The condensation of DNA into an ordered chromatin structure allows the cell to solve the topological problems associated with storing huge molecules of chromosomal DNA within the nucleus. DNA is packaged into chromatin in orderly repeating protein-DNA complexes called nucleosomes. Each nucleosome consists of approximately 146bp of dsDNA (double-stranded DNA) wound 1.8 times around a histone octamer (Ref.1). Two molecules each of H2A, H2B, H3, and H4 comprise the histone ramp around which the DNA superhelix winds. Stretches of DNA upto 100bp separate adjacent nucleosomes. Multiple nuclear proteins bind to this linker region, some of which may be responsible for the ordered wrapping of strings of nucleosomes into higher-order chromatin structures (Ref.2).
Chromatin assembly involves the formation of nucleosomes from [...]