scholarly journals Role of the Escherichia coli RecQ DNA helicase in SOS signaling and genome stabilization at stalled replication forks

2004 ◽  
Vol 18 (15) ◽  
pp. 1886-1897 ◽  
Author(s):  
T. Hishida
Keyword(s):  
Escherichia Coli ◽  
Dna Helicase ◽  
Replication Forks ◽  
Stalled Replication Forks ◽  
Genome Stabilization

scholarly journals The epigenetic regulator LSH maintains fork protection and genomic stability via MacroH2A deposition and RAD51 filament formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaoping Xu ◽  
Kai Ni ◽  
Yafeng He ◽  
Jianke Ren ◽  
Chongkui Sun ◽  
...  
Keyword(s):  
Chromatin Remodeling ◽  
Critical Role ◽  
Genomic Stability ◽  
Dna Degradation ◽  
Replication Forks ◽  
Filament Formation ◽  
Epigenetic Regulator ◽  
Centromeric Instability ◽  
Stalled Replication Forks

AbstractThe Immunodeficiency Centromeric Instability Facial Anomalies (ICF) 4 syndrome is caused by mutations in LSH/HELLS, a chromatin remodeler promoting incorporation of histone variant macroH2A. Here, we demonstrate that LSH depletion results in degradation of nascent DNA at stalled replication forks and the generation of genomic instability. The protection of stalled forks is mediated by macroH2A, whose knockdown mimics LSH depletion and whose overexpression rescues nascent DNA degradation. LSH or macroH2A deficiency leads to an impairment of RAD51 loading, a factor that prevents MRE11 and EXO1 mediated nascent DNA degradation. The defect in RAD51 loading is linked to a disbalance of BRCA1 and 53BP1 accumulation at stalled forks. This is associated with perturbed histone modifications, including abnormal H4K20 methylation that is critical for BRCA1 enrichment and 53BP1 exclusion. Altogether, our results illuminate the mechanism underlying a human syndrome and reveal a critical role of LSH mediated chromatin remodeling in genomic stability.

scholarly journals Interactions and Localization of Escherichia coli Error-Prone DNA Polymerase IV after DNA Damage

2015 ◽  
Vol 197 (17) ◽  
pp. 2792-2809 ◽  
Author(s):  
Sarita Mallik ◽  
Ellen M. Popodi ◽  
Andrew J. Hanson ◽  
Patricia L. Foster
Keyword(s):  
Dna Damage ◽  
Dna Polymerase ◽  
Dna Helicase ◽  
Dna Lesions ◽  
Replication Forks ◽  
Content Type ◽  
Pol Iv ◽  
Dna Polymerase Iv ◽  
Stalled Replication Forks

ABSTRACTEscherichia coli's DNA polymerase IV (Pol IV/DinB), a member of the Y family of error-prone polymerases, is induced during the SOS response to DNA damage and is responsible for translesion bypass and adaptive (stress-induced) mutation. In this study, the localization of Pol IV after DNA damage was followed using fluorescent fusions. After exposure ofE. colito DNA-damaging agents, fluorescently tagged Pol IV localized to the nucleoid as foci. Stepwise photobleaching indicated ∼60% of the foci consisted of three Pol IV molecules, while ∼40% consisted of six Pol IV molecules. Fluorescently tagged Rep, a replication accessory DNA helicase, was recruited to the Pol IV foci after DNA damage, suggesting that thein vitrointeraction between Rep and Pol IV reported previously also occursin vivo. Fluorescently tagged RecA also formed foci after DNA damage, and Pol IV localized to them. To investigate if Pol IV localizes to double-strand breaks (DSBs), an I-SceI endonuclease-mediated DSB was introduced close to a fluorescently labeled LacO array on the chromosome. After DSB induction, Pol IV localized to the DSB site in ∼70% of SOS-induced cells. RecA also formed foci at the DSB sites, and Pol IV localized to the RecA foci. These results suggest that Pol IV interacts with RecAin vivoand is recruited to sites of DSBs to aid in the restoration of DNA replication.IMPORTANCEDNA polymerase IV (Pol IV/DinB) is an error-prone DNA polymerase capable of bypassing DNA lesions and aiding in the restart of stalled replication forks. In this work, we demonstratein vivolocalization of fluorescently tagged Pol IV to the nucleoid after DNA damage and to DNA double-strand breaks. We show colocalization of Pol IV with two proteins: Rep DNA helicase, which participates in replication, and RecA, which catalyzes recombinational repair of stalled replication forks. Time course experiments suggest that Pol IV recruits Rep and that RecA recruits Pol IV. These findings providein vivoevidence that Pol IV aids in maintaining genomic stability not only by bypassing DNA lesions but also by participating in the restoration of stalled replication forks.

scholarly journals A Critical Role of the 3′ Terminus of Nascent DNA Chains in Recognition of Stalled Replication Forks

2003 ◽  
Vol 278 (43) ◽  
pp. 42234-42239 ◽  
Author(s):  
Toshimi Mizukoshi ◽  
Taku Tanaka ◽  
Ken-ichi Arai ◽  
Daisuke Kohda ◽  
Hisao Masai
Keyword(s):  
Critical Role ◽  
Replication Forks ◽  
Stalled Replication Forks

scholarly journals DisA limits RecA- and RadA/Sms-mediated replication fork remodelling to prevent genome instability

