We show that nucleosomal particles from transcriptionally active chromatin (MgCl2-soluble fraction) of Physarum polycephalum have lower electrophoretic mobility than those of the bulk chromatin (MgCl2-insoluble fraction). Altered electrophoretic behaviour is observed even at the level of the nucleosomal core, and is shown not to result from its different DNA, RNA or protein content, nor to be a consequence of the process of DNA replication. Analysis of nucelosomes from both fractions on density gradient gels reveals that the slow migration of active nucleosomes is due to increased friction, i.e., more asymmetrical (unfolded) conformation of the nucleosomal core.
- (P. polycephalum)
- Nucleosome structure
- Transcriptionally active chromatin