scholarly journals Genome duplication in Leishmania major relies on DNA replication outside S phase

2019 ◽  
Author(s):  
Jeziel D. Damasceno ◽  
Catarina A. Marques ◽  
Dario Beraldi ◽  
Kathryn Crouch ◽  
Craig Lapsley ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Genome Stability ◽  
Leishmania Major ◽  
Genome Duplication ◽  
S Phase ◽  
Replication Initiation ◽  
Dna Replication Initiation ◽  
Synthesis Activity ◽  
Important Parasite

AbstractOnce every cell cycle, DNA replication takes place to allow cells to duplicate their genome and segregate the two resulting copies into offspring cells. In eukaryotes, the number of DNA replication initiation loci, termed origins, is proportional to chromosome size. However, previous studies have suggested that in Leishmania, a group of single-celled eukaryotic parasites, DNA replication starts from just a single origin per chromosome, which is predicted to be insufficient to secure complete genome duplication within S phase. Here, we show that the paucity of origins activated in early S phase is balanced by DNA synthesis activity outside S phase. Simultaneous recruitment of acetylated histone H3 (AcH3), modified base J and the kinetochore factor KKT1 is exclusively found at the origins used in early S phase, while subtelomeric DNA replication can only be linked to AcH3 and displays persistent activity through the cell cycle, including in G2/M and G1 phases. We also show that subtelomeric DNA replication, unlike replication from the previously mapped origins, is sensitive to hydroxyurea and dependent on subunits of the 9-1-1 complex. Our work indicates that Leishmania genome transmission relies on an unconventional DNA replication programme, which may have implications for genome stability in this important parasite.

scholarly journals Genome duplication in Leishmania major relies on persistent subtelomeric DNA replication

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Jeziel Dener Damasceno ◽  
Catarina A Marques ◽  
Dario Beraldi ◽  
Kathryn Crouch ◽  
Craig Lapsley ◽  
...  
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Leishmania Major ◽  
Genome Duplication ◽  
Histone H3 ◽  
S Phase ◽  
Replication Initiation ◽  
G1 Phase ◽  
Dna Replication Initiation ◽  
Single Region

DNA replication is needed to duplicate a cell’s genome in S phase and segregate it during cell division. Previous work in Leishmania detected DNA replication initiation at just a single region in each chromosome, an organisation predicted to be insufficient for complete genome duplication within S phase. Here, we show that acetylated histone H3 (AcH3), base J and a kinetochore factor co-localise in each chromosome at only a single locus, which corresponds with previously mapped DNA replication initiation regions and is demarcated by localised G/T skew and G4 patterns. In addition, we describe previously undetected subtelomeric DNA replication in G2/M and G1-phase-enriched cells. Finally, we show that subtelomeric DNA replication, unlike chromosome-internal DNA replication, is sensitive to hydroxyurea and dependent on 9-1-1 activity. These findings indicate that Leishmania’s genome duplication programme employs subtelomeric DNA replication initiation, possibly extending beyond S phase, to support predominantly chromosome-internal DNA replication initiation within S phase.

Efficiency and equity in origin licensing to ensure complete DNA replication

2021 ◽  
Author(s):  
Liu Mei ◽  
Jeanette Gowen Cook
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Genome Stability ◽  
S Phase ◽  
Replication Initiation ◽  
G1 Phase ◽  
Dna Replication Initiation ◽  
Origin Licensing ◽  
Dna Replication Origins

The cell division cycle must be strictly regulated during both development and adult maintenance, and efficient and well-controlled DNA replication is a key event in the cell cycle. DNA replication origins are prepared in G1 phase of the cell cycle in a process known as origin licensing which is essential for DNA replication initiation in the subsequent S phase. Appropriate origin licensing includes: (1) Licensing enough origins at adequate origin licensing speed to complete licensing before G1 phase ends; (2) Licensing origins such that they are well-distributed on all chromosomes. Both aspects of licensing are critical for replication efficiency and accuracy. In this minireview, we will discuss recent advances in defining how origin licensing speed and distribution are critical to ensure DNA replication completion and genome stability.

scholarly journals Regulation of DNA Replication Licensing and Re-Replication by Cdt1

2021 ◽  
Vol 22 (10) ◽  
pp. 5195
Author(s):  
Hui Zhang
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Genome Stability ◽  
E3 Ligase ◽  
S Phase ◽  
Replication Initiation ◽  
Nuclear Antigen ◽  
Repair Synthesis ◽  
Ubiquitin E3 Ligase

