scholarly journals Limiting DNA polymerase delta alters replication dynamics and leads to a dependence on checkpoint activation and recombination-mediated DNA repair

PLoS Genetics ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. e1009322
Author(s):  
Natasha C. Koussa ◽  
Duncan J. Smith
Keyword(s):  
Dna Polymerase ◽  
Genome Instability ◽  
Dna Polymerase Delta ◽  
Origin Firing ◽  
Checkpoint Signaling ◽  
A Genome ◽  
Dna Replication And Repair ◽  
The Impact ◽  
Lagging Strand

DNA polymerase delta (Pol δ) plays several essential roles in eukaryotic DNA replication and repair. At the replication fork, Pol δ is responsible for the synthesis and processing of the lagging-strand. At replication origins, Pol δ has been proposed to initiate leading-strand synthesis by extending the first Okazaki fragment. Destabilizing mutations in human Pol δ subunits cause replication stress and syndromic immunodeficiency. Analogously, reduced levels of Pol δ in Saccharomyces cerevisiae lead to pervasive genome instability. Here, we analyze how the depletion of Pol δ impacts replication origin firing and lagging-strand synthesis during replication elongation in vivo in S. cerevisiae. By analyzing nascent lagging-strand products, we observe a genome-wide change in both the establishment and progression of replication. S-phase progression is slowed in Pol δ depletion, with both globally reduced origin firing and slower replication progression. We find that no polymerase other than Pol δ is capable of synthesizing a substantial amount of lagging-strand DNA, even when Pol δ is severely limiting. We also characterize the impact of impaired lagging-strand synthesis on genome integrity and find increased ssDNA and DNA damage when Pol δ is limiting; these defects lead to a strict dependence on checkpoint signaling and resection-mediated repair pathways for cellular viability.

scholarly journals Limiting DNA polymerase delta alters replication dynamics and leads to a dependence on checkpoint activation and recombination-mediated DNA repair

2019 ◽  
Author(s):  
Natasha C Koussa ◽  
Duncan J. Smith
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Genome Instability ◽  
Dna Polymerase Delta ◽  
Origin Firing ◽  
A Genome ◽  
Synthesis And Processing ◽  
The Impact ◽  
Lagging Strand

ABSTRACTDNA polymerase delta (Pol δ) plays several essential roles in eukaryotic DNA replication and repair. At the replication fork, Pol δ is responsible for the synthesis and processing of the lagging-strand. At replication origins, Pol δ has been proposed to initiate leading-strand synthesis by extending the first Okazaki fragment. Destabilizing mutations in human Pol δ subunits cause replication stress and syndromic immunodeficiency. Analogously, reduced levels of Pol δ in Saccharomyces cerevisiae lead to pervasive genome instability. Here, we analyze how the depletion of Pol δ impacts replication origin firing and lagging-strand synthesis during replication elongation in vivo in S. cerevisiae. By analyzing nascent lagging-strand products, we observe a genome-wide change in both the establishment and progression of replication. S-phase progression is slowed in Pol δ depletion, with both globally reduced origin firing and slower replication progression. We find that no polymerase other than Pol δ is capable of synthesizing a substantial amount of lagging-strand DNA, even when Pol δ is severely limiting. We also characterize the impact of impaired lagging-strand synthesis on genome integrity and find increased ssDNA and DNA damage when Pol δ is limiting; these defects lead to a strict dependence on checkpoint signaling and resection-mediated repair pathways for cellular viability.SIGNIFICANCE STATEMENTDNA replication in eukaryotes is carried out by the replisome – a multi-subunit complex comprising the enzymatic activities required to generate two intact daughter DNA strands. DNA polymerase delta (Pol δ) is a multi-functional replisome enzyme responsible for synthesis and processing of the lagging-strand. Mutations in Pol δ cause a variety of human diseases: for example, destabilizing mutations lead to immunodeficiency. We titrate the concentration of Pol δ in budding yeast – a simple model eukaryote with conserved DNA replication machinery. We characterize several replication defects associated with Pol δ scarcity. The defects we observe provide insight into how destabilizing Pol δ mutations lead to genome instability.

scholarly journals Processing of eukaryotic Okazaki fragments by redundant nucleases can be uncoupled from ongoing DNA replicationin vivo

