1
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Adhikari S, Orrit M. Progress and perspectives in single-molecule optical spectroscopy. J Chem Phys 2022; 156:160903. [PMID: 35489995 DOI: 10.1063/5.0087003] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We review some of the progress of single-molecule optical experiments in the past 20 years and propose some perspectives for the coming years. We particularly focus on methodological advances in fluorescence, super-resolution, photothermal contrast, and interferometric scattering and briefly discuss a few of the applications. These advances have enabled the exploration of new emitters and quantum optics; the chemistry and biology of complex heterogeneous systems, nanoparticles, and plasmonics; and the detection and study of non-fluorescing and non-absorbing nano-objects. We conclude by proposing some ideas for future experiments. The field will move toward more and better signals of a broader variety of objects and toward a sharper view of the surprising complexity of the nanoscale world of single (bio-)molecules, nanoparticles, and their nano-environments.
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Affiliation(s)
- Subhasis Adhikari
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2333 CA Leiden, The Netherlands
| | - Michel Orrit
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2333 CA Leiden, The Netherlands
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2
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Nicholson DA, Nesbitt DJ. Pushing Camera-Based Single-Molecule Kinetic Measurements to the Frame Acquisition Limit with Stroboscopic smFRET. J Phys Chem B 2021; 125:6080-6089. [PMID: 34097408 DOI: 10.1021/acs.jpcb.1c01036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Single-molecule fluorescence resonance energy transfer (smFRET) experiments permit detailed examination of microscopic dynamics. However, kinetic rate constants determined by smFRET are susceptible to systematic underestimation when the rate constants are comparable to the data acquisition rate. We demonstrate how such systematic errors in camera-based total internal reflection fluorescence microscopy experiments can be greatly reduced by using stroboscopic illumination/detection, allowing accurate rate constant determination up to the data sampling rate and yielding an order of magnitude increase in the dynamic range. Implementation of these stroboscopic smFRET ideas is straightforward, and the stroboscopically obtained data are compatible with multiple trajectory analysis methods, including dwell-time analysis and hidden Markov modeling. Such stroboscopic methods therefore offer a remarkably simple yet valuable addition to the smFRET toolkit, requiring only relatively modest modification to the normal data collection and analysis procedures.
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Affiliation(s)
- David A Nicholson
- National Institute of Standards and Technology and University of Colorado, JILA, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David J Nesbitt
- National Institute of Standards and Technology and University of Colorado, JILA, Boulder, Colorado 80309, United States.,Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States.,Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
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3
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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.
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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
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4
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De Jesús-Kim L, Friedman LJ, Lõoke M, Ramsoomair CK, Gelles J, Bell SP. DDK regulates replication initiation by controlling the multiplicity of Cdc45-GINS binding to Mcm2-7. eLife 2021; 10:65471. [PMID: 33616038 PMCID: PMC7954526 DOI: 10.7554/elife.65471] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/21/2021] [Indexed: 01/07/2023] Open
Abstract
The committed step of eukaryotic DNA replication occurs when the pairs of Mcm2-7 replicative helicases that license each replication origin are activated. Helicase activation requires the recruitment of Cdc45 and GINS to Mcm2-7, forming Cdc45-Mcm2-7-GINS complexes (CMGs). Using single-molecule biochemical assays to monitor CMG formation, we found that Cdc45 and GINS are recruited to loaded Mcm2-7 in two stages. Initially, Cdc45, GINS, and likely additional proteins are recruited to unstructured Mcm2-7 N-terminal tails in a Dbf4-dependent kinase (DDK)-dependent manner, forming Cdc45-tail-GINS intermediates (CtGs). DDK phosphorylation of multiple phosphorylation sites on the Mcm2-7 tails modulates the number of CtGs formed per Mcm2-7. In a second, inefficient event, a subset of CtGs transfer their Cdc45 and GINS components to form CMGs. Importantly, higher CtG multiplicity increases the frequency of CMG formation. Our findings reveal the molecular mechanisms sensitizing helicase activation to DDK levels with implications for control of replication origin efficiency and timing.
