1
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Wang JE, Zhou YC, Wu BH, Chen XC, Zhai J, Tan JH, Huang ZS, Chen SB. A rapid and highly sensitive immunosorbent assay to monitor helicases unwinding diverse nucleic acid structures. Analyst 2023; 148:2343-2351. [PMID: 37185609 DOI: 10.1039/d2an01989b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Helicases are crucial enzymes in DNA and RNA metabolism and function by unwinding particular nucleic acid structures. However, most convenient and high-throughput helicase assays are limited to the typical duplex DNA. Herein, we developed an immunosorbent assay to monitor the Werner syndrome (WRN) helicase unwinding a wide range of DNA structures, such as a replication fork, a bubble, Holliday junction, G-quadruplex and hairpin. This assay could sensitively detect the unwinding of DNA structures with detection limits around 0.1 nM, and accurately monitor the substrate-specificity of WRN with a comparatively less time-consuming and high throughput process. Remarkably, we have established that this new assay was compatible in evaluating helicase inhibitors and revealed that the inhibitory effect was substrate-dependent, suggesting that diverse substrate structures other than duplex structures should be considered in discovering new inhibitors. Our study provided a foundational example for using this new assay as a powerful tool to study helicase functions and discover potent inhibitors.
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Affiliation(s)
- Jia-En Wang
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
| | - Ying-Chen Zhou
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
| | - Bi-Han Wu
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
| | - Xiu-Cai Chen
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
| | - Junqiu Zhai
- Guangzhou University of Chinese Medicine, Guangzhou, Guangzhou 510330, China
| | - Jia-Heng Tan
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
| | - Shuo-Bin Chen
- School of Pharmaceutical Sciences, Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou 510006, China.
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2
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Bianco PR. Insight into the biochemical mechanism of DNA helicases provided by bulk-phase and single-molecule assays. Methods 2021; 204:348-360. [PMID: 34896247 PMCID: PMC9534331 DOI: 10.1016/j.ymeth.2021.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 12/01/2021] [Accepted: 12/03/2021] [Indexed: 10/19/2022] Open
Abstract
There are multiple assays available that can provide insight into the biochemical mechanism of DNA helicases. For the first 22 years since their discovery, bulk-phase assays were used. These include gel-based, spectrophotometric, and spectrofluorometric assays that revealed many facets of these enzymes. From 2001, single-molecule studies have contributed additional insight into these DNA nanomachines to reveal details on energy coupling, step size, processivity as well as unique aspects of individual enzyme behavior that were masked in the averaging inherent in ensemble studies. In this review, important aspects of the study of helicases are discussed including beginning with active, nuclease-free enzyme, followed by several bulk-phase approaches that have been developed and still find widespread use today. Finally, two single-molecule approaches are discussed, and the resulting findings are related to the results obtained in bulk-phase studies.
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Affiliation(s)
- Piero R Bianco
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA.
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3
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Zhong Y, Paudel BP, Ryan DP, Low JKK, Franck C, Patel K, Bedward MJ, Torrado M, Payne RJ, van Oijen AM, Mackay JP. CHD4 slides nucleosomes by decoupling entry- and exit-side DNA translocation. Nat Commun 2020; 11:1519. [PMID: 32251276 PMCID: PMC7090039 DOI: 10.1038/s41467-020-15183-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 02/21/2020] [Indexed: 11/09/2022] Open
Abstract
Chromatin remodellers hydrolyse ATP to move nucleosomal DNA against histone octamers. The mechanism, however, is only partially resolved, and it is unclear if it is conserved among the four remodeller families. Here we use single-molecule assays to examine the mechanism of action of CHD4, which is part of the least well understood family. We demonstrate that the binding energy for CHD4-nucleosome complex formation-even in the absence of nucleotide-triggers significant conformational changes in DNA at the entry side, effectively priming the system for remodelling. During remodelling, flanking DNA enters the nucleosome in a continuous, gradual manner but exits in concerted 4-6 base-pair steps. This decoupling of entry- and exit-side translocation suggests that ATP-driven movement of entry-side DNA builds up strain inside the nucleosome that is subsequently released at the exit side by DNA expulsion. Based on our work and previous studies, we propose a mechanism for nucleosome sliding.
