TY - JOUR
T1 - A Conserved Mechanism for Regulating Replisome Disassembly in Eukaryotes
AU - Jenkyn-Bedford, Michael
AU - Jones, Morgan L.
AU - Baris, Yasemin
AU - Labib, Karim P. M.
AU - Cannone, Giuseppe
AU - Yeeles, Joseph T. P.
AU - Deegan, Tom D.
N1 - Funding Information:
Ubiquitin and yeast Uba1 were provided by A. Knebel (MRC PPU, Dundee) and antibodies were provided by MRC PPU Reagents and Services (https://mrcppureagents.dundee.ac.uk) unless otherwise stated. This work was supported by the MRC, as part of UK Research and Innovation (MRC grants MC_UP_1201/12 to J.T.P.Y. and MC_UU_12016/13 to K.P.M.L.) and the Wellcome Trust (reference 204678/Z/16/Z for a Sir Henry Wellcome Postdoctoral Fellowship to T.D.D.).
PY - 2021/12/23
Y1 - 2021/12/23
N2 - Replisome disassembly is the final step of eukaryotic DNA replication and is triggered by ubiquitylation of the CDC45–MCM–GINS (CMG) replicative helicase
1–3. Despite being driven by evolutionarily diverse E3 ubiquitin ligases in different eukaryotes (SCF
Dia2 in budding yeast
1, CUL2
LRR1 in metazoa
4–7), 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 DNA
8–10. However, it is unknown how SCF
Dia2 and CUL2
LRR1 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.
AB - Replisome disassembly is the final step of eukaryotic DNA replication and is triggered by ubiquitylation of the CDC45–MCM–GINS (CMG) replicative helicase
1–3. Despite being driven by evolutionarily diverse E3 ubiquitin ligases in different eukaryotes (SCF
Dia2 in budding yeast
1, CUL2
LRR1 in metazoa
4–7), 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 DNA
8–10. However, it is unknown how SCF
Dia2 and CUL2
LRR1 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.
KW - Electron microscopy
KW - Replisome
UR - http://www.scopus.com/inward/record.url?scp=85118127100&partnerID=8YFLogxK
U2 - 10.1038/s41586-021-04145-3
DO - 10.1038/s41586-021-04145-3
M3 - Article
C2 - 34700328
SN - 0028-0836
VL - 600
SP - 743
EP - 747
JO - Nature
JF - Nature
ER -