Evidence for cohesin sliding along budding yeast chromosomes

The ring-shaped cohesin complex is thought to topologically hold sister chromatids together from their synthesis in S-phase until chromosome segregation in mitosis. How cohesin stably binds to chromosomes for extended periods, without impeding other chromosomal processes that also require access to the DNA, is poorly understood. Budding yeast cohesin is loaded onto DNA by the Scc2-Scc4 cohesin loader at centromeres and promoters of active genes, from where cohesin translocates to more permanent places of residence at transcription termination sites. Here we show that, at the GAL2 and MET17 loci, pre-existing cohesin is pushed downstream along the DNA in response to transcriptional gene activation, apparently without need for intermittent dissociation or reloading. We observe translocation intermediates and find that the distribution of most chromosomal cohesin is shaped by transcription. Our observations support a model in which cohesin is able to slide laterally along chromosomes while maintaining topological contact with DNA. In this way, stable cohesin binding to DNA and enduring sister chromatid cohesion become compatible with simultaneous underlying chromosomal activities, including but maybe not limited to transcription. The Affymetrix Saccharomyces cerevisiae Chip Tiling 1.0R Arrays (catalog number 900645) and S. cerevisiae whole genome forward tiling arrays (catalog number 520286) were used to analyze the localization of Scc1 in Saccharomyces cerevisiae. Quantitative processed data (normalized signal for IP vs input) are only available for GSM2127850 - GSM2127853. Processed data for all other samples were temporarily created but not saved by the software that used the CEL files to generate the graphical result output files.