协同作用。这些研究表明，至少在没有DNA的情况下，这类结构域在金属结合方面是相互独立的。这一观察结果对于这类蛋白质的活性是否可能受到可用锌浓度调节的问题具有启示意义。
