Ivanchenko M, Hassan A, van Holde K, Zlatanova J
Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331-7305, USA.
J Biol Chem. 1996 Dec 20;271(51):32580-5. doi: 10.1074/jbc.271.51.32580.
The preference of the linker histones to bind to superhelical DNA in comparison with linear or relaxed molecules suggests that these proteins might, in turn, change the twist and/or writhe of DNA molecules upon binding. In order to explore such a possibility, we looked for changes in the linking number of plasmid pBR322 caused by H1 binding, using assays that involve nicking and resealing of DNA strands. Two types of enzymes were used, eukaryotic topoisomerase I and prokaryotic DNA ligase. The results revealed that H1 binding causes unwinding of the DNA, with the unwinding angle being approximately 10 degrees . The globular domain of histone H1 is also capable of unwinding DNA, but to a lesser degree.
与线性或松弛分子相比，连接组蛋白更倾向于结合超螺旋DNA，这表明这些蛋白质在结合时可能会改变DNA分子的扭曲和/或缠绕。为了探究这种可能性，我们利用涉及DNA链切口和重新封闭的实验方法，寻找由H1结合导致的质粒pBR322连接数的变化。我们使用了两种类型的酶，真核拓扑异构酶I和原核DNA连接酶。结果显示，H1结合会导致DNA解旋，解旋角度约为10度。组蛋白H1的球状结构域也能够使DNA解旋，但程度较小。
