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Ma G, Zhang P, Zhou X, Wan Z, Wang S. Label-Free Single-Molecule Pulldown for the Detection of Released Cellular Protein Complexes. ACS CENTRAL SCIENCE 2022; 8:1272-1281. [PMID: 36188347 PMCID: PMC9523780 DOI: 10.1021/acscentsci.2c00602] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Indexed: 06/16/2023]
Abstract
Precise and sensitive detection of intracellular proteins and complexes is key to the understanding of signaling pathways and cell functions. Here, we present a label-free single-molecule pulldown (LFSMP) technique for the imaging of released cellular protein and protein complexes with single-molecule sensitivity and low sample consumption down to a few cells per mm2. LFSMP is based on plasmonic scattering imaging and thus can directly image the surface-captured molecules without labels and quantify the binding kinetics. In this paper, we demonstrate the detection principle for LFSMP, study the phosphorylation of protein complexes involved in a signaling pathway, and investigate how kinetic analysis can be used to improve the pulldown specificity. We wish our technique can contribute to uncovering the molecular mechanisms in cells with single-molecule resolution.
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Affiliation(s)
- Guangzhong Ma
- Biodesign
Center for Biosensors and Bioelectronics, Arizona State University, Tempe, Arizona 85287, United States
| | - Pengfei Zhang
- Biodesign
Center for Biosensors and Bioelectronics, Arizona State University, Tempe, Arizona 85287, United States
| | - Xinyu Zhou
- Biodesign
Center for Biosensors and Bioelectronics, Arizona State University, Tempe, Arizona 85287, United States
- School
of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, United States
| | - Zijian Wan
- Biodesign
Center for Biosensors and Bioelectronics, Arizona State University, Tempe, Arizona 85287, United States
- School
of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, United States
| | - Shaopeng Wang
- Biodesign
Center for Biosensors and Bioelectronics, Arizona State University, Tempe, Arizona 85287, United States
- School
of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, United States
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2
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Li H, Liu T, Yang H. Amplifying Intermolecular Events by Streptavidin-Induced Proximity. J Am Chem Soc 2022; 144:11377-11385. [PMID: 35715211 DOI: 10.1021/jacs.2c03666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Weak interactions between biomolecules play important roles in many cellular functions. Structural and kinetic analyses of these interactions, however, have been hindered by the transient nature of such events. Here, we pointed out a general approach to overcome this obstacle─anchoring the molecular partners to streptavidin hosts─and achieved constrained proximity and stoichiometry for the sought-after molecular coupling. We elaborated this idea through a series of DNA hybridization reactions and quantitatively characterized them using single-molecule experiments. Compared to a nominally 1 μM solution, for example, the streptavidin-induced proximity (SIP) amounted to an effective molarity of ∼10-30 μM for the binding partners. There was also a significantly increased proportion of molecular association, manifested in both ensemble population and single-molecule residence time. As an application example, we showed how SIP enabled the observation and quantitative characterization of an unstable complex between Cas9-RNA and noncognate DNA substrates, interactions that had been challenging to characterize previously. Conceptually simple and implementationally robust, SIP was shown to considerably enhance the efficacy in capturing weak interactions and, as demonstrated here, could empower scientists to see the otherwise unseeable.
