Caserta M, di Mauro E
Centro di Studio per gli Acidi Nucleici (CNR), Università di Roma, La Sapienza, Italy.
Bioessays. 1996 Aug;18(8):685-93. doi: 10.1002/bies.950180813.
Histone octamers (hos) and DNA topoisomerase I contribute, along with other proteins, to the higher order structure of chromatin. Here we report on the similar topological requirements of these two protein model systems for their interaction with DNA. Both histone octamers and topoisomerase I positively and consistently respond to DNA supercoiling and curvature, and to the spatial accessibility of the preferential interaction sites. These findings (1) point to the relevance of the topology-related DNA conformation in protein interactions and define the particular role of the helically phased rotational information; and (2) help to solve the apparent paradoxical behaviour of ubiquitous and abundant proteins that interact with defined DNA sites in spite of the lack of clear sequence consensuses. Considering firstly, that the interactions with DNA of both DNA topoisomerase I and histone octamers are topology-sensitive and that upon their interaction the DNA conformation is modified; and secondly, that similar behaviours have also been reported for DNA topoisomerase II and histone H1, a topology-based functional correlation among all these determinants of the higher order structure of chromatin is here suggested.
组蛋白八聚体（hos）和DNA拓扑异构酶I与其他蛋白质一起，对染色质的高级结构有贡献。在此我们报告这两种蛋白质模型系统与DNA相互作用时相似的拓扑学要求。组蛋白八聚体和拓扑异构酶I都对DNA超螺旋和曲率以及优先相互作用位点的空间可及性产生积极且一致的反应。这些发现（1）指出了拓扑相关DNA构象在蛋白质相互作用中的相关性，并定义了螺旋相位旋转信息的特殊作用；（2）有助于解决尽管缺乏明确的序列共识，但与特定DNA位点相互作用的普遍存在且丰富的蛋白质的明显矛盾行为。首先考虑到DNA拓扑异构酶I和组蛋白八聚体与DNA的相互作用对拓扑结构敏感，并且在它们相互作用时DNA构象会发生改变；其次，对于DNA拓扑异构酶II和组蛋白H1也报道了类似的行为，在此提出了染色质高级结构的所有这些决定因素之间基于拓扑的功能相关性。