2020 ◽  
Author(s):  
Rubén Torres ◽  
Juan C. Alonso
Keyword(s):  
Genome Instability ◽  
Dna Helicase ◽  
Template Switching ◽  
Replication Forks ◽  
Lesion Bypass ◽  
Branched Dna ◽  
Subject Categories ◽  
Negative Effect ◽  
Dna Replication Stress ◽  
Stalled Replication Forks

AbstractThe DisA diadenylate cyclase (DAC), the DNA helicase RadA/Sms and the RecA recombinase are required to prevent a DNA replication stress during the revival of haploid Bacillus subtilis spores. Moreover, disA, radA and recA are epistatic among them in response to DNA damage. We show that DisA inhibits the ATPase activity of RadA/Sms C13A by competing for single-stranded (ss) DNA. In addition, DisA inhibits the helicase activity of RadA/Sms. RecA filamented onto ssDNA interacts with and recruits DisA and RadA/Sms onto branched DNA intermediates. In fact, RecA binds a reversed fork and facilitates RadA/Sms-mediated unwinding to restore a 3′-fork intermediate, but DisA inhibits it. Finally, RadA/Sms inhibits DisA DAC activity, but RecA counters this negative effect. We propose that RecA, DisA and RadA/Sms interactions, which are mutually exclusive, limit remodelling of stalled replication forks. DisA, in concert with RecA and/or RadA/Sms, indirectly contributes to template switching or lesion bypass, prevents fork breakage and facilitates the recovery of c-di-AMP levels to re-initiate cell proliferation.Subject CategoriesGenomic stability & Dynamics

scholarly journals The RecQ DNA helicase Rqh1 constrains Exonuclease 1-dependent recombination at stalled replication forks

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Fekret Osman ◽  
Jong Sook Ahn ◽  
Alexander Lorenz ◽  
Matthew C. Whitby
Keyword(s):  
Dna Helicase ◽  
Replication Forks ◽  
Exonuclease 1 ◽  
Stalled Replication Forks

scholarly journals Escherichia coli Cells with Increased Levels of DnaA and Deficient in Recombinational Repair Have Decreased Viability

2003 ◽  
Vol 185 (2) ◽  
pp. 630-644 ◽  
Author(s):  
Aline V. Grigorian ◽  
Rachel B. Lustig ◽  
Elena C. Guzmán ◽  
Joseph M. Mahaffy ◽  
Judith W. Zyskind
Keyword(s):  
Escherichia Coli ◽  
Dna Polymerase ◽  
Replication Fork ◽  
Replication Initiation ◽  
Recombinational Repair ◽  
Replication Forks ◽  
Dna Replication Initiation ◽  
Escherichia Coli Cells ◽  
Repair Pathways ◽  
Stalled Replication Forks

ABSTRACT The dnaA operon of Escherichia coli contains the genes dnaA, dnaN, and recF encoding DnaA, β clamp of DNA polymerase III holoenzyme, and RecF. When the DnaA concentration is raised, an increase in the number of DNA replication initiation events but a reduction in replication fork velocity occurs. Because DnaA is autoregulated, these results might be due to the inhibition of dnaN and recF expression. To test this, we examined the effects of increasing the intracellular concentrations of DnaA, β clamp, and RecF, together and separately, on initiation, the rate of fork movement, and cell viability. The increased expression of one or more of the dnaA operon proteins had detrimental effects on the cell, except in the case of RecF expression. A shorter C period was not observed with increased expression of the β clamp; in fact, many chromosomes did not complete replication in runout experiments. Increased expression of DnaA alone resulted in stalled replication forks, filamentation, and a decrease in viability. When the three proteins of the dnaA operon were simultaneously overexpressed, highly filamentous cells were observed (>50 μm) with extremely low viability and, in runout experiments, most chromosomes had not completed replication. The possibility that recombinational repair was responsible for the survival of cells overexpressing DnaA was tested by using mutants in different recombinational repair pathways. The absence of RecA, RecB, RecC, or the proteins in the RuvABC complex caused an additional ∼100-fold drop in viability in cells with increased levels of DnaA, indicating a requirement for recombinational repair in these cells.

scholarly journals Regulation of Rtt107 Recruitment to Stalled DNA Replication Forks by the Cullin Rtt101 and the Rtt109 Acetyltransferase

2008 ◽  
Vol 19 (1) ◽  
pp. 171-180 ◽  
Author(s):  
Tania M. Roberts ◽  
Iram Waris Zaidi ◽  
Jessica A. Vaisica ◽  
Matthias Peter ◽  
Grant W. Brown
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Replication Forks ◽  
Chromatin Binding ◽  
Direct Role ◽  
Repair Enzymes ◽  
Damage Response ◽  
Stalled Replication Forks

