Project description:We report change in the nucleosome occupancy and accessibility upon deletion of ATP-dependent chromatin remodellers (ISW1, ISW2 & CHD1) in Saccharomyces cerevisiae.
Project description:We generated S.cerevisiae strains in which endogenous copies of candidate nucleosome spacing factors were replaced with the K.lactis copies. With this candidate approach, we found that K.lactis Chd1 directed longer nucleosome repeat length in S.cerevisiae. Generating chimeric proteins revealed that the strongest contribution to this differential spacing lies in the undercharacterised N-terminus of Chd1.
Project description:Numerous nucleosome remodeling enzymes tightly regulate nucleosome positions in eukaryotic cells. Transcription and statistical positioning of nucleosomes may also contribute to proper nucleosome organization. Individual contributions remain controversial due to strong redundancy of processes acting on the nucleosome landscape. By incisive yeast genome engineering we radically decreased their redundancy. We find the transcriptional machinery to be disruptive of evenly spaced nucleosomes, and proper nucleosome density critical for their biogenesis. INO80 spaces nucleosomes in vivo and positions the first nucleosome covering genes. It requires its Arp8 and Ies2 subunits, but unexpectedly not the Nhp10 module, for spacing. Whereas H2A.Z stimulates INO80 in vitro, its presence is dispensable for INO80 +1 positioning function in vivo. DNA damage, recombination and transposon integration assays suggest that evenly spaced nucleosomes protect cells against genotoxic stress. We derive a unifying model of the biogenesis of the nucleosome landscape and suggest that it evolved not only to regulate but also to protect the genome.
Project description:We addressed the roles of three nucleosome spacing enzymes (ISW1, ISW2 and CHD1) in specifying chromatin organization in S. cerevisiae.
