Isalan M, Choo Y, Klug A
Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
Proc Natl Acad Sci U S A. 1997 May 27;94(11):5617-21. doi: 10.1073/pnas.94.11.5617.
Zif268-like zinc fingers are generally regarded as independent DNA-binding modules that each specify three base pairs in adjacent, but discrete, subsites. However, crystallographic evidence suggests that a contact also can occur from the second helical position of one finger to the subsite of the preceding finger. Here we show for the three-finger DNA-binding domain of the protein Zif268, and a panel of variants, that deleting the putative contact from finger 3 can affect the binding specificity for the 5' base in the adjoining triplet, which forms part of the binding site of finger 2. This finding demonstrates that Zif268-like zinc fingers can specify overlapping 4-bp subsites, and that sequence specificity at the boundary between subsites arises from synergy between adjacent fingers. This has important implications for the design and selection of zinc fingers with novel DNA binding specificities.
锌指蛋白Zif268样锌指通常被视为独立的DNA结合模块，每个模块在相邻但离散的亚位点中指定三个碱基对。然而，晶体学证据表明，一个锌指的第二个螺旋位置与前一个锌指的亚位点之间也可能发生接触。在这里，我们展示了蛋白质Zif268的三指DNA结合结构域以及一组变体，即删除锌指3的假定接触会影响相邻三联体中5'碱基的结合特异性，该三联体构成锌指2结合位点的一部分。这一发现表明，锌指蛋白Zif268样锌指可以指定重叠的4碱基对亚位点，并且亚位点之间边界处的序列特异性源于相邻锌指之间的协同作用。这对具有新型DNA结合特异性的锌指的设计和选择具有重要意义。
