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Synergy of Topoisomerase and Structural-Maintenance-of-Chromosomes Proteins Creates a Universal Pathway to Simplify Genome Topology

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Original languageEnglish
JournalProceedings of the National Academy of Sciences
Early online date8 Apr 2019
Publication statusPublished - 23 Apr 2019


Topological entanglements severely interfere with important biological processes. For this reason, genomes must be kept unknotted and unlinked during most of a cell cycle. Type II Topoisomerase (TopoII) enzymes play an important role in this process but the precise mechanisms yielding systematic disentanglement of DNA in vivo are not clear. Here we report computational evidence that Structural Maintenance of Chromosomes (SMC) proteins -- such as cohesins and condensins -- can cooperate with TopoII to establish a synergistic mechanism to resolve topological entanglements. SMC-driven loop extrusion (or diffusion) induces the spatial localisation of essential crossings in turn catalysing the simplification of knots and links by TopoII enzymes even in crowded and confined conditions. The mechanism we uncover is universal in that it does not qualitatively depend on the specific substrate, whether DNA or chromatin, or on SMC processivity; we thus argue that this synergy may be at work across organisms and throughout the cell cycle.

    Research areas

  • cond-mat.soft, physics.bio-ph, q-bio.BM, q-bio.SC

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