Pedone P V, Ghirlando R, Clore G M, Gronenborn A M, Felsenfeld G, Omichinski J G
Laboratory of Molecular Biology, Naional Institutes of Health, Bethesda, MD 20892-0530, USA.
Proc Natl Acad Sci U S A. 1996 Apr 2;93(7):2822-6. doi: 10.1073/pnas.93.7.2822.
Specific DNA binding to the core consensus site GAGAGAG has been shown with an 82-residue peptide (residues 310-391) taken from the Drosophila transcription factor GAGA. Using a series of deletion mutants, it was demonstrated that the minimal domain required for specific binding (residues 310-372) includes a single zinc finger of the Cys2-His2 family and a stretch of basic amino acids located on the N-terminal end of the zinc finger. In gel retardation assays, the specific binding seen with either the peptide or the whole protein is zinc dependent and corresponds to a dissociation constant of approximately 5 x 10(-9) M for the purified peptide. It has previously been thought that a single zinc finger of the Cys2-His2 family is incapable of specific, high-affinity binding to DNA. The combination of an N-terminal basic region with a single Cys2-His2 zinc finger in the GAGA protein can thus be viewed as a novel DNA binding domain. This raises the possibility that other proteins carrying only one Cys2-His2 finger are also capable of high-affinity specific binding to DNA.
研究表明，从果蝇转录因子GAGA中提取的一段82个氨基酸残基的肽段（残基310 - 391）能够特异性结合核心共有序列GAGAGAG。通过一系列缺失突变体实验证明，特异性结合所需的最小结构域（残基310 - 372）包括一个Cys2-His2家族的单锌指结构以及位于锌指N端的一段碱性氨基酸序列。在凝胶阻滞分析中，肽段或完整蛋白的特异性结合都依赖于锌，纯化肽段的解离常数约为5×10⁻⁹ M。此前人们一直认为Cys2-His2家族的单个锌指无法特异性、高亲和力地结合DNA。因此，GAGA蛋白中N端碱性区域与单个Cys2-His2锌指的组合可被视为一种新型的DNA结合结构域。这就增加了其他仅携带一个Cys2-His2锌指的蛋白也能够高亲和力特异性结合DNA的可能性。