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Affiliation(s)
- Hao Li
- Department of Chemistry, Princeton University,, Princeton, New Jersey 08544, United States
| | - Tao Liu
- Department of Chemistry, Princeton University,, Princeton, New Jersey 08544, United States
| | - Haw Yang
- Department of Chemistry, Princeton University,, Princeton, New Jersey 08544, United States
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3
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Loeff L, Kerssemakers JWJ, Joo C, Dekker C. AutoStepfinder: A fast and automated step detection method for single-molecule analysis. PATTERNS 2021; 2:100256. [PMID: 34036291 PMCID: PMC8134948 DOI: 10.1016/j.patter.2021.100256] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/12/2020] [Accepted: 04/08/2021] [Indexed: 01/05/2023]
Abstract
Single-molecule techniques allow the visualization of the molecular dynamics of nucleic acids and proteins with high spatiotemporal resolution. Valuable kinetic information of biomolecules can be obtained when the discrete states within single-molecule time trajectories are determined. Here, we present a fast, automated, and bias-free step detection method, AutoStepfinder, that determines steps in large datasets without requiring prior knowledge on the noise contributions and location of steps. The analysis is based on a series of partition events that minimize the difference between the data and the fit. A dual-pass strategy determines the optimal fit and allows AutoStepfinder to detect steps of a wide variety of sizes. We demonstrate step detection for a broad variety of experimental traces. The user-friendly interface and the automated detection of AutoStepfinder provides a robust analysis procedure that enables anyone without programming knowledge to generate step fits and informative plots in less than an hour. Fast, automated, and bias-free detection of steps within single-molecule trajectories Robust step detection without any prior knowledge on the data A dual-pass strategy for the detection of steps over a wide variety of scales A user-friendly interface for a simplified step fitting procedure
Single-molecule techniques have made it possible to track individual protein complexes in real time with a nanometer spatial resolution and a millisecond timescale. Accurate determination of the dynamic states within single-molecule time traces provides valuable kinetic information that underlie the function of biological macromolecules. Here, we present a new automated step detection method called AutoStepfinder, a versatile, robust, and easy-to-use algorithm that allows researchers to determine the kinetic states within single-molecule time trajectories without any bias.
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Affiliation(s)
- Luuk Loeff
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Jacob W J Kerssemakers
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Chirlmin Joo
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Cees Dekker
- Kavli Institute of Nanoscience and Department of Bionanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
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4
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Wang H, Sun L, Gaba A, Qu X. An in vitro single-molecule assay for eukaryotic cap-dependent translation initiation kinetics. Nucleic Acids Res 2020; 48:e6. [PMID: 31722415 PMCID: PMC7145701 DOI: 10.1093/nar/gkz1066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/18/2019] [Accepted: 10/29/2019] [Indexed: 11/12/2022] Open
Abstract
Eukaryotic mRNAs are predominantly translated via the cap-dependent pathway. Initiation is a rate-limiting step in cap-dependent translation and is the main target of translational control mechanisms. There is a lack of high-resolution techniques for characterizing the cap-dependent initiation kinetics. Here, we report an in vitro single-molecule assay that allows characterization of both initiation and peptide chain elongation kinetics for cap-dependent translation. Surprisingly, the histogram of the first-round initiation time is highly asymmetrical and spans a large time range that is several-fold greater than the average peptide synthesis time in translation reactions with a firefly luciferase-encoding mRNA. Both the histogram and single-molecule trajectories reveal an unexpected high-degree of asynchrony in translation activity between mRNA molecules. Furthermore, by inserting a small stem-loop (ΔG = -4.8 kcal/mol) in the middle of the mRNA 5' untranslated region (UTR), our assay robustly detects small changes in budding yeast initiation kinetics, which could not be resolved by bulk luminescence kinetics. Lastly, we demonstrate the general applicability of this assay to distinct cell-free translation systems by using extracts prepared from budding yeast, wheat germ, and rabbit reticulocyte lysates. This assay should facilitate mechanistic studies of eukaryotic cap-dependent translation initiation and translational control.