2018 ◽  
Author(s):  
Malik Kahli ◽  
Joseph S. Osmundson ◽  
Rani Yeung ◽  
Duncan J. Smith
Keyword(s):  
Dna Polymerase ◽  
Systematic Evaluation ◽  
Additional Contribution ◽  
Strand Displacement ◽  
Dna Polymerase Delta ◽  
Okazaki Fragment ◽  
Okazaki Fragments ◽  
The Impact ◽  
Lagging Strand

ABSTRACTPrior to ligation, each Okazaki fragment synthesized on the lagging strand in eukaryotes must be nucleolytically processed. Nuclease cleavage takes place in the context of 5’ flap structures generated via strand-displacement synthesis by DNA polymerase delta. At least three DNA nucleases: Rad27 (Fen1), Dna2, and Exo1, have been implicated in processing Okazaki fragment flaps. However, neither the contributions of individual nucleases to lagging-strand synthesis nor the structure of the DNA intermediates formed in their absence have been clearly definedin vivo.By conditionally depleting lagging-strand nucleases and directly analyzing Okazaki fragments synthesizedin vivoinS. cerevisiae, we conduct a systematic evaluation of the impact of Rad27, Dna2 and Exo1 on lagging-strand synthesis. We find that Rad27 processes the majority of lagging-strand flaps, with a significant additional contribution from Exo1 but not from Dna2. When nuclease cleavage is impaired, we observe a reduction in strand-displacement synthesis as opposed to the widespread generation of long Okazaki fragment 5’ flaps, as predicted by some models. Further, using cell cycle-restricted constructs, we demonstrate that both the nucleolytic processing and the ligation of Okazaki fragments can be uncoupled from DNA replication and delayed until after synthesis of the majority of the genome is complete.

scholarly journals Regulation and Modulation of Human DNA Polymerase δ Activity and Function

2017 ◽  
Author(s):  
Mariettta Y.W.T. Lee ◽  
Xiaoxiao Wang ◽  
Sufang Zhang ◽  
Zhongtao Zhang ◽  
Ernest Y.C. Lee.
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Polymerase ◽  
Dna Polymerase Delta ◽  
Cellular Functions ◽  
Human Dna ◽  
Delta Activity ◽  
Dna Replication And Repair ◽  
And Function ◽  
The Impact

This review focuses on the regulation and modulation of human DNA polymerase δ (Pol δ). The emphasis is on mechanisms that regulate the activity and properties of Pol δ in DNA repair and replication. The areas covered are the degradation of the p12 subunit of Pol δ, which converts it from a heterotetramer (Pol δ4) to a heterotrimer (Pol δ3), in response to DNA damage and also during the cell cycle. The biochemical mechanisms that lead to degradation of p12 are reviewed, as well as the properties of Pol δ4 and Pol δ3 that provide insights into their functions in DNA replication and repair. The second focus of the review involves the functions of two Pol δ binding proteins, PDIP46 and PDIP38, both of which are multi-functional proteins. PDIP46 is a novel activator of Pol δ4, and the impact of this function is discussed in relation to its potential roles in DNA replication. Several new models for the roles of Pol δ3 and Pol δ4 in leading and lagging strand DNA synthesis that integrate a role for PDIP46 are presented. PDIP38 has multiple cellular localizations including the mitochondria, the splicesosomes and the nucleus. It has been implicated in a number of cellular functions, including the regulation of specialized DNA polymerases, mitosis, the DNA damage response, Mdm2 alternative splicing and the regulation of the Nox4 NADPH oxidase.

Involvement of proliferating cell nuclear antigen (cyclin) in DNA replication in living cells

1989 ◽  
Vol 9 (1) ◽  
pp. 57-66
Author(s):  
M Zuber ◽  
E M Tan ◽  
M Ryoji
Keyword(s):  
Dna Polymerase ◽  
Proliferating Cell Nuclear Antigen ◽  
Living Cells ◽  
Nuclear Antigen ◽  
Plasmid Replication ◽  
Dna Polymerase Delta ◽  
Dna Polymerase Alpha ◽  
Proliferating Cell

