1
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Swain BC, Sarkis P, Ung V, Rousseau S, Fernandez L, Meltonyan A, Aho VE, Mercadante D, Mackereth CD, Aznauryan M. Disordered regions of human eIF4B orchestrate a dynamic self-association landscape. Nat Commun 2024; 15:8766. [PMID: 39384813 PMCID: PMC11464913 DOI: 10.1038/s41467-024-53136-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Accepted: 10/03/2024] [Indexed: 10/11/2024] Open
Abstract
Eukaryotic translation initiation factor eIF4B is required for efficient cap-dependent translation, it is overexpressed in cancer cells, and may influence stress granule formation. Due to the high degree of intrinsic disorder, eIF4B is rarely observed in cryo-EM structures of translation complexes and only ever by its single structured RNA recognition motif domain, leaving the molecular details of its large intrinsically disordered region (IDR) unknown. By integrating experiments and simulations we demonstrate that eIF4B IDR orchestrates and fine-tunes an intricate transition from monomers to a condensed phase, in which large-size dynamic oligomers form before mesoscopic phase separation. Single-molecule spectroscopy combined with molecular simulations enabled us to characterize the conformational ensembles and underlying intra- and intermolecular dynamics across the oligomerization transition. The observed sensitivity to ionic strength and molecular crowding in the self-association landscape suggests potential regulation of eIF4B nanoscopic and mesoscopic behaviors such as driven by protein modifications, binding partners or changes to the cellular environment.
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Affiliation(s)
- Bikash Chandra Swain
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France
| | - Pascale Sarkis
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France
| | - Vanessa Ung
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Sabrina Rousseau
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France
| | - Laurent Fernandez
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France
| | - Ani Meltonyan
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France
| | - V Esperance Aho
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France
- Institut de Biologie Structurale (IBS), UMR 5075, F-38044, Grenoble, France
| | - Davide Mercadante
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Cameron D Mackereth
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, F-33000, Bordeaux, France.
| | - Mikayel Aznauryan
- University of Bordeaux, Inserm, CNRS, ARNA Laboratory, U1212, UMR 5320, Institut Européen de Chimie et Biologie, F-33600, Pessac, France.
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2
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Nüesch MF, Pietrek L, Holmstrom ED, Nettels D, von Roten V, Kronenberg-Tenga R, Medalia O, Hummer G, Schuler B. Nanosecond chain dynamics of single-stranded nucleic acids. Nat Commun 2024; 15:6010. [PMID: 39019880 PMCID: PMC11255343 DOI: 10.1038/s41467-024-50092-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 07/01/2024] [Indexed: 07/19/2024] Open
Abstract
The conformational dynamics of single-stranded nucleic acids are fundamental for nucleic acid folding and function. However, their elementary chain dynamics have been difficult to resolve experimentally. Here we employ a combination of single-molecule Förster resonance energy transfer, nanosecond fluorescence correlation spectroscopy, and nanophotonic enhancement to determine the conformational ensembles and rapid chain dynamics of short single-stranded nucleic acids in solution. To interpret the experimental results in terms of end-to-end distance dynamics, we utilize the hierarchical chain growth approach, simple polymer models, and refinement with Bayesian inference to generate structural ensembles that closely align with the experimental data. The resulting chain reconfiguration times are exceedingly rapid, in the 10-ns range. Solvent viscosity-dependent measurements indicate that these dynamics of single-stranded nucleic acids exhibit negligible internal friction and are thus dominated by solvent friction. Our results provide a detailed view of the conformational distributions and rapid dynamics of single-stranded nucleic acids.
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Affiliation(s)
- Mark F Nüesch
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Lisa Pietrek
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Erik D Holmstrom
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Department of Chemistry, University of Kansas, Lawrence, KS, USA.
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA.
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Valentin von Roten
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Rafael Kronenberg-Tenga
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany.
