1
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Ma R, Liu Z, Zhu B. The romance of replication: Hand in hand, from dawn to dusk. Sci Bull (Beijing) 2024; 69:2474-2475. [PMID: 38969536 DOI: 10.1016/j.scib.2024.06.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2024]
Affiliation(s)
- Runze Ma
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Epigenetic Regulation and Intervention, Chinese Academy of Sciences, Beijing 100101, China
| | - Zijing Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Epigenetic Regulation and Intervention, Chinese Academy of Sciences, Beijing 100101, China
| | - Bing Zhu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Epigenetic Regulation and Intervention, Chinese Academy of Sciences, Beijing 100101, China; New Cornerstone Science Laboratory, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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2
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Liu Y, Zhangding Z, Liu X, Gan T, Ai C, Wu J, Liang H, Chen M, Guo Y, Lu R, Jiang Y, Ji X, Gao N, Kong D, Li Q, Hu J. Fork coupling directs DNA replication elongation and termination. Science 2024; 383:1215-1222. [PMID: 38484065 DOI: 10.1126/science.adj7606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 02/09/2024] [Indexed: 03/19/2024]
Abstract
DNA replication is initiated at multiple loci to ensure timely duplication of eukaryotic genomes. Sister replication forks progress bidirectionally, and replication terminates when two convergent forks encounter one another. To investigate the coordination of replication forks, we developed a replication-associated in situ HiC method to capture chromatin interactions involving nascent DNA. We identify more than 2000 fountain-like structures of chromatin contacts in human and mouse genomes, indicative of coupling of DNA replication forks. Replication fork interaction not only occurs between sister forks but also involves forks from two distinct origins to predetermine replication termination. Termination-associated chromatin fountains are sensitive to replication stress and lead to coupled forks-associated genomic deletions in cancers. These findings reveal the spatial organization of DNA replication forks within the chromatin context.
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Affiliation(s)
- Yang Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
| | - Zhengrong Zhangding
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
| | - Xuhao Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
| | - Tingting Gan
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
- Peking University ChengDu Academy for Advanced Interdisciplinary Biotechnologies, Chengdu, Sichuan 610213, China
| | - Chen Ai
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
| | - Jinchun Wu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
| | - Haoxin Liang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
| | - Mohan Chen
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
| | - Yuefeng Guo
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
| | - Rusen Lu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
| | - Yongpeng Jiang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
| | - Xiong Ji
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
| | - Ning Gao
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking University, Beijing 100871, China
| | - Daochun Kong
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Qing Li
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jiazhi Hu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Genome Editing Research Center, Peking University; Beijing 100871, China
- PKU-THU Center for Life Sciences, Peking University, Beijing 100871, China
- Peking University ChengDu Academy for Advanced Interdisciplinary Biotechnologies, Chengdu, Sichuan 610213, China
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3
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Joshi V, Joshi M, Penalosa A. Comparative analysis of tissue-specific transcriptomic responses to nitrogen stress in spinach (Spinacia oleracea). PLoS One 2020; 15:e0232011. [PMID: 32374731 PMCID: PMC7202632 DOI: 10.1371/journal.pone.0232011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 04/05/2020] [Indexed: 12/11/2022] Open
Abstract
Nitrogen (N) is critical to the growth and productivity of crops. To understand the molecular mechanisms influenced by N stress, we used RNA-Sequencing (RNA-Seq) to analyze differentially expressed genes (DEGs) in root and leaf tissues of spinach. N stress negatively influenced photosynthesis, biomass accumulation, amino acid profiles, and partitioning of N across tissues. RNA-seq analysis revealed that N stress caused most transcriptomic changes in roots, identifying 1,346 DEGs. High-affinity nitrate transporters (NRT2.1, NRT2.5) and glutamine amidotransferase (GAT1) genes were strongly induced in roots in response to N deplete and replete conditions, respectively. GO and KEGG analyses revealed that the functions associated with metabolic pathways and nutrient reservoir activity were enriched due to N stress. Whereas KEGG pathway enrichment analysis indicated the upregulation of DEGs associated with DNA replication, pyrimidine, and purine metabolism in the presence of high N in leaf tissue. A subset of transcription factors comprising bHLH, MYB, WRKY, and AP2/ERF family members was over-represented in both tissues in response to N perturbation. Interesting DEGs associated with N uptake, amino acid metabolism, hormonal pathway, carbon metabolism, along with transcription factors, were highlighted. The results provide valuable information about the underlying molecular processes in response to N stress in spinach and; could serve as a resource for functional analysis of candidate genes/pathways and enhancement of nitrogen use efficiency.
