Smc3 acetylation, Pds5 and Scc2 control the translocase activity that establishes cohesin dependent chromatin loops

Cohesin is a DNA translocase instrumental in the folding of the genome into chromatin loops, with functional consequences on DNA-related processes. Chromatin loop length and organization likely depend on cohesin processivity, translocation rate, and stability on DNA. Here we investigate and provide a comprehensive overview of the roles of various cohesin regulators in tuning chromatin loop expansion. We demonstrate that Scc2, which stimulates cohesin ATPase activity, is also essential for cohesin translocation, driving loop expansion in vivo. Smc3 acetylation during S-phase counteracts this activity through the stabilization of Pds5, which finely tunes the size and stability of loops in G2. Examination of cohesin subunit occupancy on genome in the presence of non acetylable Smc3-RR and analysis of 3D chromosome configuration using HiC methods and yeast mutants