In eukaryotic cells, DNA replication licensing is precisely regulated to ensure that the initiation of genomic DNA replication in S phase occurs once and only once for each mitotic cell division. A key regulatory mechanism by which DNA re-replication is suppressed is the S phase-dependent proteolysis of Cdt1, an essential replication protein for licensing DNA replication origins by loading the Mcm2-7 replication helicase for DNA duplication in S phase. Cdt1 degradation is mediated by CRL4Cdt2 ubiquitin E3 ligase, which further requires Cdt1 binding to proliferating cell nuclear antigen (PCNA) through a PIP box domain in Cdt1 during DNA synthesis. Recent studies found that Cdt2, the specific subunit of CRL4Cdt2 ubiquitin E3 ligase that targets Cdt1 for degradation, also contains an evolutionarily conserved PIP box-like domain that mediates the interaction with PCNA. These findings suggest that the initiation and elongation of DNA replication or DNA damage-induced repair synthesis provide a novel mechanism by which Cdt1 and CRL4Cdt2 are both recruited onto the trimeric PCNA clamp encircling the replicating DNA strands to promote the interaction between Cdt1 and CRL4Cdt2. The proximity of PCNA-bound Cdt1 to CRL4Cdt2 facilitates the destruction of Cdt1 in response to DNA damage or after DNA replication initiation to prevent DNA re-replication in the cell cycle. CRL4Cdt2 ubiquitin E3 ligase may also regulate the degradation of other PIP box-containing proteins, such as CDK inhibitor p21 and histone methylase Set8, to regulate DNA replication licensing, cell cycle progression, DNA repair, and genome stability by directly interacting with PCNA during DNA replication and repair synthesis.

scholarly journals Unscheduled DNA replication in G1 causes genome instability through head-to-tail replication fork collisions

2021 ◽  
Author(s):  
Karl-Uwe Reusswig ◽  
Julia Bittmann ◽  
Martina Peritore ◽  
Michael Wierer ◽  
Matthias Mann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Replication Fork ◽  
Genome Instability ◽  
S Phase ◽  
Replication Initiation ◽  
Dna Replication Initiation ◽  
Chromosome Breaks ◽  
Naturally Occurring ◽  
Identical Response

DNA replicates once per cell cycle. Interfering with the regulation of DNA replication initiation generates genome instability through over-replication and has been linked to early stages of cancer development. Here, we engineered genetic systems in budding yeast to induce unscheduled replication in the G1-phase of the cell cycle. Unscheduled G1 replication initiated at canonical S-phase origins across the genome. We quantified differences in replisomes in G1- and S-phase and identified firing factors, polymerase α, and histone supply as factors that limit replication outside S-phase. G1 replication per se did not trigger cellular checkpoints. Subsequent replication during S-phase, however, resulted in over-replication and led to chromosome breaks via head-to-tail replication fork collisions that are marked by chromosome-wide, strand-biased occurrence of RPA-bound single-stranded DNA. Low-level, sporadic induction of G1 replication induced an identical response, indicating findings from synthetic systems are applicable to naturally occurring scenarios of unscheduled replication initiation by G1/S deregulation.

scholarly journals FBL17 targets CDT1a for degradation in early S-phase to prevent Arabidopsis genome instability

2019 ◽  
Author(s):  
Bénédicte Desvoyes ◽  
Sandra Noir ◽  
Kinda Masoud ◽  
María Isabel López ◽  
Pascal Genschik ◽  
...  
Keyword(s):  
Dna Replication ◽  
Genome Stability ◽  
Genome Instability ◽  
S Phase ◽  
Replication Initiation ◽  
Genome Integrity ◽  
Dependent Manner ◽  
Dna Replication Initiation ◽  
Oscillatory Pattern ◽  
F Box Protein

AbstractMaintenance of genome integrity depends on controlling the availability of DNA replication initiation proteins, e.g., CDT1, a component of the pre-replication complexes that regulates chromatin licensing for replication. To understand the evolutionary history of CDT1 regulation, we have identified the mechanisms involved in CDT1 dynamics. During cell cycle, CDT1a starts to be loaded early after mitotic exit and maintains high levels until the G1/S transition. Soon after the S-phase onset, CDT1a is rapidly degraded in a proteasome-dependent manner. Plant cells use a specific SCF-mediated pathway that relies on the FBL17 F-box protein for CDT1a degradation, which is independent of CUL4a-containing complexes. A similar oscillatory pattern occurs in endoreplicating cells, where CDT1a is loaded just after finishing the S-phase. CDT1a is necessary to maintain genome stability, an ancient strategy although unique proteins and mechanisms have evolved in different eukaryotic lineages to ensure its degradation during S-phase.Impact statementThe DNA replication protein CDT1a is crucial for genome integrity and is targeted for proteasome degradation just after S-phase initiation by FBL17 in proliferating and endoreplicating cells of Arabidopsis

scholarly journals Polar Remodeling and Histidine Kinase Activation, Which Is Essential for Caulobacter Cell Cycle Progression, Are Dependent on DNA Replication Initiation

