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bioRxiv · 10.1101/2020.06.03.132233

Scc2 and Scc3 promote distinct modes of topological association between cohesin and DNA

Collier, J. E.·Brunet-Roig, M.·Yatskevich, S.·Petela, N. J.·Metson, J.·Voulgaris, M.·Lee, B.-G.·Lowe, J.·nasmyth, k. a.
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Abstract

In addition to extruding DNA loops, cohesin entraps within its SMC-kleisin ring (S-K) individual DNAs during G1 and sister DNAs during S-phase. All three activities require related hook-shaped proteins called Scc2 and Scc3. Using thiol-specific crosslinking we provide rigorous proof of entrapment activity in vitro. Scc2 alone promotes entrapment of DNAs in the E-S and E-K compartments, between ATP-bound engaged heads and the SMC hinge and associated kleisin, respectively. This does not require ATP hydrolysis nor is it accompanied by entrapment within S-K rings, which is a slower process requiring Scc3. Cryo-EM reveals that DNAs transported into E-S/E-K compartments are "clamped" in a sub-compartment created by Scc2s association with engaged heads whose coiled coils are folded around their elbow. We suggest that clamping may be a recurrent feature of cohesin complexes active in loop extrusion and that this conformation precedes the S-K entrapment required for sister chromatid cohesion.

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Collier, J. E., Brunet-Roig, M., Yatskevich, S., Petela, N. J., Metson, J., Voulgaris, M., Lee, B.-G., Lowe, J., nasmyth, k. a.. 2020-06-03. Scc2 and Scc3 promote distinct modes of topological association between cohesin and DNA. https://doi.org/10.1101/2020.06.03.132233

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