DOCSLIB.ORG

The Incredible Ways of DNA Replication

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Incredible Ways of DNA Replication The Incredible Ways of DNA Replication Professor Michael O’Donnell THE INCREDIBLE WAYS OF DNA REPLICATION For over 30 years, Professor Michael O’Donnell, based at the Rockefeller University in New York, has focused on the mechanisms involved in the duplication of genetic material in cells, a process known as DNA replication. Professor O’Donnell’s work spans from the early 1990s, when his team was the first to discover a ring- shaped protein that encircles DNA and clamps the replication machine to DNA. Most recently, the team has been studying the proteins involved in mammalian DNA replication. The ability to reproduce is one of the In the DNA helix, adenine bases only most fundamental mechanisms needed pair with thymine, and the cytosine by every cell. In order to reproduce, cells bases only pair with guanine. The DNA must be able to make a copy of their polymerase recognises each base along own genetic information and pass it on the template sequence and finds the to the daughter cells. This is known as correct base pair match from a pool DNA replication. of free bases. The replicating machine contains two DNA polymerases, one The genetic material present in for each unzipped strand, resulting in every cell – DNA – is made of two two new duplex copies and providing complementary strands, organised in all the instructions needed for two the classic double helix. Each strand new living cells. Indeed, Dr Arthur is a long chain with four different Kornberg (Stanford University), who was bases, adenine, cytosine, guanine awarded a Nobel Prize in 1959 for the and thymine, and the sequence of discovery of DNA polymerases, provided these bases forms a code needed to postdoctoral training to Dr (now make every protein required for life. Professor) Michael O’Donnell. It is therefore essential that the DNA For Professor O’Donnell, now at the sequence is copied with great precision At first glance, matching two sets of Rockefeller University in New York, this and accuracy. bases may seem an easy process, but creates an interesting conundrum: How when you take into account that it can the DNA polymerase stay bound The DNA helix is duplicated by many needs to be repeated 6 billion times to to DNA and accurately replicate DNA proteins that work together as a make a new copy of DNA in a human while at the same time move along machine. One protein, called a helicase, cell, then it is inevitable that mistakes the new strand at a relatively high unzips the two strands of the double can happen and must be minimised. speed? ‘It seems a contradiction, that helix. This is where an enzyme called This susceptibility to error may suggest a DNA polymerase could achieve an DNA polymerase comes in. DNA the need for a slow and careful enzyme, extremely tight grip to DNA, yet move polymerase works by using each strand but surprisingly DNA polymerases are very fast during synthesis,’ explains as a template to make a new strand, quite fast and in bacteria can go 1000 Professor O’Donnell. ‘The finding resulting in a new copy of the double bases every single second. came as a complete surprise, which is helix. actually quite typical of most scientific discoveries. This puzzle has a beautiful solution.’ WWW.SCIENTIA.GLOBAL ‘The finding came as a complete surprise, which is actually quite typical of most scientific discoveries. This puzzle has a beautiful solution.’ Eukaryotic PCNA Bacterial ẞ Gulbis, Kelman, O’Donnell and Kuriyan Kong, Onrust, O’Donnell and Kuriyan (1996) Cell 87, 297-306. (1992) Cell 69, 425-437 Human (left) and Bacterial Clamps (right). Credit Michael O’Donnell. It’s a Doughnut! special DNA cutting enzyme, the protein Exploring Ways to Load the Clamp did not stay on the cut DNA, implying it The first clue came quite unexpectedly was sliding off the new and unblocked Professor O’Donnell very quickly in the early 1990s. Professor O’Donnell DNA end. Professor O’Donnell proposed realised that the clamp can’t get onto had started a set of experiments with the circular structure of the protein and DNA by itself, but it needs a ‘clamp circular DNA (typical of bacteria) but named the protein a ‘sliding clamp’. loader’ to open the clamp and then ran out of this half-way through his close the ring around DNA. In fact, their experiments and decided to try linear Many scientists did not accept the studies identified that a five-protein DNA instead. This lucky decision would interpretation of a ring protein, so machine was needed to put the clamp turn out to be key in solving the mystery. Professor O’Donnell enlisted the help of onto DNA. But understanding the clamp ‘I ran out of circular DNA, but there was Professor John Kuriyan at Rockefeller loader mechanism proved more difficult a linear DNA in the freezer so I tried this University, a world-leading expert to achieve. ‘I used to think that each instead,’ said Professor O’Donnell. ‘To in X-ray crystallography (a method of the five different clamp loader units my dismay, the protein did not bind the to determine the atomic structure must have one function, and therefore linear DNA. I tried it again, thinking I′d of a protein) to determine the exact there must be five functional steps made a mistake, but still the protein did structure of this enigmatic protein. to the clamp loading process. This not bind the linear DNA.’ ‘When John called me up to take a way of thinking did make progress in look at the results, I′ll never forget his understanding clamp loader function, Professor O’Donnell realised that the words “Mike – you wanted a doughnut, but…in the end, it was the wrong way simplest explanation was that the and we give you a doughnut,”’ joked to think about the clamp loader,’ says protein is also a circle, and encircles Professor O’Donnell. ‘Indeed, it was a Professor O’Donnell. the DNA, and therefore slides off the ring, but never would I have expected end of linear DNA but stays on circular it to look so very beautiful.’ It turned Eventually, the team realised the DNA because it has no ends from which out the sliding clamp protein has a clamp loader cannot be thought of as to slide off. The researcher knew this wonderful structure, built from two separate components with separate was a crazy idea at first because there subunits, each having three identically functions, but as a single multi- were no other proteins known to do shaped domains that together formed a component machine that opens and this. Professor O’Donnell confirmed this beautiful six domain circle. closes the clamp. Professor O’Donnell’s provocative idea when linear DNA with biochemical studies, in collaboration blocks at the ends behaved the same with Professor Kuriyan’s structural work, way as circular DNA, but when the end- revealed a beautifully orchestrated blocked DNA was cut in two pieces by a mechanism in which the clamp loader WWW.SCIENTIA.GLOBAL A Broader Research Focus After solving the clamp mystery, Professor O’Donnell’s research interests expanded to include not only the clamp/clamp loader but also all the components involved in DNA replication, in both eukaryotic cells (like mammals) and bacteria. After a painstakingly slow and complex process, the team was the first to purify and reconstitute a functional eukaryotic replication machine involving 31 different proteins with each component individually cloned and purified. The team knows this is only the first step and there remains binds to the enzyme, warping the clamp in such a way that a long road ahead of them, along with the work of many the ring opens up, allowing DNA to enter into the centre. Once other laboratories, to fully understand DNA replication. They the DNA is inside, the clamp loader changes its conformation, may not know exact details yet, but they have no doubts this allowing the clamp to close. will be a highly regulated and complex mechanism. After all, these proteins must be able to cope with errors during Moving to Mammals replications as well as orchestrate numerous encounters with multiple enzymes and unrelated proteins. Professor At the same time as this work in bacteria was being carried out, O’Donnell is very excited about this field, stating ‘Many labs several research groups were also working on a mammalian worldwide work on this complex replication machinery, and system to study replication. Among the proteins identified, we look forward to all of our labs contributing pieces of the there were two that caught Professor O’Donnell’s attention: one puzzle that finally, someday, understand the whole picture. called PCNA and one called RFC. ‘John Kuriyan and I proposed It is important to human health and disease, because when that PCNA would be a ring of six domains arranged on three gone awry, the process makes mistakes that can cause cancer. subunits and that RFC would be a clamp loader.’ So, understanding exactly how it works will shed light on new medical applications to help people.’ In continued collaboration with Professor Kuriyan, Professor O’Donnell’s team showed that the bacterial and mammalian Professor O’Donnell adds, ‘the mammalian system is much clamp and clamp loader have a strikingly similar structure. more complicated than viral or bacterial systems and very ‘The nearly identical structure of human and bacterial sliding little is presently known about how its functions. Many of its clamps supports the hypothesis that humans and bacteria components are present to regulate the replication machinery, evolved from a common ancestor cell that lived billions of or simply known to be important for replication through years ago.