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Affiliation(s)
- Lorraine De Jesús-Kim
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Larry J Friedman
- Department of Biochemistry, Brandeis UniversityWalthamUnited States
| | - Marko Lõoke
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Christian K Ramsoomair
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Jeff Gelles
- Department of Biochemistry, Brandeis UniversityWalthamUnited States
| | - Stephen P Bell
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
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5
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Sinha A, Eniyan K, Manohar P, Ramesh N, Bajpai U. Characterization and genome analysis of B1 sub-cluster mycobacteriophage PDRPxv. Virus Res 2020; 279:197884. [PMID: 31981773 DOI: 10.1016/j.virusres.2020.197884] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/21/2020] [Accepted: 01/21/2020] [Indexed: 11/15/2022]
Abstract
Mycobacteriophages are viruses specific to mycobacteria that have gained attention as alternative therapeutic strategies for treating antibiotic-resistant infections. Mycobacteriophages are highly diverse and have been grouped into 29 clusters, 71 sub-clusters and 10 singletons based on the genome sequence. Here, we annotate the genome of PDRPxv, a lytic mycobacteriophage isolated from New Delhi; it belongs to the Siphoviridae family as determined by transmission electron microscopy. This phage survives at higher temperatures (up to 55 °C) and in alkaline conditions (up to pH11). PDRPxv phage genome is 69,171 bp in length with 66.35 % GC content and encodes 107 putative open reading frames and belongs to the B1 sub-cluster. Genome annotation indicated that genes for DNA encapsidation, structural proteins, replication/transcription and lysis of the host are present in functional clusters. Structural proteins encoded by Gp10-Gp12, Gp18, Gp25 and Gp28-Gp33 were identified by mass spectrometry. Interestingly, no gene encoding a holin function was found. Single-step growth curve revealed that PDRPxv has an adsorption time of 45 min, a latency time of 135 min and an average burst size of 99 phage particles per infected cell. The short latency period and the large burst size mark the lytic nature of the PDRPxv phage, which could therefore be a promising therapeutic candidate against pathogenic Mycobacterium species.
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Affiliation(s)
- Avni Sinha
- Department of Biomedical Science, Acharya Narendra Dev College (University of Delhi) Govindpuri, Kalkaji, New-Delhi, 110019, India
| | - Kandasamy Eniyan
- Department of Biomedical Science, Acharya Narendra Dev College (University of Delhi) Govindpuri, Kalkaji, New-Delhi, 110019, India; Antibiotic Resistance and Phage Therapy Laboratory, School of Bioscience and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Prasanth Manohar
- Antibiotic Resistance and Phage Therapy Laboratory, School of Bioscience and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Nachimuthu Ramesh
- Antibiotic Resistance and Phage Therapy Laboratory, School of Bioscience and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Urmi Bajpai
- Department of Biomedical Science, Acharya Narendra Dev College (University of Delhi) Govindpuri, Kalkaji, New-Delhi, 110019, India.
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6
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Mohapatra S, Lin CT, Feng XA, Basu A, Ha T. Single-Molecule Analysis and Engineering of DNA Motors. Chem Rev 2019; 120:36-78. [DOI: 10.1021/acs.chemrev.9b00361] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | | | | | | | - Taekjip Ha
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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7
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Ho HN, Zalami D, Köhler J, van Oijen AM, Ghodke H. Identification of Multiple Kinetic Populations of DNA-Binding Proteins in Live Cells. Biophys J 2019; 117:950-961. [PMID: 31383358 DOI: 10.1016/j.bpj.2019.07.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 06/28/2019] [Accepted: 07/08/2019] [Indexed: 01/20/2023] Open
Abstract
Understanding how multiprotein complexes function in cells requires detailed quantitative understanding of their association and dissociation kinetics. Analysis of the heterogeneity of binding lifetimes enables the interrogation of the various intermediate states formed during the reaction. Single-molecule fluorescence imaging permits the measurement of reaction kinetics inside living organisms with minimal perturbation. However, poor photophysical properties of fluorescent probes limit the dynamic range and accuracy of measurements of off rates in live cells. Time-lapse single-molecule fluorescence imaging can partially overcome the limits of photobleaching; however, limitations of this technique remain uncharacterized. Here, we present a structured analysis of which timescales are most accessible using the time-lapse imaging approach and explore uncertainties in determining kinetic subpopulations. We demonstrate the effect of shot noise on the precision of the measurements as well as the resolution and dynamic range limits that are inherent to the method. Our work provides a convenient implementation to determine theoretical errors from measurements and to support interpretation of experimental data.