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Affiliation(s)
- Hongyun Wang
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Lexi Sun
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.,Department of Physiology, Biophysics and Systems Biology, Weill Cornell Graduate School of Medical Sciences, Cornell University, New York, NY 10065, USA
| | - Anthony Gaba
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Xiaohui Qu
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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5
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Fareh M, van Lopik J, Katechis I, Bronkhorst AW, Haagsma AC, van Rij RP, Joo C. Viral suppressors of RNAi employ a rapid screening mode to discriminate viral RNA from cellular small RNA. Nucleic Acids Res 2019; 46:3187-3197. [PMID: 29325071 PMCID: PMC5888754 DOI: 10.1093/nar/gkx1316] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 01/03/2018] [Indexed: 11/14/2022] Open
Abstract
RNA interference (RNAi) is an indispensable mechanism for antiviral defense in insects, including mosquitoes that transmit human diseases. To escape this antiviral defense system, viruses encode suppressors of RNAi that prevent elimination of viral RNAs, and thus ensure efficient virus accumulation. Although the first animal Viral Suppressor of RNAi (VSR) was identified more than a decade ago, the molecular basis of RNAi suppression by these viral proteins remains unclear. Here, we developed a single-molecule fluorescence assay to investigate how VSRs inhibit the recognition of viral RNAs by Dcr-2, a key endoribonuclease enzyme in the RNAi pathway. Using VSRs from three insect RNA viruses (Culex Y virus, Drosophila X virus and Drosophila C virus), we reveal bimodal physical interactions between RNA molecules and VSRs. During initial interactions, these VSRs rapidly discriminate short RNA substrates from long dsRNA. VSRs engage nearly irreversible binding with long dsRNAs, thereby shielding it from recognition by Dcr-2. We propose that the length-dependent switch from rapid screening to irreversible binding reflects the main mechanism by which VSRs distinguish viral dsRNA from cellular RNA species such as microRNAs.
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Affiliation(s)
- Mohamed Fareh
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Jasper van Lopik
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Iason Katechis
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Alfred W Bronkhorst
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands
| | - Anna C Haagsma
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft 2629 HZ, The Netherlands
| | - Ronald P van Rij
- Department of Medical Microbiology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Nijmegen 6525 GA, The Netherlands
| | - Chirlmin Joo
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft 2629 HZ, The Netherlands
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6
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Deriving a sub-nanomolar affinity peptide from TAP to enable smFRET analysis of RNA polymerase II complexes. Methods 2019; 159-160:59-69. [PMID: 30742995 DOI: 10.1016/j.ymeth.2019.02.006] [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] [Received: 11/30/2018] [Revised: 01/30/2019] [Accepted: 02/05/2019] [Indexed: 12/17/2022] Open
Abstract
Our capability to visualize protein complexes such as RNA polymerase II (pol II) by single-molecule imaging techniques has largely been hampered by the absence of a simple bio-orthogonal approach for selective labeling with a fluorescent probe. Here, we modify the existing calmodulin-binding peptide (CBP) in the widely used Tandem Affinity Purification (TAP) tag to endow it with a high affinity for calmodulin (CaM) and use dye-CaM to conduct site-specific labeling of pol II. To demonstrate the single molecule applicability of this approach, we labeled the C-terminus of the Rpb9 subunit of pol II with donor-CaM and a site in TFIIF with an acceptor to generate a FRET (fluorescence resonance energy transfer) pair in the pol II-TFIIF complex. We then used total internal reflection fluorescence microscopy (TIRF) with alternating excitation to measure the single molecule FRET (smFRET) efficiency between these two sites in pol II-TFIIF. We found they exhibited a proximity consistent with that observed in the transcription pre-initiation complex by cryo-electron microscopy (cryo-EM). We further compared our non-covalent labeling approach with an enzyme-enabled covalent labeling method. The virtually indistinguishable results validate our smFRET approach and show that the observed proximity between the two sites represents a hallmark of the pol II-TFIIF complex. Taken together, we present a simple and versatile bio-orthogonal method derived from TAP to enable selective labeling of a protein complex. This method is suitable for analyzing dynamic relationships among proteins involved in transcription and it can be readily extended to many other biological processes.