Load more

Recommended publications
  • Introduction of Human Telomerase Reverse Transcriptase to Normal Human Fibroblasts Enhances DNA Repair Capacity
    Vol. 10, 2551–2560, April 1, 2004 Clinical Cancer Research 2551 Introduction of Human Telomerase Reverse Transcriptase to Normal Human Fibroblasts Enhances DNA Repair Capacity Ki-Hyuk Shin,1 Mo K. Kang,1 Erica Dicterow,1 INTRODUCTION Ayako Kameta,1 Marcel A. Baluda,1 and Telomerase, which consists of the catalytic protein subunit, No-Hee Park1,2 human telomerase reverse transcriptase (hTERT), the RNA component of telomerase (hTR), and several associated pro- 1School of Dentistry and 2Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California teins, has been primarily associated with maintaining the integ- rity of cellular DNA telomeres in normal cells (1, 2). Telomer- ase activity is correlated with the expression of hTERT, but not ABSTRACT with that of hTR (3, 4). Purpose: From numerous reports on proteins involved The involvement of DNA repair proteins in telomere main- in DNA repair and telomere maintenance that physically tenance has been well documented (5–8). In eukaryotic cells, associate with human telomerase reverse transcriptase nonhomologous end-joining requires a DNA ligase and the (hTERT), we inferred that hTERT/telomerase might play a DNA-activated protein kinase, which is recruited to the DNA role in DNA repair. We investigated this possibility in nor- ends by the DNA-binding protein Ku. Ku binds to hTERT mal human oral fibroblasts (NHOF) with and without ec- without the need for telomeric DNA or hTR (9), binds the topic expression of hTERT/telomerase. telomere repeat-binding proteins TRF1 (10) and TRF2 (11), and Experimental Design: To study the effect of hTERT/ is thought to regulate the access of telomerase to telomere DNA telomerase on DNA repair, we examined the mutation fre- ends (12, 13).
    [Show full text]
  • T-Loops and the Origin of Telomeres E
    PERSPECTIVES 66. Steinman, R. M., Mellman, I. S., Muller, W. A. & Cohn, Z. A. Acknowledgments eukaryotes evolved. The presence of t-loops at Endocytosis and the recycling of plasma membrane. H.S. is supported by the Norwegian Cancer Society and the J. Cell Biol. 96, 1–27 (1983). Research Council of Norway, and J.G. by the Swiss National present-day telomeres and their association 67. Lafont, F., Lecat, S., Verkade, P. & Simons, K. Annexin Science Foundation and the Human Frontier Science Programme with proteins that have evolved from RDR XIIIb associates with lipid microdomains to function in Organization. apical delivery. J. Cell Biol. 142, 1413–1427 (1998). factors might be remnants of the original 68. Aniento, F., Gu, F., Parton, R. & Gruenberg, J. Competing interests statement telomere system. Furthermore, the relative An endosomal βcop is involved in the pH-dependent The authors declare that they have no competing financial interests. formation of transport vesicles destined for late ease with which many eukaryotes can main- endosomes. J. Cell Biol. 133, 29–41 (1996). tain telomeres without telomerase might 69. Gu, F., Aniento, F., Parton, R. & Gruenberg, J. Functional Online links dissection of COP-I subunits in the biogenesis of reflect this ancient system of chromosome-end multivesicular endosomes. J. Cell Biol. 139, 1183–1195 DATABASES replication. This proposal ends with a dis- (1997). The following terms in this article are linked online to: 70. Gu, F. & Gruenberg, J. ARF1 regulates pH-dependent Interpro: http://www.ebi.ac.uk/interpro/ cussion of the advantages of the telom- COP functions in the early endocytic pathway.
