1
|
Guo L, Bao Y, Zhao Y, Ren Z, Bi L, Zhang X, Liu C, Hou X, Wang MD, Sun B. Joint Efforts of Replicative Helicase and SSB Ensure Inherent Replicative Tolerance of G-Quadruplex. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307696. [PMID: 38126671 PMCID: PMC10916570 DOI: 10.1002/advs.202307696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/28/2023] [Indexed: 12/23/2023]
Abstract
G-quadruplex (G4) is a four-stranded noncanonical DNA structure that has long been recognized as a potential hindrance to DNA replication. However, how replisomes effectively deal with G4s to avoid replication failure is still obscure. Here, using single-molecule and ensemble approaches, the consequence of the collision between bacteriophage T7 replisome and an intramolecular G4 located on either the leading or lagging strand is examined. It is found that the adjacent fork junctions induced by G4 formation incur the binding of T7 DNA polymerase (DNAP). In addition to G4, these inactive DNAPs present insuperable obstacles, impeding the progression of DNA synthesis. Nevertheless, T7 helicase can dismantle them and resolve lagging-strand G4s, paving the way for the advancement of the replication fork. Moreover, with the assistance of the single-stranded DNA binding protein (SSB) gp2.5, T7 helicase is also capable of maintaining a leading-strand G4 structure in an unfolded state, allowing for a fraction of T7 DNAPs to synthesize through without collapse. These findings broaden the functional repertoire of a replicative helicase and underscore the inherent G4 tolerance of a replisome.
Collapse
Affiliation(s)
- Lijuan Guo
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Yanling Bao
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Yilin Zhao
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Zhiyun Ren
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell BiologyChinese Academy of SciencesShanghai200031China
- University of Chinese Academy of SciencesBeijing100049China
| | - Lulu Bi
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Xia Zhang
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai201210China
| | - Xi‐Miao Hou
- College of Life SciencesNorthwest A&F UniversityYanglingShaanxi712100China
| | - Michelle D. Wang
- Department of Physics, Laboratory of Atomic and Solid State PhysicsCornell UniversityIthacaNY14853USA
- Howard Hughes Medical InstituteCornell UniversityIthacaNY14853USA
| | - Bo Sun
- School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China
| |
Collapse
|
2
|
Langston LD, Georgescu RE, O'Donnell ME. Mechanism of eukaryotic origin unwinding is a dual helicase DNA shearing process. Proc Natl Acad Sci U S A 2023; 120:e2316466120. [PMID: 38109526 PMCID: PMC10756200 DOI: 10.1073/pnas.2316466120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Accepted: 11/17/2023] [Indexed: 12/20/2023] Open
Abstract
DNA replication in all cells begins with the melting of base pairs at the duplex origin to allow access to single-stranded DNA templates which are replicated by DNA polymerases. In bacteria, origin DNA is presumed to be melted by accessory proteins that allow loading of two ring-shaped replicative helicases around single-strand DNA (ssDNA) for bidirectional unwinding and DNA replication. In eukaryotes, by contrast, two replicative CMG (Cdc45-Mcm2-7-GINS) helicases are initially loaded head to head around origin double-strand DNA (dsDNA), and there does not appear to be a separate origin unwinding factor. This led us to investigate whether head-to-head CMGs use their adenosine triphosphate (ATP)-driven motors to initiate duplex DNA unwinding at the origin. Here, we show that CMG tracks on one strand of the duplex while surrounding it, and this feature allows two head-to-head CMGs to unwind dsDNA by using their respective motors to pull on opposite strands of the duplex. We further show that while CMG is capable of limited duplex unwinding on its own, the extent of unwinding is greatly and rapidly stimulated by addition of the multifunctional CMG-binding protein Mcm10 that is critical for productive initiation of DNA replication in vivo. On the basis of these findings, we propose that Mcm10 is a processivity or positioning factor that helps translate the work performed by the dual CMG motors at the origin into productive unwinding that facilitates bidirectional DNA replication.
Collapse
Affiliation(s)
- Lance D. Langston
- The Rockefeller University, New York City, NY10065
- HHMI, New York City, NY10065
| | - Roxana E. Georgescu
- The Rockefeller University, New York City, NY10065
- HHMI, New York City, NY10065
| | | |
Collapse
|
3
|
Neitz H, Bessi I, Kuper J, Kisker C, Höbartner C. Programmable DNA Interstrand Crosslinking by Alkene-Alkyne [2 + 2] Photocycloaddition. J Am Chem Soc 2023; 145:9428-9433. [PMID: 37071840 DOI: 10.1021/jacs.3c01611] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
Covalent crosslinking of DNA strands provides a useful tool for medical, biochemical, and DNA nanotechnology applications. Here we present a light-induced interstrand DNA crosslinking reaction using the modified nucleoside 5-phenylethynyl-2'-deoxyuridine (PhedU). The crosslinking ability of PhedU was programmed by base pairing and by metal ion interaction at the Watson-Crick base pairing site. Rotation to intrahelical positions was favored by hydrophobic stacking and enabled an unexpected photochemical alkene-alkyne [2 + 2] cycloaddition within the DNA duplex, resulting in efficient formation of a PhedU dimer after short irradiation times of a few seconds. A PhedU-dimer-containing DNA was shown to efficiently bind a helicase complex, but the covalent crosslink completely prevented DNA unwinding, suggesting possible applications in biochemistry or structural biology.
Collapse
Affiliation(s)
- Hermann Neitz
- Institute of Organic Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Irene Bessi
- Institute of Organic Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jochen Kuper
- Rudolf-Virchow-Zentrum - Center for Integrative and Translational Bioimaging, Universität Würzburg, Josef-Schneider-Straße 2, 97080 Würzburg, Germany
| | - Caroline Kisker
- Rudolf-Virchow-Zentrum - Center for Integrative and Translational Bioimaging, Universität Würzburg, Josef-Schneider-Straße 2, 97080 Würzburg, Germany
| | - Claudia Höbartner
- Institute of Organic Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for Nanosystems Chemistry (CNC), Universität Würzburg, 97074 Würzburg, Germany
| |
Collapse
|
4
|
Plaza-G A I, Lemishko KM, Crespo R, Truong TQ, Kaguni LS, Cao-García FJ, Ciesielski GL, Ibarra B. Mechanism of strand displacement DNA synthesis by the coordinated activities of human mitochondrial DNA polymerase and SSB. Nucleic Acids Res 2023; 51:1750-1765. [PMID: 36744436 PMCID: PMC9976888 DOI: 10.1093/nar/gkad037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 12/16/2022] [Accepted: 01/12/2023] [Indexed: 02/07/2023] Open
Abstract
Many replicative DNA polymerases couple DNA replication and unwinding activities to perform strand displacement DNA synthesis, a critical ability for DNA metabolism. Strand displacement is tightly regulated by partner proteins, such as single-stranded DNA (ssDNA) binding proteins (SSBs) by a poorly understood mechanism. Here, we use single-molecule optical tweezers and biochemical assays to elucidate the molecular mechanism of strand displacement DNA synthesis by the human mitochondrial DNA polymerase, Polγ, and its modulation by cognate and noncognate SSBs. We show that Polγ exhibits a robust DNA unwinding mechanism, which entails lowering the energy barrier for unwinding of the first base pair of the DNA fork junction, by ∼55%. However, the polymerase cannot prevent the reannealing of the parental strands efficiently, which limits by ∼30-fold its strand displacement activity. We demonstrate that SSBs stimulate the Polγ strand displacement activity through several mechanisms. SSB binding energy to ssDNA additionally increases the destabilization energy at the DNA junction, by ∼25%. Furthermore, SSB interactions with the displaced ssDNA reduce the DNA fork reannealing pressure on Polγ, in turn promoting the productive polymerization state by ∼3-fold. These stimulatory effects are enhanced by species-specific functional interactions and have significant implications in the replication of the human mitochondrial DNA.