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7
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Rodriques SG, Marblestone AH, Boyden ES. A theoretical analysis of single molecule protein sequencing via weak binding spectra. PLoS One 2019; 14:e0212868. [PMID: 30921350 PMCID: PMC6438480 DOI: 10.1371/journal.pone.0212868] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 02/11/2019] [Indexed: 02/06/2023] Open
Abstract
We propose and theoretically study an approach to massively parallel single molecule peptide sequencing, based on single molecule measurement of the kinetics of probe binding (Havranek, et al., 2013) to the N-termini of immobilized peptides. Unlike previous proposals, this method is robust to both weak and non-specific probe-target affinities, which we demonstrate by applying the method to a range of randomized affinity matrices consisting of relatively low-quality binders. This suggests a novel principle for proteomic measurement whereby highly non-optimized sets of low-affinity binders could be applicable for protein sequencing, thus shifting the burden of amino acid identification from biomolecular design to readout. Measurement of probe occupancy times, or of time-averaged fluorescence, should allow high-accuracy determination of N-terminal amino acid identity for realistic probe sets. The time-averaged fluorescence method scales well to weakly-binding probes with dissociation constants of tens or hundreds of micromolar, and bypasses photobleaching limitations associated with other fluorescence-based approaches to protein sequencing. We argue that this method could lead to an approach with single amino acid resolution and the ability to distinguish many canonical and modified amino acids, even using highly non-optimized probe sets. This readout method should expand the design space for single molecule peptide sequencing by removing constraints on the properties of the fluorescent binding probes.
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Affiliation(s)
- Samuel G. Rodriques
- Synthetic Neurobiology Group, MIT, Cambridge, MA, United States of America
- Department of Physics, MIT, Cambridge, MA, United States of America
| | | | - Edward S. Boyden
- Synthetic Neurobiology Group, MIT, Cambridge, MA, United States of America
- McGovern Institute, MIT, Cambridge, MA, United States of America
- Media Lab, MIT, Cambridge, MA, United States of America
- Department of Biological Engineering, MIT, Cambridge, MA, United States of America
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, United States of America
- Koch Institute, MIT, Cambridge, MA, United States of America
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8
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Oligomerization of the tetramerization domain of p53 probed by two- and three-color single-molecule FRET. Proc Natl Acad Sci U S A 2017; 114:E6812-E6821. [PMID: 28760960 DOI: 10.1073/pnas.1700357114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We describe a method that combines two- and three-color single-molecule FRET spectroscopy with 2D FRET efficiency-lifetime analysis to probe the oligomerization process of intrinsically disordered proteins. This method is applied to the oligomerization of the tetramerization domain (TD) of the tumor suppressor protein p53. TD exists as a monomer at subnanomolar concentrations and forms a dimer and a tetramer at higher concentrations. Because the dissociation constants of the dimer and tetramer are very close, as we determine in this paper, it is not possible to characterize different oligomeric species by ensemble methods, especially the dimer that cannot be readily separated. However, by using single-molecule FRET spectroscopy that includes measurements of fluorescence lifetime and two- and three-color FRET efficiencies with corrections for submillisecond acceptor blinking, we show that it is possible to obtain structural information for individual oligomers at equilibrium and to determine the dimerization kinetics. From these analyses, we show that the monomer is intrinsically disordered and that the dimer conformation is very similar to that of the tetramer but the C terminus of the dimer is more flexible.
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9
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Ishitsuka Y, Azadfar N, Kobitski AY, Nienhaus K, Johnsson N, Nienhaus GU. Evaluation of Genetically Encoded Chemical Tags as Orthogonal Fluorophore Labeling Tools for Single-Molecule FRET Applications. J Phys Chem B 2015; 119:6611-9. [PMID: 25978145 DOI: 10.1021/acs.jpcb.5b03584] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Fluorescence resonance energy transfer (FRET) is a superb technique for measuring conformational changes of proteins on the single molecule level (smFRET) in real time. It requires introducing a donor and acceptor fluorophore pair at specific locations on the protein molecule of interest, which has often been a challenging task. By using two different self-labeling chemical tags, such as Halo-, TMP-, SNAP- and CLIP-tags, orthogonal labeling may be achieved rapidly and reliably. However, these comparatively large tags add extra distance and flexibility between the desired labeling location on the protein and the fluorophore position, which may affect the results. To systematically characterize chemical tags for smFRET measurement applications, we took the SNAP-tag/CLIP-tag combination as a model system and fused a flexible unstructured peptide, rigid polyproline peptides of various lengths, and the calcium sensor protein calmodulin between the tags. We could reliably identify length variations as small as four residues in the polyproline peptide. In the calmodulin system, the added length introduced by these tags was even beneficial for revealing subtle conformational changes upon variation of the buffer conditions. This approach opens up new possibilities for studying conformational dynamics, especially in large protein systems that are difficult to specifically conjugate with fluorophores.
