CHANGING NUCLEOSOME POSITIONS THROUGH MODIFICATION OF THE DNA ROTATIONAL INFORMATION

The effects of the rotational information of DNA in determining the in vitro localization of nucleosomal core particles (ncps) have been stu died in the Saccharomyces cerevisiae 5S rRNA repeat gene. We have alte red the distribution of the phased series of flexibility signals prese nt on this DNA by inserting a 25-bp tract, and we have analyzed the ef fects of this mutation on the distribution and on the frequencies of n cps, as compared with the wild type and a reference 21-bp insertion mu tant. The variation of the standard free energy of nucleosome reconsti tution was determined. The results show that the DNA rotational inform ation is a major determinant of ncps positioning, define how many rota tionally phased signals are required for the formation of a stable par ticle, and teach how to modify their distribution through the alterati on of the rotational signals.