title: Addition of histones to histone-depleted nuclei: effect on template activity toward DNA and RNA polymerases.
abstract: The ability of histones to block the accessibility of DNA in chromatin to DNA and RNA polymerases was measured by addition of lysine-rich or arginine-rich histones to nuclei selectively depleted of these histones. By this procedure nuclei were obtained in which all of the original lysine-rich histone in the chromatin was replaced by arginine-rich histone. Conversely in other nuclei, additional lysine-rich histone replaced some of the endogenous arginine-rich histone. Lysine-rich histone was much more effective than arginine-rich histone in blocking accessibility to DNA polymerase. Both classes of histone inhibited template activity toward RNA polymerase to a similar extent. In addition to lysine-rich histone and total arginine-rich histone, phosphorylated lysine-rich histone, two fragments of lysine-rich histone produced by cleavage with N-bromosuccinamide, and fractions IIB and IV of arginine-rich histone were added to histone-depleted nuclei. With both DNA and RNA polymerases as probes, no differences in inhibition of template activity were found when native lysine-rich histone was compared to phosphorylated lysine-rich histone. Similarly, fractions IIB and IV were indistinguishable from total arginine-rich histone. On a molar basis, the carboxyl fragment of lysine-rich histone was as effective as intact lysine-rich histone only when the amino fragment was added to it. By itself, the amino portion of lysine-rich histone was without inhibitory effect in the RNA polymerase assay and resulted in only slight inhibition of template activity toward DNA polymerase.
mesh_terms: D001120:Arginine / Q000032:analysis; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin; D004247:DNA / Q000037:antagonists & inhibitors*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D006657:Histones / Q000032:analysis / Q000494:pharmacology*; D008239:Lysine / Q000032:analysis; D013698:Templates, Genetic
chemical_list: D002843:Chromatin; D006657:Histones; D004247:DNA; D001120:Arginine; D004254:DNA Nucleotidyltransferases; D012321:DNA-Directed RNA Polymerases; D008239:Lysine