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Affiliation(s)
- Vijay Joshi
- Texas A&M AgriLife Research and Extension Center, Uvalde, Texas, United States of America
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Madhumita Joshi
- Texas A&M AgriLife Research and Extension Center, Uvalde, Texas, United States of America
| | - Arianne Penalosa
- College of Science, University of Texas, Arlington, Texas, United States of America
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4
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Perl AL, O'Connor CM, Fa P, Mayca Pozo F, Zhang J, Zhang Y, Narla G. Protein phosphatase 2A controls ongoing DNA replication by binding to and regulating cell division cycle 45 (CDC45). J Biol Chem 2019; 294:17043-17059. [PMID: 31562245 DOI: 10.1074/jbc.ra119.010432] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/20/2019] [Indexed: 11/06/2022] Open
Abstract
Genomic replication is a highly regulated process and represents both a potential benefit and liability to rapidly dividing cells; however, the precise post-translational mechanisms regulating genomic replication are incompletely understood. Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that regulates a diverse array of cellular processes. Here, utilizing both a gain-of-function chemical biology approach and loss-of-function genetic approaches to modulate PP2A activity, we found that PP2A regulates DNA replication. We demonstrate that increased PP2A activity can interrupt ongoing DNA replication, resulting in a prolonged S phase. The impaired replication resulted in a collapse of replication forks, inducing dsDNA breaks, homologous recombination, and a PP2A-dependent replication stress response. Additionally, we show that during replication, PP2A exists in complex with cell division cycle 45 (CDC45) and that increased PP2A activity caused dissociation of CDC45 and polymerase α from the replisome. Furthermore, we found that individuals harboring mutations in the PP2A Aα gene have a higher fraction of genomic alterations, suggesting that PP2A regulates ongoing replication as a mechanism for maintaining genomic integrity. These results reveal a new function for PP2A in regulating ongoing DNA replication and a potential role for PP2A in the intra-S-phase checkpoint.
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Affiliation(s)
- Abbey L Perl
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Caitlin M O'Connor
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Pengyan Fa
- Department of Radiation Oncology, Ohio State University James Comprehensive Cancer Center and College of Medicine, Columbus, Ohio 43210
| | - Franklin Mayca Pozo
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Junran Zhang
- Department of Radiation Oncology, Ohio State University James Comprehensive Cancer Center and College of Medicine, Columbus, Ohio 43210
| | - Youwei Zhang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Goutham Narla
- Department of Internal Medicine, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 .,Department of Internal Medicine, Division of Genetic Medicine, University of Michigan, Ann Arbor, Michigan 48105
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5
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Maffeo C, Chou HY, Aksimentiev A. Molecular Mechanisms of DNA Replication and Repair Machinery: Insights from Microscopic Simulations. ADVANCED THEORY AND SIMULATIONS 2019; 2:1800191. [PMID: 31728433 PMCID: PMC6855400 DOI: 10.1002/adts.201800191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Indexed: 12/15/2022]
Abstract
Reproduction, the hallmark of biological activity, requires making an accurate copy of the genetic material to allow the progeny to inherit parental traits. In all living cells, the process of DNA replication is carried out by a concerted action of multiple protein species forming a loose protein-nucleic acid complex, the replisome. Proofreading and error correction generally accompany replication but also occur independently, safeguarding genetic information through all phases of the cell cycle. Advances in biochemical characterization of intracellular processes, proteomics and the advent of single-molecule biophysics have brought about a treasure trove of information awaiting to be assembled into an accurate mechanistic model of the DNA replication process. In this review, we describe recent efforts to model elements of DNA replication and repair processes using computer simulations, an approach that has gained immense popularity in many areas of molecular biophysics but has yet to become mainstream in the DNA metabolism community. We highlight the use of diverse computational methods to address specific problems of the fields and discuss unexplored possibilities that lie ahead for the computational approaches in these areas.
