Characterization of DNase-I Cleavage Sites in the Nucleosome
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Excerpt
The use of nucleases as structural probes has proven to be a very successful approach in studying the organization of chromatin. Digestion of nuclei or chromatin with an endogenous rat-liver nuclease (Hewish and Burgoyne 1973) or micrococcal nuclease (for review, see R. D. Kornberg 1977) resulted in the identification and isolation of the nucleosome (the repeating subunit of chromatin), which contains nine histones and on the order of 200 base pairs of DNA.
That the DNA of chromatin is regularly arranged at a still lower level was revealed by the use of another nuclease, pancreatic deoxyribonuclease I (DNase I) (Noll 1974). Noll found that DNase I produced single-stranded cleavages at multiples of 10 bases, indicating a regular arrangement of the DNA within the nucleosome. This paper describes experiments which give further information about the organization of the DNA in the nucleosome by establishing two characteristics of the DNase-I digestion: (1)...
