DNA associated with hyperacetylated histone is preferentially digested by DNase I (original) (raw)
1978, Nucleic Acids Research
Butyrate-treated cells give rise to massive hyperacetylation of histones and have been used to test the idea that regions of DNA in association with hyperacetylated histones are preferentially solubilized upon digestion with DNase I. Such hyperacetylated histones can be derived from both pre-existing histones or from histone newly synthesized in the presence of butyrate which leads to extreme modification. The DNA in association with both types of hypermodified histone is equally and selectively digested. INTRODUCTI ON Several workers have described a method for the selective solubilization of active genes by digestion of nuclei with DNase I (2-5). It has been suggested that the active qenes are in a different conformation (2,3,6) which provides for preferential attack by DNase I. There is conflicting evidence (7-9) whether actively transcribed genes have gross changes in nucleosome structure, at least as viewed in the electron microscope. However, ribosomal genes and some unique sequences appear to be organized in structures which respond to micrococcal nuclease in a normal manner reflectinq at least in general terms a normal nucleosomal organization (2,10-14). It seems likely that the (perhaps stubtle) changes in nucleosome organization which lead to selective solubilization of active genes by DNase I also may play a critical role in permitting RNA polymerase to migrate through the compact nucleosome structure. The mechanism whereby actively transcribed reqions in chromatin could become more available to both nucleases and polymerases has long been thought to involve histone modification (15-27). Since histone phosnhorylation anpears to be primarily concerned with replication processes (28-32), interest now centers upon histone acetylation. Histone acetylation occurs to the level of the accumulation of up to four acetate groups per molecule (24,25,33,34), the modification occuring in the same amino terminal region of the protein 1863 C) Information Retrieval Limited 1 Falconberg Court London Wl V 5FG England Volume 5 Number
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