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Affiliation(s)
- Christopher Maffeo
- Department of Physics, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign,1110 W Green St, Urbana, IL 61801, USA
| | - Han-Yi Chou
- Department of Physics, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign,1110 W Green St, Urbana, IL 61801, USA
| | - Aleksei Aksimentiev
- Department of Physics, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign,1110 W Green St, Urbana, IL 61801, USA
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6
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Hill FR, van Oijen AM, Duderstadt KE. Detection of kinetic change points in piece-wise linear single molecule motion. J Chem Phys 2018; 148:123317. [PMID: 29604840 DOI: 10.1063/1.5009387] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Single-molecule approaches present a powerful way to obtain detailed kinetic information at the molecular level. However, the identification of small rate changes is often hindered by the considerable noise present in such single-molecule kinetic data. We present a general method to detect such kinetic change points in trajectories of motion of processive single molecules having Gaussian noise, with a minimum number of parameters and without the need of an assumed kinetic model beyond piece-wise linearity of motion. Kinetic change points are detected using a likelihood ratio test in which the probability of no change is compared to the probability of a change occurring, given the experimental noise. A predetermined confidence interval minimizes the occurrence of false detections. Applying the method recursively to all sub-regions of a single molecule trajectory ensures that all kinetic change points are located. The algorithm presented allows rigorous and quantitative determination of kinetic change points in noisy single molecule observations without the need for filtering or binning, which reduce temporal resolution and obscure dynamics. The statistical framework for the approach and implementation details are discussed. The detection power of the algorithm is assessed using simulations with both single kinetic changes and multiple kinetic changes that typically arise in observations of single-molecule DNA-replication reactions. Implementations of the algorithm are provided in ImageJ plugin format written in Java and in the Julia language for numeric computing, with accompanying Jupyter Notebooks to allow reproduction of the analysis presented here.
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Affiliation(s)
- Flynn R Hill
- Centre for Medical and Molecular Bioscience, Illawarra Health and Medical Research Institute and University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Antoine M van Oijen
- Centre for Medical and Molecular Bioscience, Illawarra Health and Medical Research Institute and University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Karl E Duderstadt
- Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, Martinsried, Germany
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7
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Quentin Y, Siguier P, Chandler M, Fichant G. Single-strand DNA processing: phylogenomics and sequence diversity of a superfamily of potential prokaryotic HuH endonucleases. BMC Genomics 2018; 19:475. [PMID: 29914351 PMCID: PMC6006769 DOI: 10.1186/s12864-018-4836-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/29/2018] [Indexed: 12/11/2022] Open
Abstract
Background Some mobile genetic elements target the lagging strand template during DNA replication. Bacterial examples are insertion sequences IS608 and ISDra2 (IS200/IS605 family members). They use obligatory single-stranded circular DNA intermediates for excision and insertion and encode a transposase, TnpAIS200, which recognizes subterminal secondary structures at the insertion sequence ends. Similar secondary structures, Repeated Extragenic Palindromes (REP), are present in many bacterial genomes. TnpAIS200-related proteins, TnpAREP, have been identified and could be responsible for REP sequence proliferation. These proteins share a conserved HuH/Tyrosine core domain responsible for catalysis and are involved in processes of ssDNA cleavage and ligation. Our goal is to characterize the diversity of these proteins collectively referred as the TnpAY1 family. Results A genome-wide analysis of sequences similar to TnpAIS200 and TnpAREP in prokaryotes revealed a large number of family members with a wide taxonomic distribution. These can be arranged into three distinct classes and 12 subclasses based on sequence similarity. One subclass includes sequences similar to TnpAIS200. Proteins from other subclasses are not associated with typical insertion sequence features. These are characterized by specific additional domains possibly involved in protein/DNA or protein/protein interactions. Their genes are found in more than 25% of species analyzed. They exhibit a patchy taxonomic distribution consistent with dissemination by horizontal gene transfers followed by loss. The tnpAREP genes of five subclasses are flanked by typical REP sequences in a REPtron-like arrangement. Four distinct REP types were characterized with a subclass specific distribution. Other subclasses are not associated with REP sequences but have a large conserved domain located in C-terminal end of their sequence. This unexpected diversity suggests that, while most likely involved in processing single-strand DNA, proteins from different subfamilies may play a number of different roles. Conclusions We established a detailed classification of TnpAY1 proteins, consolidated by the analysis of the conserved core domains and the characterization of additional domains. The data obtained illustrate the unexpected diversity of the TnpAY1 family and provide a strong framework for future evolutionary and functional studies. By their potential function in ssDNA editing, they may confer adaptive responses to host cell physiology and metabolism. Electronic supplementary material The online version of this article (10.1186/s12864-018-4836-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yves Quentin
- Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31062, Toulouse, France.
