Checkpoint inhibition of origin firing prevents inappropriate replication outside of S-phase

Johnson, Mark C.; Can, Geylani; Santos, Miguel M.; Alexander, D.J.; Zegerman, Philip

doi:10.7554/elife.63589

Cited by 9 publications

(4 citation statements)

References 48 publications

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“…In metazoa and yeast, CMG formation involves the factors Treslin/Sld3, MTBP/Sld7, RecQL4/DONSON/Sld2, TopBP1/Dpb11 and the Mcm2-7 helicase itself. Apart from coupling origin firing to the S phase via S-CDK and DDK, these signal integrators are targeted by the DNA damage checkpoint and other regulatory pathways to mediate DNA damage-dependent origin firing control, execution of the temporal replication program and fine-tuning of origin firing 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67 . Such regulation helps avoid replication stress that is key to structural and numerical chromosomal instability in cancer cells 68 .…”

Section: Discussionmentioning

confidence: 99%

TopBP1 utilises a bipartite GINS binding mode to support genome replication

Day

Tetik

Parlak

et al. 2023

Preprint

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How the replicative Mcm2-7 helicase is activated during replication origin firing remains largely unknown. Our biochemical and structural studies reported here, demonstrate that the helicase activator GINS interacts with TopBP1 through two separate binding surfaces, the first involving a stretch of highly conserved amino acids in the TopBP1-GINI region, the second a surface located on TopBP1-BRCT4. The two surfaces bind to opposite ends of the A domain of the GINS subunit Psf1, and their cooperation is required for a biochemically stable TopBP1-GINS interaction. The GINI and BRCT4 domains also cooperate during replication origin firing, as revealed by immuno-replacement experiments in Xenopus egg extracts using different sets of mutations in either interface. Furthermore, the TopBP1-GINS interaction is incompatible with simultaneous binding of DNA polymerase epsilon to GINS when bound to Mcm2-7-Cdc45. Our TopBP1-GINS model predicts the coordination of three molecular processes, DNA polymerase epsilon arrival, TopBP1 ejection and GINS integration into Mcm2-7-Cdc45.

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Section: Discussionmentioning

confidence: 99%

TopBP1 utilises a bipartite GINS binding mode to support genome replication

Day

Tetik

Parlak

et al. 2023

Preprint

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“…Although we do not yet know the functional importance of Rad53-dependent phosphorylation of Sld7, in human cells this phosphorylation has been shown to regulate origin firing during a normal S-phase ( Ferreira et al , 2021 ). In yeast, Rad53 inhibits origin firing in the presence of replication stress or DNA damage through phosphorylation of Sld3 and Dbf4 ( Johnson et al , 2021 ; Lopez-Mosqueda et al , 2010 ; Zegerman & Diffley, 2010 ), but it is possible that phosphorylation of Sld7 further enhances this regulation or could modulate functions of Sld7 beyond origin firing. Additionally, we identified the DNA polymerase subunit of Pol α (Pol1) as a new direct interactor with Rad53.…”

Section: Discussionmentioning

confidence: 99%

Checkpoint kinase interaction with DNA polymerase alpha regulates replication progression during stress

Hadjicharalambous¹,

Whale²,

Can³

et al. 2023

Wellcome Open Res

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Background: In eukaryotes, replication stress activates a checkpoint response, which facilitates genome duplication by stabilising the replisome. How the checkpoint kinases regulate the replisome remains poorly understood. The aim of this study is to identify new targets of checkpoint kinases within the replisome during replication stress. Methods: Here we use an unbiased biotin proximity-ligation approach in Saccharomyces cerevisiae to identify new interactors and substrates of the checkpoint kinase Rad53 in vivo. Results: From this screen, we identified the replication initiation factor Sld7 as a Rad53 substrate, and Pol1, the catalytic subunit of polymerase a, as a Rad53-interactor. We showed that CDK phosphorylation of Pol1 mediates its interaction with Rad53. Combined with other interactions between Rad53 and the replisome, this Rad53-Pol1 interaction is important for viability and replisome progression during replication stress. Conclusions: Together, we explain how the interactions of Rad53 with the replisome are controlled by both replication stress and the cell cycle, and why these interactions might be important for coordinating the stabilisation of both the leading and lagging strand machineries.

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“…In mitosis and the G1 phase, Sld2 levels are attenuated by degradation and other mechanisms to prevent genetic instability and to maintain origin firing time [ 60 , 64 , 65 , 66 , 76 , 77 ]. Moreover, Sld3 phosphorylation by checkpoint kinases in G2 was found to help prevent re-replication [ 78 ]. For the sake of brevity, we refer for details to the papers cited in our recent review on origin firing regulation [ 79 ].…”

Section: Molecular Processes Of Cmg Formationmentioning

confidence: 99%

The Role of MTBP as a Replication Origin Firing Factor

Zaffar

Ferreira

Sánchez‐Pulido

et al. 2022

Biology

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The initiation step of replication at replication origins determines when and where in the genome replication machines, replisomes, are generated. Tight control of replication initiation helps facilitate the two main tasks of genome replication, to duplicate the genome accurately and exactly once each cell division cycle. The regulation of replication initiation must ensure that initiation occurs during the S phase specifically, that no origin fires more than once per cell cycle, that enough origins fire to avoid non-replicated gaps, and that the right origins fire at the right time but only in favorable circumstances. Despite its importance for genetic homeostasis only the main molecular processes of eukaryotic replication initiation and its cellular regulation are understood. The MTBP protein (Mdm2-binding protein) is so far the last core replication initiation factor identified in metazoan cells. MTBP is the orthologue of yeast Sld7. It is essential for origin firing, the maturation of pre-replicative complexes (pre-RCs) into replisomes, and is emerging as a regulation focus targeted by kinases and by regulated degradation. We present recent insight into the structure and cellular function of the MTBP protein in light of recent structural and biochemical studies revealing critical molecular details of the eukaryotic origin firing reaction. How the roles of MTBP in replication and other cellular processes are mutually connected and are related to MTBP’s contribution to tumorigenesis remains largely unclear.

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Checkpoint inhibition of origin firing prevents inappropriate replication outside of S-phase

Cited by 9 publications

References 48 publications

TopBP1 utilises a bipartite GINS binding mode to support genome replication

TopBP1 utilises a bipartite GINS binding mode to support genome replication

Checkpoint kinase interaction with DNA polymerase alpha regulates replication progression during stress

The Role of MTBP as a Replication Origin Firing Factor

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