组蛋白H1与超螺旋DNA可溶性复合物的形成与表征

Formation and characterization of soluble complexes of histone H1 with supercoiled DNA.

作者信息

De Bernardin W, Losa R, Koller T

出版信息

J Mol Biol. 1986 Jun 5;189(3):503-17. doi: 10.1016/0022-2836(86)90320-7.

Abstract

We have analyzed the interaction of rat liver histone H1 with superhelical DNA. Depending on the ratio of H1 to DNA and the concentration of salt, two different types of complexes were found. Above a critical ratio of H1 to DNA, called the aggregation point, large aggregates are formed, which have a cable-like appearance in the electron microscope. Below the aggregation point, individual soluble complexes are formed, which are the subject of this study. With increasing ionic strength, the aggregation point is shifted towards lower ratios of H1 to DNA. In the soluble complexes, H1 appears to bind along superhelically intertwined DNA strands, forming a polymer. Partial digestion of the complexes with protease suggests protection of the N-terminal tail and the globular domain of H1. Similar soluble complexes were observed with various H1 fragments but not with the core histones. In the soluble complexes, similar regions of the H1 molecule are considered to be protected from cleavage by protease, as in chromatin. Therefore, these complexes appear to be a valuable model for the interaction of H1 in chromatin fibers.

摘要

我们分析了大鼠肝脏组蛋白H1与超螺旋DNA的相互作用。根据H1与DNA的比例以及盐浓度，发现了两种不同类型的复合物。在H1与DNA的临界比例（称为聚集点）以上，会形成大的聚集体，在电子显微镜下呈缆绳状外观。在聚集点以下，会形成单个可溶性复合物，这是本研究的对象。随着离子强度的增加，聚集点向H1与DNA的较低比例移动。在可溶性复合物中，H1似乎沿着超螺旋缠绕的DNA链结合，形成聚合物。用蛋白酶对复合物进行部分消化表明，H1的N端尾部和球状结构域受到保护。用各种H1片段观察到了类似的可溶性复合物，但核心组蛋白则未观察到。在可溶性复合物中，与染色质一样，H1分子的类似区域被认为受到蛋白酶切割的保护。因此，这些复合物似乎是染色质纤维中H1相互作用的一个有价值的模型。