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Affiliation(s)
- Han N Ho
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Daniel Zalami
- Spectroscopy of Soft Matter, University of Bayreuth, Bayreuth, Germany
| | - Jürgen Köhler
- Spectroscopy of Soft Matter, University of Bayreuth, Bayreuth, Germany; Bavarian Polymer Institute, Bayreuth, Germany; Bayreuth Institute of Macromolecular Research, University of Bayreuth, Bayreuth, Germany
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia.
| | - Harshad Ghodke
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia.
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8
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Mueller SH, Spenkelink LM, van Oijen AM. When proteins play tag: the dynamic nature of the replisome. Biophys Rev 2019; 11:641-651. [PMID: 31273608 PMCID: PMC6682189 DOI: 10.1007/s12551-019-00569-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 06/24/2019] [Indexed: 02/06/2023] Open
Abstract
DNA replication, or the copying of DNA, is a fundamental process to all life. The system of proteins that carries out replication, the replisome, encounters many roadblocks on its way. An inability of the replisome to properly overcome these roadblocks will negatively affect genomic integrity which in turn can lead to disease. Over the past decades, efforts by many researchers using a broad array of approaches have revealed roles for many different proteins during the initial response of the replisome upon encountering roadblocks. Here, we revisit what is known about DNA replication and the effect of roadblocks during DNA replication across different organisms. We also address how advances in single-molecule techniques have changed our view of the replisome from a highly stable machine with behavior dictated by deterministic principles to a dynamic system that is controlled by stochastic processes. We propose that these dynamics will play crucial roles in roadblock bypass. Further single-molecule studies of this bypass will, therefore, be essential to facilitate the in-depth investigation of multi-protein complexes that is necessary to understand complicated collisions on the DNA.
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Affiliation(s)
- Stefan H Mueller
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, New South Wales, 2522, Australia
| | - Lisanne M Spenkelink
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, New South Wales, 2522, Australia
| | - Antoine M van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
- Illawarra Health & Medical Research Institute, Wollongong, New South Wales, 2522, Australia.
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9
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Rescuing Replication from Barriers: Mechanistic Insights from Single-Molecule Studies. Mol Cell Biol 2019; 39:MCB.00576-18. [PMID: 30886122 DOI: 10.1128/mcb.00576-18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
To prevent replication failure due to fork barriers, several mechanisms have evolved to restart arrested forks independent of the origin of replication. Our understanding of these mechanisms that underlie replication reactivation has been aided through unique dynamic perspectives offered by single-molecule techniques. These techniques, such as optical tweezers, magnetic tweezers, and fluorescence-based methods, allow researchers to monitor the unwinding of DNA by helicase, nucleotide incorporation during polymerase synthesis, and replication fork progression in real time. In addition, they offer the ability to distinguish DNA intermediates after obstacles to replication at high spatial and temporal resolutions, providing new insights into the replication reactivation mechanisms. These and other highlights of single-molecule techniques and remarkable studies on the recovery of the replication fork from barriers will be discussed in this review.
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10
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Johnston CL, Marzano NR, van Oijen AM, Ecroyd H. Using Single-Molecule Approaches to Understand the Molecular Mechanisms of Heat-Shock Protein Chaperone Function. J Mol Biol 2018; 430:4525-4546. [PMID: 29787765 DOI: 10.1016/j.jmb.2018.05.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/11/2018] [Accepted: 05/13/2018] [Indexed: 02/01/2023]
Abstract
The heat-shock proteins (Hsp) are a family of molecular chaperones, which collectively form a network that is critical for the maintenance of protein homeostasis. Traditional ensemble-based measurements have provided a wealth of knowledge on the function of individual Hsps and the Hsp network; however, such techniques are limited in their ability to resolve the heterogeneous, dynamic and transient interactions that molecular chaperones make with their client proteins. Single-molecule techniques have emerged as a powerful tool to study dynamic biological systems, as they enable rare and transient populations to be identified that would usually be masked in ensemble measurements. Thus, single-molecule techniques are particularly amenable for the study of Hsps and have begun to be used to reveal novel mechanistic details of their function. In this review, we discuss the current understanding of the chaperone action of Hsps and how gaps in the field can be addressed using single-molecule methods. Specifically, this review focuses on the ATP-independent small Hsps and the broader Hsp network and describes how these dynamic systems are amenable to single-molecule techniques.