- Institute for Biophysics, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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3
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Chen Q, Zhou J, Sun R. Carbon Nanotube Loading Strategies for Peptide Drugs: Insights from Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13515-13526. [PMID: 38887887 DOI: 10.1021/acs.langmuir.4c00973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Carbon nanotubes (CNTs) can be regarded as a potential platform for transmembrane drug delivery as many experimental works have demonstrated their capability to effectively transport bioactive molecules into living cells. Within this framework, the loading of a peptide drug onto either the interior or exterior of CNTs has gained considerable interest. This study aims to conduct a comprehensive comparison of these two loading methods. To this end, we performed molecular dynamics simulations and the umbrella sampling technique to investigate the interaction energy, conformational changes, and free energy changes of a model peptide drug containing α-helical structure interacting with the inner or outer walls of a 14.7-nm-long (20,20) CNT. Our finding reveals that, for a tube of such dimensions, it is thermodynamically more favorable for the peptide to be loaded onto the inner tube wall than the outer tube wall, primarily due to a larger free energy change for the former strategy. Conversely, unloading the drug from the tube interior poses greater challenges. Moreover, the tube's curvature plays an essential role in influencing the conformation of the adsorbed peptide. Despite the relatively weaker van der Waals interaction between the CNT exterior and the peptide, loading the peptide onto the exterior may induce significant conformational changes, particularly affecting the peptide's α-helix structure. In contrast, loading of the peptide on the CNT interior could maintain most of the α-helical content. CNTs do not typically attract specific peptide residues, with adsorbed groups primarily determined by the peptide's configurations and orientations. Finally, we offer a guideline for selecting an optimal loading strategy for CNT-based drug delivery.
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Affiliation(s)
- Qu Chen
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, People's Republic of China
| | - Jianping Zhou
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, People's Republic of China
| | - Rong Sun
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, People's Republic of China
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4
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Miller JJ, Mallimadugula UL, Zimmerman MI, Stuchell-Brereton MD, Soranno A, Bowman GR. Accounting for fast vs slow exchange in single molecule FRET experiments reveals hidden conformational states. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.03.597137. [PMID: 38895430 PMCID: PMC11185552 DOI: 10.1101/2024.06.03.597137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Proteins are dynamic systems whose structural preferences determine their function. Unfortunately, building atomically detailed models of protein structural ensembles remains challenging, limiting our understanding of the relationships between sequence, structure, and function. Combining single molecule Förster resonance energy transfer (smFRET) experiments with molecular dynamics simulations could provide experimentally grounded, all-atom models of a protein's structural ensemble. However, agreement between the two techniques is often insufficient to achieve this goal. Here, we explore whether accounting for important experimental details like averaging across structures sampled during a given smFRET measurement is responsible for this apparent discrepancy. We present an approach to account for this time-averaging by leveraging the kinetic information available from Markov state models of a protein's dynamics. This allows us to accurately assess which timescales are averaged during an experiment. We find this approach significantly improves agreement between simulations and experiments in proteins with varying degrees of dynamics, including the well-ordered protein T4 lysozyme, the partially disordered protein apolipoprotein E (ApoE), and a disordered amyloid protein (Aβ40). We find evidence for hidden states that are not apparent in smFRET experiments because of time averaging with other structures, akin to states in fast exchange in NMR, and evaluate different force fields. Finally, we show how remaining discrepancies between computations and experiments can be used to guide additional simulations and build structural models for states that were previously unaccounted for. We expect our approach will enable combining simulations and experiments to understand the link between sequence, structure, and function in many settings.
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Affiliation(s)
- Justin J. Miller
- Departments of Biochemistry & Biophysics and Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, United States
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Upasana L. Mallimadugula
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Maxwell I. Zimmerman
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Melissa D. Stuchell-Brereton
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Gregory R. Bowman
- Departments of Biochemistry & Biophysics and Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, United States
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States
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5
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Cubuk J, Greenberg L, Greenberg AE, Emenecker RJ, Stuchell-Brereton MD, Holehouse AS, Soranno A, Greenberg MJ. Structural dynamics of the intrinsically disordered linker region of cardiac troponin T. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.30.596451. [PMID: 38853835 PMCID: PMC11160775 DOI: 10.1101/2024.05.30.596451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
The cardiac troponin complex, composed of troponins I, T, and C, plays a central role in regulating the calcium-dependent interactions between myosin and the thin filament. Mutations in troponin can cause cardiomyopathies; however, it is still a major challenge for the field to connect how changes in sequence affect troponin's function. Recent high-resolution structures of the thin filament revealed critical insights into the structure-function relationship of the troponin complex, but there remain large, unresolved segments of troponin, including the troponin-T linker region that is a hotspot for several cardiomyopathy mutations. This unresolved yet functionally-significant linker region has been proposed to be intrinsically disordered, with behaviors that are not well described by traditional structural approaches; however, this proposal has not been experimentally verified. Here, we used a combination of single-molecule Förster resonance energy transfer (FRET), molecular dynamics simulations, and functional reconstitution assays to investigate the troponin-T linker region. We experimentally and computationally show that in the context of both isolated troponin and the fully regulated troponin complex, the linker behaves as a dynamic, intrinsically disordered region. This region undergoes polyampholyte expansion in the presence of high salt and distinct conformational changes during the assembly of the troponin complex. We also examine the ΔE160 hypertrophic cardiomyopathy mutation in the linker, and we demonstrate that this mutation does not affect the conformational dynamics of the linker, rather it allosterically affects interactions with other subunits of the troponin complex, leading to increased molecular contractility. Taken together, our data clearly demonstrate the importance of disorder within the troponin-T linker and provide new insights into the molecular mechanisms controlling the pathogenesis of cardiomyopathies.
