Reduced transcription activity of rat liver chromatin after protein restriction and selective digestion of nuclei with micrococcus nuclease.
Restriction of protein intake in the diet has been shown to produce a change in transcription activity as determined in vitro. Conditions for a reduced transcription activity were investigated with selective digestion of nuclei with micrococcus nuclease (EC 3.1.4.7). Liver nuclei from young male rats fed a diet containing either 20 or 3% casein for 6 days were digested with 1.3 microgram of micrococcus nuclease protein/mg of nuclear DNA (specific enzyme activity 15,000 or 150 units/mg of protein). Part of the chromatin-bound RNA polymerase activity was transferred from the 2,000 x g to the 102,000 x g pellet. Independent of the type of endonuclease use, the specific activity of chromatin-bound and soluble RNA polymerase I plus III was similar in the two groups of rats. After protein restriction RNA polymerase II activity was significantly diminished in the 2,000 x g pellet, and was unchanged in the 102,000 x g pellet. Heparin-stimulated and soluble RNA polymerase II activities were significantly reduced. Number and length of RNA chains synthetized by chromatin-bound RNA polymerase I plus III remained unchanged by dietary treatment. After a low protein diet, RNA polymerase II in the absence and presence of heparin synthesized an unchanged number of RNA chains with reduced length. A selective digestion of chromatin with micrococcus nuclease is needed to show the reduction in RNA polymerase II activity after protein restriction.
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004789:Enzyme Activation / Q000187:drug effects; D006493:Heparin / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D008297:Male; D008836:Micrococcal Nuclease; D012313:RNA / Q000096:biosynthesis; D012319:RNA Polymerase II / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects*
D002843:Chromatin; D004044:Dietary Proteins; D012313:RNA; D006493:Heparin; D012319:RNA Polymerase II; D008836:Micrococcal Nuclease