    [Show full text]
  • Telomeres.Pdf
    Telomeres Secondary article Elizabeth H Blackburn, University of California, San Francisco, California, USA Article Contents . Introduction Telomeres are specialized DNA–protein structures that occur at the ends of eukaryotic . The Replication Paradox chromosomes. A special ribonucleoprotein enzyme called telomerase is required for the . Structure of Telomeres synthesis and maintenance of telomeric DNA. Synthesis of Telomeric DNA by Telomerase . Functions of Telomeres Introduction . Telomere Homeostasis . Alternatives to Telomerase-generated Telomeric DNA Telomeres are the specialized chromosomal DNA–protein . Evolution of Telomeres and Telomerase structures that comprise the terminal regions of eukaryotic chromosomes. As discovered through studies of maize and somes. One critical part of this protective function is to fruitfly chromosomes in the 1930s, they are required to provide a means by which the linear chromosomal DNA protect and stabilize the genetic material carried by can be replicated completely, without the loss of terminal eukaryotic chromosomes. Telomeres are dynamic struc- DNA nucleotides from the 5’ end of each strand of this tures, with their terminal DNA being constantly built up DNA. This is necessary to prevent progressive loss of and degraded as dividing cells replicate their chromo- terminal DNA sequences in successive cycles of chromo- somes. One strand of the telomeric DNA is synthesized by somal replication. a specialized ribonucleoprotein reverse transcriptase called telomerase. Telomerase is required for both
    [Show full text]
  • DNA Replication
    9 DNA Replication To understand the chemistry Living cells must be able to duplicate their entire set of genetic instructions Goal of DNA synthesis and how every time they divide. Likewise, multicellular organisms must be able to DNA is replicated with high pass on complete copies of their genetic information to future generations. accuracy. This requires that the instructions are stored in a form that is capable of Objectives being duplicated. As we have seen (and will return to in Chapter 11), genetic instructions are embedded in the order of nucleobases in the DNA. As we After this chapter, you should be able to have also seen, the self-complementary nature of the double helix provides • describe the experiment that proved a simple (in principle) templating mechanism for replicating DNA into two that DNA replication is semi- identical copies. Only DNA (and in some instances RNA when, as in the conservative. case of the genomes of RNA viruses, it is used as a repository of genetic • diagram the reaction for information) are self-complementary and hence capable of being replicated. phosphodiester bond formation. The other three categories of macromolecules—carbohydrates, lipids, and • explain the energetics of DNA proteins—are not self-complementary and do not serve as templates for synthesis. their own production. Instead, the synthesis of these macromolecules is • explain why the 5’-to-3’ rule creates a ultimately directed by information stored in DNA through the action of conundrum during replication. enzymes and other proteins. Here we focus on the chemical and enzymatic • explain how DNA is replicated mechanisms by which DNA acts as a template for its own duplication and accurately.
    [Show full text]
  • Getting Ready for DNA Duplication
    INSIGHT INTRACELLULAR ORGANIZATION Getting ready for DNA duplication The discovery of a biomolecular condensate involved in DNA replication has wide-ranging implications. NINA Y YAO AND MICHAEL E O’DONNELL involves regions with different physical proper- Related research article Parker MW, Bell ties separating from each other). The molecules M, Mir M, Kao JA, Darzacq X, Botchan MR, required for the formation of condensates are Berger JM. 2019. A new class of disordered called scaffolding factors, while the molecules elements controls DNA replication through encapsulated inside are known as clients. A initiator self-assembly. eLife 8:e48562. DOI: given condensate typically contains only those 10.7554/eLife.48562 clients involved in the relevant reaction. Now, in eLife, Michael Botchan (UC Berkeley), James Berger (Johns Hopkins) and colleagues – including Matthew Parker as first author – report on the discovery of a biomolecular condensate esearch into biomolecular condensates – required for the initiation of DNA replication in self-contained regions within cells where the fruit fly Drosophila melanogaster R specific reactions take place – is taking (Parker et al., 2019). Three proteins – ORC, cell biology by storm. Biomolecular condensates Cdc6 and Cdt1 – form the scaffold along with do not have membranes, but they are able to DNA, while a hexamer ring protein called keep the proteins and/or nucleic acids involved Mcm2-7 is the client. During the G1 phase of the in a particular reaction separate from the rest of cell cycle, the scaffold proteins load two Mcm2- the cell. Biomolecular condensates do not have 7 hexamers onto the DNA to form the pre-repli- membranes, but they are able to keep the mole- cative complex, which marks the spot where cules involved in a particular reaction (usually DNA replication will begin (Figure 1A–C; proteins, but sometimes also nucleic acids) sepa- Bell and Labib, 2016; Bleichert et al., 2017).