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Affiliation(s)
- Jasmine Cubuk
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Lina Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
| | - Akiva E. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
| | - Ryan J. Emenecker
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Melissa D. Stuchell-Brereton
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Alex S. Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Andrea Soranno
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
- Center for Biomolecular Condensates, Washington University in St Louis, 1 Brookings Drive, 63130, Saint Louis, MO, USA
| | - Michael J. Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University in St Louis, 660 Euclid Ave, 63110, Saint Louis, MO, USA
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6
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Clark BS, Silvernail I, Gordon K, Castaneda JF, Morgan AN, Rolband LA, LeBlanc SJ. A practical guide to time-resolved fluorescence microscopy and spectroscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.25.577300. [PMID: 38586000 PMCID: PMC10996486 DOI: 10.1101/2024.01.25.577300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Time-correlated single photon counting (TCSPC) coupled with confocal microscopy is a versatile biophysical tool that enables real-time monitoring of biomolecular dynamics across many timescales. With TCSPC, Fluorescence correlation spectroscopy (FCS) and pulsed interleaved excitation-Förster resonance energy transfer (PIE-FRET) are collected simultaneously on diffusing molecules to extract diffusion characteristics and proximity information. This article is a guide to calibrating FCS and PIE-FRET measurements with several biological samples including liposomes, streptavidin-coated quantum dots, proteins, and nucleic acids for reliable determination of diffusion coefficients and FRET efficiency. The FRET efficiency results are also compared to surface-attached single molecules using fluorescence lifetime imaging microscopy (FLIM-FRET). Combining the methods is a powerful approach to revealing mechanistic details of biological processes and pathways.
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7
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Sano Y, Itoh Y, Kamonprasertsuk S, Suzuki L, Fukasawa A, Oikawa H, Takahashi S. Simple and Efficient Detection Scheme of Two-Color Fluorescence Correlation Spectroscopy for Protein Dynamics Investigation from Nanoseconds to Milliseconds. ACS PHYSICAL CHEMISTRY AU 2024; 4:85-93. [PMID: 38283787 PMCID: PMC10811772 DOI: 10.1021/acsphyschemau.3c00040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/29/2023] [Accepted: 10/30/2023] [Indexed: 01/30/2024]
Abstract
Nanosecond resolved fluorescence correlation spectroscopy (ns-FCS) based on two-color fluorescence detection is a powerful strategy for investigating the fast dynamics of biological macromolecules labeled with donor and acceptor fluorophores. The standard methods of ns-FCS use two single-photon avalanche diodes (SPADs) for the detection of single-color signals (four SPADs for two-color signals) to eliminate the afterpulse artifacts of SPAD at the expense of the efficiency of utilizing photon data in the calculation of correlograms. Herein, we demonstrated that hybrid photodetectors (HPDs) enable the recording of fluorescence photons in ns-FCS based on the minimal system using two HPDs for the detection of two-color signals. However, HPD exhibited afterpulses at a yield with respect to the rate of photodetection (<10-4) much lower than that of SPADs (∼10-2), which could still hamper correlation measurements. We demonstrated that the simple subtraction procedure could eliminate afterpulse artifacts. While the quantum efficiency of photodetection for HPDs is lower than that for high-performance SPADs, the developed system can be practically used for two-color ns-FCS in a time domain longer than a few nanoseconds. The fast chain dynamics of the B domain of protein A in the unfolded state was observed using the new method.
