Studies on protein organization of nucleosomes using cross-linking

When chromosomal proteins in chromatin or in mononucleosomes were extensively cross-linked with an imido ester, the H1-containing nonameric histone complex was revealed. In this complex, histone H1 is connected with the octamer of core histones. The cross-linking of H1 to the octamer is realized preferentially through H2a and H3 histones. Some HMG (high mobility group) proteins located presumably in the linker regions of a nucleosome fiber also take part in the formation of dimers, possibly with the histones of a nucleosomal core. The results suggest mutual interactions between some linker-associated proteins and intranucleosomal histones. Experiments involving extensive cross-linking of proteins in the purified mononucleosome subfractions demonstrated differences in the organization of core histones between complete nucleosomes and nucleosomes lacking H1.Abbreviations HMG proteins high mobility group proteins - DMA dimethyladipimidate dihydrochloride - DMP dimethyl-3,3-dithio-bis-propionimidate dihydrochloride