Repository logo
 

A conserved mechanism for regulating replisome disassembly in eukaryotes.

Published version
Peer-reviewed

Change log

Authors

Jenkyn-Bedford, Michael  ORCID logo  https://orcid.org/0000-0003-2335-8278
Baris, Yasemin 
Labib, Karim PM 
Cannone, Giuseppe 

Abstract

Replisome disassembly is the final step of eukaryotic DNA replication and is triggered by ubiquitylation of the CDC45-MCM-GINS (CMG) replicative helicase1-3. Despite being driven by evolutionarily diverse E3 ubiquitin ligases in different eukaryotes (SCFDia2 in budding yeast1, CUL2LRR1 in metazoa4-7), replisome disassembly is governed by a common regulatory principle, in which ubiquitylation of CMG is suppressed before replication termination, to prevent replication fork collapse. Recent evidence suggests that this suppression is mediated by replication fork DNA8-10. However, it is unknown how SCFDia2 and CUL2LRR1 discriminate terminated from elongating replisomes, to selectively ubiquitylate CMG only after termination. Here we used cryo-electron microscopy to solve high-resolution structures of budding yeast and human replisome-E3 ligase assemblies. Our structures show that the leucine-rich repeat domains of Dia2 and LRR1 are structurally distinct, but bind to a common site on CMG, including the MCM3 and MCM5 zinc-finger domains. The LRR-MCM interaction is essential for replisome disassembly and, crucially, is occluded by the excluded DNA strand at replication forks, establishing the structural basis for the suppression of CMG ubiquitylation before termination. Our results elucidate a conserved mechanism for the regulation of replisome disassembly in eukaryotes, and reveal a previously unanticipated role for DNA in preserving replisome integrity.

Description

Keywords

Cryoelectron Microscopy, DNA, DNA Helicases, DNA Replication, Eukaryota, Humans, Ubiquitin-Protein Ligases

Journal Title

Nature

Conference Name

Journal ISSN

0028-0836
1476-4687

Volume Title

600

Publisher

Springer Science and Business Media LLC