DNase I sensitivity of ribosomal genes in isolated nucleosome core particles.
The level of chromatin structure at which DNase I recognizes conformational differences between inert and activated genes has been investigated. Bulk and ribosomal DNA's of Tetrahymena pyriformis were differentially labeled in vivo with [14C]- and [3H]-thymidine, respectively, utilizing a defined starvation-refeeding protocol. The 3H-labeled ribosomal genes were shown to be preferentially digested by DNase I in isolated nuclei. Staphylococcal nuclease digested the ribosomal genes more slowly than bulk DNA, probably owing to the higher GC content of rDNA. DNase I and staphylococcal nuclease digestions of purified nucleosomes and of nucleosome core particles isolated from dual-labeled, starved-refed nuclei were indistinguishable from those of intact nuclei. We conclude from these studies that DNase I recognizes an alteration in the internal nucleosome core structure of activated ribosomal genes.
D000818:Animals; D002467:Cell Nucleus / Q000032:analysis; D004247:DNA / Q000302:isolation & purification; D003851:Deoxyribonucleases / Q000378:metabolism; D007700:Kinetics; D008836:Micrococcal Nuclease; D009707:Nucleosomes / Q000032:analysis*; D012270:Ribosomes / Q000032:analysis*; D013769:Tetrahymena pyriformis / Q000032:analysis*
D009707:Nucleosomes; D004247:DNA; D003851:Deoxyribonucleases; D008836:Micrococcal Nuclease