Primary organization of nucleosomes and its functional implications

• Published in: BioSystems Vol. 12; no. 3; pp. 265 - 271
• Main Authors: Mirzabekov, A.D., Belyavsky, A.V., Bavykin, S.G., Shick, V.V.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 1980
• Subjects: Animals; Chromatin - ultrastructure; DNA - analysis; Histones - analysis; Nucleosomes - ultrastructure
• ISSN: 0303-2647; 1872-8324
• DOI: 10.1016/0303-2647(80)90023-4

A number of new approaches have been developed to study the arrangement of histones on DNA in chromatin. Methylation of DNA in chromatin with dimethyl sulfate demonstrates that histones leave the minor groove and the predominant portion of the major groove open and interact with the DNA-sugar-phosphate backbone from the side of the major groove. The sequential arrangement of histones H2A, H2B, H3, H4, and H1 along the DNA in several nucleosome particles has been determined by crosslinking histones to DNA. Models for binding histones to DNA in linearized and folded nucleosomes have been proposed on the basis of these data. The data strongly suggest that histones are located on DNA in a lateral way and are bound to the DNA helix from one side, do not form topological locks around DNA and can oscillate between two complementary DNA strands across the major groove. The lateral neutralization of phosphate groups in DNA by histones could induce the folding of DNA in nucleosomes. The structural data obtained provide some evidence on the possible mechanism of nucleosome functioning.