PT - JOURNAL ARTICLE AU - Stephanie A. Schalbetter AU - Anton Goloborodko AU - Geoffrey Fudenberg AU - Jon M. Belton AU - Catrina Miles AU - Miao Yu AU - Job Dekker AU - Leonid Mirny AU - Jon Baxter TI - Cohesin dependent compaction of mitotic chromosomes AID - 10.1101/094946 DP - 2016 Jan 01 TA - bioRxiv PG - 094946 4099 - http://biorxiv.org/content/early/2016/12/17/094946.short 4100 - http://biorxiv.org/content/early/2016/12/17/094946.full AB - Structural Maintenance of Chromosomes (SMC) protein complexes are key determinants of chromosome conformation. Using Hi-C and polymer modelling, we study how cohesin and condensin, two deeply-conserved SMC complexes, organize chromosomes in budding yeast. The canonical role of cohesins is to co-align sister chromatids whilst condensins generally compact mitotic chromosomes. We find strikingly different roles in budding yeast mitosis. First, cohesin is responsible for compacting mitotic chromosomes arms, independent of and in addition to its role in sister-chromatid cohesion. Cohesin dependent mitotic chromosome compaction can be fully accounted for through cis-looping of chromatin by loop extrusion. Second, condensin is dispensable for compaction along chromosomal arms and instead plays a specialized role, structuring rDNA and peri-centromeric regions. Our results argue that the conserved mechanism of SMC complexes is to form chromatin loops and that SMC-dependent looping is readily deployed in a range of contexts to functionally organize chromosomes.Cohesin compacts mitotic chromosomes independently of sister chromatid cohesion.Formation of cis-loops by loop extrusion fully accounts for cohesin-mediated compaction.Condensin is not required for mitotic chromosome compaction of yeast chromosome armsCondensin has a focused pre-anaphase role at centromeres and rDNA in yeastHighlights