Proliferating cell nuclear antigen (PCNA) (also called cyclin) is known to stimulate the activity of DNA polymerase delta but not the other DNA polymerases in vitro. We injected a human autoimmune antibody against PCNA into unfertilized eggs of Xenopus laevis and examined the effects of this antibody on the replication of injected plasmid DNA as well as egg chromosomes. The anti-PCNA antibody inhibited plasmid replication by up to 67%, demonstrating that PCNA is involved in plasmid replication in living cells. This result further implies that DNA polymerase delta is necessary for plasmid replication in vivo. Anti-PCNA antibody alone did not block plasmid replication completely, but the residual replication was abolished by coinjection of a monoclonal antibody against DNA polymerase alpha. Anti-DNA polymerase alpha alone inhibited plasmid replication by 63%. Thus, DNA polymerase alpha is also required for plasmid replication in this system. In similar studies on the replication of egg chromosomes, the inhibition by anti-PCNA antibody was only 30%, while anti-DNA polymerase alpha antibody blocked 73% of replication. We concluded that the replication machineries of chromosomes and plasmid differ in their relative content of DNA polymerase delta. In addition, we obtained evidence through the use of phenylbutyl deoxyguanosine, an inhibitor of DNA polymerase alpha, that the structure of DNA polymerase alpha holoenzyme for chromosome replication is significantly different from that for plasmid replication.

scholarly journals Ribonucleotide incorporation characteristics around yeast autonomously replicating sequences reveal the labor division of replicative DNA polymerases

2020 ◽  
Author(s):  
Penghao Xu ◽  
Francesca Storici
Keyword(s):  
Dna Polymerase ◽  
Genome Instability ◽  
Dna Polymerases ◽  
Yeast Cells ◽  
Yeast Genome ◽  
Wild Type ◽  
Specific Sequence ◽  
Leading Strand ◽  
Mapping Techniques ◽  
Lagging Strand

ABSTRACTRibonucleoside monophosphate (rNMP) incorporation in DNA is a natural and prominent phenomenon resulting in DNA structural change and genome instability. While DNA polymerases have different rNMP incorporation rates, little is known whether these enzymes incorporate rNMPs following specific sequence patterns. In this study, we analyzed a series of rNMP incorporation datasets, generated from three rNMP mapping techniques, and obtained from Saccharomyces cerevisiae cells expressing wild-type or mutant replicative DNA polymerase and ribonuclease H2 genes. We performed computational analyses of rNMP sites around early and late firing autonomously replicating sequences (ARS’s) of the yeast genome, from which bidirectional, leading and lagging DNA synthesis starts. We find the preference of rNMP incorporation on the leading strand in wild-type DNA polymerase yeast cells. The leading/lagging-strand ratio of rNMP incorporation changes dramatically within 500 nt from ARS’s, highlighting the Pol δ - Pol ε handoff during early leading-strand synthesis. Furthermore, the pattern of rNMP incorporation is markedly distinct between the leading the lagging strand. Overall, our results show the different counts and patterns of rNMP incorporation during DNA replication from ARS, which reflects the different labor of division and rNMP incorporation pattern of Pol δ and Pol ε.

scholarly journals An in vivo study of the impact of deficiency in the DNA repair proteins PAXX and XLF on development and maturation of the hemolymphoid system

2020 ◽  
Vol 295 (8) ◽  
pp. 2398-2406 ◽  
Author(s):  
Stefania Musilli ◽  
Vincent Abramowski ◽  
Benoit Roch ◽  
Jean-Pierre de Villartay
Keyword(s):  
Class Switch Recombination ◽  
Adaptive Immune System ◽  
Nonhomologous End Joining ◽  
Dna Double Strand Breaks ◽  
Hematopoietic Progenitors ◽  
End Joining ◽  
Class Switch ◽  
A Genome ◽  
The Impact

Repair of DNA double-strand breaks by the nonhomologous end joining pathway is central for proper development of the adaptive immune system. This repair pathway involves eight factors, including XRCC4-like factor (XLF)/Cernunnos and the paralog of XRCC4 and XLF, PAXX nonhomologous end joining factor (PAXX). Xlf−/− and Paxx−/− mice are viable and exhibit only a mild immunophenotype. However, mice lacking both PAXX and XLF are embryonic lethal because postmitotic neurons undergo massive apoptosis in embryos. To decipher the roles of PAXX and XLF in both variable, diversity, and joining recombination and immunoglobulin class switch recombination, here, using Cre/lox-specific deletion to prevent double-KO embryonic lethality, we developed two mouse models of a conditional Xlf KO in a Paxx−/− background. Cre expressed under control of the iVav or CD21 promoter enabled Xlf deletion in early hematopoietic progenitors and splenic mature B cells, respectively. We demonstrate the XLF and PAXX interplay during variable, diversity, and joining recombination in vivo but not during class switch recombination, for which PAXX appeared to be fully dispensable. Xlf/Paxx double KO in hematopoietic progenitors resulted in a shorter lifespan associated with onset of thymic lymphomas, revealing a genome caretaking function of XLF/PAXX.