    [Show full text]
  • Telomere and Telomerase in Oncology
    Cell Research (2002); 12(1):1-7 http://www.cell-research.com REVIEW Telomere and telomerase in oncology JIAO MU*, LI XIN WEI International Joint Cancer Institute, Second Military Medical University, Shanghai 200433, China ABSTRACT Shortening of the telomeric DNA at the chromosome ends is presumed to limit the lifespan of human cells and elicit a signal for the onset of cellular senescence. To continually proliferate across the senescent checkpoint, cells must restore and preserve telomere length. This can be achieved by telomerase, which has the reverse transcriptase activity. Telomerase activity is negative in human normal somatic cells but can be detected in most tumor cells. The enzyme is proposed to be an essential factor in cell immortalization and cancer progression. In this review we discuss the structure and function of telomere and telomerase and their roles in cell immortalization and oncogenesis. Simultaneously the experimental studies of telomerase assays for cancer detection and diagnosis are reviewed. Finally, we discuss the potential use of inhibitors of telomerase in anti-cancer therapy. Key words: Telomere, telomerase, cancer, telomerase assay, inhibitor. Telomere and cell replicative senescence base pairs of the end of telomeric DNA with each Telomeres, which are located at the end of round of DNA replication. Hence, the continual chromosome, are crucial to protect chromosome cycles of cell growth and division bring on progress- against degeneration, rearrangment and end to end ing telomere shortening[4]. Now it is clear that te- fusion[1]. Human telomeres are tandemly repeated lomere shortening is responsible for inducing the units of the hexanucleotide TTAGGG. The estimated senescent phenotype that results from repeated cell length of telomeric DNA varies from 2 to 20 kilo division, but the mechanism how a short telomere base pairs, depending on factors such as tissue type induces the senescence is still unknown.
    [Show full text]
  • Ch 7 -Brock Information Flow in Biological Systems
    Systems Microbiology Monday Oct 2 - Ch 7 -Brock Information flow in biological systems •• DNADNA replicationreplication •• TranscriptionTranscription •• TranslationTranslation Central Dogma DNA Replication Transcription Images removed due to copyright restrictions. RNA Reverse Transcription Translation Protein Flow of information replication DNA → DNA transcription ↓ RNA translation ↓ protein 5' end ring numbering system for -P-O-C deoxyribose 5’ -C O O 4’ 1’ P O- O 3’ 2’ C ssDNA 3’ end HO In a nucleotide, e.g., adenosine monophosphate (AMP), the base is bonded to a ribose sugar, which has a phosphate in ester linkage to the 5' hydroxyl. NH NH NH2 2 2 adenine N N N N N N N N N N N N H −2 HO O3P O CH CH 5' 2 O 2 O 4' H H 1' H H ribose H 3' 2' H H H OH OH OH OH adenine adenosine adenosine monophosphate (AMP) Nucleic acids have a NH2 backbone of adenine N N alternating Pi & ribose moieties. N NH − N 2 Phosphodiester 5' end O cytosine − 5' O P O CH N linkages form as the 2 O 4' 1' O H H ribose 5' phosphate of one N O H 3' 2' H nucleotide forms an O OH − 5' ester link with the 3' O P O CH 2 O OH of the adjacent O H H ribose nucleotide. H 3' H O OH − O P O (etc) nucleic acid 3' end O H N H O N Guanine Cytosine N H N N N N O H N Backbone Backbone Hydrogen H bond H O H N CH3 N Thymine N H N N Adenine N N Hydrogen O bond Backbone Backbone Figure by MIT OCW.
