On the location of histones H1 and H5 in the chromatin fiber. Studies with immobilized trypsin and chymotrypsin.
On the location of histones H1 and H5 in the chromatin fiber. Studies with immobilized trypsin and chymotrypsin.
复制标题
关于组蛋白 H1 和 H5 在染色质纤维中的位置。
DOI：
10.1006/jmbi.1993.1096
复制
发表时间：
1993
影响因子：
5.6
通讯作者：
vanHolde,K
中科院分区：
文献类型：
--
作者：
Leuba,SH;Zlatanova,J;vanHolde,K
通过使用固定在Immobilon膜上的蛋白水解酶，研究了连接体组蛋白H1和H5在鸡红细胞染色质中的位置与纤维结构的关系。胰蛋白酶和胰凝乳蛋白酶的固定产生蛋白水解探针，其分别对分子的末端部分或球状结构域中的苯丙氨酸具有特异性，其不能渗透到凝聚纤维的内部。染色质纤维在三种不同的构象中进行了研究：开放之字形（在Tris缓冲液中），闭合之字形（在添加10 mM-NaC时）或30 nm纤维（在添加0·35 mM-MgCl 2时）。对鸡红细胞染色质中的、或在溶液中游离的或结合在单核体中的连接体组蛋白进行的消化实验的结果揭示了与连接体组蛋白位置相关的几个特征：（1）在纤维中组蛋白H5比组蛋白H1更受保护;（2）在纤维压实时，组蛋白H1的N和C末端部分不改变它们的可接近性，因此不改变它们的位置; H1的这种行为与组蛋白H5的相反，组蛋白H5的尾部在30 nm纤维中变得显著内化;（3）H1和H5的球状结构域中的苯丙氨酸在纤维和单核体颗粒中都不可接近（掩埋）。在胰蛋白酶消化过程中进行的沉降速度测量表明，即使是一些接头组蛋白分子中的几个切口，纤维的构象也是高度敏感的;因此，接头组蛋白是纤维在其所有不同缩合状态下的组织中的重要因素。
The location of linker histones H1 and H5 in chicken erythrocyte chromatin was studied as a function of the fiber structure by the use of proteolytic enzymes immobilized onto Immmobilon membranes. The immobilization of trypsin and chymotrypsin creates proteolytic probes, specific respectively to the terminal portions of the molecules or to the phenylalanine in the globular domain, that are incapable of penetrating into the interior of the condensed fiber. The chromatin fiber was studied in three different conformations: open zig-zag (in Tris buffer), closed zig-zag (upon addition of 10 mM-NaC), or 30 nm fiber (upon addition of 0·35 mM-MgCl2). The results from digestion experiments performed on linker histones either in chicken erythrocyte chromatin, or free in solution or bound in mononucleosomes revealed several features relevant to linker histone location: (1) histone H5 is more protected than histone H1 in the fiber; (2) the N and C-terminal portions of histone H1 do not change their accessibility, and hence their location, upon compaction of the fiber; this behavior of H1 is in contrast to that of histone H5, whose tails become significantly internalized in the 30 nm fiber; (3) phenylalanine in the globular domain of both H1 and H5 is inaccessible (buried) both in the fiber and in the mononucleosomal particle. Sedimentation velocity measurements performed during the course of trypsin digestion demonstrate that the conformation of the fiber is highly sensitive to even a few cuts in some of the linker histone molecules; hence, the linker histones are an important factor in the organization of the fiber in all its different condensation states.