A Role for Snf2-Related Nucleosome-Spacing Enzymes in Genome-Wide Nucleosome Organization

The positioning of nucleosomes within the coding regions of eukaryotic genes is aligned with respect to transcriptional start sites. This organization is likely to influence many genetic processes, requiring access to the underlying DNA. Here, we show that the combined action of Isw1 and Chd1 nucleosome-spacing enzymes is required to maintain this organization. In the absence of these enzymes, regular positioning of the majority of nucleosomes is lost. Exceptions include the region upstream of the promoter, the +1 nucleosome, and a subset of locations distributed throughout coding regions where other factors are likely to be involved. These observations indicate that adenosine triphosphate-dependent remodeling enzymes are responsible for directing the positioning of the majority of nucleosomes within the Saccharomyces cerevisiae genome.