Characterization of a topoisomerase-like activity at specific hypersensitive sites in the Drosophila histone gene cluster.
It is well known that treatment of DNA-topoisomerase complexes with SDS induces cleavage of the DNA by trapping a reactive intermediate in which the topoisomerase is covalently linked to the terminal phosphates of the cut DNA. I have used this technique to examine potential topoisomerase binding sites in the histone gene chromatin of Drosophila Kc cells. Treatment of Kc nuclei with SDS induces Mg++-dependent DNA cleavage near the borders of two nuclease-hypersensitive sites located 5' and 3' of histone H4. It is likely that the SDS-induced cleavage at these hypersensitive sites is due to a topoisomerase because protein becomes tightly bound to the ends of the cleaved DNA fragments. Preliminary experiments suggest that a type II topoisomerase may be responsible for the cleavage.
Villeponteau
B
B
Department of Biological Chemistry, University of Michigan, Ann Arbor 48109-2007.
D000818:Animals; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics*; D006657:Histones / Q000235:genetics*; D008274:Magnesium; D005810:Multigene Family / Q000187:drug effects; D009690:Nucleic Acid Conformation; D012967:Sodium Dodecyl Sulfate
D006657:Histones; D012967:Sodium Dodecyl Sulfate; D004247:DNA; D004250:DNA Topoisomerases, Type II; D008274:Magnesium