Localization of histone H1 binding sites within the nucleosome by UV-induced H1-DNA crosslinking in vivo.

In our previous paper (Belikov et al., (1993), Nucl. Acids Res., 21, 4796-4802) we had studied DNA-protein architecture of so-called Alu-repeats in D. melanogaster ribosomal nontranscribed spacer using DNase I genomic footprinting and UV-induced DNA-protein crosslinking. Our data indicated precise positioning of two non-histone proteins (rABP50 and rABP 70), histone octamer, and histone H1 within the sequences of Alu-repeats. The data on the histone H1 binding sites within Alu-repeat region was presented, but not discussed as the authors could not reach a consensus in its evaluation. Here, the authors use these data to present a model of placement of the linker histone(s) within nucleosome. Our model places one contact of the globular domain of linker histone in the major groove on the inside of DNA superhelix just within the end of the core particle (site +6.5) and the second, close to the dyad (site -1). C-terminal tail binds to the internucleosomal spacer and N-terminal tail interacts simultaneously with the adjacent gyres thus stabilizing DNA superhelix.