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Affiliation(s)
- Yuji Ishitsuka
- †Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Naghmeh Azadfar
- †Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Andrei Yu Kobitski
- †Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Karin Nienhaus
- †Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - Nils Johnsson
- §Institute of Molecular Genetics and Cell Biology, Ulm University, James Franck Ring N27, 89081 Ulm, Germany
| | - G Ulrich Nienhaus
- †Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany.,∥Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.,⊥Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
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10
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Bosch PJ, Corrêa IR, Sonntag MH, Ibach J, Brunsveld L, Kanger JS, Subramaniam V. Evaluation of fluorophores to label SNAP-tag fused proteins for multicolor single-molecule tracking microscopy in live cells. Biophys J 2015; 107:803-14. [PMID: 25140415 DOI: 10.1016/j.bpj.2014.06.040] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/22/2014] [Accepted: 06/10/2014] [Indexed: 11/19/2022] Open
Abstract
Single-molecule tracking has become a widely used technique for studying protein dynamics and their organization in the complex environment of the cell. In particular, the spatiotemporal distribution of membrane receptors is an active field of study due to its putative role in the regulation of signal transduction. The SNAP-tag is an intrinsically monovalent and highly specific genetic tag for attaching a fluorescent label to a protein of interest. Little information is currently available on the choice of optimal fluorescent dyes for single-molecule microscopy utilizing the SNAP-tag labeling system. We surveyed 6 green and 16 red excitable dyes for their suitability in single-molecule microscopy of SNAP-tag fusion proteins in live cells. We determined the nonspecific binding levels and photostability of these dye conjugates when bound to a SNAP-tag fused membrane protein in live cells. We found that only a limited subset of the dyes tested is suitable for single-molecule tracking microscopy. The results show that a careful choice of the dye to conjugate to the SNAP-substrate to label SNAP-tag fusion proteins is very important, as many dyes suffer from either rapid photobleaching or high nonspecific staining. These characteristics appear to be unpredictable, which motivated the need to perform the systematic survey presented here. We have developed a protocol for evaluating the best dyes, and for the conditions that we evaluated, we find that Dy 549 and CF 640 are the best choices tested for single-molecule tracking. Using an optimal dye pair, we also demonstrate the possibility of dual-color single-molecule imaging of SNAP-tag fusion proteins. This survey provides an overview of the photophysical and imaging properties of a range of SNAP-tag fluorescent substrates, enabling the selection of optimal dyes and conditions for single-molecule imaging of SNAP-tagged fusion proteins in eukaryotic cell lines.
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Affiliation(s)
- Peter J Bosch
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | | | - Michael H Sonntag
- Laboratory of Chemical Biology, Department of Biomedical Engineering, and Institute of Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jenny Ibach
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Luc Brunsveld
- Laboratory of Chemical Biology, Department of Biomedical Engineering, and Institute of Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Johannes S Kanger
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Vinod Subramaniam
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
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11
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Blosser TR, Loeff L, Westra ER, Vlot M, Künne T, Sobota M, Dekker C, Brouns SJJ, Joo C. Two distinct DNA binding modes guide dual roles of a CRISPR-Cas protein complex. Mol Cell 2015; 58:60-70. [PMID: 25752578 DOI: 10.1016/j.molcel.2015.01.028] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/29/2014] [Accepted: 01/20/2015] [Indexed: 12/21/2022]
Abstract
Small RNA-guided protein complexes play an essential role in CRISPR-mediated immunity in prokaryotes. While these complexes initiate interference by flagging cognate invader DNA for destruction, recent evidence has implicated their involvement in new CRISPR memory formation, called priming, against mutated invader sequences. The mechanism by which the target recognition complex mediates these disparate responses-interference and priming-remains poorly understood. Using single-molecule FRET, we visualize how bona fide and mutated targets are differentially probed by E. coli Cascade. We observe that the recognition of bona fide targets is an ordered process that is tightly controlled for high fidelity. Mutated targets are recognized with low fidelity, which is featured by short-lived and PAM- and seed-independent binding by any segment of the crRNA. These dual roles of Cascade in immunity with distinct fidelities underpin CRISPR-Cas robustness, allowing for efficient degradation of bona fide targets and priming of mutated DNA targets.