    [Show full text]
  • Dynamics of DNA Replication in a Eukaryotic Cell
    Dynamics of DNA replication in a eukaryotic cell Thomas Kellya,1 and A. John Callegaria,2 aProgram in Molecular Biology, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Contributed by Thomas Kelly, December 26, 2018 (sent for review October 30, 2018; reviewed by Paul Nurse and Nicholas Rhind) Each genomic locus in a eukaryotic cell has a distinct average time A deeper understanding of the dynamics of eukaryotic DNA of replication during S phase that depends on the spatial and replication will require a quantitative model describing the spatial temporal pattern of replication initiation events. Replication distribution of potential initiation sites and the time course of their timing can affect genomic integrity because late replication is activation during S phase. The fission yeast Schizosaccharomyces associated with an increased mutation rate. For most eukaryotes, pombe represents a useful system for developing such a model the features of the genome that specify the location and timing of because its genome has many characteristics in common with initiation events are unknown. To investigate these features for that of other eukaryotes. Early genetic studies identified seg- Schizosaccharomyces pombe the fission yeast, , we developed an ments of the S. pombe genome, called autonomously replicating integrative model to analyze large single-molecule and global ge- sequence (ars) elements, that function as origins of DNA repli- nomic datasets. The model provides an accurate description of the > S. pombe cation (14). These elements are large ( 1 kb) and rich in A and complex dynamics of DNA replication at high resolution. T residues but do not contain a common sequence motif (15, 16).
    [Show full text]
  • DNA REPLICATION, REPAIR, and RECOMBINATION Figure 5–1 Different Proteins Evolve at Very Different Rates
    5 THE MAINTENANCE OF DNA DNA REPLICATION, SEQUENCES DNA REPLICATION MECHANISMS REPAIR, AND THE INITIATION AND COMPLETION OF DNA REPLICATION IN RECOMBINATION CHROMOSOMES DNA REPAIR GENERAL RECOMBINATION SITE-SPECIFIC RECOMBINATION The ability of cells to maintain a high degree of order in a chaotic universe depends upon the accurate duplication of vast quantities of genetic information carried in chemical form as DNA. This process, called DNA replication, must occur before a cell can produce two genetically identical daughter cells. Main- taining order also requires the continued surveillance and repair of this genetic information because DNA inside cells is repeatedly damaged by chemicals and radiation from the environment, as well as by thermal accidents and reactive molecules. In this chapter we describe the protein machines that replicate and repair the cell’s DNA. These machines catalyze some of the most rapid and accu- rate processes that take place within cells, and their mechanisms clearly demon- strate the elegance and efficiency of cellular chemistry. While the short-term survival of a cell can depend on preventing changes in its DNA, the long-term survival of a species requires that DNA sequences be changeable over many generations. Despite the great efforts that cells make to protect their DNA, occasional changes in DNA sequences do occur. Over time, these changes provide the genetic variation upon which selection pressures act during the evolution of organisms. We begin this chapter with a brief discussion of the changes that occur in DNA as it is passed down from generation to generation. Next, we discuss the cellular mechanisms—DNA replication and DNA repair—that are responsible for keeping these changes to a minimum.
    [Show full text]
  • Cell Life Cycle and Reproduction the Cell Cycle (Cell-Division Cycle), Is a Series of Events That Take Place in a Cell Leading to Its Division and Duplication
    Cell Life Cycle and Reproduction The cell cycle (cell-division cycle), is a series of events that take place in a cell leading to its division and duplication. The main phases of the cell cycle are interphase, nuclear division, and cytokinesis. Cell division produces two daughter cells. In cells without a nucleus (prokaryotic), the cell cycle occurs via binary fission. Interphase Gap1(G1)- Cells increase in size. The G1checkpointcontrol mechanism ensures that everything is ready for DNA synthesis. Synthesis(S)- DNA replication occurs during this phase. DNA Replication The process in which DNA makes a duplicate copy of itself. Semiconservative Replication The process in which the DNA molecule uncoils and separates into two strands. Each original strand becomes a template on which a new strand is constructed, resulting in two DNA molecules identical to the original DNA molecule. Gap 2(G2)- The cell continues to grow. The G2checkpointcontrol mechanism ensures that everything is ready to enter the M (mitosis) phase and divide. Mitotic(M) refers to the division of the nucleus. Cell growth stops at this stage and cellular energy is focused on the orderly division into daughter cells. A checkpoint in the middle of mitosis (Metaphase Checkpoint) ensures that the cell is ready to complete cell division. The final event is cytokinesis, in which the cytoplasm divides and the single parent cell splits into two daughter cells. Reproduction Cellular reproduction is a process by which cells duplicate their contents and then divide to yield multiple cells with similar, if not duplicate, contents. Mitosis Mitosis- nuclear division resulting in the production of two somatic cells having the same genetic complement (genetically identical) as the original cell.
