RESUMEN
In eukaryotes, the basic structural unit of chromatin is the nucleosome, and genomic DNA iscompressed in chromatin. The presence of nucleosomes usually inhibits the biological processes that occuron the DNA templates, such as transcription, replication, repair, and recombination,. The histonevariant H2A.Z can regulate the structure of chromatin and affect the transcription process of genes, but itsdetailed regulation mechanism remains unclear. In this paper, the method of Förster resonance energytransfer (FRET) was used to detect the influence of sodium chloride, potassium chloride, manganesechloride, calcium chloride and magnesium chloride on the dissociation of nucleosomes. Then, the stabilitydifferences between the nucleosomes containing the histone variant H2A. Z and the conventionalnucleosomes were compared under the action of salt ions. Widom 601 DNA sequence was labeled withdual fluorescence Cy3 and Cy5, and the dissociation of nucleosomes was reflected by the change offluorescence signal value. FRET results showed that the dissociation speed of nucleosomes containing thehistone variant H2A. Z under the action of sodium chloride, potassium chloride, manganese chloride, calcium chloride and magnesium chloride is slower than that of canonical nucleosomes, and the influenceof calcium chloride, manganese chloride and magnesium chloride on dissociation is more obvious thansodium chloride, potassium chloride. The results of electrophoresis analysis showed that the dissociationrate of nucleosomes containing histone variant H2A. Z was significantly lower than that of canonicalnucleosomes at 75℃. Fluorescence thermal shift (FTS) was used to further analyze the stability ofnucleosomes containing histone variant H2A.Z. It was found that the fluorescence signals of the two typesof nucleosomes showed two distinct growth periods, and the fluorescence signals generated in thedissociation process of the two types of nucleosomes showed two distinct growth periods. The temperaturecorresponding to the first increasing period of fluorescence signal in the dissociation process of H2A. Z-containing nucleosome is significantly higher than that in the dissociation process of the canonicalnucleosome, which indicated that the dissociation and denaturation temperature of the H2A.Z / H2B dimerin the nucleosome is higher than that of the canonical H2A / H2B dimer, and the H2A. Z-containingnucleosomes have high thermal stability. The results indicated that the structure of nucleosomes containingthe histone variant H2A.Z is more stable than that of canonical nucleosomes.