Collapse
Affiliation(s)
- Ismael Plaza-G A
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain
| | - Kateryna M Lemishko
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain
| | - Rodrigo Crespo
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| | - Thinh Q Truong
- Department of Chemistry, Auburn University at Montgomery, Montgomery, AL 36117, USA
| | - Laurie S Kaguni
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Francisco J Cao-García
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| | - Grzegorz L Ciesielski
- Department of Chemistry, Auburn University at Montgomery, Montgomery, AL 36117, USA.,Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain.,Nanobiotecnología (IMDEA-Nanociencia), Unidad Asociada al Centro Nacional de Biotecnología (CSIC), 28049 Madrid, Spain
| |
Collapse
|
5
|
Ming H, Yan G, Zhang X, Pei X, Fu L, Zhou D. Harsh temperature induces Microcystis aeruginosa growth enhancement and water deterioration during vernalization. WATER RESEARCH 2022; 223:118956. [PMID: 35985140 DOI: 10.1016/j.watres.2022.118956] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
Cyanobacterial blooms are seasonal phenomena in eutrophic water. Cyanobacteria grow fast in the warm spring/summer while disappearing in cold autumn/winter. The temperature change induces algal vernalization. However, whether vernalization affects cyanobacterial blooms, and the regulatory signaling mechanisms are unclear. This study used Microcystis aeruginosa as the model cyanobacteria, and 4 °C and 10 °C as the low-temperature stimulation to explore the cell growth, metabolites, and signaling pathways in cyanobacteria vernalization. Low temperatures induced M. aeruginosa vernalization; the growth rate and cell density increased by 35±4% and 33±2%. Vernalization influenced peptidoglycan synthesis and cell permeability. Soluble microbial products (SMPs) in water increased by 109±5%, resulting in water deterioration. Polysaccharides were the predominant SMPs during the initial term of vernalization. Tryptophan protein-like & humic acid-like substances became the main increased SMPs in the middle-later period of vernalization. Harsh temperatures triggered quorum sensing and two-component system. Signaling sensing systems upregulated photosynthesis, glycolysis, TCA cycle, oxidative phosphorylation, and DNA replication, enhancing M. aeruginosa growth and metabolism during vernalization. This study verified that low temperature stimulates cyanobacteria growth and metabolism, and vernalization possibly aggravates cyanobacterial blooms and water deterioration. It provides new insights into the mechanism of seasonal cyanobacterial blooms and the pivotal role of signaling regulation.
Collapse
Affiliation(s)
- Hao Ming
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, Jilin, China
| | - Ge Yan
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, Jilin, China
| | - Xue Zhang
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, Jilin, China
| | - Xiaofen Pei
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, Jilin, China
| | - Liang Fu
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, Jilin, China.
| | - Dandan Zhou
- Engineering Lab for Water Pollution Control and Resources Recovery of Jilin Province, School of Environment, Northeast Normal University, Changchun 130117, Jilin, China
| |
Collapse
|
6
|
Lo CY, Gao Y. Assembling bacteriophage T7 leading-strand replisome for structural investigation. Methods Enzymol 2022; 672:103-123. [PMID: 35934471 DOI: 10.1016/bs.mie.2022.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Replicative helicase and polymerase form the leading-strand replisome that unwinds parental DNA and performs continuous leading-strand DNA synthesis. Uncoupling of the helicase-polymerase complex results in replication stress, replication errors, and genome instability. Although numerous replisomes from different biological systems have been reconstituted and characterized, structural investigations of the leading-strand replisome complex are hindered by its large size and dynamics. We have determined the first replisome structure on a fork substrate with bacteriophage T7 replisome as a model system. Here, we summarized our protocols to prepare and characterize the coupled T7 replisome complex. Similar methods can potentially be applied for structural investigations of more complicated replisomes.
Collapse
|
7
|
Singh A, Patel SS. Quantitative methods to study helicase, DNA polymerase, and exonuclease coupling during DNA replication. Methods Enzymol 2022; 672:75-102. [PMID: 35934486 PMCID: PMC9933136 DOI: 10.1016/bs.mie.2022.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Genome replication is accomplished by highly regulated activities of enzymes in a multi-protein complex called the replisome. Two major enzymes, DNA polymerase and helicase, catalyze continuous DNA synthesis on the leading strand of the parental DNA duplex while the lagging strand is synthesized discontinuously. The helicase and DNA polymerase on their own are catalytically inefficient and weak motors for unwinding/replicating double-stranded DNA. However, when a helicase and DNA polymerase are functionally and physically coupled, they catalyze fast and highly processive leading strand DNA synthesis. DNA polymerase has a 3'-5' exonuclease activity, which removes nucleotides misincorporated in the nascent DNA. DNA synthesis kinetics, processivity, and accuracy are governed by the interplay of the helicase, DNA polymerase, and exonuclease activities within the replisome. This chapter describes quantitative biochemical and biophysical methods to study the coupling of these three critical activities during DNA replication. The methods include real-time quantitation of kinetics of DNA unwinding-synthesis by a coupled helicase-DNA polymerase complex, a 2-aminopurine fluorescence-based assay to map the precise positions of helicase and DNA polymerase with respect to the replication fork junction, and a radiometric assay to study the coupling of DNA polymerase, exonuclease, and helicase activities during processive leading strand DNA synthesis. These methods are presented here with bacteriophage T7 replication proteins as an example but can be applied to other systems with appropriate modifications.
Collapse
|
8
|
Abstract
Ring-shaped hexameric helicases are essential motor proteins that separate duplex nucleic acid strands for DNA replication, recombination, and transcriptional regulation. Two evolutionarily distinct lineages of these enzymes, predicated on RecA and AAA+ ATPase folds, have been identified and characterized to date. Hexameric helicases couple NTP hydrolysis with conformational changes that move nucleic acid substrates through a central pore in the enzyme. How hexameric helicases productively engage client DNA or RNA segments and use successive rounds of NTPase activity to power translocation and unwinding have been longstanding questions in the field. Recent structural and biophysical findings are beginning to reveal commonalities in NTP hydrolysis and substrate translocation by diverse hexameric helicase families. Here, we review these molecular mechanisms and highlight aspects of their function that are yet to be understood.
Collapse
|
9
|
Zwinderman MRH, Lobo TJ, van der Wouden PE, Spierings DCJ, van Vugt MATM, Lansdorp PM, Guryev V, Dekker FJ. Deposition Bias of Chromatin Proteins Inverts under DNA Replication Stress Conditions. ACS Chem Biol 2021; 16:2193-2201. [PMID: 34592816 PMCID: PMC8609521 DOI: 10.1021/acschembio.1c00321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Following DNA replication,
equal amounts of chromatin proteins
are distributed over sister chromatids by re-deposition of parental
chromatin proteins and deposition of newly synthesized chromatin proteins.
Molecular mechanisms balancing the allocation of new and old chromatin
proteins remain largely unknown. Here, we studied the genome-wide
distribution of new chromatin proteins relative to parental DNA template
strands and replication initiation zones using the double-click-seq.
Under control conditions, new chromatin proteins were preferentially
found on DNA replicated by the lagging strand machinery. Strikingly,
replication stress induced by hydroxyurea or curaxin treatment and
inhibition of ataxia telangiectasia and Rad3-related protein (ATR)
or p53 inactivation inverted the observed chromatin protein deposition
bias to the strand replicated by the leading strand polymerase in
line with previously reported effects on replication protein A occupancy.
We propose that asymmetric deposition of newly synthesized chromatin
proteins onto sister chromatids reflects differences in the processivity
of leading and lagging strand synthesis.