    [Show full text]
  • Control of Eukaryotic DNA Replication Initiation—Mechanisms to Ensure Smooth Transitions
    G C A T T A C G G C A T genes Review Control of Eukaryotic DNA Replication Initiation—Mechanisms to Ensure Smooth Transitions Karl-Uwe Reusswig and Boris Pfander * Max Planck Institute of Biochemistry, DNA Replication and Genome Integrity, 82152 Martinsried, Germany; [email protected] * Correspondence: [email protected] Received: 31 December 2018; Accepted: 25 January 2019; Published: 29 January 2019 Abstract: DNA replication differs from most other processes in biology in that any error will irreversibly change the nature of the cellular progeny. DNA replication initiation, therefore, is exquisitely controlled. Deregulation of this control can result in over-replication characterized by repeated initiation events at the same replication origin. Over-replication induces DNA damage and causes genomic instability. The principal mechanism counteracting over-replication in eukaryotes is a division of replication initiation into two steps—licensing and firing—which are temporally separated and occur at distinct cell cycle phases. Here, we review this temporal replication control with a specific focus on mechanisms ensuring the faultless transition between licensing and firing phases. Keywords: DNA replication; DNA replication initiation; cell cycle; post-translational protein modification; protein degradation; cell cycle transitions 1. Introduction DNA replication control occurs with exceptional accuracy to keep genetic information stable over as many as 1016 cell divisions (estimations based on [1]) during, for example, an average human lifespan. A fundamental part of the DNA replication control system is dedicated to ensure that the genome is replicated exactly once per cell cycle. If this control falters, deregulated replication initiation occurs, which leads to parts of the genome becoming replicated more than once per cell cycle (reviewed in [2–4]).
    [Show full text]
  • A Free-Living Protist That Lacks Canonical Eukaryotic DNA Replication and Segregation Systems
    bioRxiv preprint doi: https://doi.org/10.1101/2021.03.14.435266; this version posted March 15, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 A free-living protist that lacks canonical eukaryotic DNA replication and segregation systems 2 Dayana E. Salas-Leiva1, Eelco C. Tromer2,3, Bruce A. Curtis1, Jon Jerlström-Hultqvist1, Martin 3 Kolisko4, Zhenzhen Yi5, Joan S. Salas-Leiva6, Lucie Gallot-Lavallée1, Geert J. P. L. Kops3, John M. 4 Archibald1, Alastair G. B. Simpson7 and Andrew J. Roger1* 5 1Centre for Comparative Genomics and Evolutionary Bioinformatics (CGEB), Department of 6 Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada, B3H 4R2 2 7 Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom 8 3Oncode Institute, Hubrecht Institute – KNAW (Royal Netherlands Academy of Arts and Sciences) 9 and University Medical Centre Utrecht, Utrecht, The Netherlands 10 4Institute of Parasitology Biology Centre, Czech Acad. Sci, České Budějovice, Czech Republic 11 5Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, School of Life Science, 12 South China Normal University, Guangzhou 510631, China 13 6CONACyT-Centro de Investigación en Materiales Avanzados, Departamento de medio ambiente y 14 energía, Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31136 Chihuahua, Chih., México 15 7Centre for Comparative Genomics and Evolutionary Bioinformatics (CGEB), Department of 16 Biology, Dalhousie University, Halifax, NS, Canada, B3H 4R2 17 *corresponding author: [email protected] 18 D.E.S-L ORCID iD: 0000-0003-2356-3351 19 E.C.T.
    [Show full text]