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Affiliation(s)
- Yutaka Sano
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Yuji Itoh
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Supawich Kamonprasertsuk
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Leo Suzuki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Atsuhito Fukasawa
- Electron Tube Division, Hamamatsu Photonics K. K., Iwata, Shizuoka 438-0193, Japan
| | - Hiroyuki Oikawa
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
- MOLCURE, Kawasaki, Kanagawa 212-0032, Japan
| | - Satoshi Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577, Japan
- Department of Chemistry, Graduate School of Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan
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8
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Kayyil Veedu M, Osmólska J, Hajda A, Olesiak-Bańska J, Wenger J. Unveiling the photoluminescence dynamics of gold nanoclusters with fluorescence correlation spectroscopy. NANOSCALE ADVANCES 2024; 6:570-577. [PMID: 38235077 PMCID: PMC10790814 DOI: 10.1039/d3na00869j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/02/2023] [Indexed: 01/19/2024]
Abstract
Gold nanoclusters (AuNCs) have captured significant interest for their photoluminescent properties; however, their rapid photodynamics remain elusive while probed by ensemble-averaging spectroscopy techniques. To address this challenge, we use fluorescence correlation spectroscopy (FCS) to uncover the photoluminescence dynamics of colloidal Au18(SG)14 nanoclusters. Our FCS analysis reveals the photoluminescence (PL) brightness per nanocluster, elucidating the impact of photoexcitation saturation and ligand interactions. Unlike DNA-encapsulated silver nanoclusters, their gold counterparts notably exhibit minimal blinking, with moderate amplitudes and 200 μs characteristic times. Our data also clearly reveal the occurrence of photon antibunching in the PL emission, showcasing the quantum nature of the PL process, with each AuNC acting as an individual quantum source. Using zero-mode waveguide nanoapertures, we achieve a 16-fold enhancement of the PL brightness of individual AuNCs. This constitutes an important enabling proof-of-concept for tailoring emission properties through nanophotonics. Overall, our study bridges the gap between ensemble-averaged techniques and single-molecule spectroscopy, offering new insights into AuNC photodynamics for biosensing and imaging applications.
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Affiliation(s)
- Malavika Kayyil Veedu
- Aix Marseille Univ, CNRS, Centrale Med, Institut Fresnel, AMUTech 13013 Marseille France
| | - Julia Osmólska
- Institute of Advanced Materials, Wroclaw University of Science and Technology Wrocław Poland
| | - Agata Hajda
- Institute of Advanced Materials, Wroclaw University of Science and Technology Wrocław Poland
| | - Joanna Olesiak-Bańska
- Institute of Advanced Materials, Wroclaw University of Science and Technology Wrocław Poland
| | - Jérôme Wenger
- Aix Marseille Univ, CNRS, Centrale Med, Institut Fresnel, AMUTech 13013 Marseille France
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9
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Barulin A, Kim Y, Oh DK, Jang J, Park H, Rho J, Kim I. Dual-wavelength metalens enables Epi-fluorescence detection from single molecules. Nat Commun 2024; 15:26. [PMID: 38167868 PMCID: PMC10761847 DOI: 10.1038/s41467-023-44407-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/12/2023] [Indexed: 01/05/2024] Open
Abstract
Single molecule fluorescence spectroscopy is at the heart of molecular biophysics research and the most sensitive biosensing assays. The growing demand for precision medicine and environmental monitoring requires the creation of miniaturized and portable sensing platforms. However, the need for highly sophisticated objective lenses has precluded the development of single molecule detection systems for truly portable devices. Here, we propose a dielectric metalens device of submicrometer thickness to excite and collect light from fluorescent molecules instead of an objective lens. The high numerical aperture, high focusing efficiency, and dual-wavelength operation of the metalens enable the implementation of fluorescence correlation spectroscopy with a single Alexa 647 molecule in the focal volume. Moreover, the metalens enables real-time monitoring of individual fluorescent nanoparticle transitions and identification of hydrodynamic diameters ranging from a few to hundreds of nanometers. This advancement in sensitivity extends the application of the metalens technology to ultracompact single-molecule sensors.
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Affiliation(s)
- Aleksandr Barulin
- Department of Biophysics, Institute of Quantum Biophysics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yeseul Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Dong Kyo Oh
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jaehyuck Jang
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
- POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics, Pohang, 37673, Republic of Korea
| | - Hyemi Park
- Department of Biophysics, Institute of Quantum Biophysics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Junsuk Rho
- Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
- POSCO-POSTECH-RIST Convergence Research Center for Flat Optics and Metaphotonics, Pohang, 37673, Republic of Korea.
- National Institute of Nanomaterials Technology (NINT), Pohang, 37673, Republic of Korea.
| | - Inki Kim
- Department of Biophysics, Institute of Quantum Biophysics, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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10
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Vermeer B, van Ossenbruggen J, Schmid S. Single-Molecule FRET-Resolved Protein Dynamics - from Plasmid to Data in Six Steps. Methods Mol Biol 2024; 2694:267-291. [PMID: 37824009 DOI: 10.1007/978-1-0716-3377-9_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is a powerful technique for the detection of conformational dynamics of biomolecules. While many smFRET experiments are performed using dye-labeled DNA, here we describe a comprehensive protocol to resolve the conformational dynamics of a protein system - notably from plasmid to data. Using the example of the heat-shock protein Hsp90, we describe the protein production and threefold site-specific bioconjugation, the smFRET measurement using total internal reflection fluorescence microscopy (TIRFM), and raw data processing to reveal time-resolved protein dynamics. The described smFRET approach is readily transferrable to the study of many more all-protein systems and their conformational energy landscape.