RTT107 (ESC4, YHR154W) encodes a BRCA1 C-terminal domain protein that is important for recovery from DNA damage during S phase. Rtt107 is a substrate of the checkpoint kinase Mec1, and it forms complexes with DNA repair enzymes, including the nuclease subunit Slx4, but the role of Rtt107 in the DNA damage response remains unclear. We find that Rtt107 interacts with chromatin when cells are treated with compounds that cause replication forks to arrest. This damage-dependent chromatin binding requires the acetyltransferase Rtt109, but it does not require acetylation of the known Rtt109 target, histone H3-K56. Chromatin binding of Rtt107 also requires the cullin Rtt101, which seems to play a direct role in Rtt107 recruitment, because the two proteins are found in complex with each other. Finally, we provide evidence that Rtt107 is bound at or near stalled replication forks in vivo. Together, these results indicate that Rtt109, Rtt101, and Rtt107, which genetic evidence suggests are functionally related, form a DNA damage response pathway that recruits Rtt107 complexes to damaged or stalled replication forks.

scholarly journals Double-Strand Break Generation under Deoxyribonucleotide Starvation in Escherichia coli

2007 ◽  
Vol 189 (15) ◽  
pp. 5782-5786 ◽  
Author(s):  
Estrella Guarino ◽  
Israel Salguero ◽  
Alfonso Jiménez-Sánchez ◽  
Elena C. Guzmán
Keyword(s):  
Escherichia Coli ◽  
Replication Fork ◽  
Thermal Inactivation ◽  
Strand Break ◽  
Double Strand Break ◽  
Replication Forks ◽  
Thymine Starvation ◽  
Hydroxyurea Treatment ◽  
Deoxynucleoside Triphosphate ◽  
Stalled Replication Forks

ABSTRACT Stalled replication forks produced by three different ways of depleting deoxynucleoside triphosphate showed different capacities to undergo “replication fork reversal.” This reaction occurred at the stalled forks generated by hydroxyurea treatment, was impaired under thermal inactivation of ribonucleoside reductase, and did not take place under thymine starvation.

scholarly journals RAD51 and mitotic function of mus81 are essential for recovery from low-dose of camptothecin in the absence of the WRN exonuclease

2019 ◽  
Vol 47 (13) ◽  
pp. 6796-6810 ◽  
Author(s):  
Francesca Antonella Aiello ◽  
Anita Palma ◽  
Eva Malacaria ◽  
Li Zheng ◽  
Judith L Campbell ◽  
...  
Keyword(s):  
Topoisomerase I ◽  
Genome Instability ◽  
Genome Integrity ◽  
Replication Forks ◽  
Wild Type ◽  
Alternative Processing ◽  
Mitotic Abnormalities ◽  
Mitotic Phosphorylation ◽  
Stalled Replication Forks

Abstract Stabilization of stalled replication forks prevents excessive fork reversal or degradation, which can undermine genome integrity. The WRN protein is unique among the other human RecQ family members to possess exonuclease activity. However, the biological role of the WRN exonuclease is poorly defined. Recently, the WRN exonuclease has been linked to protection of stalled forks from degradation. Alternative processing of perturbed forks has been associated to chemoresistance of BRCA-deficient cancer cells. Thus, we used WRN exonuclease-deficiency as a model to investigate the fate of perturbed forks undergoing degradation, but in a BRCA wild-type condition. We find that, upon treatment with clinically-relevant nanomolar doses of the Topoisomerase I inhibitor camptothecin, loss of WRN exonuclease stimulates fork inactivation and accumulation of parental gaps, which engages RAD51. Such mechanism affects reinforcement of CHK1 phosphorylation and causes persistence of RAD51 during recovery from treatment. Notably, in WRN exonuclease-deficient cells, persistence of RAD51 correlates with elevated mitotic phosphorylation of MUS81 at Ser87, which is essential to prevent excessive mitotic abnormalities. Altogether, these findings indicate that aberrant fork degradation, in the presence of a wild-type RAD51 axis, stimulates RAD51-mediated post-replicative repair and engagement of the MUS81 complex to limit genome instability and cell death.

scholarly journals Growth Phase Variation in Cell and Nucleoid Morphology in a Bacillus subtilis recAMutant

2001 ◽  
Vol 183 (9) ◽  
pp. 2963-2968 ◽  
Author(s):  
Stephen A. Sciochetti ◽  
Garry W. Blakely ◽  
Patrick J. Piggot
Keyword(s):  
Bacillus Subtilis ◽  
Growth Phase ◽  
Exponential Growth ◽  
Parent Strain ◽  
Phase Variation ◽  
Normal Growth ◽  
Replication Forks ◽  
Diminished Capacity ◽  
Stalled Replication Forks

ABSTRACT The major role of RecA is thought to be in helping repair and restart stalled replication forks. During exponential growth,Bacillus subtilis recA cells exhibited few microscopically observable nucleoid defects. However, the efficiency of plating was about 12% of that of the parent strain. A substantial and additive defect in viability was also seen for addB andrecF mutants, suggesting a role for the corresponding recombination paths during normal growth. Upon entry into stationary phase, a subpopulation (∼15%) of abnormally long cells and nucleoids developed in B. subtilis recA mutants. In addition,recA mutants showed a delay in, and a diminished capacity for, effecting prespore nucleoid condensation.

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