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Affiliation(s)
- Yichen Zhong
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Bishnu P Paudel
- Molecular Horizons, School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - Daniel P Ryan
- Department of Genome Sciences, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, 2601, Australia
| | - Jason K K Low
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Charlotte Franck
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.,School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Karishma Patel
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Max J Bedward
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Mario Torrado
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Richard J Payne
- School of Chemistry, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Antoine M van Oijen
- Molecular Horizons, School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
| | - Joel P Mackay
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
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4
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Chakrabarti S, Jarzynski C, Thirumalai D. Processivity, Velocity, and Universal Characteristics of Nucleic Acid Unwinding by Helicases. Biophys J 2019; 117:867-879. [PMID: 31400912 PMCID: PMC6731385 DOI: 10.1016/j.bpj.2019.07.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 06/20/2019] [Accepted: 07/12/2019] [Indexed: 12/20/2022] Open
Abstract
Helicases are components of the cellular replisome that are essential for unwinding double-strand nucleic acids during the process of replication. Intriguingly, most helicases are inefficient and require either oligomerization or assistance from other partner proteins to increase the processivity of unwinding in the presence of the replication fork, which acts as a barrier to progress. Single-molecule force spectroscopy has emerged as a promising experimental technique to probe how relieving this barrier on the helicase can allow for increased efficiency of unwinding. However, there exists no comprehensive theoretical framework to provide unique interpretations of the underlying helicase kinetics from the force spectroscopy data. This remains a major confounding issue in the field. Here, we develop a mathematical framework and derive analytic expressions for the velocity and run length of a general model of finitely processive helicases, the two most commonly measured experimental quantities. We show that in contrast to the unwinding velocity, the processivity exhibits a universal increase in response to external force, irrespective of the underlying architecture and unwinding kinetics of the helicase. Our work provides the first, to our knowledge, explanation to a wide array of experiments and suggests that helicases may have evolved to maximize processivity rather than speed. To demonstrate the use of our theory on experimental data, we analyze velocity and processivity data on the T7 helicase and provide unique inferences on the kinetics of the helicase. Our results show that T7 is a weakly active helicase that destabilizes the fork ahead by less than 1 kBT and back steps very frequently while unwinding DNA. Our work generates fundamental insights into the force response of helicases and provides a widely applicable method for inferring the underlying helicase kinetics from force spectroscopy data.
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Affiliation(s)
- Shaon Chakrabarti
- Department of Data Sciences, Dana-Farber Cancer Institute, Boston, Massachusetts; Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts; Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts.
| | - Christopher Jarzynski
- Department of Chemistry and Biochemistry, Institute for Physical Sciences and Technology, Department of Physics, University of Maryland, College Park, Maryland
| | - D Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, Texas
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5
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Seol Y, Harami GM, Kovács M, Neuman KC. Homology sensing via non-linear amplification of sequence-dependent pausing by RecQ helicase. eLife 2019; 8:e45909. [PMID: 31464683 PMCID: PMC6773442 DOI: 10.7554/elife.45909] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 08/28/2019] [Indexed: 12/25/2022] Open
Abstract
RecQ helicases promote genomic stability through their unique ability to suppress illegitimate recombination and resolve recombination intermediates. These DNA structure-specific activities of RecQ helicases are mediated by the helicase-and-RNAseD like C-terminal (HRDC) domain, via unknown mechanisms. Here, employing single-molecule magnetic tweezers and rapid kinetic approaches we establish that the HRDC domain stabilizes intrinsic, sequence-dependent, pauses of the core helicase (lacking the HRDC) in a DNA geometry-dependent manner. We elucidate the core unwinding mechanism in which the unwinding rate depends on the stability of the duplex DNA leading to transient sequence-dependent pauses. We further demonstrate a non-linear amplification of these transient pauses by the controlled binding of the HRDC domain. The resulting DNA sequence- and geometry-dependent pausing may underlie a homology sensing mechanism that allows rapid disruption of unstable (illegitimate) and stabilization of stable (legitimate) DNA strand invasions, which suggests an intrinsic mechanism of recombination quality control by RecQ helicases.