| | - Patricia Siguier
- Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31062, Toulouse, France
| | - Mick Chandler
- Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31062, Toulouse, France.
| | - Gwennaele Fichant
- Laboratoire de Microbiologie et Génétique Moléculaires, UMR5100, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31062, Toulouse, France
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8
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Maffeo C, Aksimentiev A. Molecular mechanism of DNA association with single-stranded DNA binding protein. Nucleic Acids Res 2017; 45:12125-12139. [PMID: 29059392 PMCID: PMC5716091 DOI: 10.1093/nar/gkx917] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/28/2017] [Indexed: 01/10/2023] Open
Abstract
During DNA replication, the single-stranded DNA binding protein (SSB) wraps single-stranded DNA (ssDNA) with high affinity to protect it from degradation and prevent secondary structure formation. Although SSB binds ssDNA tightly, it can be repositioned along ssDNA to follow the advancement of the replication fork. Using all-atom molecular dynamics simulations, we characterized the molecular mechanism of ssDNA association with SSB. Placed in solution, ssDNA–SSB assemblies were observed to change their structure spontaneously; such structural changes were suppressed in the crystallographic environment. Repeat simulations of the SSB–ssDNA complex under mechanical tension revealed a multitude of possible pathways for ssDNA to come off SSB punctuated by prolonged arrests at reproducible sites at the SSB surface. Ensemble simulations of spontaneous association of short ssDNA fragments with SSB detailed a three-dimensional map of local affinity to DNA; the equilibrium amount of ssDNA bound to SSB was found to depend on the electrolyte concentration but not on the presence of the acidic tips of the SSB tails. Spontaneous formation of ssDNA bulges and their diffusive motion along SSB surface was directly observed in multiple 10-µs-long simulations. Such reptation-like motion was confined by DNA binding to high-affinity spots, suggesting a two-step mechanism for SSB diffusion.
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Affiliation(s)
- Christopher Maffeo
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Ave, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 1205 W Clark St, Urbana, IL 61801, USA
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Ave, Urbana, IL 61801, USA.,National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 1205 W Clark St, Urbana, IL 61801, USA.,Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL 61801, USA
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9
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Burnham DR, Nijholt B, De Vlaminck I, Quan J, Yusufzai T, Dekker C. Annealing helicase HARP closes RPA-stabilized DNA bubbles non-processively. Nucleic Acids Res 2017; 45:4687-4695. [PMID: 28334870 PMCID: PMC5416776 DOI: 10.1093/nar/gkx147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/27/2017] [Indexed: 02/06/2023] Open
Abstract
We investigate the mechanistic nature of the Snf2 family protein HARP, mutations of which are responsible for Schimke immuno-osseous dysplasia. Using a single-molecule magnetic tweezers assay, we construct RPA-stabilized DNA bubbles within torsionally constrained DNA to investigate the annealing action of HARP on a physiologically relevant substrate. We find that HARP closes RPA-stabilized bubbles in a slow reaction, taking on the order of tens of minutes for ∼600 bp of DNA to be re-annealed. The data indicate that DNA re-anneals through the removal of RPA, which is observed as clear steps in the bubble-closing traces. The dependence of the closing rate on both ionic strength and HARP concentration indicates that removal of RPA occurs via an association-dissociation mechanism where HARP does not remain associated with the DNA. The enzyme exhibits classical Michaelis–Menten kinetics and acts cooperatively with a Hill coefficient of 3 ± 1. Our work also allows the determination of some important features of RPA-bubble structures at low supercoiling, including the existence of multiple bubbles and that RPA molecules are mis-registered on the two strands.
