Studies on protein organization of nucleosomes using cross-linking

Abstract

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 of the octamer is realized preferentially through H2a and H3 histones. Some HMG (high mortality 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 mutant 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.

Use of histone antibodies for studying chromatin topography and the phosphorylation of chromatin subunits.

“…Our results are in agreement with earlier data describing a relaxation of chromatin depleted of HI and H5. Some of the antigenic determinants that became unmasked may also correspond to regions in these histones that interact with HI; cross-linking experiments have shown that HI is interacting with various core histones (Ring and Cole, 1979;Boulikas et al, 1980;Bakayev et al, 1981).…”