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Affiliation(s)
- Yeonee Seol
- Laboratory of Single Molecule BiophysicsNational Heart, Lung, and Blood Institute, National Institutes of HealthBethesdaUnited States
| | - Gábor M Harami
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research GroupEötvös Loránd UniversityBudapestHungary
| | - Mihály Kovács
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research GroupEötvös Loránd UniversityBudapestHungary
- Department of Biochemistry, MTA-ELTE Motor Pharmacology Research GroupEötvös Loránd UniversityBudapestHungary
| | - Keir C Neuman
- Laboratory of Single Molecule BiophysicsNational Heart, Lung, and Blood Institute, National Institutes of HealthBethesdaUnited States
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6
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Bagchi D, Manosas M, Zhang W, Manthei KA, Hodeib S, Ducos B, Keck JL, Croquette V. Single molecule kinetics uncover roles for E. coli RecQ DNA helicase domains and interaction with SSB. Nucleic Acids Res 2019; 46:8500-8515. [PMID: 30053104 PMCID: PMC6144805 DOI: 10.1093/nar/gky647] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/15/2018] [Indexed: 12/16/2022] Open
Abstract
Most RecQ DNA helicases share a conserved domain arrangement that mediates their activities in genomic stability. This arrangement comprises a helicase motor domain, a RecQ C-terminal (RecQ-C) region including a winged-helix (WH) domain, and a ‘Helicase and RNase D C-terminal’ (HRDC) domain. Single-molecule real-time translocation and DNA unwinding by full-length Escherichia coli RecQ and variants lacking either the HRDC or both the WH and HRDC domains was analyzed. RecQ operated under two interconvertible kinetic modes, ‘slow’ and ‘normal’, as it unwound duplex DNA and translocated on single-stranded (ss) DNA. Consistent with a crystal structure of bacterial RecQ bound to ssDNA by base stacking, abasic sites blocked RecQ unwinding. Removal of the HRDC domain eliminates the slow mode while preserving the normal mode of activity. Unexpectedly, a RecQ variant lacking both the WH and HRDC domains retains weak helicase activity. The inclusion of E. coli ssDNA-binding protein (SSB) induces a third ‘fast’ unwinding mode four times faster than the normal RecQ mode and enhances the overall helicase activity (affinity, rate, and processivity). SSB stimulation was, furthermore, observed in the RecQ deletion variants, including the variant missing the WH domain. Our results support a model in which RecQ and SSB have multiple interacting modes.
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Affiliation(s)
- Debjani Bagchi
- Physics Department, Faculty of Science, Maharaja Sayajirao University of Baroda, Vadodara, Gujarat - 390002, India
| | - Maria Manosas
- Departament de Física de la Materia Condensada, Universitat de Barcelona, Barcelona 08028, Spain.,CIBER-BBN de Bioingenieria, Biomateriales y Nanomedicina, Instituto de Sanidad Carlos III, Madrid, Spain
| | - Weiting Zhang
- Laboratoire de physique statistique, Département de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS, 75005 Paris, France. IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Kelly A Manthei
- Department of Biomolecular Chemistry, University of Wisconsin Medical School, Madison, WI 53706-1532, USA
| | - Samar Hodeib
- Laboratoire de physique statistique, Département de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS, 75005 Paris, France. IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Bertrand Ducos
- Laboratoire de physique statistique, Département de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS, 75005 Paris, France. IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - James L Keck
- Department of Biomolecular Chemistry, University of Wisconsin Medical School, Madison, WI 53706-1532, USA
| | - Vincent Croquette
- Laboratoire de physique statistique, Département de physique de l'ENS, École normale supérieure, PSL Research University, Université Paris Diderot, Sorbonne Paris Cité, Sorbonne Universités, UPMC Univ. Paris 06, CNRS, 75005 Paris, France. IBENS, Département de biologie, École normale supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
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7
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Mills M, Harami GM, Seol Y, Gyimesi M, Martina M, Kovács ZJ, Kovács M, Neuman KC. RecQ helicase triggers a binding mode change in the SSB-DNA complex to efficiently initiate DNA unwinding. Nucleic Acids Res 2017; 45:11878-11890. [PMID: 29059328 PMCID: PMC5714189 DOI: 10.1093/nar/gkx939] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/29/2017] [Accepted: 10/09/2017] [Indexed: 11/12/2022] Open
Abstract
The single-stranded DNA binding protein (SSB) of Escherichia coli plays essential roles in maintaining genome integrity by sequestering ssDNA and mediating DNA processing pathways through interactions with DNA-processing enzymes. Despite its DNA-sequestering properties, SSB stimulates the DNA processing activities of some of its binding partners. One example is the genome maintenance protein RecQ helicase. Here, we determine the mechanistic details of the RecQ-SSB interaction using single-molecule magnetic tweezers and rapid kinetic experiments. Our results reveal that the SSB-RecQ interaction changes the binding mode of SSB, thereby allowing RecQ to gain access to ssDNA and facilitating DNA unwinding. Conversely, the interaction of RecQ with the SSB C-terminal tail increases the on-rate of RecQ-DNA binding and has a modest stimulatory effect on the unwinding rate of RecQ. We propose that this bidirectional communication promotes efficient DNA processing and explains how SSB stimulates rather than inhibits RecQ activity.