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Affiliation(s)
- Benjamin Vermeer
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, The Netherlands
| | | | - Sonja Schmid
- Laboratory of Biophysics, Wageningen University & Research, Wageningen, The Netherlands.
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11
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Vancraenenbroeck R, Hofmann H. Electrostatics and hydrophobicity in the dynamics of intrinsically disordered proteins. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:133. [PMID: 38127117 PMCID: PMC10739388 DOI: 10.1140/epje/s10189-023-00383-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 11/20/2023] [Indexed: 12/23/2023]
Abstract
Internal friction is a major contribution to the dynamics of intrinsically disordered proteins (IDPs). Yet, the molecular origin of internal friction has so far been elusive. Here, we investigate whether attractive electrostatic interactions in IDPs modulate internal friction differently than the hydrophobic effect. To this end, we used nanosecond fluorescence correlation spectroscopy (nsFCS) and single-molecule Förster resonance energy transfer (FRET) to quantify the conformation and dynamics of the disordered DNA-binding domains Myc, Max and Mad at different salt concentrations. We find that internal friction effects are stronger when the chain is compacted by electrostatic attractions compared to the hydrophobic effect. Although the effect is moderate, the results show that the heteropolymeric nature of IDPs is reflected in their dynamics.
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Affiliation(s)
- Renee Vancraenenbroeck
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Herzl St. 234, 76100, Rehovot, Israel
- Present Address: Department of Structural and Molecular Biology, University College London, Darwin Building, 107 Gower Street, London, WC1E 6BT, UK
| | - Hagen Hofmann
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Herzl St. 234, 76100, Rehovot, Israel.
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12
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Sohmen B, Beck C, Frank V, Seydel T, Hoffmann I, Hermann B, Nüesch M, Grimaldo M, Schreiber F, Wolf S, Roosen‐Runge F, Hugel T. The Onset of Molecule-Spanning Dynamics in Heat Shock Protein Hsp90. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304262. [PMID: 37984887 PMCID: PMC10754087 DOI: 10.1002/advs.202304262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/06/2023] [Indexed: 11/22/2023]
Abstract
Protein dynamics have been investigated on a wide range of time scales. Nano- and picosecond dynamics have been assigned to local fluctuations, while slower dynamics have been attributed to larger conformational changes. However, it is largely unknown how fast (local) fluctuations can lead to slow global (allosteric) changes. Here, fast molecule-spanning dynamics on the 100 to 200 ns time scale in the heat shock protein 90 (Hsp90) are shown. Global real-space movements are assigned to dynamic modes on this time scale, which is possible by a combination of single-molecule fluorescence, quasi-elastic neutron scattering and all-atom molecular dynamics (MD) simulations. The time scale of these dynamic modes depends on the conformational state of the Hsp90 dimer. In addition, the dynamic modes are affected to various degrees by Sba1, a co-chaperone of Hsp90, depending on the location within Hsp90, which is in very good agreement with MD simulations. Altogether, this data is best described by fast molecule-spanning dynamics, which precede larger conformational changes in Hsp90 and might be the molecular basis for allostery. This integrative approach provides comprehensive insights into molecule-spanning dynamics on the nanosecond time scale for a multi-domain protein.
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Affiliation(s)
- Benedikt Sohmen
- Institute of Physical ChemistryUniversity of FreiburgAlbertstrasse 2179104FreiburgGermany
| | - Christian Beck
- Institute of Applied PhysicsUniversity of TübingenAuf der Morgenstelle 1072076TübingenGermany
- Science DivisionInstitut Max von Laue ‐ Paul Langevin71 avenue des MartyrsGrenoble38042France
| | - Veronika Frank
- Institute of Physical ChemistryUniversity of FreiburgAlbertstrasse 2179104FreiburgGermany
| | - Tilo Seydel
- Science DivisionInstitut Max von Laue ‐ Paul Langevin71 avenue des MartyrsGrenoble38042France
| | - Ingo Hoffmann
- Science DivisionInstitut Max von Laue ‐ Paul Langevin71 avenue des MartyrsGrenoble38042France
| | - Bianca Hermann
- Institute of Physical ChemistryUniversity of FreiburgAlbertstrasse 2179104FreiburgGermany
| | - Mark Nüesch
- Department of BiochemistryUniversity of ZurichWinterthurerstrasse 190CH‐8057ZurichSwitzerland
| | - Marco Grimaldo
- Science DivisionInstitut Max von Laue ‐ Paul Langevin71 avenue des MartyrsGrenoble38042France
| | - Frank Schreiber
- Institute of Applied PhysicsUniversity of TübingenAuf der Morgenstelle 1072076TübingenGermany
| | - Steffen Wolf
- Biomolecular Dynamics, Institute of PhysicsUniversity of FreiburgHermann‐Herder‐Strasse 379104FreiburgGermany
| | - Felix Roosen‐Runge
- Department of Biomedical Sciences and Biofilms‐Research Center for Biointerfaces (BRCB)Malmö University20506MalmöSweden
- Division of Physical ChemistryLund UniversityNaturvetarvägen 1422100LundSweden
| | - Thorsten Hugel
- Institute of Physical ChemistryUniversity of FreiburgAlbertstrasse 2179104FreiburgGermany
- Signalling Research Centers BIOSS and CIBSSUniversity of FreiburgSchänzlestrasse 1879104FreiburgGermany
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13
