title: Histone inhibition of DNA synthesis in eukaryotic cells permeable to macromolecules.
abstract: Mouse L Cells, grown in suspension culture can be rendered permeable to exogenous deoxynucleoside triphosphates by a cold shock in a near isotonic buffer system. These cells use the deoxynucleotides to synthesize DNA in a semiconservative fashion. The addition of 0.05% Triton X-100 to this system increases the permeability of the cells so that exogenously supplied macromolecules gain access to the DNA. When DNAase and phosphodiesterase are added to the detergent-permeabilized cells, the cell DNA is rapidly degraded, demonstrating that the enzymes reach the DNA within the first 2 min of the incubation period. Addition of whole calf thymus histone or histone fractions to the detergent-permeabilized cells inhibits DNA synthesis. The lysine-rich histone, F is a more effective inhibitor than the arginine-rich histone, F3. The other histone fractions including the slightly lysine-rich fractions, F2a and F2b, are intermediate between F1 and F3 as inhibitors of DNA- synthesis. Kinetic analysis demonstrates that the added histones increase apparent Km and reduce V of DNA synthesis in the permeabilized cells. These studies suggest the possibility that histones alter the association of the DNA replication complex and the DNA template in a manner that reduces the rate of DNA synthesis.
mesh_terms: D001692:Biological Transport; D002463:Cell Membrane Permeability; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects*; D003854:Deoxyribonucleotides / Q000378:metabolism; D006657:Histones / Q000494:pharmacology*; D007700:Kinetics; D007739:L Cells / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D011092:Polyethylene Glycols / Q000494:pharmacology
chemical_list: D003854:Deoxyribonucleotides; D006657:Histones; D011092:Polyethylene Glycols