Selective insolubility of active hsp70 gene chromatin.
A gentle chromatin fractionation procedure was used to investigate solubility properties of Drosophila hsp70 heat-shock genes. After a brief digestion of isolated nuclei with micrococcal nuclease, most DNA is readily solubilized under low-ionic-strength conditions that maintain native nucleosomal organization. Actively transcribing hsp70 genes, however, are found to be enriched in the insoluble nuclear residue. Inactive genes are not resistant to solubilization, showing a fractionation pattern similar to that of bulk DNA. The insolubility characteristic correlates well with two other structural features of active hsp70 chromatin: increased sensitivity to endonuclease attack and disruption of the nucleosomal repeat pattern. The 5'-flanking regulatory region of active hsp70 genes is particularly resistant to solubilization, suggesting a role for binding of transcription factors in mediating this effect.
D000818:Animals; D005591:Chemical Fractionation; D002843:Chromatin / Q000378:metabolism*; D003001:Cloning, Molecular; D004247:DNA / Q000302:isolation & purification; D004331:Drosophila melanogaster / Q000235:genetics; D005796:Genes; D006360:Heat-Shock Proteins / Q000235:genetics*; D008836:Micrococcal Nuclease; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012995:Solubility; D014158:Transcription, Genetic
D002843:Chromatin; D006360:Heat-Shock Proteins; D004247:DNA; D008836:Micrococcal Nuclease