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Affiliation(s)
- Caitlin L Johnston
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - Nicholas R Marzano
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - Antoine M van Oijen
- School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
| | - Heath Ecroyd
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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11
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Xue H, Bei Y, Zhan Z, Chen X, Xu X, Fu YV. Utilizing Biotinylated Proteins Expressed in Yeast to Visualize DNA-Protein Interactions at the Single-Molecule Level. Front Microbiol 2017; 8:2062. [PMID: 29123507 PMCID: PMC5662892 DOI: 10.3389/fmicb.2017.02062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/09/2017] [Indexed: 11/30/2022] Open
Abstract
Much of our knowledge in conventional biochemistry has derived from bulk assays. However, many stochastic processes and transient intermediates are hidden when averaged over the ensemble. The powerful technique of single-molecule fluorescence microscopy has made great contributions to the understanding of life processes that are inaccessible when using traditional approaches. In single-molecule studies, quantum dots (Qdots) have several unique advantages over other fluorescent probes, such as high brightness, extremely high photostability, and large Stokes shift, thus allowing long-time observation and improved signal-to-noise ratios. So far, however, there is no convenient way to label proteins purified from budding yeast with Qdots. Based on BirA-Avi and biotin-streptavidin systems, we have established a simple method to acquire a Qdot-labeled protein and visualize its interaction with DNA using total internal reflection fluorescence microscopy. For proof-of-concept, we chose replication protein A (RPA) and origin recognition complex (ORC) as the proteins of interest. Proteins were purified from budding yeast with high biotinylation efficiency and rapidly labeled with streptavidin-coated Qdots. Interactions between proteins and DNA were observed successfully at the single-molecule level.
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Affiliation(s)
- Huijun Xue
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Yuanyuan Bei
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Zhengyan Zhan
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xiuqiang Chen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Xin Xu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yu V. Fu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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12
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Gahlon HL, Romano LJ, Rueda D. Influence of DNA Lesions on Polymerase-Mediated DNA Replication at Single-Molecule Resolution. Chem Res Toxicol 2017; 30:1972-1983. [PMID: 29020440 DOI: 10.1021/acs.chemrestox.7b00224] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Faithful replication of DNA is a critical aspect in maintaining genome integrity. DNA polymerases are responsible for replicating DNA, and high-fidelity polymerases do this rapidly and at low error rates. Upon exposure to exogenous or endogenous substances, DNA can become damaged and this can alter the speed and fidelity of a DNA polymerase. In this instance, DNA polymerases are confronted with an obstacle that can result in genomic instability during replication, for example, by nucleotide misinsertion or replication fork collapse. It is important to know how DNA polymerases respond to damaged DNA substrates to understand the mechanism of mutagenesis and chemical carcinogenesis. Single-molecule techniques have helped to improve our current understanding of DNA polymerase-mediated DNA replication, as they enable the dissection of mechanistic details that can otherwise be lost in ensemble-averaged experiments. These techniques have also been used to gain a deeper understanding of how single DNA polymerases behave at the site of the damage in a DNA substrate. In this review, we evaluate single-molecule studies that have examined the interaction between DNA polymerases and damaged sites on a DNA template.