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Affiliation(s)
- Maria Mills
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gábor M. Harami
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Yeonee Seol
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Máté Gyimesi
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Máté Martina
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Zoltán J. Kovács
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Mihály Kovács
- Department of Biochemistry, ELTE-MTA “Momentum” Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Keir C. Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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8
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Pavankumar TL, Exell JC, Kowalczykowski SC. Direct Fluorescent Imaging of Translocation and Unwinding by Individual DNA Helicases. Methods Enzymol 2016; 581:1-32. [PMID: 27793277 DOI: 10.1016/bs.mie.2016.09.010] [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] [Indexed: 12/02/2022]
Abstract
The unique translocation and DNA unwinding properties of DNA helicases can be concealed by the stochastic behavior of enzyme molecules within the necessarily large populations used in ensemble experiments. With recent technological advances, the direct visualization of helicases acting on individual DNA molecules has contributed significantly to the current understanding of their mechanisms of action and biological functions. The combination of single-molecule techniques that enable both manipulation of individual protein or DNA molecules and visualization of their actions has made it possible to literally see novel and unique biochemical characteristics that were previously masked. Here, we describe the execution and use of single-molecule fluorescence imaging techniques, focusing on methods that include optical trapping in conjunction with epifluorescent imaging, and also surface immobilization in conjunction with total internal reflection fluorescence visualization. Combined with microchannel flow cells and microfluidic control, these methods allow individual fluorescently labeled protein and DNA molecules to be imaged and tracked, affording measurement of DNA unwinding and translocation at single-molecule resolution.
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Affiliation(s)
| | - J C Exell
- University of California, Davis, CA, United States
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9
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Abstract
The repair of DNA by homologous recombination is an essential, efficient, and high-fidelity process that mends DNA lesions formed during cellular metabolism; these lesions include double-stranded DNA breaks, daughter-strand gaps, and DNA cross-links. Genetic defects in the homologous recombination pathway undermine genomic integrity and cause the accumulation of gross chromosomal abnormalities-including rearrangements, deletions, and aneuploidy-that contribute to cancer formation. Recombination proceeds through the formation of joint DNA molecules-homologously paired but metastable DNA intermediates that are processed by several alternative subpathways-making recombination a versatile and robust mechanism to repair damaged chromosomes. Modern biophysical methods make it possible to visualize, probe, and manipulate the individual molecules participating in the intermediate steps of recombination, revealing new details about the mechanics of genetic recombination. We review and discuss the individual stages of homologous recombination, focusing on common pathways in bacteria, yeast, and humans, and place particular emphasis on the molecular mechanisms illuminated by single-molecule methods.
