胸腺嘧啶二聚体会使DNA弯曲。

Husain I, Griffith J, Sancar A

Department of Biochemistry, University of North Carolina School of Medicine, Chapel Hill 27514.

Proc Natl Acad Sci U S A. 1988 Apr;85(8):2558-62. doi: 10.1073/pnas.85.8.2558.

A 32-base-pair DNA fragment containing a thymine photodimer was constructed and ligated head-to-tail to obtain multimers of this sequence in which thymine dimers were in phase with the helix screw axis (approximately equal to 3 turns apart). The ligation products were analyzed by one- and two-dimensional gel electrophoresis and quantitative electron microscopy. These analyses show that the thymine photodimer introduces a bend of approximately equal to 30 degrees in DNA, which causes anomalously slow migration of DNA fragments in polyacrylamide gels and facilitates the formation of small covalent circles. Repair of thymine dimers by DNA photolyase abolishes the anomalous migration.

构建了一个包含胸腺嘧啶光二聚体的32个碱基对的DNA片段，并将其首尾相连进行连接，以获得该序列的多聚体，其中胸腺嘧啶二聚体与螺旋轴同相（相隔约3圈）。通过一维和二维凝胶电泳以及定量电子显微镜对连接产物进行了分析。这些分析表明，胸腺嘧啶光二聚体在DNA中引入了约30度的弯曲，这导致DNA片段在聚丙烯酰胺凝胶中异常缓慢迁移，并促进了小共价环的形成。DNA光解酶对胸腺嘧啶二聚体的修复消除了这种异常迁移。