Lack of nucleosomal structure in a DNase-I-solubilized transcriptionally active chromatin fraction of Physarum polycephalum.
Light treatment of nuclei of Physarum polycephalum microplasmodia with DNase I, at low MgCl2 concentration (less than or equal to 3% DNA acid solubility, 0.1 mM MgCl2) selectively solubilizes a defined fraction of chromatin, in the form of a macromolecular complex. This fraction (up to 15% of the total chromatin) contains a full complement of the core histones and a reduced amount of histone H1, and is enriched in the high-mobility-group type of proteins. It is preferentially associated with nascent RNA and RNA polymerase B actively engaged in transcription. Digestion of DNAase-I-solubilized chromatin by micrococcal nuclease releases a size-heterogeneous population of cleavage products, indicative of lack of a typical nucleosomal packaging. It is concluded that the procedure used allows the isolation of structurally and functionally distinct regions of Physarum chromatin.
D055598:Chemical Phenomena; D002621:Chemistry; D002843:Chromatin / Q000032:analysis*; D002850:Chromatography, Gel; D004271:DNA, Fungal / Q000032:analysis; D003720:Densitometry; D003850:Deoxyribonuclease I; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000032:analysis; D008836:Micrococcal Nuclease; D009707:Nucleosomes / Q000032:analysis*; D010804:Physarum / Q000235:genetics*; D012995:Solubility; D014158:Transcription, Genetic
D002843:Chromatin; D004271:DNA, Fungal; D005656:Fungal Proteins; D009707:Nucleosomes; D003850:Deoxyribonuclease I; D008836:Micrococcal Nuclease