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Affiliation(s)
- Daniel R Burnham
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629 HZ, The Netherlands
| | - Bas Nijholt
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629 HZ, The Netherlands
| | - Iwijn De Vlaminck
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629 HZ, The Netherlands
| | - Jinhua Quan
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Timur Yusufzai
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2629 HZ, The Netherlands
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10
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Wiest NE, Tomkinson AE. Optimization of Native and Formaldehyde iPOND Techniques for Use in Suspension Cells. Methods Enzymol 2017. [PMID: 28645366 DOI: 10.1016/bs.mie.2017.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The isolation of proteins on nascent DNA (iPOND) technique developed by the Cortez laboratory allows a previously unparalleled ability to examine proteins associated with replicating and newly synthesized DNA in mammalian cells. Both the original, formaldehyde-based iPOND technique and a more recent derivative, accelerated native iPOND (aniPOND), have mostly been performed in adherent cell lines. Here, we describe modifications to both protocols for use with suspension cell lines. These include cell culture, pulse, and chase conditions that optimize sample recovery in both protocols using suspension cells and several key improvements to the published aniPOND technique that reduce sample loss, increase signal to noise, and maximize sample recovery. Additionally, we directly and quantitatively compare the iPOND and aniPOND protocols to test the strengths and limitations of both. Finally, we present a detailed protocol to perform the optimized aniPOND protocol in suspension cell lines.
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Affiliation(s)
- Nathaniel E Wiest
- University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Alan E Tomkinson
- University of New Mexico School of Medicine, Albuquerque, NM, United States.
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11
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Lewis JS, Spenkelink LM, Jergic S, Wood EA, Monachino E, Horan NP, Duderstadt KE, Cox MM, Robinson A, Dixon NE, van Oijen AM. Single-molecule visualization of fast polymerase turnover in the bacterial replisome. eLife 2017; 6. [PMID: 28432790 PMCID: PMC5419744 DOI: 10.7554/elife.23932] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/20/2017] [Indexed: 11/13/2022] Open
Abstract
The Escherichia coli DNA replication machinery has been used as a road map to uncover design rules that enable DNA duplication with high efficiency and fidelity. Although the enzymatic activities of the replicative DNA Pol III are well understood, its dynamics within the replisome are not. Here, we test the accepted view that the Pol III holoenzyme remains stably associated within the replisome. We use in vitro single-molecule assays with fluorescently labeled polymerases to demonstrate that the Pol III* complex (holoenzyme lacking the β2 sliding clamp), is rapidly exchanged during processive DNA replication. Nevertheless, the replisome is highly resistant to dilution in the absence of Pol III* in solution. We further show similar exchange in live cells containing labeled clamp loader and polymerase. These observations suggest a concentration-dependent exchange mechanism providing a balance between stability and plasticity, facilitating replacement of replisomal components dependent on their availability in the environment. DOI:http://dx.doi.org/10.7554/eLife.23932.001
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Affiliation(s)
- Jacob S Lewis
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Lisanne M Spenkelink
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia.,Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Slobodan Jergic
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Elizabeth A Wood
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Enrico Monachino
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia.,Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Nicholas P Horan
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Karl E Duderstadt
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.,Max Planck Institute of Biochemistry, Martinsried, Germany.,Physik Department, Technishche Universität München, Garching, Germany
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States
| | - Andrew Robinson
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Nicholas E Dixon
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Antoine M van Oijen
- Centre for Medical and Molecular Bioscience, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
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12
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Duderstadt KE, Geertsema HJ, Stratmann SA, Punter CM, Kulczyk AW, Richardson CC, van Oijen AM. Simultaneous Real-Time Imaging of Leading and Lagging Strand Synthesis Reveals the Coordination Dynamics of Single Replisomes. Mol Cell 2016; 64:1035-1047. [PMID: 27889453 DOI: 10.1016/j.molcel.2016.10.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/18/2016] [Accepted: 10/20/2016] [Indexed: 11/16/2022]
Abstract
The molecular machinery responsible for DNA replication, the replisome, must efficiently coordinate DNA unwinding with priming and synthesis to complete duplication of both strands. Due to the anti-parallel nature of DNA, the leading strand is copied continuously, while the lagging strand is produced by repeated cycles of priming, DNA looping, and Okazaki-fragment synthesis. Here, we report a multidimensional single-molecule approach to visualize this coordination in the bacteriophage T7 replisome by simultaneously monitoring the kinetics of loop growth and leading-strand synthesis. We show that loops in the lagging strand predominantly occur during priming and only infrequently support subsequent Okazaki-fragment synthesis. Fluorescence imaging reveals polymerases remaining bound to the lagging strand behind the replication fork, consistent with Okazaki-fragment synthesis behind and independent of the replication complex. Individual replisomes display both looping and pausing during priming, reconciling divergent models for the regulation of primer synthesis and revealing an underlying plasticity in replisome operation.
