Thomas J O, Rees C, Finch J T
Department of Biochemistry, University of Cambridge, UK.
Nucleic Acids Res. 1992 Jan 25;20(2):187-94. doi: 10.1093/nar/20.2.187.
In view of the likely role of H1-H1 interactions in the stabilization of chromatin higher order structure, we have asked whether interactions can occur between the globular domains of the histone molecules. We have studied the properties of the isolated globular domains of H1 and the variant H5 (GH1 and GH5) and we have shown (by sedimentation analysis, electron microscopy, chemical cross-linking and nucleoprotein gel electrophoresis) that although GH1 shows no, and GH5 little if any, tendency to self-associate in dilute solution, they bind highly cooperatively to DNA. The resulting complexes appear to contain essentially continuous arrays of globular domains bridging 'tramlines' of DNA, similar to those formed with intact H1, presumably reflecting the ability of the globular domain to bind more than one DNA segment, as it is likely to do in the nucleosome. Additional (thicker) complexes are also formed with GH5, probably resulting from association of the primary complexes, possibly with binding of additional GH5. The highly cooperative nature of the binding, in close apposition, of GH1 and GH5 to DNA is fully compatible with the involvement of interactions between the globular domains of H1 and its variants in chromatin folding.
鉴于H1-H1相互作用在染色质高级结构稳定中可能发挥的作用，我们探究了组蛋白分子球状结构域之间是否会发生相互作用。我们研究了H1及其变体H5的分离球状结构域（GH1和GH5）的特性，并且已经表明（通过沉降分析、电子显微镜、化学交联和核蛋白凝胶电泳），尽管GH1在稀溶液中没有自缔合倾向，GH5即使有也很微弱，但它们与DNA的结合具有高度协同性。形成的复合物似乎包含基本连续的球状结构域阵列，这些阵列横跨DNA的“轨道”，类似于与完整H1形成的结构，大概反映了球状结构域结合多个DNA片段的能力，就像它在核小体中可能做的那样。GH5还会形成额外的（更厚的）复合物，可能是由于初级复合物的缔合，也可能伴随着额外GH5的结合。GH1和GH5与DNA紧密相邻结合的高度协同性质，与H1及其变体的球状结构域之间的相互作用参与染色质折叠完全相符。
