TY - JOUR
T1 - Multistep mechanism of G-quadruplex resolution during DNA replication
AU - Sato, Koichi
AU - Martin-Pintado, Nerea
AU - Post, Harm
AU - Altelaar, Maarten
AU - Knipscheer, Puck
N1 - Publisher Copyright:
Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).
PY - 2021/9
Y1 - 2021/9
N2 - G-quadruplex (or G4) structures form in guanine-rich DNA sequences and threaten genome stability when not properly resolved. G4 unwinding occurs during S phase via an unknown mechanism. Using Xenopus egg extracts, we define a three-step G4 unwinding mechanism that acts during DNA replication. First, the replicative helicase composed of Cdc45, MCM2-7 and GINS (CMG) stalls at a leading strand G4 structure. Second, the DEAH-box helicase 36 (DHX36) mediates bypass of the CMG past the intact G4 structure, allowing approach of the leading strand to the G4. Third, G4 structure unwinding by the Fanconi anemia complementation group J helicase (FANCJ) enables DNA polymerase to synthesize past the G4 motif. A G4 on the lagging strand template does not stall CMG but still requires DNA replication for unwinding. DHX36 and FANCJ have partially redundant roles, conferring pathway robustness. This previously unknown genome maintenance pathway promotes faithful G4 replication, thereby avoiding genome instability.
AB - G-quadruplex (or G4) structures form in guanine-rich DNA sequences and threaten genome stability when not properly resolved. G4 unwinding occurs during S phase via an unknown mechanism. Using Xenopus egg extracts, we define a three-step G4 unwinding mechanism that acts during DNA replication. First, the replicative helicase composed of Cdc45, MCM2-7 and GINS (CMG) stalls at a leading strand G4 structure. Second, the DEAH-box helicase 36 (DHX36) mediates bypass of the CMG past the intact G4 structure, allowing approach of the leading strand to the G4. Third, G4 structure unwinding by the Fanconi anemia complementation group J helicase (FANCJ) enables DNA polymerase to synthesize past the G4 motif. A G4 on the lagging strand template does not stall CMG but still requires DNA replication for unwinding. DHX36 and FANCJ have partially redundant roles, conferring pathway robustness. This previously unknown genome maintenance pathway promotes faithful G4 replication, thereby avoiding genome instability.
UR - http://www.scopus.com/inward/record.url?scp=85115892796&partnerID=8YFLogxK
U2 - 10.1126/sciadv.abf8653
DO - 10.1126/sciadv.abf8653
M3 - Article
C2 - 34559566
AN - SCOPUS:85115892796
VL - 7
SP - 1
EP - 16
JO - Science advances
JF - Science advances
IS - 39
M1 - eabf8653
ER -