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Vedel IM, Papagiannoula A, Naudi-Fabra S, Milles S. Nuclear magnetic resonance/single molecule fluorescence combinations to study dynamic protein systems. Curr Opin Struct Biol 2023; 82:102659. [PMID: 37499445 PMCID: PMC10565672 DOI: 10.1016/j.sbi.2023.102659] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 05/04/2023] [Accepted: 06/28/2023] [Indexed: 07/29/2023]
Abstract
Many proteins require different structural states or conformations for function, and intrinsically disordered proteins, i.e. proteins without stable three-dimensional structure, are certainly an extreme. Single molecule fluorescence and nuclear magnetic resonance (NMR) spectroscopy are both exceptionally well suited to decipher and describe these states and their interconversion. Different time scales, from picoseconds to several milliseconds, can be addressed by both techniques. The length scales probed and the sample requirements (e.g. concentration, molecular weight, sample complexity) are, however, vastly different, making NMR and single molecule fluorescence an excellent combination for integrated studies. Here, we review recently undertaken approaches for the combined use of NMR and single molecule fluorescence to study protein dynamics.
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Affiliation(s)
- Ida Marie Vedel
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Andromachi Papagiannoula
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Samuel Naudi-Fabra
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Sigrid Milles
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany.
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14
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Vovk A, Zilman A. Effects of Sequence Composition, Patterning and Hydrodynamics on the Conformation and Dynamics of Intrinsically Disordered Proteins. Int J Mol Sci 2023; 24:1444. [PMID: 36674958 PMCID: PMC9867189 DOI: 10.3390/ijms24021444] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/24/2022] [Accepted: 12/25/2022] [Indexed: 01/13/2023] Open
Abstract
Intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs) perform diverse functions in cellular organization, transport and signaling. Unlike the well-defined structures of the classical natively folded proteins, IDPs and IDRs dynamically span large conformational and structural ensembles. This dynamic disorder impedes the study of the relationship between the amino acid sequences of the IDPs and their spatial structures and dynamics, with different experimental techniques often offering seemingly contradictory results. Although experimental and theoretical evidence indicates that some IDP properties can be understood based on their average biophysical properties and amino acid composition, other aspects of IDP function are dictated by the specifics of the amino acid sequence. We investigate the effects of several key variables on the dimensions and the dynamics of IDPs using coarse-grained polymer models. We focus on the sequence "patchiness" informed by the sequence and biophysical properties of different classes of IDPs-and in particular FG nucleoporins of the nuclear pore complex (NPC). We show that the sequence composition and patterning are well reflected in the global conformational variables such as the radius of gyration and hydrodynamic radius, while the end-to-end distance and dynamics are highly sequence-specific. We find that in good solvent conditions highly heterogeneous sequences of IDPs can be well mapped onto averaged minimal polymer models for the purpose of prediction of the IDPs dimensions and dynamic relaxation times. The coarse-grained simulations are in a good agreement with the results of atomistic MD. We discuss the implications of these results for the interpretation of the recent experimental measurements, and for the further applications of mesoscopic models of FG nucleoporins and IDPs more broadly.
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Affiliation(s)
- Andrei Vovk
- Department of Physics, University of Toronto, 60 St George Street, Toronto, ON M1M 2P7, Canada
| | - Anton Zilman
- Department of Physics, University of Toronto, 60 St George Street, Toronto, ON M1M 2P7, Canada
- Institute for Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada
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15
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Sakhapov D, Gregor I, Karedla N, Enderlein J. Measuring Photophysical Transition Rates with Fluorescence Correlation Spectroscopy and Antibunching. J Phys Chem Lett 2022; 13:4823-4830. [PMID: 35616286 DOI: 10.1021/acs.jpclett.2c00896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We present a new method that combines fluorescence correlation spectroscopy (FCS) on the microsecond time scale with fluorescence antibunching measurements on the nanosecond time scale for measuring photophysical rate constants of fluorescent molecules. The antibunching measurements allow us to quantify the average excitation rate of fluorescent molecules within the confocal detection volume of the FCS measurement setup. Knowledge of this value allows us then to quantify, in an absolute manner, the intersystem crossing rate and triplet state lifetime from the microsecond temporal decay of the FCS curves. We present a theoretical analysis of the method and estimate the maximum bias caused by the averaging of all quantities (excitation rate and photophysical rates) over the confocal detection volume, and we show that this bias is smaller than 5% in most cases. We apply the method for measuring the photophysical rate constants of the widely used dyes Rhodamine 110 and ATTO 655.
