Biology subjects

Peacock, E. M.

Publications and source records attributed to Peacock, E. M..

3 recordsLinked to original sources

bioRxiv2026

FBH1 Reverses Stalled Replication Forks via Sequential Unwinding of Nascent Strands

Replication fork reversal is a DNA damage tolerance mechanism important for genome stability that entails annealing of parental DNA to push the fork backwards. F-box helicase 1 (FBH1) is a 3'-5' ssDNA translocase and SCF (SKP-CUL1-F box) E3 ubiquitin ligase that catalyzes fork reversal and limits aberrant recombination, yet how its helicase activity drives strand annealing is unknown. Here, using single-molecule and biochemical assays, we show that SCFFBH1 reverses forks through a two-stage reaction in which translocation on the lagging strand template while remaining affixed at the junction destabilizes the leading strand duplex to ultimately displace the nascent leading strand. Reversal is force-sensitive and does not generate a four-way junction, revealing an annealing-independent mechanism distinct from those of SMARCAL1, HLTF, and ZRANB3. These results establish the importance of nascent strand unwinding to fork reversal and suggest the existence of distinct pathways that produce unique DNA structures, which has implications for fork restart and its measurement in cells.

biochemistry↗

bioRxiv2025

Structural basis for fork reversal and RAD51 regulation by the SCF ubiquitin ligase complex of F-box helicase 1

Replication fork reversal helps maintain genomic stability during replication stress. F-box helicase 1 (FBH1) catalyzes fork reversal and is an SCF (SKP-CUL1-F-box) E3 ubiquitin ligase that limits RAD51 association with chromatin. Here, we show that preferential binding of SCFFBH1 to the lagging strand template at DNA fork structures stimulates helicase activity and is required for fork reversal. A cryo-EM structure of SCFFBH1 bound to DNA representing a stalled fork reveals an intimate interaction between FBH1 and the fork junction. Disruption of this interface severely curtails fork reversal in vitro and replication progression in cells, providing a model for how ssDNA translocation by FBH1 facilitates annealing of parental DNA by a fundamentally different mechanism than the fork remodelers SMARCAL, HLTF, and ZRANB3. The structure also provides a model for SCFFBH1 disassembly of RAD51 filaments through translocation and ubiquitination, and implies that RAD51 is associated with the lagging strand at stalled forks.

biochemistry↗

bioRxiv2023

HLTF Prevents G4 Accumulation and Promotes G4-induced Fork Slowing to Maintain Genome Stability

G-quadruplexes (G4s) form throughout the genome and influence important cellular processes, but their deregulation can challenge DNA replication fork progression and threaten genome stability. Here, we demonstrate an unexpected, dual role for the dsDNA translocase HLTF in G4 metabolism. First, we find that HLTF is enriched at G4s in the human genome and suppresses G4 accumulation throughout the cell cycle using its ATPase activity. This function of HLTF affects telomere maintenance by restricting alternative lengthening of telomeres, a process stimulated by G4s. We also show that HLTF and MSH2, a mismatch repair factor that binds G4s, act in independent pathways to suppress G4s and to promote resistance to G4 stabilization. In a second, distinct role, HLTF restrains DNA synthesis upon G4 stabilization by suppressing PrimPol-dependent repriming. Together, the dual functions of HLTF in the G4 response prevent DNA damage and potentially mutagenic replication to safeguard genome stability.

molecular biology↗