2010 ◽  
Vol 192 (15) ◽  
pp. 3893-3902 ◽  
Author(s):  
Antonio A. Iniesta ◽  
Nathan J. Hillson ◽  
Lucy Shapiro
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Histidine Kinase ◽  
Cell Cycle Progression ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Cycle Progression ◽  
Dna Replication Initiation ◽  
Flagellar Biosynthesis ◽  
Initiation Of Dna Replication

ABSTRACT Caulobacter crescentus initiates a single round of DNA replication during each cell cycle. Following the initiation of DNA replication, the essential CckA histidine kinase is activated by phosphorylation, which (via the ChpT phosphotransferase) enables the phosphorylation and activation of the CtrA global regulator. CtrA∼P then blocks the reinitiation of replication while regulating the transcription of a large number of cell cycle-controlled genes. It has been shown that DNA replication serves as a checkpoint for flagellar biosynthesis and cell division and that this checkpoint is mediated by the availability of active CtrA. Because CckA∼P promotes the activation of CtrA, we addressed the question of what controls the temporal activation of CckA. We found that the initiation of DNA replication is a prerequisite for remodeling the new cell pole, which includes the localization of the DivL protein kinase to that pole and, consequently, the localization, autophosphorylation, and activation of CckA at that pole. Thus, CckA activation is dependent on polar remodeling and a DNA replication initiation checkpoint that is tightly integrated with the polar phospho-signaling cascade governing cell cycle progression.

scholarly journals Activation of the DNA Damage Checkpoint in Mutants Defective in DNA Replication Initiation

2008 ◽  
Vol 19 (10) ◽  
pp. 4374-4382 ◽  
Author(s):  
Ling Yin ◽  
Alexandra Monica Locovei ◽  
Gennaro D'Urso
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Replication Fork ◽  
S Phase ◽  
Replication Initiation ◽  
Dna Damage Checkpoint ◽  
Origin Firing ◽  
Dna Replication Initiation ◽  
Fork Stalling ◽  
S Phase Checkpoint

In the fission yeast, Schizosaccharomyces pombe, blocks to DNA replication elongation trigger the intra-S phase checkpoint that leads to the activation of the Cds1 kinase. Cds1 is required to both prevent premature entry into mitosis and to stabilize paused replication forks. Interestingly, although Cds1 is essential to maintain the viability of mutants defective in DNA replication elongation, mutants defective in DNA replication initiation require the Chk1 kinase. This suggests that defects in DNA replication initiation can lead to activation of the DNA damage checkpoint independent of the intra-S phase checkpoint. This might result from reduced origin firing that leads to an increase in replication fork stalling or replication fork collapse that activates the G2 DNA damage checkpoint. We refer to the Chk1-dependent, Cds1-independent phenotype as the rid phenotype (for replication initiation defective). Chk1 is active in rid mutants, and rid mutant viability is dependent on the DNA damage checkpoint, and surprisingly Mrc1, a protein required for activation of Cds1. Mutations in Mrc1 that prevent activation of Cds1 have no effect on its ability to support rid mutant viability, suggesting that Mrc1 has a checkpoint-independent role in maintaining the viability of mutants defective in DNA replication initiation.

scholarly journals Cell Cycle-Dependent Switch of TopBP1 Functions by Cdk2 and Akt

2020 ◽  
Vol 40 (8) ◽  
Author(s):  
Kang Liu ◽  
Joshua D. Graves ◽  
Yu-Ju Lee ◽  
Fang-Tsyr Lin ◽  
Weei-Chin Lin
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cancer Cells ◽  
Cyclin A ◽  
Replication Initiation ◽  
Dna Replication Initiation ◽  
Cycle Dependent

ABSTRACT Cdk2-dependent TopBP1-treslin interaction is critical for DNA replication initiation. However, it remains unclear how this association is terminated after replication initiation is finished. Here, we demonstrate that phosphorylation of TopBP1 by Akt coincides with cyclin A activation during S and G2 phases and switches the TopBP1-interacting partner from treslin to E2F1, which results in the termination of replication initiation. Premature activation of Akt in G1 phase causes an early switch and inhibits DNA replication. TopBP1 is often overexpressed in cancer and can bypass control by Cdk2 to interact with treslin, leading to enhanced DNA replication. Consistent with this notion, reducing the levels of TopBP1 in cancer cells restores sensitivity to a Cdk2 inhibitor. Together, our study links Cdk2 and Akt pathways to the control of DNA replication through the regulation of TopBP1-treslin interaction. These data also suggest an important role for TopBP1 in driving abnormal DNA replication in cancer.

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