Nucleosomal Structure of Two Drosophila melanogaster Simple

Nucleosomes have been fractionated on nondenaturing polyacrylamide gels, and nucleosome subtypes containing the Drosophila melanogaster specific protein D l and ubiquitinated core histone H2A were identified by solubility in 0.1 M NaCl before nucleoprotein gel electrophoresis. Nucleosomes which contain DNA complementary to the 1.672 density simple satellite (sequence -AATAT-) bind protein D l , as demonstrated by two-dimensional hybridization mapping. This hybridization pattern allows the identification of D l dinucleosomes, which, like D l mononucleosomes, are reduced in mobility on the first dimension (nucleoprotein) gel by the addition of D l , an AT sequence-specific DNAbinding protein. The 1.705 density simple satellite (sequence -AAGAG-) is also found in nucleosomes, in a radically different subset from those of the -GATATDNA sequence. -AAGAGnucleosomes do not contain D l protein, but appear to be enriched in ubiquitinated core histone H2A. One-dimensional hybridization patterns suggest that -AAGAGnucleosomal DNA is rapidly trimmed to a shorter DNA length than either bulk or -AATATnucleosomes.