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Affiliation(s)
- Hailey L Gahlon
- Molecular Virology, Department of Medicine, Imperial College London , Du Cane Road, London W12 0NN, U.K.,Single Molecule Imaging Group, MRC London Institute of Medical Sciences , Du Cane Road, London W12 0NN, U.K
| | - Louis J Romano
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - David Rueda
- Molecular Virology, Department of Medicine, Imperial College London , Du Cane Road, London W12 0NN, U.K.,Single Molecule Imaging Group, MRC London Institute of Medical Sciences , Du Cane Road, London W12 0NN, U.K
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13
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Caldas VEA, Punter CM, Ghodke H, Robinson A, van Oijen AM. iSBatch: a batch-processing platform for data analysis and exploration of live-cell single-molecule microscopy images and other hierarchical datasets. MOLECULAR BIOSYSTEMS 2016. [PMID: 26198886 DOI: 10.1039/c5mb00321k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recent technical advances have made it possible to visualize single molecules inside live cells. Microscopes with single-molecule sensitivity enable the imaging of low-abundance proteins, allowing for a quantitative characterization of molecular properties. Such data sets contain information on a wide spectrum of important molecular properties, with different aspects highlighted in different imaging strategies. The time-lapsed acquisition of images provides information on protein dynamics over long time scales, giving insight into expression dynamics and localization properties. Rapid burst imaging reveals properties of individual molecules in real-time, informing on their diffusion characteristics, binding dynamics and stoichiometries within complexes. This richness of information, however, adds significant complexity to analysis protocols. In general, large datasets of images must be collected and processed in order to produce statistically robust results and identify rare events. More importantly, as live-cell single-molecule measurements remain on the cutting edge of imaging, few protocols for analysis have been established and thus analysis strategies often need to be explored for each individual scenario. Existing analysis packages are geared towards either single-cell imaging data or in vitro single-molecule data and typically operate with highly specific algorithms developed for particular situations. Our tool, iSBatch, instead allows users to exploit the inherent flexibility of the popular open-source package ImageJ, providing a hierarchical framework in which existing plugins or custom macros may be executed over entire datasets or portions thereof. This strategy affords users freedom to explore new analysis protocols within large imaging datasets, while maintaining hierarchical relationships between experiments, samples, fields of view, cells, and individual molecules.
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Affiliation(s)
- Victor E A Caldas
- Zernike Institute for Advanced Materials, Centre for Synthetic Biology, University of Groningen, The Netherlands
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14
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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.
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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.
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15
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Deniz AA. Deciphering Complexity in Molecular Biophysics with Single-Molecule Resolution. J Mol Biol 2015; 428:301-307. [PMID: 26707199 DOI: 10.1016/j.jmb.2015.12.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/16/2015] [Accepted: 12/16/2015] [Indexed: 01/12/2023]
Abstract
The structural features and dynamics of biological macromolecules underlie the molecular biology and correct functioning of cells. However, heterogeneity and other complexity of these molecules and their interactions often lead to loss of important information in traditional biophysical experiments. Single-molecule methods have dramatically altered the conceptual thinking and experimental tests available for such studies, leveraging their ability to avoid ensemble averaging. Here, I discuss briefly the rise of fluorescence single-molecule methods over the past two decades, a few key applications, and end with a view to challenges and future prospects.
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Affiliation(s)
- Ashok A Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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16
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van Oijen AM, Dixon NE. Probing molecular choreography through single-molecule biochemistry. Nat Struct Mol Biol 2015; 22:948-52. [DOI: 10.1038/nsmb.3119] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/06/2015] [Indexed: 01/09/2023]
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17
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Zhang H, Tang Y, Lee SJ, Wei Z, Cao J, Richardson CC. Binding Affinities among DNA Helicase-Primase, DNA Polymerase, and Replication Intermediates in the Replisome of Bacteriophage T7. J Biol Chem 2015; 291:1472-80. [PMID: 26620561 DOI: 10.1074/jbc.m115.698233] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Indexed: 11/06/2022] Open
Abstract
The formation of a replication loop on the lagging strand facilitates coordinated synthesis of the leading- and lagging-DNA strands and provides a mechanism for recycling of the lagging-strand DNA polymerase. As an Okazaki fragment is completed, the loop is released, and a new loop is formed as the synthesis of a new Okazaki fragment is initiated. Loop release requires the dissociation of the complex formed by the interactions among helicase, DNA polymerase, and DNA. The completion of the Okazaki fragment may result in either a nick or a single-stranded DNA region. In the replication system of bacteriophage T7, the dissociation of the polymerase from either DNA region is faster than that observed for the dissociation of the helicase from DNA polymerase, implying that the replication loop is released more likely through the dissociation of the lagging-strand DNA from polymerase, retaining the polymerase at replication fork. Both dissociation of DNA polymerase from DNA and that of helicase from a DNA polymerase · DNA complex are much faster at a nick DNA region than the release from a ssDNA region. These results suggest that the replication loop is released as a result of the nick formed when the lagging-strand DNA polymerase encounters the previously synthesized Okazaki fragment, releasing lagging-strand DNA and retaining DNA polymerase at the replication fork for the synthesis of next Okazaki fragment.
