6t9q
Crystal structure of the second, C-terminal repeat of the DNA-binding domain of human TImeless
Structural highlights
Function[TIM_HUMAN] Plays an important role in the control of DNA replication, maintenance of replication fork stability, maintenance of genome stability throughout normal DNA replication and in the regulation of the circadian clock. Involved in the determination of period length and in the DNA damage-dependent phase advancing of the circadian clock. Negatively regulates CLOCK|NPAS2-ARTNL/BMAL1|ARTNL2/BMAL2-induced transactivation of PER1 possibly via translocation of PER1 into the nucleus. Forms a complex with TIPIN and this complex regulates DNA replication processes under both normal and stress conditions, stabilizes replication forks and influences both CHEK1 phosphorylation and the intra-S phase checkpoint in response to genotoxic stress. Timeless promotes TIPIN nuclear localization. Involved in cell survival after DNA damage or replication stress. May be specifically required for the ATR-CHEK1 pathway in the replication checkpoint induced by hydroxyurea or ultraviolet light. May also play an important role in epithelial cell morphogenesis and formation of branching tubules.[1] [2] [3] [4] Publication Abstract from PubMedRegions of the genome with the potential to form secondary DNA structures pose a frequent and significant impediment to DNA replication and must be actively managed in order to preserve genetic and epigenetic integrity. How the replisome detects and responds to secondary structures is poorly understood. Here, we show that a core component of the fork protection complex in the eukaryotic replisome, Timeless, harbours in its C-terminal region a previously unappreciated DNA-binding domain that exhibits specific binding to G-quadruplex (G4) DNA structures. We show that this domain contributes to maintaining processive replication through G4-forming sequences, and exhibits partial redundancy with an adjacent PARP-binding domain. Further, this function of Timeless requires interaction with and activity of the helicase DDX11. Loss of both Timeless and DDX11 causes epigenetic instability at G4-forming sequences and DNA damage. Our findings indicate that Timeless contributes to the ability of the replisome to sense replication-hindering G4 formation and ensures the prompt resolution of these structures by DDX11 to maintain processive DNA synthesis. Timeless couples G-quadruplex detection with processing by DDX11 helicase during DNA replication.,Lerner LK, Holzer S, Kilkenny ML, Svikovic S, Murat P, Schiavone D, Eldridge CB, Bittleston A, Maman JD, Branzei D, Stott K, Pellegrini L, Sale JE EMBO J. 2020 Jul 23:e104185. doi: 10.15252/embj.2019104185. PMID:32705708[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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