Scc2 counteracts a Wapl-independent mechanism that releases cohesin from chromosomes during G1 but is unnecessary during S phase for establishing cohesion

Madhusudhan Srinivasan; Naomi J Petela; Johanna C. Scheinost; James Collier; Menelaos Voulgaris; Maurici Brunet Roig; Frédéric Beckouët; Bin Hu; Kim Nasmyth

doi:10.1101/513960

Molecular BiologybioRxivJan 9, 2019

Preprint

Scc2 counteracts a Wapl-independent mechanism that releases cohesin from chromosomes during G1 but is unnecessary during S phase for establishing cohesion

Madhusudhan Srinivasan iD, Naomi J Petela iD, Johanna C. Scheinost, James Collier iD, Menelaos Voulgaris, Maurici Brunet Roig iD, Frédéric Beckouët iD, Bin Hu iD, Kim Nasmyth iD

Abstract

Cohesins association with chromosomes is determined by loading dependent on the Scc2/4 complex and release due to Wapl. We show here that Scc2/4 is not merely a loading complex and that it actively maintains cohesin on chromosomes during G1. It does so by blocking a Wapl-independent release reaction that requires opening the cohesin ring at its Smc3/Scc1 interface as well as the D loop of Smc1s ATPase. The Wapl-independent release mechanism is switched off as cells activate Cdk1 and enter G2/M and cannot be turned back on without cohesins dissociation from chromosomes. The latter phenomenon enabled us to show that cohesin that has already captured DNA in a Scc2-dependent manner before replication no longer requires Scc2 to capture sister DNAs during S phase.

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