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Affiliation(s)
- Timothy R Blosser
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Luuk Loeff
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Edze R Westra
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB, Wageningen, The Netherlands
| | - Marnix Vlot
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB, Wageningen, The Netherlands
| | - Tim Künne
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB, Wageningen, The Netherlands
| | - Małgorzata Sobota
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB, Wageningen, The Netherlands
| | - Cees Dekker
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Stan J J Brouns
- Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB, Wageningen, The Netherlands
| | - Chirlmin Joo
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, 2628 CJ, Delft, The Netherlands
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12
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Greenfeld M, van de Meent JW, Pavlichin DS, Mabuchi H, Wiggins CH, Gonzalez RL, Herschlag D. Single-molecule dataset (SMD): a generalized storage format for raw and processed single-molecule data. BMC Bioinformatics 2015; 16:3. [PMID: 25591752 PMCID: PMC4384321 DOI: 10.1186/s12859-014-0429-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 12/11/2014] [Indexed: 12/15/2022] Open
Abstract
Background Single-molecule techniques have emerged as incisive approaches for addressing a wide range of questions arising in contemporary biological research [Trends Biochem Sci 38:30–37, 2013; Nat Rev Genet 14:9–22, 2013; Curr Opin Struct Biol 2014, 28C:112–121; Annu Rev Biophys 43:19–39, 2014]. The analysis and interpretation of raw single-molecule data benefits greatly from the ongoing development of sophisticated statistical analysis tools that enable accurate inference at the low signal-to-noise ratios frequently associated with these measurements. While a number of groups have released analysis toolkits as open source software [J Phys Chem B 114:5386–5403, 2010; Biophys J 79:1915–1927, 2000; Biophys J 91:1941–1951, 2006; Biophys J 79:1928–1944, 2000; Biophys J 86:4015–4029, 2004; Biophys J 97:3196–3205, 2009; PLoS One 7:e30024, 2012; BMC Bioinformatics 288 11(8):S2, 2010; Biophys J 106:1327–1337, 2014; Proc Int Conf Mach Learn 28:361–369, 2013], it remains difficult to compare analysis for experiments performed in different labs due to a lack of standardization. Results Here we propose a standardized single-molecule dataset (SMD) file format. SMD is designed to accommodate a wide variety of computer programming languages, single-molecule techniques, and analysis strategies. To facilitate adoption of this format we have made two existing data analysis packages that are used for single-molecule analysis compatible with this format. Conclusion Adoption of a common, standard data file format for sharing raw single-molecule data and analysis outcomes is a critical step for the emerging and powerful single-molecule field, which will benefit both sophisticated users and non-specialists by allowing standardized, transparent, and reproducible analysis practices. Electronic supplementary material The online version of this article (doi:10.1186/s12859-014-0429-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Max Greenfeld
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA. .,Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA.
| | | | | | - Hideo Mabuchi
- Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
| | - Chris H Wiggins
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027, USA.
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia University, New York, NY, 10027, USA.
| | - Daniel Herschlag
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA. .,Department of Biochemistry, Stanford University, Stanford, CA, 94305, USA. .,Department of Biochemistry, B400, Stanford University, Stanford, CA, 94305, USA.
