All eukaryotic SMC proteins induce a twist of −0.6 at each DNA loop extrusion step
Richard Janissen, Roman Barth, Iain F. Davidson, Jan-Michael Peters, Cees Dekker
Eukaryotes carry three types of structural maintenance of chromosome (SMC) protein complexes, condensin, cohesin, and SMC5/6, which are ATP-dependent motor proteins that remodel the genome via DNA loop extrusion (LE). SMCs modulate DNA supercoiling but remains incompletely understood how this is achieved. Using a single-molecule magnetic tweezers assay that directly measures how much twist is induced by individual SMCs in each LE step, we demonstrate that all three SMC complexes induce the same large negative twist (i.e., linking number change