[Occurrence of DNA structures which differ from the canonic B-form in sites of highly specific interaction with chromatin proteins].

According to the three-dimensional structure of DNase I and the mechanism of its action on linear double-stranded DNA, helix regions in conformations considerably different from the canonical B-form should be resistant to endonucleolysis. A number of DNA sequences specifically bound by nonhistone factors within 5'-flanking regions of the chicken beta A-globin, beta H-globin and c-myc genes are shown to contain short DNase I-resistant DNA domains. Several examples of the occurrence of such DNase I-resistant domains within the sites for high-specific recognition by different proteins are given. The role of the DNA structural polymorphism in site-specific interaction with protein factors is discussed.