Piña B, Barettino D, Truss M, Beato M
Institut für Molekularbiologie und Tumorforschung, Marburg, F.R.G.
J Mol Biol. 1990 Dec 20;216(4):975-90. doi: 10.1016/S0022-2836(99)80015-1.
DNA sequences from the long terminal repeat of the mouse mammary tumor virus (MMTV-LTR) position nucleosomes both in vivo and in vitro. Here, were present chromatin reconstitution experiments showing that MMTV-LTR sequences from -236 to +204 accommodate two histone octamers in positions compatible with the in vivo data. This positioning is not influenced by the length of the DNA fragment and occurs in linear as well as in closed circular DNA molecules. MMTV-LTR DNA sequences show an intrinsic bendability that closely resembles its wrapping around the histone octamer. We propose that bendability is responsible for the observed rotational nucleosome positioning. Translational nucleosome positioning seems also to be determined by the DNA sequence. These data, along with the results from reconstitution experiments with insertion mutants, support a modular model of nucleosome phasing on MMTV-LTR, where the actual positioning of the histone octamer results from the additive effect of multiple features of the DNA sequence.
来自小鼠乳腺肿瘤病毒长末端重复序列（MMTV-LTR）的DNA序列在体内和体外都能定位核小体。在此，我们展示了染色质重建实验，结果表明，从-236到+204的MMTV-LTR序列在与体内数据相符的位置容纳两个组蛋白八聚体。这种定位不受DNA片段长度的影响，并且在线性以及闭环DNA分子中均会出现。MMTV-LTR DNA序列显示出一种内在的可弯曲性，这与它围绕组蛋白八聚体的包裹情况极为相似。我们认为，可弯曲性是观察到的旋转核小体定位的原因。平移核小体定位似乎也由DNA序列决定。这些数据，连同插入突变体重建实验的结果，支持了MMTV-LTR上核小体相位的模块化模型，其中组蛋白八聚体的实际定位是由DNA序列的多个特征的累加效应导致的。