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Affiliation(s)
- Jason C Bell
- Department of Microbiology and Molecular Genetics, and Department of Molecular and Cellular Biology, University of California, Davis, California 95616;
| | - Stephen C Kowalczykowski
- Department of Microbiology and Molecular Genetics, and Department of Molecular and Cellular Biology, University of California, Davis, California 95616;
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10
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Yuan Z, Bai L, Sun J, Georgescu R, Liu J, O'Donnell ME, Li H. Structure of the eukaryotic replicative CMG helicase suggests a pumpjack motion for translocation. Nat Struct Mol Biol 2016; 23:217-24. [PMID: 26854665 PMCID: PMC4812828 DOI: 10.1038/nsmb.3170] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/06/2016] [Indexed: 01/06/2023]
Abstract
The CMG helicase is composed of Cdc45, Mcm2-7 and GINS. Here we report the structure of the Saccharomyces cerevisiae CMG, determined by cryo-EM at a resolution of 3.7-4.8 Å. The structure reveals that GINS and Cdc45 scaffold the N tier of the helicase while enabling motion of the AAA+ C tier. CMG exists in two alternating conformations, compact and extended, thus suggesting that the helicase moves like an inchworm. The N-terminal regions of Mcm2-7, braced by Cdc45-GINS, form a rigid platform upon which the AAA+ C domains make longitudinal motions, nodding up and down like an oil-rig pumpjack attached to a stable platform. The Mcm ring is remodeled in CMG relative to the inactive Mcm2-7 double hexamer. The Mcm5 winged-helix domain is inserted into the central channel, thus blocking entry of double-stranded DNA and supporting a steric-exclusion DNA-unwinding model.
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Affiliation(s)
- Zuanning Yuan
- Department of Biochemistry &Cell Biology, Stony Brook University, Stony Brook, New York, USA.,Biology Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Lin Bai
- Biology Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Jingchuan Sun
- Biology Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Roxana Georgescu
- DNA Replication Laboratory, Rockefeller University, New York, New York, USA.,Howard Hughes Medical Institute, Rockefeller University, New York, New York, USA
| | - Jun Liu
- Department of Pathology and Laboratory Medicine, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Michael E O'Donnell
- DNA Replication Laboratory, Rockefeller University, New York, New York, USA.,Howard Hughes Medical Institute, Rockefeller University, New York, New York, USA
| | - Huilin Li
- Department of Biochemistry &Cell Biology, Stony Brook University, Stony Brook, New York, USA.,Biology Department, Brookhaven National Laboratory, Upton, New York, USA
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11
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Single-molecule visualization of RecQ helicase reveals DNA melting, nucleation, and assembly are required for processive DNA unwinding. Proc Natl Acad Sci U S A 2015; 112:E6852-61. [PMID: 26540728 DOI: 10.1073/pnas.1518028112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA helicases are motor proteins that unwind double-stranded DNA (dsDNA) to reveal single-stranded DNA (ssDNA) needed for many biological processes. The RecQ helicase is involved in repairing damage caused by DNA breaks and stalled replication forks via homologous recombination. Here, the helicase activity of RecQ was visualized on single molecules of DNA using a fluorescent sensor that directly detects ssDNA. By monitoring the formation and progression of individual unwinding forks, we observed that both the frequency of initiation and the rate of unwinding are highly dependent on RecQ concentration. We establish that unwinding forks can initiate internally by melting dsDNA and can proceed in both directions at up to 40-60 bp/s. The findings suggest that initiation requires a RecQ dimer, and that continued processive unwinding of several kilobases involves multiple monomers at the DNA unwinding fork. We propose a distinctive model wherein RecQ melts dsDNA internally to initiate unwinding and subsequently assembles at the fork into a distribution of multimeric species, each encompassing a broad distribution of rates, to unwind DNA. These studies define the species that promote resection of DNA, proofreading of homologous pairing, and migration of Holliday junctions, and they suggest that various functional forms of RecQ can be assembled that unwind at rates tailored to the diverse biological functions of RecQ helicase.
