染色质模型系统中的DNA拓扑结构。

DNA topology in a chromatin model system.

作者信息

Calascibetta F G, De Santis P, Morosetti S, Savino M, Scipioni A

出版信息

Cell Biophys. 1986 Jun;8(3):177-88. doi: 10.1007/BF02788493.

Abstract

The synthetic copolypeptide (Lys33, Leu67)100-Orn20, modeled on some general features of the histone sequences, has been found to supercoil the DNA double helix, wrapping it into a micelle, as a result of cohesive interactions between the polypeptide hydrophobic moieties. X-ray low-angle diffraction of complexes between the polypeptide and DNA is characterized by maxima at 50, 32, and 23 A, reminiscent of the chromatin pattern. The existence of a nucleosome-like structure along the DNA is suggested by gel electrophoresis analysis of DNA fragments after micrococcal nuclease digestion, showing the presence of a fragment of about 100 basepairs (bp) long. Topological experiments on the complexes with supercoiled as well as relaxed circular DNA by two-dimensional gel electrophoresis show the presence of left-handed superhelical turns. The results are in agreement with an intrinsic propensity of B-DNA to writhe into left-handed supercoils.

摘要

模拟组蛋白序列某些一般特征的合成共聚多肽（Lys33，Leu67）100-Orn20，由于多肽疏水部分之间的内聚相互作用，已被发现能使DNA双螺旋超螺旋化，将其包裹成胶束。多肽与DNA复合物的X射线低角度衍射的特征是在50、32和23 Å处出现最大值，这让人联想到染色质模式。微球菌核酸酶消化后DNA片段的凝胶电泳分析表明，DNA上存在类似核小体的结构，显示出存在一个约100个碱基对（bp）长的片段。通过二维凝胶电泳对超螺旋以及松弛环状DNA复合物进行的拓扑实验表明存在左手超螺旋。结果与B-DNA扭结成左手超螺旋的内在倾向一致。