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Gust A, Zander A, Gietl A, Holzmeister P, Schulz S, Lalkens B, Tinnefeld P, Grohmann D. A starting point for fluorescence-based single-molecule measurements in biomolecular research. Molecules 2014; 19:15824-65. [PMID: 25271426 PMCID: PMC6271140 DOI: 10.3390/molecules191015824] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/17/2014] [Accepted: 09/17/2014] [Indexed: 01/24/2023] Open
Abstract
Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET) experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research.
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Affiliation(s)
- Alexander Gust
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Adrian Zander
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Andreas Gietl
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Phil Holzmeister
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Sarah Schulz
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Birka Lalkens
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Philip Tinnefeld
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Dina Grohmann
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany.
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14
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Affiliation(s)
- Vasudha Aggarwal
- Center for Biophysics and Computational Biology; University of Illinois Urbana Champaign; Urbana IL USA
| | - Taekjip Ha
- Center for Biophysics and Computational Biology; University of Illinois Urbana Champaign; Urbana IL USA
- Department of Physics; University of Illinois Urbana Champaign; Urbana IL USA
- Howard Hughes Medical Institute; Urbana IL USA
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15
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Chandradoss SD, Haagsma AC, Lee YK, Hwang JH, Nam JM, Joo C. Surface passivation for single-molecule protein studies. J Vis Exp 2014. [PMID: 24797261 PMCID: PMC4179479 DOI: 10.3791/50549] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Single-molecule fluorescence spectroscopy has proven to be instrumental in understanding a wide range of biological phenomena at the nanoscale. Important examples of what this technique can yield to biological sciences are the mechanistic insights on protein-protein and protein-nucleic acid interactions. When interactions of proteins are probed at the single-molecule level, the proteins or their substrates are often immobilized on a glass surface, which allows for a long-term observation. This immobilization scheme may introduce unwanted surface artifacts. Therefore, it is essential to passivate the glass surface to make it inert. Surface coating using polyethylene glycol (PEG) stands out for its high performance in preventing proteins from non-specifically interacting with a glass surface. However, the polymer coating procedure is difficult, due to the complication arising from a series of surface treatments and the stringent requirement that a surface needs to be free of any fluorescent molecules at the end of the procedure. Here, we provide a robust protocol with step-by-step instructions. It covers surface cleaning including piranha etching, surface functionalization with amine groups, and finally PEG coating. To obtain a high density of a PEG layer, we introduce a new strategy of treating the surface with PEG molecules over two rounds, which remarkably improves the quality of passivation. We provide representative results as well as practical advice for each critical step so that anyone can achieve the high quality surface passivation.
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Affiliation(s)
- Stanley D Chandradoss
- Kavli Institute of NanoScience, Department of BioNanoScience, Delft University of Technology
| | - Anna C Haagsma
- Kavli Institute of NanoScience, Department of BioNanoScience, Delft University of Technology
| | | | - Jae-Ho Hwang
- Department of Chemistry, Seoul National University
| | - Jwa-Min Nam
- Department of Chemistry, Seoul National University
| | - Chirlmin Joo
- Kavli Institute of NanoScience, Department of BioNanoScience, Delft University of Technology;
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16
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Asymmetric perturbations of signalling oligomers. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 114:153-69. [PMID: 24650570 DOI: 10.1016/j.pbiomolbio.2014.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 02/26/2014] [Accepted: 03/04/2014] [Indexed: 01/06/2023]
Abstract
This review focuses on rapid and reversible noncovalent interactions for symmetric oligomers of signalling proteins. Symmetry mismatch, transient symmetry breaking and asymmetric perturbations via chemical (ligand binding) and physical (electric or mechanic) effects can initiate the signalling events. Advanced biophysical methods can reveal not only structural symmetries of stable membrane-bound signalling proteins but also asymmetric functional transition states. Relevant techniques amenable to distinguish between symmetric and asymmetric architectures are discussed including those with the capability of capturing low-populated transient conformational states. Typical examples of signalling proteins are overviewed for symmetry breaking in dimers (GPCRs, growth factor receptors, transcription factors); trimers (acid-sensing ion channels); tetramers (voltage-gated cation channels, ionotropic glutamate receptor, CNG and CHN channels); pentameric ligand-gated and mechanosensitive channels; higher order oligomers (gap junction channel, chaperonins, proteasome, virus capsid); as well as primary and secondary transporters. In conclusion, asymmetric perturbations seem to play important functional roles in a broad range of communicating networks.
