Diekmann S
Abteilung Molekulare Biologie, Max-Planck-Institut für biophysikalische Chemie Am Fassberg, Goettingen-Nikolausberg, FRG.
EMBO J. 1987 Dec 20;6(13):4213-7. doi: 10.1002/j.1460-2075.1987.tb02769.x.
Oligomers of different palindromic sequences (EcoRI, BamHI, and ClaI linkers) were ligated to form distributions of multimers. These long ligation ladders were methylated using corresponding methylases. The migration of the unmethylated as well as the methylated multimer distributions was analysed in 10% polyacrylamide gels. The migration anomaly of these sequences is interpreted in terms of the curvature of the DNA helix axis. The double-stranded oligomer dCGGAATTCCG is considerably curved in its unmodified form. Its curvature is strongly enhanced when the central dAs are methylated. This result is predicted by a model for DNA curvature. Multimers of the closely related sequence dCGGGATCCCG are straight. When methylated at the central dAs or at the most central dCs, a small curvature of the helix axis is induced. The double-stranded oligomer dCCATCGATGG is straight in its unmodified form as well as when it is methylated. Thus, DNA curvature can be induced or enhanced by methylation. However, DNA methylation at palindromic sequences seems not always to influence the linear path of the DNA helix axis.
将不同回文序列（EcoRI、BamHI和ClaI连接子）的寡聚体连接起来，形成多聚体分布。使用相应的甲基化酶对这些长连接梯进行甲基化。在10%聚丙烯酰胺凝胶中分析未甲基化以及甲基化的多聚体分布的迁移情况。这些序列的迁移异常现象是根据DNA螺旋轴的曲率来解释的。双链寡聚体dCGGAATTCCG在其未修饰形式下有相当程度的弯曲。当中央的dA被甲基化时，其曲率会大大增强。这一结果由一个DNA曲率模型预测得出。密切相关序列dCGGGATCCCG的多聚体是直的。当在中央的dA或最中央的dC处甲基化时，会诱导螺旋轴产生小的曲率。双链寡聚体dCCATCGATGG在其未修饰形式以及甲基化时都是直的。因此，DNA甲基化可以诱导或增强DNA曲率。然而，回文序列处的DNA甲基化似乎并不总是会影响DNA螺旋轴的线性路径。
