McNamara P T, Harrington R E
Department of Biochemistry, University of Nevada, Reno 89557.
J Biol Chem. 1991 Jul 5;266(19):12548-54.
Sequence-directed DNA curvature is most commonly associated with AA dinucleotides in the form of polyadenine runs. We demonstrate inherent curvature in DNA which lacks AA/TT dinucleotides using the criteria of polyacrylamide gel mobility and efficiency of DNA cyclization. These studies are based upon two 21-base pair synthetic DNA fragments designed to exhibit fixed curvature according to deflections made to the helical axis by non-AA dinucleotide stacks. Repeats of these sequences display anomalously slow migration in polyacrylamide gels. Moreover, both sequences describe helical conformations that are closed into circles by DNA ligase at much smaller sizes than is typical of nondeformed DNA. Chemical cleavage of these DNA molecules with hydroxyl radical is also consistent with local variation in helical conformation at specific dinucleotide steps.
序列导向的DNA弯曲最常与多聚腺嘌呤形式的AA二核苷酸相关。我们使用聚丙烯酰胺凝胶迁移率和DNA环化效率的标准，证明了缺乏AA/TT二核苷酸的DNA中存在固有弯曲。这些研究基于两个21碱基对的合成DNA片段，这些片段根据非AA二核苷酸堆积对螺旋轴的偏转设计，以呈现固定的弯曲。这些序列的重复在聚丙烯酰胺凝胶中显示出异常缓慢的迁移。此外，这两个序列描述的螺旋构象在比未变形DNA典型的尺寸小得多的情况下就被DNA连接酶封闭成环。用羟基自由基对这些DNA分子进行化学切割也与特定二核苷酸步骤处螺旋构象的局部变化一致。