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Affiliation(s)
- Damir Sakhapov
- III. Institute of Physics - Biophysics, Georg-August-University, 37077 Göttingen, Germany
| | - Ingo Gregor
- III. Institute of Physics - Biophysics, Georg-August-University, 37077 Göttingen, Germany
| | - Narain Karedla
- The Rosalind Franklin Institute, Harwell Campus, Didcot OX11 0FA, U.K
| | - Jörg Enderlein
- III. Institute of Physics - Biophysics, Georg-August-University, 37077 Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg August University, 37077 Göttingen, Germany
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16
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Vermeer B, Schmid S. Can DyeCycling break the photobleaching limit in single-molecule FRET? NANO RESEARCH 2022; 15:9818-9830. [PMID: 35582137 PMCID: PMC9101981 DOI: 10.1007/s12274-022-4420-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 05/03/2023]
Abstract
Biomolecular systems, such as proteins, crucially rely on dynamic processes at the nanoscale. Detecting biomolecular nanodynamics is therefore key to obtaining a mechanistic understanding of the energies and molecular driving forces that control biomolecular systems. Single-molecule fluorescence resonance energy transfer (smFRET) is a powerful technique to observe in real-time how a single biomolecule proceeds through its functional cycle involving a sequence of distinct structural states. Currently, this technique is fundamentally limited by irreversible photobleaching, causing the untimely end of the experiment and thus, a narrow temporal bandwidth of ≤ 3 orders of magnitude. Here, we introduce "DyeCycling", a measurement scheme with which we aim to break the photobleaching limit in smFRET. We introduce the concept of spontaneous dye replacement by simulations, and as an experimental proof-of-concept, we demonstrate the intermittent observation of a single biomolecule for one hour with a time resolution of milliseconds. Theoretically, DyeCycling can provide > 100-fold more information per single molecule than conventional smFRET. We discuss the experimental implementation of DyeCycling, its current and fundamental limitations, and specific biological use cases. Given its general simplicity and versatility, DyeCycling has the potential to revolutionize the field of time-resolved smFRET, where it may serve to unravel a wealth of biomolecular dynamics by bridging from milliseconds to the hour range. Electronic Supplementary Material Supplementary material is available for this article at 10.1007/s12274-022-4420-5 and is accessible for authorized users.
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Affiliation(s)
- Benjamin Vermeer
- NanoDynamicsLab, Laboratory of Biophysics, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
| | - Sonja Schmid
- NanoDynamicsLab, Laboratory of Biophysics, Wageningen University, Stippeneng 4, 6708WE Wageningen, The Netherlands
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17
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Barth A, Opanasyuk O, Peulen TO, Felekyan S, Kalinin S, Sanabria H, Seidel CAM. Unraveling multi-state molecular dynamics in single-molecule FRET experiments. I. Theory of FRET-lines. J Chem Phys 2022; 156:141501. [PMID: 35428384 PMCID: PMC9014241 DOI: 10.1063/5.0089134] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 02/27/2022] [Indexed: 01/31/2023] Open
Abstract
Conformational dynamics of biomolecules are of fundamental importance for their function. Single-molecule studies of Förster Resonance Energy Transfer (smFRET) between a tethered donor and acceptor dye pair are a powerful tool to investigate the structure and dynamics of labeled molecules. However, capturing and quantifying conformational dynamics in intensity-based smFRET experiments remains challenging when the dynamics occur on the sub-millisecond timescale. The method of multiparameter fluorescence detection addresses this challenge by simultaneously registering fluorescence intensities and lifetimes of the donor and acceptor. Together, two FRET observables, the donor fluorescence lifetime τD and the intensity-based FRET efficiency E, inform on the width of the FRET efficiency distribution as a characteristic fingerprint for conformational dynamics. We present a general framework for analyzing dynamics that relates average fluorescence lifetimes and intensities in two-dimensional burst frequency histograms. We present parametric relations of these observables for interpreting the location of FRET populations in E-τD diagrams, called FRET-lines. To facilitate the analysis of complex exchange equilibria, FRET-lines serve as reference curves for a graphical interpretation of experimental data to (i) identify conformational states, (ii) resolve their dynamic connectivity, (iii) compare different kinetic models, and (iv) infer polymer properties of unfolded or intrinsically disordered proteins. For a simplified graphical analysis of complex kinetic networks, we derive a moment-based representation of the experimental data that decouples the motion of the fluorescence labels from the conformational dynamics of the biomolecule. Importantly, FRET-lines facilitate exploring complex dynamic models via easily computed experimental observables. We provide extensive computational tools to facilitate applying FRET-lines.