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17
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Anderson EG, Hoskins AA. Single molecule approaches for studying spliceosome assembly and catalysis. Methods Mol Biol 2014; 1126:217-41. [PMID: 24549668 DOI: 10.1007/978-1-62703-980-2_17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Single molecule assays of splicing and spliceosome assembly can provide unique insights into pre-mRNA processing that complement other technologies. Key to these experiments is the fabrication of fluorescent molecules (pre-mRNAs and spliceosome components) and passivated glass slides for each experiment. Here we describe how to produce fluorescent RNAs by splinted RNA ligation and fluorescent spliceosome subunits by SNAP-tagging proteins in cell lysate. We then depict how to passivate glass slides with polyethylene glycol for use on an inverted microscope with objective-based total internal reflection fluorescence (TIRF) optics. Finally, we describe how to tether the pre-mRNA onto the passivated slide surface and introduce the SNAP-tagged cell lysate for analysis of spliceosome assembly by single molecule fluorescence.
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Affiliation(s)
- Eric G Anderson
- Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
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18
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Affiliation(s)
- Jens Michaelis
- Biophysics
Institute, Faculty of Natural Sciences, Ulm University, Albert-Einstein-Allee
11, 89081 Ulm, Germany
- Center
for Integrated Protein Science Munich (CIPSM), Department
of Chemistry and Biochemistry, Munich University, Butenandtstrasse 5-13, 81377 München, Germany
| | - Barbara Treutlein
- Department
of Bioengineering, Stanford University, James H. Clark Center, E-300, 318
Campus Drive, Stanford, California 94305-5432, United States
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Abstract
MicroRNAs (miRNAs) regulate the expression of most genes in animals, but we are only now beginning to understand how they are generated, assembled into functional complexes and destroyed. Various mechanisms have now been identified that regulate miRNA stability and that diversify miRNA sequences to create distinct isoforms. The production of different isoforms of individual miRNAs in specific cells and tissues may have broader implications for miRNA-mediated gene expression control. Rigorously testing the many discrepant models for how miRNAs function using quantitative biochemical measurements made in vivo and in vitro remains a major challenge for the future.
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Making connections--strategies for single molecule fluorescence biophysics. Curr Opin Chem Biol 2013; 17:691-8. [PMID: 23769868 PMCID: PMC3989056 DOI: 10.1016/j.cbpa.2013.05.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/02/2013] [Accepted: 05/17/2013] [Indexed: 11/28/2022]
Abstract
The single-molecule approach yields exciting insights for many biomolecular applications. There are significant challenges to achieve main-stream single-molecule measurements. New labelling chemistries enable multiple tagged molecules in vitro and in live cells. Single-molecule pull-down expands the toolbox complementing co-immunoprecipitation. Breaking the single-molecule concentration barrier is within reach.
Fluorescence spectroscopy and fluorescence microscopy carried out on the single molecule level are elegant methods to decipher complex biological systems; it can provide a wealth of information that frequently is obscured in the averaging of ensemble measurements. Fluorescence can be used to localise a molecule, study its binding with interaction partners and ligands, or to follow conformational changes in large multicomponent systems. Efficient labelling of proteins and nucleic acids is very important for any fluorescence method, and equally the development of novel fluorophores has been crucial in making biomolecules amenable to single molecule fluorescence methods. In this paper we review novel coupling strategies that permit site-specific and efficient labelling of proteins. Furthermore, we will discuss progressive single molecule approaches that allow the detection of individual molecules and biomolecular complexes even directly isolated from cellular extracts at much higher and much lower concentrations than has been possible so far.
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