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12
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Harami GM, Nagy NT, Martina M, Neuman KC, Kovács M. The HRDC domain of E. coli RecQ helicase controls single-stranded DNA translocation and double-stranded DNA unwinding rates without affecting mechanoenzymatic coupling. Sci Rep 2015; 5:11091. [PMID: 26067769 PMCID: PMC4464074 DOI: 10.1038/srep11091] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/05/2015] [Indexed: 01/01/2023] Open
Abstract
DNA-restructuring activities of RecQ-family helicases play key roles in genome maintenance. These activities, driven by two tandem RecA-like core domains, are thought to be controlled by accessory DNA-binding elements including the helicase-and-RnaseD-C-terminal (HRDC) domain. The HRDC domain of human Bloom’s syndrome (BLM) helicase was shown to interact with the RecA core, raising the possibility that it may affect the coupling between ATP hydrolysis, translocation along single-stranded (ss)DNA and/or unwinding of double-stranded (ds)DNA. Here, we determined how these activities are affected by the abolition of the ssDNA interaction of the HRDC domain or the deletion of the entire domain in E. coli RecQ helicase. Our data show that the HRDC domain suppresses the rate of DNA-activated ATPase activity in parallel with those of ssDNA translocation and dsDNA unwinding, regardless of the ssDNA binding capability of this domain. The HRDC domain does not affect either the processivity of ssDNA translocation or the tight coupling between the ATPase, translocation, and unwinding activities. Thus, the mechanochemical coupling of E. coli RecQ appears to be independent of HRDC-ssDNA and HRDC-RecA core interactions, which may play roles in more specialized functions of the enzyme.
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Affiliation(s)
- Gábor M Harami
- Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Nikolett T Nagy
- Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Máté Martina
- Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
| | - Keir C Neuman
- Laboratory of Molecular Biophysics, National Heart, Lung and Blood Institute, National Institutes of
| | - Mihály Kovács
- Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös Loránd University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
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13
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Sarlós K, Gyimesi M, Kele Z, Kovács M. Mechanism of RecQ helicase mechanoenzymatic coupling reveals that the DNA interactions of the ADP-bound enzyme control translocation run terminations. Nucleic Acids Res 2014; 43:1090-7. [PMID: 25539922 PMCID: PMC4333385 DOI: 10.1093/nar/gku1333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The processing of various DNA structures by RecQ helicases is crucial for genome maintenance in both bacteria and eukaryotes. RecQ helicases perform active destabilization of DNA duplexes, based on tight coupling of their ATPase activity to moderately processive translocation along DNA strands. Here, we determined the ATPase kinetic mechanism of E. coli RecQ helicase to reveal how mechanoenzymatic coupling is achieved. We found that the interaction of RecQ with DNA results in a drastic acceleration of the rate-limiting ATP cleavage step, which occurs productively due to subsequent rapid phosphate release. ADP release is not rate-limiting and ADP-bound RecQ molecules make up a small fraction during single-stranded DNA translocation. However, the relatively rapid release of the ADP-bound enzyme from DNA causes the majority of translocation run terminations (i.e. detachment from the DNA track). Thus, the DNA interactions of ADP-bound RecQ helicase, probably dependent on DNA structure, will mainly determine translocation processivity and may control the outcome of DNA processing. Comparison with human Bloom's syndrome (BLM) helicase reveals that similar macroscopic parameters are achieved by markedly different underlying mechanisms of RecQ homologs, suggesting diversity in enzymatic tuning.
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Affiliation(s)
- Kata Sarlós
- Department of Biochemistry, ELTE-MTA 'Momentum' Motor Enzymology Research Group, Eötvös University, Pázmány P. s. 1/c, Budapest, H-1117, Hungary
| | - Máté Gyimesi
- Department of Biochemistry, ELTE-MTA 'Momentum' Motor Enzymology Research Group, Eötvös University, Pázmány P. s. 1/c, Budapest, H-1117, Hungary
| | - Zoltán Kele
- Department of Medical Chemistry, University of Szeged, Dóm sqr. 8. Szeged, H-6720, Hungary
| | - Mihály Kovács
- Department of Biochemistry, ELTE-MTA 'Momentum' Motor Enzymology Research Group, Eötvös University, Pázmány P. s. 1/c, Budapest, H-1117, Hungary
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14
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Kocsis ZS, Sarlós K, Harami GM, Martina M, Kovács M. A nucleotide-dependent and HRDC domain-dependent structural transition in DNA-bound RecQ helicase. J Biol Chem 2014; 289:5938-49. [PMID: 24403069 DOI: 10.1074/jbc.m113.530741] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The allosteric communication between the ATP- and DNA-binding sites of RecQ helicases enables efficient coupling of ATP hydrolysis to translocation along single-stranded DNA (ssDNA) and, in turn, the restructuring of multistranded DNA substrates during genome maintenance processes. In this study, we used the tryptophan fluorescence signal of Escherichia coli RecQ helicase to decipher the kinetic mechanism of the interaction of the enzyme with ssDNA. Rapid kinetic experiments revealed that ssDNA binding occurs in a two-step mechanism in which the initial binding step is followed by a structural transition of the DNA-bound helicase. We found that the nucleotide state of RecQ greatly influences the kinetics of the detected structural transition, which leads to a high affinity DNA-clamped state in the presence of the nucleotide analog ADP-AlF4. The DNA binding mechanism is largely independent of ssDNA length, indicating the independent binding of RecQ molecules to ssDNA and the lack of significant DNA end effects. The structural transition of DNA-bound RecQ was not detected when the ssDNA binding capability of the helicase-RNase D C-terminal domain was abolished or the domain was deleted. The results shed light on the nature of conformational changes leading to processive ssDNA translocation and multistranded DNA processing by RecQ helicases.
