Sister chromatid cohesion halts DNA loop expansion

Eukaryotic genomes are folded into DNA loops mediated by SMC complexes, like cohesin, condensin and Smc5/6. This organization regulates different DNA related processes along the cell cycle such as transcription, recombination, segregation and DNA repair. During G2/M phases, SMC complexes mediated DNA loops coexist with cohesin complexes involved in sister chromatid cohesion (SCC). It remains unknown whether SCC and DNA loop expansion influence each other and if they cooperate to regulate DNA-related processes. Here we show that SCC is indeed a barrier to DNA loop expansion mediated by cohesin in G2. Examination of the interplay between DNA loop extrusion mediated by cohesin and sister chromatid cohesion in yeast using HiC and ChIP-seq methods, yeast mutants, cell synchonisation and protein depletion and or expression