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Affiliation(s)
- Karl E Duderstadt
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands; Structure and Dynamics of Molecular Machines, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Physik Department, Technische Universität München, 85748 Garching, Germany.
| | - Hylkje J Geertsema
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands
| | - Sarah A Stratmann
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands
| | - Christiaan M Punter
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands
| | - Arkadiusz W Kulczyk
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Charles C Richardson
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Antoine M van Oijen
- Zernike Institute for Advanced Materials and Centre for Synthetic Biology, University of Groningen, 9700 AB Groningen, the Netherlands; Centre for Medical and Molecular Bioscience, Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.
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13
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Abstract
The cellular replicating machine, or "replisome," is composed of numerous different proteins. The core replication proteins in all cell types include a helicase, primase, DNA polymerases, sliding clamp, clamp loader, and single-strand binding (SSB) protein. The core eukaryotic replisome proteins evolved independently from those of bacteria and thus have distinct architectures and mechanisms of action. The core replisome proteins of the eukaryote include: an 11-subunit CMG helicase, DNA polymerase alpha-primase, leading strand DNA polymerase epsilon, lagging strand DNA polymerase delta, PCNA clamp, RFC clamp loader, and the RPA SSB protein. There are numerous other proteins that travel with eukaryotic replication forks, some of which are known to be involved in checkpoint regulation or nucleosome handling, but most have unknown functions and no bacterial analogue. Recent studies have revealed many structural and functional insights into replisome action. Also, the first structure of a replisome from any cell type has been elucidated for a eukaryote, consisting of 20 distinct proteins, with quite unexpected results. This review summarizes the current state of knowledge of the eukaryotic core replisome proteins, their structure, individual functions, and how they are organized at the replication fork as a machine.
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Affiliation(s)
- D Zhang
- The Rockefeller University, New York, NY, United States
| | - M O'Donnell
- The Rockefeller University, New York, NY, United States; Howard Hughes Medical Institute, The Rockefeller University, New York, NY, United States.
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14
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Mettrick KA, Grainge I. Stability of blocked replication forks in vivo. Nucleic Acids Res 2016; 44:657-68. [PMID: 26490956 PMCID: PMC4737137 DOI: 10.1093/nar/gkv1079] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 10/06/2015] [Accepted: 10/07/2015] [Indexed: 11/17/2022] Open
Abstract
Replication of chromosomal DNA must be carried out to completion in order for a cell to proliferate. However, replication forks can stall during this process for a variety of reasons, including nucleoprotein 'roadblocks' and DNA lesions. In these circumstances the replisome copying the DNA may disengage from the chromosome to allow various repair processes to restore DNA integrity and enable replication to continue. Here, we report the in vivo stability of the replication fork when it encounters a nucleoprotein blockage in Escherichia coli. Using a site-specific and reversible protein block system in conjunction with the temperature sensitive DnaC helicase loader and DnaB replicative helicase, we monitored the disappearance of the Y-shaped DNA replication fork structures using neutral-neutral 2D agarose gels. We show the replication fork collapses within 5 min of encountering the roadblock. Therefore, the stalled replication fork does not pause at a block in a stable confirmation for an extended period of time as previously postulated.
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Affiliation(s)
- Karla A Mettrick
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Ian Grainge
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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15
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DNA interstrand cross-link repair requires replication-fork convergence. Nat Struct Mol Biol 2015; 22:242-7. [PMID: 25643322 PMCID: PMC4351167 DOI: 10.1038/nsmb.2956] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/17/2014] [Indexed: 12/14/2022]
Abstract
DNA interstrand cross-links (ICLs) prevent strand separation during DNA replication and transcription and therefore are extremely cytotoxic. In metazoans, a major pathway of ICL repair is coupled to DNA replication, and it requires the Fanconi anemia pathway. In most current models, collision of a single DNA replication fork with an ICL is sufficient to initiate repair. In contrast, we show here that in Xenopus egg extracts two DNA replication forks must converge on an ICL to trigger repair. When only one fork reaches the ICL, the replicative CMG helicase fails to unload from the stalled fork, and repair is blocked. Arrival of a second fork, even when substantially delayed, rescues repair. We conclude that ICL repair requires a replication-induced X-shaped DNA structure surrounding the lesion, and we speculate on how this requirement helps maintain genomic stability in S phase.