Collapse
Affiliation(s)
- Martijn R. H. Zwinderman
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Thamar Jessurun Lobo
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Petra E. van der Wouden
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Diana C. J. Spierings
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Marcel A. T. M. van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, 9713 GZ Groningen, The Netherlands
| | - Peter M. Lansdorp
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, V5Z 1L3 British Columbia, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, V6T 1Z4 British Columbia, Canada
| | - Victor Guryev
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, The Netherlands
| | - Frank J. Dekker
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands
| |
Collapse
|
10
|
Spinks RR, Spenkelink LM, Dixon NE, van Oijen AM. Single-Molecule Insights Into the Dynamics of Replicative Helicases. Front Mol Biosci 2021; 8:741718. [PMID: 34513934 PMCID: PMC8426354 DOI: 10.3389/fmolb.2021.741718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/13/2021] [Indexed: 11/13/2022] Open
Abstract
Helicases are molecular motors that translocate along single-stranded DNA and unwind duplex DNA. They rely on the consumption of chemical energy from nucleotide hydrolysis to drive their translocation. Specialized helicases play a critically important role in DNA replication by unwinding DNA at the front of the replication fork. The replicative helicases of the model systems bacteriophages T4 and T7, Escherichia coli and Saccharomyces cerevisiae have been extensively studied and characterized using biochemical methods. While powerful, their averaging over ensembles of molecules and reactions makes it challenging to uncover information related to intermediate states in the unwinding process and the dynamic helicase interactions within the replisome. Here, we describe single-molecule methods that have been developed in the last few decades and discuss the new details that these methods have revealed about replicative helicases. Applying methods such as FRET and optical and magnetic tweezers to individual helicases have made it possible to access the mechanistic aspects of unwinding. It is from these methods that we understand that the replicative helicases studied so far actively translocate and then passively unwind DNA, and that these hexameric enzymes must efficiently coordinate the stepping action of their subunits to achieve unwinding, where the size of each step is prone to variation. Single-molecule fluorescence microscopy methods have made it possible to visualize replicative helicases acting at replication forks and quantify their dynamics using multi-color colocalization, FRAP and FLIP. These fluorescence methods have made it possible to visualize helicases in replication initiation and dissect this intricate protein-assembly process. In a similar manner, single-molecule visualization of fluorescent replicative helicases acting in replication identified that, in contrast to the replicative polymerases, the helicase does not exchange. Instead, the replicative helicase acts as the stable component that serves to anchor the other replication factors to the replisome.
Collapse
Affiliation(s)
- Richard R Spinks
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Lisanne M Spenkelink
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Nicholas E Dixon
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| |
Collapse
|
11
|
Lo CY, Gao Y. DNA Helicase-Polymerase Coupling in Bacteriophage DNA Replication. Viruses 2021; 13:v13091739. [PMID: 34578319 PMCID: PMC8472574 DOI: 10.3390/v13091739] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 12/28/2022] Open
Abstract
Bacteriophages have long been model systems to study the molecular mechanisms of DNA replication. During DNA replication, a DNA helicase and a DNA polymerase cooperatively unwind the parental DNA. By surveying recent data from three bacteriophage replication systems, we summarized the mechanistic basis of DNA replication by helicases and polymerases. Kinetic data have suggested that a polymerase or a helicase alone is a passive motor that is sensitive to the base-pairing energy of the DNA. When coupled together, the helicase-polymerase complex is able to unwind DNA actively. In bacteriophage T7, helicase and polymerase reside right at the replication fork where the parental DNA is separated into two daughter strands. The two motors pull the two daughter strands to opposite directions, while the polymerase provides a separation pin to split the fork. Although independently evolved and containing different replisome components, bacteriophage T4 replisome shares mechanistic features of Hel-Pol coupling that are similar to T7. Interestingly, in bacteriophages with a limited size of genome like Φ29, DNA polymerase itself can form a tunnel-like structure, which encircles the DNA template strand and facilitates strand displacement synthesis in the absence of a helicase. Studies on bacteriophage replication provide implications for the more complicated replication systems in bacteria, archaeal, and eukaryotic systems, as well as the RNA genome replication in RNA viruses.
Collapse
Affiliation(s)
| | - Yang Gao
- Correspondence: ; Tel.: +1-713-348-2619
| |
Collapse
|
12
|
Jarillo J, Ibarra B, Cao-García FJ. DNA replication: In vitro single-molecule manipulation data analysis and models. Comput Struct Biotechnol J 2021; 19:3765-3778. [PMID: 34285777 PMCID: PMC8267548 DOI: 10.1016/j.csbj.2021.06.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 11/05/2022] Open
Abstract
Data analysis allows to extract information from the noisy single-molecule data. Models provide insight in the underlying biochemical processes. Ligands can activate or inhibit DNA replication and DNA unwinding.
DNA replication is a key biochemical process of the cell cycle. In the last years, analysis of in vitro single-molecule DNA replication events has provided new information that cannot be obtained with ensembles studies. Here, we introduce crucial techniques for the proper analysis and modelling of DNA replication in vitro single-molecule manipulation data. Specifically, we review some of the main methods to analyze and model the real-time kinetics of the two main molecular motors of the replisome: DNA polymerase and DNA helicase. Our goal is to facilitate access to and understanding of these techniques to promotetheir use in the study of DNA replication at the single-molecule level. A proper analysis of single-molecule data is crucial to obtain a detailed picture of, among others, the kinetics rates, equilibrium contants and conformational changes of the system under study. The techniques presented here have been used or can be adapted to study the operation of other proteins involved in nucleic acids metabolism.
Collapse
Affiliation(s)
- Javier Jarillo
- University of Namur, Institute of Life-Earth-Environment, Namur Center for Complex Systems, Rue de Bruxelles 61, 5000 Namur, Belgium
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, C/ Faraday 9, 28049 Madrid, Spain
| | - Francisco Javier Cao-García
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, C/ Faraday 9, 28049 Madrid, Spain.,Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| |
Collapse
|
13
|
Bocanegra R, Ismael Plaza GA, Pulido CR, Ibarra B. DNA replication machinery: Insights from in vitro single-molecule approaches. Comput Struct Biotechnol J 2021; 19:2057-2069. [PMID: 33995902 PMCID: PMC8085672 DOI: 10.1016/j.csbj.2021.04.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/03/2021] [Accepted: 04/03/2021] [Indexed: 11/16/2022] Open
Abstract
The replisome is the multiprotein molecular machinery that replicates DNA. The replisome components work in precise coordination to unwind the double helix of the DNA and replicate the two strands simultaneously. The study of DNA replication using in vitro single-molecule approaches provides a novel quantitative understanding of the dynamics and mechanical principles that govern the operation of the replisome and its components. ‘Classical’ ensemble-averaging methods cannot obtain this information. Here we describe the main findings obtained with in vitro single-molecule methods on the performance of individual replisome components and reconstituted prokaryotic and eukaryotic replisomes. The emerging picture from these studies is that of stochastic, versatile and highly dynamic replisome machinery in which transient protein-protein and protein-DNA associations are responsible for robust DNA replication.
Collapse
Affiliation(s)
- Rebeca Bocanegra
- IMDEA Nanociencia, Faraday 9, Campus Cantoblanco, 28049 Madrid, Spain
| | - G A Ismael Plaza
- IMDEA Nanociencia, Faraday 9, Campus Cantoblanco, 28049 Madrid, Spain
| | - Carlos R Pulido
- IMDEA Nanociencia, Faraday 9, Campus Cantoblanco, 28049 Madrid, Spain
| | - Borja Ibarra
- IMDEA Nanociencia, Faraday 9, Campus Cantoblanco, 28049 Madrid, Spain
| |
Collapse
|
14
|
Singh A, Pandey M, Nandakumar D, Raney KD, Yin YW, Patel SS. Excessive excision of correct nucleotides during DNA synthesis explained by replication hurdles. EMBO J 2020; 39:e103367. [PMID: 32037587 PMCID: PMC7073461 DOI: 10.15252/embj.2019103367] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 12/23/2019] [Accepted: 01/07/2020] [Indexed: 11/25/2022] Open
Abstract
The proofreading exonuclease activity of replicative DNA polymerase excises misincorporated nucleotides during DNA synthesis, but these events are rare. Therefore, we were surprised to find that T7 replisome excised nearly 7% of correctly incorporated nucleotides during leading and lagging strand syntheses. Similar observations with two other DNA polymerases establish its generality. We show that excessive excision of correctly incorporated nucleotides is not due to events such as processive degradation of nascent DNA or spontaneous partitioning of primer‐end to the exonuclease site as a “cost of proofreading”. Instead, we show that replication hurdles, including secondary structures in template, slowed helicase, or uncoupled helicase–polymerase, increase DNA reannealing and polymerase backtracking, and generate frayed primer‐ends that are shuttled to the exonuclease site and excised efficiently. Our studies indicate that active‐site shuttling occurs at a high frequency, and we propose that it serves as a proofreading mechanism to protect primer‐ends from mutagenic extensions.
