Influence of DNA superstructural features and histone amino-terminal domains on nucleosome positioning

Nucleosome positioning has been studied on a strongly curved 268 bp DNA fragment from a Crithidia fasciculata kinetoplast, complexed with a histone octamer either normal or lacking amino-terminal domains. A very similar nucleosome multiple positioning, with the same rotational phasing, has been found, by Exo III mapping, in both cases. The experimental positioning is in fairly good agreement with that predicted using a theoretical method based on DNA distortion energy, derived from the nucleotide sequence. Taking into account that nucleosomes, without histone amino-terminal domains, lack thirty percent of electrostatic interactions, these results suggest a dominant role on nucleosome positioning of DNA distortion energy with respect to modifications in histone domains.