p53-induced DNA bending and twisting: p53 tetramer binds on the outer side of a DNA loop and increases DNA twisting
p53-induced DNA bending and twisting: p53 tetramer binds on the outer side of a DNA loop and increases DNA twisting
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DOI：
10.1073/pnas.96.5.1875
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发表时间：
1999-03-02
影响因子：
11.1
通讯作者：
Harrington, RE
中科院分区：
文献类型：
--
作者：
Nagaich, AK;Zhurkin, VB;Harrington, RE
p53 的 DNA 结合活性对其肿瘤抑制功能至关重要。我们最近的研究表明，人类 p53 DNA 结合结构域 (p53DBD) 的四个分子以高度协同性结合响应元件并使 DNA 弯曲。通过使用 A-tract 定相实验，我们发现 p53DBD 和全长人类野生型 (wt) p53 引起的 DNA 弯曲和扭曲之间存在显着差异。我们的数据显示，p53DBD 的四个亚基使 DNA 弯曲 32-36 度，而 wt p53 将其弯曲 51-57 度。弯曲的方向性与共有 DNA 响应元件中两个五聚体连接处的主要凹槽弯曲一致。更复杂的定相分析还表明，p53DBD 和 wt p53 分别将 DNA 响应元件过度扭曲约 35 度和约 70 度。这些结果与四聚体复合物的分子模型研究一致。在蛋白质亚基施加的限制下，DNA 可以呈现一系列由弯曲和扭转角度相关变化产生的构象，使得 p53-DNA 四聚体复合物通过 DNA 过度扭转和向 CATG 四聚体的主沟弯曲而稳定。这种弯曲与双链体固有的序列依赖性各向异性一致。总体而言，四个 p53 部分以交错阵列横向放置在 DNA 环的外侧，并具有大量蛋白质间相互作用，从而提高了结合的稳定性和协同性。 p53 四聚体复合物的新颖结构具有重要的功能意义，包括 p53 与染色质可能的相互作用。
DNA binding activity of p53 is crucial for its tumor suppressor function. Our recent studies have shown that four molecules of the DNA binding domain of human p53 (p53DBD) bind the response elements with high cooperativity and bend the DNA. By using A-tract phasing experiments, we find significant differences between the bending and twisting of DNA by p53DBD and by full-length human wild-type (wt) p53. Our data show that four subunits of p53DBD bend the DNA by 32-36 degrees degrees, whereas wt p53 bends it by 51-57 degrees. The directionality of bending is consistent with major groove bends at the two pentamer junctions in the consensus DNA response element. More sophisticated phasing analyses also demonstrate that p53DBD and wt p53 overtwist the DNA response element by approximate to 35 degrees and approximate to 70 degrees, respectively. These results are in accord with molecular modeling studies of the tetrameric complex Within the constraints imposed by the protein subunits, the DNA can assume a range of conformations resulting from correlated changes in bend and twist angles such that the p53-DNA tetrameric complex is stabilized by DNA overtwisting and bending toward the major groove at the CATG tetramers. This bending is consistent with the inherent sequence-dependent anisotropy of the duplex. Overall, the four p53 moieties are placed laterally in a staggered array on the external side of the DNA loop and have numerous interprotein interactions that increase the stability and cooperativity of binding. The novel architecture of the p53 tetrameric complex has important functional implications including possible p53 interactions with chromatin.