Collapse
Affiliation(s)
- Anupam Singh
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
| | - Manjula Pandey
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
| | - Divya Nandakumar
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
| | - Kevin D Raney
- Department of Biochemistry and Molecular Biology, The University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Y Whitney Yin
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX, USA
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
| |
Collapse
|
15
|
Zou Z, Liang T, Xu Z, Xie J, Zhang S, Chen W, Wan S, Ling Y, Zhang H. Protein interactions in T7 DNA replisome inhibit the bypass of abasic site by DNA polymerase. Mutagenesis 2019; 34:355-361. [PMID: 31318416 DOI: 10.1093/mutage/gez013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 05/14/2019] [Indexed: 11/13/2022] Open
Abstract
Abasic site as a common DNA lesion blocks DNA replication and is highly mutagenic. Protein interactions in T7 DNA replisome facilitate DNA replication and translesion DNA synthesis. However, bypass of an abasic site by T7 DNA replisome has never been investigated. In this work, we used T7 DNA replisome and T7 DNA polymerase alone as two models to study DNA replication on encountering an abasic site. Relative to unmodified DNA, abasic site strongly inhibited primer extension and completely blocked strand-displacement DNA synthesis, due to the decreased fraction of enzyme-DNA productive complex and the reduced average extension rates. Moreover, abasic site at DNA fork inhibited the binding of DNA polymerase or helicase onto fork and the binding between polymerase and helicase at fork. Notably and unexpectedly, we found DNA polymerase alone bypassed an abasic site on primer/template (P/T) substrate more efficiently than did polymerase and helicase complex bypass it at fork. The presence of gp2.5 further inhibited the abasic site bypass at DNA fork. Kinetic analysis showed that this inhibition at fork relative to that on P/T was due to the decreased fraction of productive complex instead of the average extension rates. Therefore, we found that protein interactions in T7 DNA replisome inhibited the bypass of DNA lesion, different from all the traditional concept that protein interactions or accessory proteins always promote DNA replication and DNA damage bypass, providing new insights in translesion DNA synthesis performed by DNA replisome.
Collapse
Affiliation(s)
- Zhenyu Zou
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Tingting Liang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Zhongyan Xu
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Jiayu Xie
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Shuming Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Weina Chen
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Siqi Wan
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Yihui Ling
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou, China
| | - Huidong Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China.,The Key Laboratory of Environment and Health Among Universities and Colleges in Fujian, School of Public Health, Fujian Medical University, Fuzhou, China
| |
Collapse
|
16
|
Cerrón F, de Lorenzo S, Lemishko KM, Ciesielski GL, Kaguni LS, Cao FJ, Ibarra B. Replicative DNA polymerases promote active displacement of SSB proteins during lagging strand synthesis. Nucleic Acids Res 2019; 47:5723-5734. [PMID: 30968132 PMCID: PMC6582349 DOI: 10.1093/nar/gkz249] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 03/22/2019] [Accepted: 03/29/2019] [Indexed: 11/23/2022] Open
Abstract
Genome replication induces the generation of large stretches of single-stranded DNA (ssDNA) intermediates that are rapidly protected by single-stranded DNA-binding (SSB) proteins. To date, the mechanism by which tightly bound SSBs are removed from ssDNA by the lagging strand DNA polymerase without compromising the advance of the replication fork remains unresolved. Here, we aimed to address this question by measuring, with optical tweezers, the real-time replication kinetics of the human mitochondrial and bacteriophage T7 DNA polymerases on free-ssDNA, in comparison with ssDNA covered with homologous and non-homologous SSBs under mechanical tension. We find important differences between the force dependencies of the instantaneous replication rates of each polymerase on different substrates. Modeling of the data supports a mechanism in which strong, specific polymerase-SSB interactions, up to ∼12 kBT, are required for the polymerase to dislodge SSB from the template without compromising its instantaneous replication rate, even under stress conditions that may affect SSB–DNA organization and/or polymerase–SSB communication. Upon interaction, the elimination of template secondary structure by SSB binding facilitates the maximum replication rate of the lagging strand polymerase. In contrast, in the absence of polymerase–SSB interactions, SSB poses an effective barrier for the advance of the polymerase, slowing down DNA synthesis.
Collapse
Affiliation(s)
- Fernando Cerrón
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Departamento Estructura de la Materia, Física Térmica y Electrónica. Universidad Complutense. 28040 Madrid, Spain
| | - Sara de Lorenzo
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain
| | - Kateryna M Lemishko
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit "Unidad de Nanobiotecnología". 28049 Madrid, Spain
| | - Grzegorz L Ciesielski
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Laurie S Kaguni
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Francisco J Cao
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Departamento Estructura de la Materia, Física Térmica y Electrónica. Universidad Complutense. 28040 Madrid, Spain
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia. 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit "Unidad de Nanobiotecnología". 28049 Madrid, Spain
| |
Collapse
|
17
|
Schlierf M, Wang G, Chen XS, Ha T. Hexameric helicase G40P unwinds DNA in single base pair steps. eLife 2019; 8:42001. [PMID: 30688211 PMCID: PMC6370340 DOI: 10.7554/elife.42001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 01/21/2019] [Indexed: 01/06/2023] Open
Abstract
Most replicative helicases are hexameric, ring-shaped motor proteins that translocate on and unwind DNA. Despite extensive biochemical and structural investigations, how their translocation activity is utilized chemo-mechanically in DNA unwinding is poorly understood. We examined DNA unwinding by G40P, a DnaB-family helicase, using a single-molecule fluorescence assay with a single base pair resolution. The high-resolution assay revealed that G40P by itself is a very weak helicase that stalls at barriers as small as a single GC base pair and unwinds DNA with the step size of a single base pair. Binding of a single ATPγS could stall unwinding, demonstrating highly coordinated ATP hydrolysis between six identical subunits. We observed frequent slippage of the helicase, which is fully suppressed by the primase DnaG. We anticipate that these findings allow a better understanding on the fine balance of thermal fluctuation activation and energy derived from hydrolysis. Living cells store their genetic code written in molecules of DNA, with two strands of DNA twisted together to form the familiar double helix. When a cell prepares to divide, it must unwind its DNA so that the individual strands can be copied. Enzymes known as DNA helicases play a vital role in this unwinding process; yet, it is not completely clear how these enzymes move along the DNA. Schlierf et al. have now developed a new approach to see how an individual DNA helicase called G40P unwinds the DNA double helix. The experiments used a molecular ruler to measure the DNA unwinding and showed that the helicase opened the double helix one letter of genetic code at a time. Also, specific sequence of letters within the DNA molecules could slow down and stop G40P or even cause it to move backwards. DNA helicases work closely with other proteins inside cells to perform their task. DNA primases, for example, are enzymes that create the starting points for making new strands of DNA. Schlierf et al. found that the primase DnaG could also prevent G40P from moving backwards on the DNA, a new and unexpected function of DnaG. These findings contribute to an ongoing debate among researchers with partially contradictory models for how DNA helicases unwind the DNA double helix. Although originally from a virus, G40P is similar to a helicase enzyme found in bacteria. Therefore, a better understanding of this helicase may lead to new ways to stop bacteria copying their DNA, which might one day become new antibiotics to treat bacterial infections.
