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.
Radiobiology Division, Academy of Sciences USSR, Pushchino, Moscow Region.
A I
AI
Gaziev
M P
MP
Kutsyi
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