Like a snap hook on a rope, cohesion is an obstacle to the expansion of DNA loops

The three-dimensional organisation of genomes is crucial to the regulation of various biological processes. Cohesin, the ‘snap hook’ of DNA, is essential to this organisation and has two functions: the cohesion of sister chromatids and the formation of loops organising the genome. Nathalie Bastié, Henri Mboumba, Olivier Gadal, Frédéric Beckouët (MCD-CBI) and their collaborators show how these two functions are complementary, opening the way to new mechanisms for regulating gene expression.