Collapse
Affiliation(s)
- Michael Schlierf
- Physics Department and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Illinois, United States.,B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany
| | - Ganggang Wang
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Xiaojiang S Chen
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, United States
| | - Taekjip Ha
- Physics Department and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Illinois, United States.,Howard Hughes Medical Institute, Baltimore, United States.,Department of Biophysics and Biophysical Chemistry, Johns Hopkins University, Baltimore, United States.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, United States.,Department of Biophysics, Johns Hopkins University, Baltimore, United States
| |
Collapse
|
18
|
Gao Y, Cui Y, Fox T, Lin S, Wang H, de Val N, Zhou ZH, Yang W. Structures and operating principles of the replisome. Science 2019; 363:science.aav7003. [PMID: 30679383 DOI: 10.1126/science.aav7003] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 01/13/2019] [Indexed: 12/12/2022]
Abstract
Visualization in atomic detail of the replisome that performs concerted leading- and lagging-DNA strand synthesis at a replication fork has not been reported. Using bacteriophage T7 as a model system, we determined cryo-electron microscopy structures up to 3.2-angstroms resolution of helicase translocating along DNA and of helicase-polymerase-primase complexes engaging in synthesis of both DNA strands. Each domain of the spiral-shaped hexameric helicase translocates sequentially hand-over-hand along a single-stranded DNA coil, akin to the way AAA+ ATPases (adenosine triphosphatases) unfold peptides. Two lagging-strand polymerases are attached to the primase, ready for Okazaki fragment synthesis in tandem. A β hairpin from the leading-strand polymerase separates two parental DNA strands into a T-shaped fork, thus enabling the closely coupled helicase to advance perpendicular to the downstream DNA duplex. These structures reveal the molecular organization and operating principles of a replisome.
Collapse
Affiliation(s)
- Yang Gao
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yanxiang Cui
- The California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Tara Fox
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.,Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Shiqiang Lin
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Huaibin Wang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Natalia de Val
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.,Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research Inc., Frederick, MD 21701, USA
| | - Z Hong Zhou
- The California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
| | - Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
19
|
Zou Z, Chen Z, Xue Q, Xu Y, Xiong J, Yang P, Le S, Zhang H. Protein Interactions in the T7 DNA Replisome Facilitate DNA Damage Bypass. Chembiochem 2018; 19:1740-1749. [PMID: 29900646 DOI: 10.1002/cbic.201800203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Indexed: 01/07/2023]
Abstract
The DNA replisome inevitably encounters DNA damage during DNA replication. The T7 DNA replisome contains a DNA polymerase (gp5), the processivity factor thioredoxin (trx), a helicase-primase (gp4), and a ssDNA-binding protein (gp2.5). T7 protein interactions mediate this DNA replication. However, whether the protein interactions could promote DNA damage bypass is still little addressed. In this study, we investigated strand-displacement DNA synthesis past 8-oxoG or O6 -MeG lesions at the synthetic DNA fork by the T7 DNA replisome. DNA damage does not obviously affect the binding affinities between helicase, polymerase, and DNA fork. Relative to unmodified G, both 8-oxoG and O6 -MeG-as well as GC-rich template sequence clusters-inhibit strand-displacement DNA synthesis and produce partial extension products. Relative to the gp4 ΔC-tail, gp4 promotes DNA damage bypass. The presence of gp2.5 also promotes it. Thus, the interactions of polymerase with helicase and ssDNA-binding protein facilitate DNA damage bypass. Accessory proteins in other complicated DNA replisomes also facilitate bypassing DNA damage in similar manner. This work provides new mechanistic information relating to DNA damage bypass by the DNA replisome.
Collapse
Affiliation(s)
- Zhenyu Zou
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Ze Chen
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Qizhen Xue
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Ying Xu
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Jingyuan Xiong
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| | - Ping Yang
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou, 511439, P. R. China
| | - Shuai Le
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, P. R. China
| | - Huidong Zhang
- Public Health Laboratory Sciences and Toxicology, West China School of Public Health, Sichuan University, No.17 People's South Road, Chengdu, 6100041, P. R. China
| |
Collapse
|
20
|
Helicase promotes replication re-initiation from an RNA transcript. Nat Commun 2018; 9:2306. [PMID: 29899338 PMCID: PMC5997990 DOI: 10.1038/s41467-018-04702-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 04/30/2018] [Indexed: 11/12/2022] Open
Abstract
To ensure accurate DNA replication, a replisome must effectively overcome numerous obstacles on its DNA substrate. After encountering an obstacle, a progressing replisome often aborts DNA synthesis but continues to unwind. However, little is known about how DNA synthesis is resumed downstream of an obstacle. Here, we examine the consequences of a non-replicating replisome collision with a co-directional RNA polymerase (RNAP). Using single-molecule and ensemble methods, we find that T7 helicase interacts strongly with a non-replicating T7 DNA polymerase (DNAP) at a replication fork. As the helicase advances, the associated DNAP also moves forward. The presence of the DNAP increases both helicase’s processivity and unwinding rate. We show that such a DNAP, together with its helicase, is indeed able to actively disrupt a stalled transcription elongation complex, and then initiates replication using the RNA transcript as a primer. These observations exhibit T7 helicase’s novel role in replication re-initiation. During DNA replication, replicative helicases play an essential role for DNA unwinding to occur. Here the authors find that bacteriophage T7 helicase is also involved in replication re-initiation by interacting with a non-replicating DNAP and increasing unwinding rate.
Collapse
|
21
|
Trakselis MA, Cranford MT, Chu AM. Coordination and Substitution of DNA Polymerases in Response to Genomic Obstacles. Chem Res Toxicol 2017; 30:1956-1971. [PMID: 28881136 DOI: 10.1021/acs.chemrestox.7b00190] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability for DNA polymerases (Pols) to overcome a variety of obstacles in its path to maintain genomic stability during replication is a complex endeavor. It requires the coordination of multiple Pols with differing specificities through molecular control and access to the replisome. Although a number of contacts directly between Pols and accessory proteins have been identified, forming the basis of a variety of holoenzyme complexes, the dynamics of Pol active site substitutions remain uncharacterized. Substitutions can occur externally by recruiting new Pols to replisome complexes through an "exchange" of enzyme binding or internally through a "switch" in the engagement of DNA from preformed associated enzymes contained within supraholoenzyme complexes. Models for how high fidelity (HiFi) replication Pols can be substituted by translesion synthesis (TLS) Pols at sites of damage during active replication will be discussed. These substitution mechanisms may be as diverse as the number of Pol families and types of damage; however, common themes can be recognized across species. Overall, Pol substitutions will be controlled by explicit protein contacts, complex multiequilibrium processes, and specific kinetic activities. Insight into how these dynamic processes take place and are regulated will be of utmost importance for our greater understanding of the specifics of TLS as well as providing for future novel chemotherapeutic and antimicrobial strategies.
Collapse
Affiliation(s)
- Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Matthew T Cranford
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Aurea M Chu
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| |
Collapse
|
22
|
Hodeib S, Raj S, Manosas M, Zhang W, Bagchi D, Ducos B, Fiorini F, Kanaan J, Le Hir H, Allemand J, Bensimon D, Croquette V. A mechanistic study of helicases with magnetic traps. Protein Sci 2017; 26:1314-1336. [PMID: 28474797 PMCID: PMC5477542 DOI: 10.1002/pro.3187] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 04/29/2017] [Accepted: 05/02/2017] [Indexed: 01/08/2023]
Abstract
Helicases are a broad family of enzymes that separate nucleic acid double strand structures (DNA/DNA, DNA/RNA, or RNA/RNA) and thus are essential to DNA replication and the maintenance of nucleic acid integrity. We review the picture that has emerged from single molecule studies of the mechanisms of DNA and RNA helicases and their interactions with other proteins. Many features have been uncovered by these studies that were obscured by bulk studies, such as DNA strands switching, mechanical (rather than biochemical) coupling between helicases and polymerases, helicase-induced re-hybridization and stalled fork rescue.