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16
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Slow unloading leads to DNA-bound β2-sliding clamp accumulation in live Escherichia coli cells. Nat Commun 2014; 5:5820. [PMID: 25520215 PMCID: PMC4284645 DOI: 10.1038/ncomms6820] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 11/11/2014] [Indexed: 11/26/2022] Open
Abstract
The ubiquitous sliding clamp facilitates processivity of the replicative polymerase and acts as a platform to recruit proteins involved in replication, recombination and repair. While the dynamics of the E. coli β2-sliding clamp have been characterized in vitro, its in vivo stoichiometry and dynamics remain unclear. To probe both β2-clamp dynamics and stoichiometry in live E. coli cells, we use custom-built microfluidics in combination with single-molecule fluorescence microscopy and photoactivated fluorescence microscopy. We quantify the recruitment, binding and turnover of β2-sliding clamps on DNA during replication. These quantitative in vivo results demonstrate that numerous β2-clamps in E. coli remain on the DNA behind the replication fork for a protracted period of time, allowing them to form a docking platform for other enzymes involved in DNA metabolism. DNA replication is accomplished by the replisome, a multi-protein complex that comprises the sliding clamp. Here, Moolman et al. present quantitative and dynamic measurements of the number of β2-sliding clamps at the single-cell level in live E. coli cells to shed light on key aspects of DNA replication.
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17
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Abstract
A cell can be thought of as a highly sophisticated micro factory: in a pool of billions of molecules - metabolites, structural proteins, enzymes, oligonucleotides - multi-subunit complexes assemble to perform a large number of basic cellular tasks, such as DNA replication, RNA/protein synthesis or intracellular transport. By purifying single components and using them to reconstitute molecular processes in a test tube, researchers have gathered crucial knowledge about mechanistic, dynamic and structural properties of biochemical pathways. However, to sort this information into an accurate cellular road map, we need to understand reactions in their relevant context within the cellular hierarchy, which is at the individual molecule level within a crowded, cellular environment. Reactions occur in a stochastic fashion, have short-lived and not necessarily well-defined intermediates, and dynamically form functional entities. With the use of single-molecule techniques these steps can be followed and detailed kinetic information that otherwise would be hidden in ensemble averaging can be obtained. One of the first complex cellular tasks that have been studied at the single-molecule level is the replication of DNA. The replisome, the multi-protein machinery responsible for copying DNA, is built from a large number of proteins that function together in an intricate and efficient fashion allowing the complex to tolerate DNA damage, roadblocks or fluctuations in subunit concentration. In this review, we summarize advances in single-molecule studies, both in vitro and in vivo, that have contributed to our current knowledge of the mechanistic principles underlying DNA replication.
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Affiliation(s)
- S A Stratmann
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, The Netherlands.
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Fricker AD, Peters JE. Vulnerabilities on the lagging-strand template: opportunities for mobile elements. Annu Rev Genet 2014; 48:167-86. [PMID: 25195506 DOI: 10.1146/annurev-genet-120213-092046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mobile genetic elements have the ability to move between positions in a genome. Some of these elements are capable of targeting one of the template strands during DNA replication. Examples found in bacteria include (a) Red recombination mediated by bacteriophage λ, (b) integration of group II mobile introns that reverse splice and reverse transcribe into DNA, (c) HUH endonuclease elements that move as single-stranded DNA, and (d) Tn7, a DNA cut-and-paste transposon that uses a target-site-selecting protein to target transposition into certain forms of DNA replication. In all of these examples, the lagging-strand template appears to be targeted using a variety of features specific to this strand. These features appear especially available in certain situations, such as when replication forks stall or collapse. In this review, we address the idea that features specific to the lagging-strand template represent vulnerabilities that are capitalized on by mobile genetic elements.
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Affiliation(s)
- Ashwana D Fricker
- Department of Microbiology, Cornell University, Ithaca, New York 14853;
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Abstract
A critical step in DNA interstrand cross-link repair is the programmed collapse of replication forks that have stalled at an ICL. This event is regulated by the Fanconi anemia pathway, which suppresses bone marrow failure and cancer. In this perspective, we focus on the structure of forks that have stalled at ICLs, how these structures might be incised by endonucleases, and how incision is regulated by the Fanconi anemia pathway.
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Affiliation(s)
- Jieqiong Zhang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States; Howard Hughes Medical Institute.
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