Isolation of folded chromosomes from the yeast Saccharomyces cerevisiae.

Two fast-sedimenting chromatin complexes with sedimentation velocities of approximately 4600 and 3000 S can be isolated from logarithmically growing diploid Saccaromyces cerevisiae cells. The DNA in both structures appears to be folded into at least 60 domains and characterized by a negative superhelical density. Sensitivity to proteases and insensitivity to RNases suggest that proteins and not RNA are important in maintaining the organization of the chromosomes in both structures. The 46000S and 3000S complexes represent folded genomes isolated from diploid cells in the G2 and G1 stages of the cell cycle, respectively.