Collapse
Affiliation(s)
- Samar Hodeib
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - Saurabh Raj
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - Maria Manosas
- Departament de Física FonamentalFacultat de Física, Universitat de BarcelonaBarcelona08028Spain
- CIBER‐BBN de BioingenieriaBiomateriales y Nanomedicina, Instituto de Sanidad Carlos IIIMadridSpain
| | - Weiting Zhang
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - Debjani Bagchi
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
- Present address: Physics DepartmentFaculty of Science, The M.S. University of BarodaVadodaraGujarat390002India
| | - Bertrand Ducos
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - Francesca Fiorini
- Univ Lyon, Molecular Microbiology and Structural Biochemistry, MMSB‐IBCP UMR5086 CNRS/Lyon1Lyon Cedex 769367France
| | - Joanne Kanaan
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - Hervé Le Hir
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - Jean‐François Allemand
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| | - David Bensimon
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
- Department of Chemistry and BiochemistryUniversity of California Los AngelesLos AngelesCalifornia90095
| | - Vincent Croquette
- Laboratoire de physique statistiqueDépartement de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS75005ParisFrance
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS)Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University75005ParisFrance
| |
Collapse
|
23
|
Cryo-EM structure of the replisome reveals multiple interactions coordinating DNA synthesis. Proc Natl Acad Sci U S A 2017; 114:E1848-E1856. [PMID: 28223502 DOI: 10.1073/pnas.1701252114] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We present a structure of the ∼650-kDa functional replisome of bacteriophage T7 assembled on DNA resembling a replication fork. A structure of the complex consisting of six domains of DNA helicase, five domains of RNA primase, two DNA polymerases, and two thioredoxin (processivity factor) molecules was determined by single-particle cryo-electron microscopy. The two molecules of DNA polymerase adopt a different spatial arrangement at the replication fork, reflecting their roles in leading- and lagging-strand synthesis. The structure, in combination with biochemical data, reveals molecular mechanisms for coordination of leading- and lagging-strand synthesis. Because mechanisms of DNA replication are highly conserved, the observations are relevant to other replication systems.
Collapse
|
24
|
Chang HW, Pandey M, Kulaeva OI, Patel SS, Studitsky VM. Overcoming a nucleosomal barrier to replication. SCIENCE ADVANCES 2016; 2:e1601865. [PMID: 27847876 PMCID: PMC5106197 DOI: 10.1126/sciadv.1601865] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/11/2016] [Indexed: 05/05/2023]
Abstract
Efficient overcoming and accurate maintenance of chromatin structure and associated histone marks during DNA replication are essential for normal functioning of the daughter cells. However, the molecular mechanisms of replication through chromatin are unknown. We have studied traversal of uniquely positioned mononucleosomes by T7 replisome in vitro. Nucleosomes present a strong, sequence-dependent barrier for replication, with particularly strong pausing of DNA polymerase at the +(31-40) and +(41-65) regions of the nucleosomal DNA. The exonuclease activity of T7 DNA polymerase increases the overall rate of progression of the replisome through a nucleosome, likely by resolving nonproductive complexes. The presence of nucleosome-free DNA upstream of the replication fork facilitates the progression of DNA polymerase through the nucleosome. After replication, at least 50% of the nucleosomes assume an alternative conformation, maintaining their original positions on the DNA. Our data suggest a previously unpublished mechanism for nucleosome maintenance during replication, likely involving transient formation of an intranucleosomal DNA loop.
Collapse
Affiliation(s)
- Han-Wen Chang
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Manjula Pandey
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | | | - Smita S. Patel
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
- Corresponding author. (S.S.P.); (V.M.S.)
| | - Vasily M. Studitsky
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
- Corresponding author. (S.S.P.); (V.M.S.)
| |
Collapse
|
25
|
The excluded DNA strand is SEW important for hexameric helicase unwinding. Methods 2016; 108:79-91. [DOI: 10.1016/j.ymeth.2016.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/07/2016] [Accepted: 04/07/2016] [Indexed: 02/04/2023] Open
|
26
|
Ganai RA, Zhang XP, Heyer WD, Johansson E. Strand displacement synthesis by yeast DNA polymerase ε. Nucleic Acids Res 2016; 44:8229-40. [PMID: 27325747 PMCID: PMC5041465 DOI: 10.1093/nar/gkw556] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/09/2016] [Indexed: 11/30/2022] Open
Abstract
DNA polymerase ε (Pol ε) is a replicative DNA polymerase with an associated 3′–5′ exonuclease activity. Here, we explored the capacity of Pol ε to perform strand displacement synthesis, a process that influences many DNA transactions in vivo. We found that Pol ε is unable to carry out extended strand displacement synthesis unless its 3′–5′ exonuclease activity is removed. However, the wild-type Pol ε holoenzyme efficiently displaced one nucleotide when encountering double-stranded DNA after filling a gap or nicked DNA. A flap, mimicking a D-loop or a hairpin structure, on the 5′ end of the blocking primer inhibited Pol ε from synthesizing DNA up to the fork junction. This inhibition was observed for Pol ε but not with Pol δ, RB69 gp43 or Pol η. Neither was Pol ε able to extend a D-loop in reconstitution experiments. Finally, we show that the observed strand displacement synthesis by exonuclease-deficient Pol ε is distributive. Our results suggest that Pol ε is unable to extend the invading strand in D-loops during homologous recombination or to add more than two nucleotides during long-patch base excision repair. Our results support the hypothesis that Pol ε participates in short-patch base excision repair and ribonucleotide excision repair.
Collapse
Affiliation(s)
- Rais A Ganai
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, NY 10016, USA
| | - Xiao-Ping Zhang
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616-8665, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616-8665, USA
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| |
Collapse
|
27
|
Nandakumar D, Patel SS. Methods to study the coupling between replicative helicase and leading-strand DNA polymerase at the replication fork. Methods 2016; 108:65-78. [PMID: 27173619 DOI: 10.1016/j.ymeth.2016.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/05/2016] [Accepted: 05/06/2016] [Indexed: 01/26/2023] Open
Abstract
Replicative helicases work closely with the replicative DNA polymerases to ensure that the genomic DNA is copied in a timely and error free manner. In the replisomes of prokaryotes, mitochondria, and eukaryotes, the helicase and DNA polymerase enzymes are functionally and physically coupled at the leading strand replication fork and rely on each other for optimal DNA strand separation and synthesis activities. In this review, we describe pre-steady state kinetic methods to quantify the base pair unwinding-synthesis rate constant, a fundamental parameter to understand how the helicase and polymerase help each other during leading strand replication. We describe a robust method to measure the chemical step size of the helicase-polymerase complex that determines how the two motors are energetically coupled while tracking along the DNA. The 2-aminopurine fluorescence-based method provide structural information on the leading strand helicase-polymerase complex, such as the distance between the two enzymes, their relative positions at the replication fork, and their roles in fork junction melting. The combined information garnered from these methods informs on the mutual dependencies between the helicase and DNA polymerase enzymes, their stepping mechanism, and their individual functions at the replication fork during leading strand replication.
Collapse
Affiliation(s)
- Divya Nandakumar
- Department of Biochemistry and Molecular Biology, Rutgers, Robert Wood Johnson Medical School, 683 Hoes Lane West, Piscataway 08854, NJ, USA
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers, Robert Wood Johnson Medical School, 683 Hoes Lane West, Piscataway 08854, NJ, USA.
| |
Collapse
|
28
|
The role of ATP-dependent machines in regulating genome topology. Curr Opin Struct Biol 2016; 36:85-96. [PMID: 26827284 DOI: 10.1016/j.sbi.2016.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/08/2016] [Accepted: 01/12/2016] [Indexed: 11/22/2022]
Abstract
All cells must copy and express genes in accord with internal and external cues. The proper timing and response of such events relies on the active control of higher-order genomic organization. Cells use ATP-dependent molecular machines to alter the local and global topology of DNA so as to promote and counteract the persistent effects of transcription and replication. X-ray crystallography and electron microscopy, coupled with biochemical and single molecule methods are continuing to provide a wealth of mechanistic information on how DNA remodeling factors are employed to dynamically shape and organize the genome.