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Affiliation(s)
- Huidong Zhang
- From the Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China and the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boson, Massachusetts 02115
| | - Yong Tang
- From the Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China and
| | - Seung-Joo Lee
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boson, Massachusetts 02115
| | - Zeliang Wei
- From the Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China and
| | - Jia Cao
- From the Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China and
| | - Charles C Richardson
- the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boson, Massachusetts 02115
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18
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Gallardo IF, Pasupathy P, Brown M, Manhart CM, Neikirk DP, Alani E, Finkelstein IJ. High-Throughput Universal DNA Curtain Arrays for Single-Molecule Fluorescence Imaging. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:10310-7. [PMID: 26325477 PMCID: PMC4624423 DOI: 10.1021/acs.langmuir.5b02416] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Single-molecule studies of protein-DNA interactions have shed critical insights into the molecular mechanisms of nearly every aspect of DNA metabolism. The development of DNA curtains-a method for organizing arrays of DNA molecules on a fluid lipid bilayer-has greatly facilitated these studies by increasing the number of reactions that can be observed in a single experiment. However, the utility of DNA curtains is limited by the challenges associated with depositing nanometer-scale lipid diffusion barriers onto quartz microscope slides. Here, we describe a UV lithography-based method for large-scale fabrication of chromium (Cr) features and organization of DNA molecules at these features for high-throughput single-molecule studies. We demonstrate this approach by assembling 792 independent DNA arrays (containing >900,000 DNA molecules) within a single microfluidic flowcell. As a first proof of principle, we track the diffusion of Mlh1-Mlh3-a heterodimeric complex that participates in DNA mismatch repair and meiotic recombination. To further highlight the utility of this approach, we demonstrate a two-lane flowcell that facilitates concurrent experiments on different DNA substrates. Our technique greatly reduces the challenges associated with assembling DNA curtains and paves the way for the rapid acquisition of large statistical data sets from individual single-molecule experiments.
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Affiliation(s)
| | | | | | - Carol M Manhart
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
| | | | - Eric Alani
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
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19
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König I, Zarrine-Afsar A, Aznauryan M, Soranno A, Wunderlich B, Dingfelder F, Stüber JC, Plückthun A, Nettels D, Schuler B. Single-molecule spectroscopy of protein conformational dynamics in live eukaryotic cells. Nat Methods 2015; 12:773-9. [PMID: 26147918 DOI: 10.1038/nmeth.3475] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/22/2015] [Indexed: 12/18/2022]
Abstract
Single-molecule methods have become widely used for quantifying the conformational heterogeneity and structural dynamics of biomolecules in vitro. Their application in vivo, however, has remained challenging owing to shortcomings in the design and reproducible delivery of labeled molecules, the range of applicable analysis methods, and suboptimal cell culture conditions. By addressing these limitations in an integrated approach, we demonstrate the feasibility of probing protein dynamics from milliseconds down to the nanosecond regime in live eukaryotic cells with confocal single-molecule Förster resonance energy transfer (FRET) spectroscopy. We illustrate the versatility of the approach by determining the dimensions and submicrosecond chain dynamics of an intrinsically disordered protein; by detecting even subtle changes in the temperature dependence of protein stability, including in-cell cold denaturation; and by quantifying the folding dynamics of a small protein. The methodology opens possibilities for assessing the effect of the cellular environment on biomolecular conformation, dynamics and function.