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Affiliation(s)
- Zsuzsa S Kocsis
- From the Department of Biochemistry, ELTE-MTA "Momentum" Motor Enzymology Research Group, Eötvös University, Pázmány P. s. 1/c, H-1117 Budapest, Hungary
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15
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Abstract
Helicases have major roles in genome maintenance by unwinding structured nucleic acids. Their prominence is marked by various cancers and genetic disorders that are linked to helicase defects. Although considerable effort has been made to understand the functions of DNA helicases that are important for genomic stability and cellular homeostasis, the complexity of the DNA damage response leaves us with unanswered questions regarding how helicase-dependent DNA repair pathways are regulated and coordinated with cell cycle checkpoints. Further studies may open the door to targeting helicases in order to improve cancer treatments based on DNA-damaging chemotherapy or radiation.
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Affiliation(s)
- Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Boulevard, Baltimore, Maryland 21224, USA.
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16
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Ramanagoudr-Bhojappa R, Chib S, Byrd AK, Aarattuthodiyil S, Pandey M, Patel SS, Raney KD. Yeast Pif1 helicase exhibits a one-base-pair stepping mechanism for unwinding duplex DNA. J Biol Chem 2013; 288:16185-95. [PMID: 23596008 DOI: 10.1074/jbc.m113.470013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kinetic analysis of the DNA unwinding and translocation activities of helicases is necessary for characterization of the biochemical mechanism(s) for this class of enzymes. Saccharomyces cerevisiae Pif1 helicase was characterized using presteady state kinetics to determine rates of DNA unwinding, displacement of streptavidin from biotinylated DNA, translocation on single-stranded DNA (ssDNA), and ATP hydrolysis activities. Unwinding of substrates containing varying duplex lengths was fit globally to a model for stepwise unwinding and resulted in an unwinding rate of ∼75 bp/s and a kinetic step size of 1 base pair. Pif1 is capable of displacing streptavidin from biotinylated oligonucleotides with a linear increase in the rates as the length of the oligonucleotides increased. The rate of translocation on ssDNA was determined by measuring dissociation from varying lengths of ssDNA and is essentially the same as the rate of unwinding of dsDNA, making Pif1 an active helicase. The ATPase activity of Pif1 on ssDNA was determined using fluorescently labeled phosphate-binding protein to measure the rate of phosphate release. The quantity of phosphate released corresponds to a chemical efficiency of 0.84 ATP/nucleotides translocated. Hence, when all of the kinetic data are considered, Pif1 appears to move along DNA in single nucleotide or base pair steps, powered by hydrolysis of 1 molecule of ATP.