Collapse
|
29
|
Abstract
Hexameric helicases control both the initiation and the elongation phase of DNA replication. The toroidal structure of these enzymes provides an inherent challenge in the opening and loading onto DNA at origins, as well as the conformational changes required to exclude one strand from the central channel and activate DNA unwinding. Recently, high-resolution structures have not only revealed the architecture of various hexameric helicases but also detailed the interactions of DNA within the central channel, as well as conformational changes that occur during loading. This structural information coupled with advanced biochemical reconstitutions and biophysical methods have transformed our understanding of the dynamics of both the helicase structure and the DNA interactions required for efficient unwinding at the replisome.
Collapse
Affiliation(s)
- Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA
| |
Collapse
|
30
|
Sun B, Pandey M, Inman JT, Yang Y, Kashlev M, Patel SS, Wang MD. T7 replisome directly overcomes DNA damage. Nat Commun 2015; 6:10260. [PMID: 26675048 PMCID: PMC4703881 DOI: 10.1038/ncomms10260] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 11/22/2015] [Indexed: 11/09/2022] Open
Abstract
Cells and viruses possess several known ‘restart' pathways to overcome lesions during DNA replication. However, these ‘bypass' pathways leave a gap in replicated DNA or require recruitment of accessory proteins, resulting in significant delays to fork movement or even cell division arrest. Using single-molecule and ensemble methods, we demonstrate that the bacteriophage T7 replisome is able to directly replicate through a leading-strand cyclobutane pyrimidine dimer (CPD) lesion. We show that when a replisome encounters the lesion, a substantial fraction of DNA polymerase (DNAP) and helicase stay together at the lesion, the replisome does not dissociate and the helicase does not move forward on its own. The DNAP is able to directly replicate through the lesion by working in conjunction with helicase through specific helicase–DNAP interactions. These observations suggest that the T7 replisome is fundamentally permissive of DNA lesions via pathways that do not require fork adjustment or replisome reassembly. Genomic instability can result from stalled or collapsed replication fork at sites of unrepaired DNA lesions. Here the authors uncover a new lesion bypass pathway for the T7 replisome, where leading strand template lesions can be overcome through interaction between the replisome's helicase and polymerase components.
Collapse
Affiliation(s)
- Bo Sun
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.,Howard Hughes Medical Institute, Cornell University, Ithaca, New York 14853, USA.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Manjula Pandey
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | - James T Inman
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.,Howard Hughes Medical Institute, Cornell University, Ithaca, New York 14853, USA
| | - Yi Yang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.,Howard Hughes Medical Institute, Cornell University, Ithaca, New York 14853, USA
| | - Mikhail Kashlev
- NCI Center for Cancer Research, Frederick, Maryland 21702, USA
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | - Michelle D Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.,Howard Hughes Medical Institute, Cornell University, Ithaca, New York 14853, USA
| |
Collapse
|
31
|
Pandey M, Elshenawy MM, Jergic S, Takahashi M, Dixon NE, Hamdan SM, Patel SS. Two mechanisms coordinate replication termination by the Escherichia coli Tus-Ter complex. Nucleic Acids Res 2015; 43:5924-35. [PMID: 26007657 PMCID: PMC4499146 DOI: 10.1093/nar/gkv527] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/10/2015] [Indexed: 11/28/2022] Open
Abstract
The Escherichia coli replication terminator protein (Tus) binds to Ter sequences to block replication forks approaching from one direction. Here, we used single molecule and transient state kinetics to study responses of the heterologous phage T7 replisome to the Tus–Ter complex. The T7 replisome was arrested at the non-permissive end of Tus–Ter in a manner that is explained by a composite mousetrap and dynamic clamp model. An unpaired C(6) that forms a lock by binding into the cytosine binding pocket of Tus was most effective in arresting the replisome and mutation of C(6) removed the barrier. Isolated helicase was also blocked at the non-permissive end, but unexpectedly the isolated polymerase was not, unless C(6) was unpaired. Instead, the polymerase was blocked at the permissive end. This indicates that the Tus–Ter mechanism is sensitive to the translocation polarity of the DNA motor. The polymerase tracking along the template strand traps the C(6) to prevent lock formation; the helicase tracking along the other strand traps the complementary G(6) to aid lock formation. Our results are consistent with the model where strand separation by the helicase unpairs the GC(6) base pair and triggers lock formation immediately before the polymerase can sequester the C(6) base.
Collapse
Affiliation(s)
- Manjula Pandey
- Department of Biochemistry and Molecular Biology, Rutgers, the State University of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Mohamed M Elshenawy
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Slobodan Jergic
- Centre for Medical and Molecular Bioscience, University of Wollongong, New South Wales 2522, Australia
| | - Masateru Takahashi
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Nicholas E Dixon
- Centre for Medical and Molecular Bioscience, University of Wollongong, New South Wales 2522, Australia
| | - Samir M Hamdan
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers, the State University of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| |
Collapse
|
32
|
Nandakumar D, Pandey M, Patel SS. Cooperative base pair melting by helicase and polymerase positioned one nucleotide from each other. eLife 2015; 4. [PMID: 25970034 PMCID: PMC4460406 DOI: 10.7554/elife.06562] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 05/13/2015] [Indexed: 12/19/2022] Open
Abstract
Leading strand DNA synthesis requires functional coupling between replicative helicase and DNA polymerase (DNAP) enzymes, but the structural and mechanistic basis of coupling is poorly understood. This study defines the precise positions of T7 helicase and T7 DNAP at the replication fork junction with single-base resolution to create a structural model that explains the mutual stimulation of activities. Our 2-aminopurine studies show that helicase and polymerase both participate in DNA melting, but each enzyme melts the junction base pair partially. When combined, the junction base pair is melted cooperatively provided the helicase is located one nucleotide ahead of the primer-end. The synergistic shift in equilibrium of junction base pair melting by combined enzymes explains the cooperativity, wherein helicase stimulates the polymerase by promoting dNTP binding (decreasing dNTP Km), polymerase stimulates the helicase by increasing the unwinding rate-constant (kcat), consequently the combined enzymes unwind DNA with kinetic parameters resembling enzymes translocating on single-stranded DNA. DOI:http://dx.doi.org/10.7554/eLife.06562.001 DNA replication is the process whereby a molecule of DNA is copied to form two identical molecules. First, an enzyme called a DNA helicase separates the two strands of the DNA double helix. This forms a structure called a replication fork that has two exposed single strands. Other enzymes called DNA polymerases then use each strand as a template to build a new matching DNA strand. DNA polymerases build the new DNA strands by joining together smaller molecules called nucleotides. One of the new DNA strands—called the ‘leading strand’—is built continuously, while the other—the ‘lagging strand’—is made as a series of short fragments that are later joined together. Building the leading strand requires the helicase and DNA polymerase to work closely together. However, it was not clear how these two enzymes coordinate their activity. Now, Nandakumar et al. have studied the helicase and DNA polymerase from a virus that infects bacteria and have pinpointed the exact positions of the enzymes at a replication fork. The experiments revealed that both the polymerase and helicase contribute to the separating of the DNA strands, and that this process is most efficient when the helicase is only a single nucleotide ahead of the polymerase. Further experiments showed that the helicase stimulates the polymerase by helping it to bind to nucleotides, and that the polymerase stimulates the helicase by helping it to separate the DNA strands at a faster rate. The next challenge is to investigate the molecular setup that allows the helicase and polymerase to increase each other's activities. DOI:http://dx.doi.org/10.7554/eLife.06562.002
Collapse
Affiliation(s)
- Divya Nandakumar
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, United States
| | - Manjula Pandey
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, United States
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, United States
| |
Collapse
|
33
|
Morin JA, Cao FJ, Lázaro JM, Arias-Gonzalez JR, Valpuesta JM, Carrascosa JL, Salas M, Ibarra B. Mechano-chemical kinetics of DNA replication: identification of the translocation step of a replicative DNA polymerase. Nucleic Acids Res 2015; 43:3643-52. [PMID: 25800740 PMCID: PMC4402526 DOI: 10.1093/nar/gkv204] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/14/2015] [Accepted: 02/27/2015] [Indexed: 11/25/2022] Open
Abstract
During DNA replication replicative polymerases move in discrete mechanical steps along the DNA template. To address how the chemical cycle is coupled to mechanical motion of the enzyme, here we use optical tweezers to study the translocation mechanism of individual bacteriophage Phi29 DNA polymerases during processive DNA replication. We determine the main kinetic parameters of the nucleotide incorporation cycle and their dependence on external load and nucleotide (dNTP) concentration. The data is inconsistent with power stroke models for translocation, instead supports a loose-coupling mechanism between chemical catalysis and mechanical translocation during DNA replication. According to this mechanism the DNA polymerase works by alternating between a dNTP/PPi-free state, which diffuses thermally between pre- and post-translocated states, and a dNTP/PPi-bound state where dNTP binding stabilizes the post-translocated state. We show how this thermal ratchet mechanism is used by the polymerase to generate work against large opposing loads (∼50 pN).