Prokaryotic DNA replication mechanisms

1987 ◽  
Vol 317 (1187) ◽  
pp. 395-420 ◽  
Keyword(s):  
Dna Replication ◽  
Dna Polymerase ◽  
Replication Fork ◽  
Kinetic Studies ◽  
Dna Helicase ◽  
Gene 32 ◽  
Dna Template ◽  
Lagging Strand

The three different prokaryotic replication systems that have been most extensively studied use the same basic components for moving a DNA replication fork, even though the individual proteins are different and lack extensive amino acid sequence homology. In the T4 bacteriophage system, the components of the DNA replication complex can be grouped into functional classes as follows: DNA polymerase (gene 43 protein), helix-destabilizing protein (gene 32 protein), polymerase accessory proteins (gene 44/62 and 45 proteins), and primosome proteins (gene 41 DNA helicase and gene 61 RNA primase). DNA synthesis in the in vitro system starts by covalent addition onto the 3'OH end at a random nick on a double-stranded DNA template and proceeds to generate a replication fork that moves at about the in vivo rate, and with approximately the in vivo base-pairing fidelity. DNA is synthesized at the fork in a continuous fashion on the leading strand and in a discontinuous fashion on the lagging strand (generating short Okazaki fragments with 5'-linked pppApCpXpYpZ pentaribonucleotide primers). Kinetic studies reveal that the DNA polymerase molecule on the lagging strand stays associated with the fork as it moves. Therefore the DNA template on the lagging strand must be folded so that the stop site for the synthesis of one Okazaki fragment is adjacent to the start site for the next such fragment, allowing the polymerase and other replication proteins on the lagging strand to recycle.

scholarly journals PrimPol is required for replication reinitiation after mtDNA damage

2017 ◽  
Vol 114 (43) ◽  
pp. 11398-11403 ◽  
Author(s):  
Rubén Torregrosa-Muñumer ◽  
Josefin M. E. Forslund ◽  
Steffi Goffart ◽  
Annika Pfeiffer ◽  
Gorazd Stojkovič ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Translesion Synthesis ◽  
Replication Forks ◽  
Mtdna Damage ◽  
Replicative Stress ◽  
Mtdna Replication ◽  
Stalled Replication Forks ◽  
Lagging Strand

Eukaryotic PrimPol is a recently discovered DNA-dependent DNA primase and translesion synthesis DNA polymerase found in the nucleus and mitochondria. Although PrimPol has been shown to be required for repriming of stalled replication forks in the nucleus, its role in mitochondria has remained unresolved. Here we demonstrate in vivo and in vitro that PrimPol can reinitiate stalled mtDNA replication and can prime mtDNA replication from nonconventional origins. Our results not only help in the understanding of how mitochondria cope with replicative stress but can also explain some controversial features of the lagging-strand replication.

scholarly journals Phosphate steering by Flap Endonuclease 1 promotes 5′-flap specificity and incision to prevent genome instability

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Susan E. Tsutakawa ◽  
Mark J. Thompson ◽  
Andrew S. Arvai ◽  
Alexander J. Neil ◽  
Steven J. Shaw ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Large Scale ◽  
Genome Instability ◽  
Flap Endonuclease 1 ◽  
Fold Reduction ◽  
Dna Replication And Repair ◽  
Switch Mechanism ◽  
Template Switch

Abstract DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5′-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5′-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5′polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via ‘phosphate steering’, basic residues energetically steer an inverted ss 5′-flap through a gateway over FEN1’s active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (GAA)n repeat expansions in vivo, implying failed phosphate-steering promotes an unanticipated lagging-strand template-switch mechanism during replication. Thus, phosphate steering is an unappreciated FEN1 function that enforces 5′-flap specificity and catalysis, preventing genomic instability.

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