Gamma-irradiated DNA activates histone H1-specific proteinase of rat liver nuclei.
We investigated the effect of various forms of DNA (double- and single-stranded calf thymus DNA, circular plasmid DNA, gamma- and UV-irradiated DNA and DNAase I-treated double-stranded DNA) aggregated with histones, on the proteolysis of these histones by proteinase associated with the rat liver nuclear scaffold. It was shown that the nuclear scaffold-associated proteinase is able to degrade selectively the histone H1 only in the presence of the DNA containing single-strand breaks induced by gamma-radiation or DNAase I treatment as well as in the presence of heat-denatured DNA. This proteinase is not activated by the double-stranded circular plasmid DNA or by UV-treated double-stranded DNA. Histone H1-specific proteinase (HSP) activated by gamma-irradiated DNA is inhibited by inhibitors of serine proteinases such as antipain, leupeptin, phenylmethylsulphonyl fluoride, as well as by dithiothreitol. The results lead us to suggest that DNA-activated HSP from rat liver nuclei is involved in the regulation of the access of repair enzymes to the damage portions of DNA within chromatin.
Gaziev
A I
AI
Radiobiology Division, Academy of Sciences USSR, Pushchino, Moscow Region.
Kutsyi
M P
MP
D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology*; D004247:DNA / Q000378:metabolism / Q000528:radiation effects*; D010450:Endopeptidases / Q000032:analysis*; D004789:Enzyme Activation; D005720:Gamma Rays / Q000009:adverse effects*; D006657:Histones / Q000378:metabolism; D066298:In Vitro Techniques; D008099:Liver / Q000201:enzymology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D006657:Histones; D004247:DNA; D010450:Endopeptidases; C021361:histone proteases