Collapse
Affiliation(s)
- José A Morin
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, 28049 Madrid, Spain
| | - Francisco J Cao
- Departamento Física Atómica, Molecular y Nuclear, Universidad Complutense, 28040 Madrid, Spain
| | - José M Lázaro
- Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - J Ricardo Arias-Gonzalez
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit 'Unidad de Nanobiotecnología', 28049 Madrid, Spain
| | - José M Valpuesta
- Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - José L Carrascosa
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit 'Unidad de Nanobiotecnología', 28049 Madrid, Spain Centro Nacional de Biotecnología (CNB-CSIC), 28049 Madrid, Spain
| | - Margarita Salas
- Centro de Biología Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia) & CNB-CSIC-IMDEA Nanociencia Associated Unit 'Unidad de Nanobiotecnología', 28049 Madrid, Spain
| |
Collapse
|
34
|
Ma W, Schulten K. Mechanism of substrate translocation by a ring-shaped ATPase motor at millisecond resolution. J Am Chem Soc 2015; 137:3031-40. [PMID: 25646698 PMCID: PMC4393844 DOI: 10.1021/ja512605w] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ring-shaped, hexameric ATPase motors fulfill key functions in cellular processes, such as genome replication, transcription, or protein degradation, by translocating a long substrate through their central pore powered by ATP hydrolysis. Despite intense research efforts, the atomic-level mechanism transmitting chemical energy from hydrolysis into mechanical force that translocates the substrate is still unclear. Here we employ all-atom molecular dynamics simulations combined with advanced path sampling techniques and milestoning analysis to characterize how mRNA substrate is translocated by an exemplary homohexameric motor, the transcription termination factor Rho. We find that the release of hydrolysis product (ADP + Pi) triggers the force-generating process of Rho through a 0.1 millisecond-long conformational transition, the time scale seen also in experiment. The calculated free energy profiles and kinetics show that Rho unidirectionally translocates the single-stranded RNA substrate via a population shift of the conformational states of Rho; upon hydrolysis product release, the most favorable conformation shifts from the pretranslocation state to the post-translocation state. Via two previously unidentified intermediate states, the RNA chain is seen to be pulled by six K326 side chains, whose motions are induced by highly coordinated relative translation and rotation of Rho's six subunits. The present study not only reveals in new detail the mechanism employed by ring-shaped ATPase motors, for example the use of loosely bound and tightly bound hydrolysis reactant and product states to coordinate motor action, but also provides an effective approach to identify allosteric sites of multimeric enzymes in general.
Collapse
|
35
|
Bharti SK, Sommers JA, Zhou J, Kaplan DL, Spelbrink JN, Mergny JL, Brosh RM. DNA sequences proximal to human mitochondrial DNA deletion breakpoints prevalent in human disease form G-quadruplexes, a class of DNA structures inefficiently unwound by the mitochondrial replicative Twinkle helicase. J Biol Chem 2014; 289:29975-93. [PMID: 25193669 DOI: 10.1074/jbc.m114.567073] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mitochondrial DNA deletions are prominent in human genetic disorders, cancer, and aging. It is thought that stalling of the mitochondrial replication machinery during DNA synthesis is a prominent source of mitochondrial genome instability; however, the precise molecular determinants of defective mitochondrial replication are not well understood. In this work, we performed a computational analysis of the human mitochondrial genome using the "Pattern Finder" G-quadruplex (G4) predictor algorithm to assess whether G4-forming sequences reside in close proximity (within 20 base pairs) to known mitochondrial DNA deletion breakpoints. We then used this information to map G4P sequences with deletions characteristic of representative mitochondrial genetic disorders and also those identified in various cancers and aging. Circular dichroism and UV spectral analysis demonstrated that mitochondrial G-rich sequences near deletion breakpoints prevalent in human disease form G-quadruplex DNA structures. A biochemical analysis of purified recombinant human Twinkle protein (gene product of c10orf2) showed that the mitochondrial replicative helicase inefficiently unwinds well characterized intermolecular and intramolecular G-quadruplex DNA substrates, as well as a unimolecular G4 substrate derived from a mitochondrial sequence that nests a deletion breakpoint described in human renal cell carcinoma. Although G4 has been implicated in the initiation of mitochondrial DNA replication, our current findings suggest that mitochondrial G-quadruplexes are also likely to be a source of instability for the mitochondrial genome by perturbing the normal progression of the mitochondrial replication machinery, including DNA unwinding by Twinkle helicase.
Collapse
Affiliation(s)
- Sanjay Kumar Bharti
- From the Laboratory of Molecular Gerontology, NIA, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224
| | - Joshua A Sommers
- From the Laboratory of Molecular Gerontology, NIA, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224
| | - Jun Zhou
- the ARNA Laboratory, University of Bordeaux, F-33000 Bordeaux, France, INSERM U869, Institut Européen de Chimie et Biologie (IECB), F-33600 Pessac, France
| | - Daniel L Kaplan
- the Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida 32312
| | - Johannes N Spelbrink
- the FinMIT Centre of Excellence, BioMediTech and Tampere University Hospital, Pirkanmaa Hospital District, University of Tampere, FI-33014 Tampere, Finland, and the Department of Pediatrics, Nijmegan Centre for Mitochondrial Disorders, Radboud University Medical Centre, Geert Grooteplein 10, P. O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Jean-Louis Mergny
- the ARNA Laboratory, University of Bordeaux, F-33000 Bordeaux, France, INSERM U869, Institut Européen de Chimie et Biologie (IECB), F-33600 Pessac, France
| | - Robert M Brosh
- From the Laboratory of Molecular Gerontology, NIA, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224,
| |
Collapse
|
36
|
Single-molecule fluorescence reveals the unwinding stepping mechanism of replicative helicase. Cell Rep 2014; 6:1037-1045. [PMID: 24630993 PMCID: PMC3988844 DOI: 10.1016/j.celrep.2014.02.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 01/10/2014] [Accepted: 02/16/2014] [Indexed: 11/21/2022] Open
Abstract
Bacteriophage T7 gp4 serves as a model protein for replicative helicases that couples deoxythymidine triphosphate (dTTP) hydrolysis to directional movement and DNA strand separation. We employed single-molecule fluorescence resonance energy transfer methods to resolve steps during DNA unwinding by T7 helicase. We confirm that the unwinding rate of T7 helicase decreases with increasing base pair stability. For duplexes containing >35% guanine-cytosine (GC) base pairs, we observed stochastic pauses every 2–3 bp during unwinding. The dwells on each pause were distributed nonexponentially, consistent with two or three rounds of dTTP hydrolysis before each unwinding step. Moreover, we observed backward movements of the enzyme on GC-rich DNAs at low dTTP concentrations. Our data suggest a coupling ratio of 1:1 between base pairs unwound and dTTP hydrolysis, and they further support the concept that nucleic acid motors can have a hierarchy of different-sized steps or can accumulate elastic energy before transitioning to a subsequent phase. Single DNA unwinding assay recapitulates sequence-dependent unwinding High-resolution data reveal an unwinding step size of 2–3 bp Two or three hidden steps precede the unwinding step, suggesting 1:1 chemical coupling 1:1 coupling is maintained at low dNTP, but helicase often slips backward
Collapse
|