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Affiliation(s)
- Iwo König
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | | | - Mikayel Aznauryan
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Andrea Soranno
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Bengt Wunderlich
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Fabian Dingfelder
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Jakob C Stüber
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
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20
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Ticau S, Friedman LJ, Ivica NA, Gelles J, Bell SP. Single-molecule studies of origin licensing reveal mechanisms ensuring bidirectional helicase loading. Cell 2015; 161:513-525. [PMID: 25892223 DOI: 10.1016/j.cell.2015.03.012] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 01/26/2015] [Accepted: 03/02/2015] [Indexed: 01/31/2023]
Abstract
Loading of the ring-shaped Mcm2-7 replicative helicase around DNA licenses eukaryotic origins of replication. During loading, Cdc6, Cdt1, and the origin-recognition complex (ORC) assemble two heterohexameric Mcm2-7 complexes into a head-to-head double hexamer that facilitates bidirectional replication initiation. Using multi-wavelength single-molecule fluorescence to monitor the events of helicase loading, we demonstrate that double-hexamer formation is the result of sequential loading of individual Mcm2-7 complexes. Loading of each Mcm2-7 molecule involves the ordered association and dissociation of distinct Cdc6 and Cdt1 proteins. In contrast, one ORC molecule directs loading of both helicases in each double hexamer. Based on single-molecule FRET, arrival of the second Mcm2-7 results in rapid double-hexamer formation that anticipates Cdc6 and Cdt1 release, suggesting that Mcm-Mcm interactions recruit the second helicase. Our findings reveal the complex protein dynamics that coordinate helicase loading and indicate that distinct mechanisms load the oppositely oriented helicases that are central to bidirectional replication initiation.
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Affiliation(s)
- Simina Ticau
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Larry J Friedman
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
| | - Nikola A Ivica
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jeff Gelles
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA.
| | - Stephen P Bell
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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21
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Gattuso H, Assfeld X, Monari A. Modeling DNA electronic circular dichroism by QM/MM methods and Frenkel Hamiltonian. Theor Chem Acc 2015. [DOI: 10.1007/s00214-015-1640-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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22
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Tethered particle analysis of supercoiled circular DNA using peptide nucleic acid handles. Nat Protoc 2014; 9:2206-23. [PMID: 25144271 DOI: 10.1038/nprot.2014.152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This protocol describes how to monitor individual naturally supercoiled circular DNA plasmids bound via peptide nucleic acid (PNA) handles between a bead and a surface. The protocol was developed for single-molecule investigation of the dynamics of supercoiled DNA, and it allows the investigation of both the dynamics of the molecule itself and of its interactions with a regulatory protein. Two bis-PNA clamps designed to bind with extremely high affinity to predetermined homopurine sequence sites in supercoiled DNA are prepared: one conjugated with digoxigenin for attachment to an anti-digoxigenin-coated glass cover slide, and one conjugated with biotin for attachment to a submicron-sized streptavidin-coated polystyrene bead. Plasmids are constructed, purified and incubated with the PNA handles. The dynamics of the construct is analyzed by tracking the tethered bead using video microscopy: less supercoiling results in more movement, and more supercoiling results in less movement. In contrast to other single-molecule methodologies, the current methodology allows for studying DNA in its naturally supercoiled state with constant linking number and constant writhe. The protocol has potential for use in studying the influence of supercoils on the dynamics of DNA and its associated proteins, e.g., topoisomerase. The procedure takes ~4 weeks.
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23
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Parks JW, Stone MD. Coordinated DNA dynamics during the human telomerase catalytic cycle. Nat Commun 2014; 5:4146. [PMID: 24923681 PMCID: PMC4107311 DOI: 10.1038/ncomms5146] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 05/15/2014] [Indexed: 11/09/2022] Open
Abstract
The human telomerase reverse transcriptase (hTERT) utilizes a template within the integral RNA subunit (hTR) to direct extension of telomeres. Telomerase exhibits repeat addition processivity (RAP) and must therefore translocate the nascent DNA product into a new RNA:DNA hybrid register to prime each round of telomere repeat synthesis. Here we use single-molecule FRET and nuclease protection assays to monitor telomere DNA structure and dynamics during the telomerase catalytic cycle. DNA translocation during RAP proceeds through a previously uncharacterized kinetic sub-step during which the 3′-end of the DNA substrate base pairs downstream within the hTR template. The rate constant for DNA primer re-alignment reveals this step is not rate-limiting for RAP, suggesting a second slow conformational change repositions the RNA:DNA hybrid into the telomerase active site and drives the extrusion of the 5′-end of the DNA primer out of the enzyme complex.
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Affiliation(s)
- Joseph W Parks
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
| | - Michael D Stone
- 1] Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA [2] Center for Molecular Biology of RNA, University of California, 1156 High Street, Santa Cruz, California 95064, USA
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