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17
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Parisse P, Vindigni A, Scoles G, Casalis L. In Vitro Enzyme Comparative Kinetics: Unwinding of Surface-Bound DNA Nanostructures by RecQ and RecQ1. JOURNAL OF PHYSICAL CHEMISTRY LETTERS 2012; 3:3532-7. [PMID: 26290984 DOI: 10.1021/jz3018682] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Pietro Parisse
- Sincrotrone Trieste S.C.p.A., s.s.14 km163,5 in Area Science Park, Trieste
34149, Italy
| | - Alessandro Vindigni
- Sincrotrone Trieste S.C.p.A., s.s.14 km163,5 in Area Science Park, Trieste
34149, Italy
- International Centre for Genetic Engineering and Biotechnology, Padriciano
99, Trieste 34149, Italy
- Department of Biochemistry and
Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - Giacinto Scoles
- Sincrotrone Trieste S.C.p.A., s.s.14 km163,5 in Area Science Park, Trieste
34149, Italy
- Department of Biological and
Medical Science, University of Udine, Ospedale
della Misericordia, Udine 33100, Italy
| | - Loredana Casalis
- Sincrotrone Trieste S.C.p.A., s.s.14 km163,5 in Area Science Park, Trieste
34149, Italy
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18
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RecQ helicase translocates along single-stranded DNA with a moderate processivity and tight mechanochemical coupling. Proc Natl Acad Sci U S A 2012; 109:9804-9. [PMID: 22665805 DOI: 10.1073/pnas.1114468109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maintenance of genome integrity is the major biological role of RecQ-family helicases via their participation in homologous recombination (HR)-mediated DNA repair processes. RecQ helicases exert their functions by using the free energy of ATP hydrolysis for mechanical movement along DNA tracks (translocation). In addition to the importance of translocation per se in recombination processes, knowledge of its mechanism is necessary for the understanding of more complex translocation-based activities, including nucleoprotein displacement, strand separation (unwinding), and branch migration. Here, we report the key properties of the ssDNA translocation mechanism of Escherichia coli RecQ helicase, the prototype of the RecQ family. We monitored the pre-steady-state kinetics of ATP hydrolysis by RecQ and the dissociation of the enzyme from ssDNA during single-round translocation. We also gained information on the translocation mechanism from the ssDNA length dependence of the steady-state ssDNA-activated ATPase activity. We show that RecQ occludes 18 ± 2 nt on ssDNA during translocation. The hydrolysis of ATP is noncooperative in the presence of ssDNA, indicating that RecQ active sites work independently during translocation. In the applied conditions, the enzyme hydrolyzes 35 ± 4 ATP molecules per second during ssDNA translocation. RecQ translocates at a moderate processivity, with a mean run length of 100-320 nt on ssDNA. The determined tight mechanochemical coupling of 1.1 ± 0.2 ATP consumed per nucleotide traveled indicates an inchworm-type mechanism.
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19
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Rad B, Kowalczykowski SC. Translocation of E. coli RecQ helicase on single-stranded DNA. Biochemistry 2012; 51:2921-9. [PMID: 22409300 DOI: 10.1021/bi3000676] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A member of the SF2 family of helicases, Escherichia coli RecQ, is involved in the recombination and repair of double-stranded DNA breaks and single-stranded DNA (ssDNA) gaps. Although the unwinding activity of this helicase has been studied biochemically, the mechanism of translocation remains unclear. To this end, using ssDNA of varying lengths, the steady-state ATP hydrolysis activity of RecQ was analyzed. We find that the rate of ATP hydrolysis increases with DNA length, reaching a maximum specific activity of 38 ± 2 ATP/RecQ/s. Analysis of the rate of ATP hydrolysis as a function of DNA length implies that the helicase has a processivity of 19 ± 6 nucleotides on ssDNA and that RecQ requires a minimal translocation site size of 10 ± 1 nucleotides. Using the T4 phage encoded gene 32 protein (G32P), which binds ssDNA cooperatively, to decrease the lengths of ssDNA gaps available for translocation, we observe a decrease in the rate of ATP hydrolysis activity that is related to lattice occupancy. Analysis of the activity in terms of the average gap sizes available to RecQ on the ssDNA coated with G32P indicates that RecQ translocates on ssDNA on average 46 ± 11 nucleotides before dissociating. Moreover, when bound to ssDNA, RecQ hydrolyzes ATP in a cooperative fashion, with a Hill coefficient of 2.1 ± 0.6, suggesting that at least a dimer is required for translocation on ssDNA. We present a kinetic model for translocation by RecQ on ssDNA based on this characterization.
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Affiliation(s)
- Behzad Rad
- Department of Microbiology, Department of Molecular and Cellular Biology, Graduate Group in Biophysics, University of California, Davis, Davis, California 95616-8665, United States
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