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Affiliation(s)
- Anders Barth
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Oleg Opanasyuk
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Thomas-Otavio Peulen
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Suren Felekyan
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Stanislav Kalinin
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29631, USA
| | - Claus A. M. Seidel
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
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18
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Abyzov A, Blackledge M, Zweckstetter M. Conformational Dynamics of Intrinsically Disordered Proteins Regulate Biomolecular Condensate Chemistry. Chem Rev 2022; 122:6719-6748. [PMID: 35179885 PMCID: PMC8949871 DOI: 10.1021/acs.chemrev.1c00774] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
Motions in biomolecules
are critical for biochemical reactions.
In cells, many biochemical reactions are executed inside of biomolecular
condensates formed by ultradynamic intrinsically disordered proteins.
A deep understanding of the conformational dynamics of intrinsically
disordered proteins in biomolecular condensates is therefore of utmost
importance but is complicated by diverse obstacles. Here we review
emerging data on the motions of intrinsically disordered proteins
inside of liquidlike condensates. We discuss how liquid–liquid
phase separation modulates internal motions across a wide range of
time and length scales. We further highlight the importance of intermolecular
interactions that not only drive liquid–liquid phase separation
but appear as key determinants for changes in biomolecular motions
and the aging of condensates in human diseases. The review provides
a framework for future studies to reveal the conformational dynamics
of intrinsically disordered proteins in the regulation of biomolecular
condensate chemistry.
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Affiliation(s)
- Anton Abyzov
- Translational Structural Biology Group, German Center for Neurodegenerative Diseases (DZNE), 37075 Göttingen, Germany
| | - Martin Blackledge
- Université Grenoble Alpes, Institut de Biologie Structurale (IBS), 38044 Grenoble, France.,CEA, DSV, IBS, 38044 Grenoble, France.,CNRS, IBS, 38044 Grenoble, France
| | - Markus Zweckstetter
- Translational Structural Biology Group, German Center for Neurodegenerative Diseases (DZNE), 37075 Göttingen, Germany.,Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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19
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Nüesch MF, Ivanović MT, Claude JB, Nettels D, Best RB, Wenger J, Schuler B. Single-molecule Detection of Ultrafast Biomolecular Dynamics with Nanophotonics. J Am Chem Soc 2022; 144:52-56. [PMID: 34970909 DOI: 10.1021/jacs.1c09387] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Single-molecule Förster resonance energy transfer (FRET) is a versatile technique for probing the structure and dynamics of biomolecules even in heterogeneous ensembles. However, because of the limited fluorescence brightness per molecule and the relatively long fluorescence lifetimes, probing ultrafast structural dynamics in the nanosecond time scale has thus far been very challenging. Here, we demonstrate that nanophotonic fluorescence enhancement in zero-mode waveguides enables measurements of previously inaccessible low-nanosecond dynamics by dramatically improving time resolution and reduces data acquisition times by more than an order of magnitude. As a prototypical example, we use this approach to probe the dynamics of a short intrinsically disordered peptide that were previously inaccessible with single-molecule FRET measurements. We show that we are now able to detect the low-nanosecond correlations in this peptide, and we obtain a detailed interpretation of the underlying distance distributions and dynamics in conjunction with all-atom molecular dynamics simulations, which agree remarkably well with the experiments. We expect this combined approach to be widely applicable to the investigation of very rapid biomolecular dynamics.
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Affiliation(s)
- Mark F Nüesch
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Miloš T Ivanović
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Jean-Benoît Claude
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
| | - Jérôme Wenger
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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20
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Maciel GS. Pushing the limits of luminescence thermometry: probing the temperature of proteins in cells. J Biol Phys 2022; 48:167-175. [PMID: 34997472 DOI: 10.1007/s10867-021-09600-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022] Open
Abstract
Proteins are involved in numerous cellular activities such as transport and catalysis. Misfolding during biosynthesis and malfunctioning as a molecular machine may lead to physiological disorders and metabolic problems. Protein folding and mechanical work may be viewed as thermodynamic energetically favorable processes in which stochastic nonequilibrium intermediate states may be present with conditions such as thermal fluctuations. In my opinion, measuring those thermal fluctuations may be a way to access the energy exchange between the protein and the physiological environment and to better understand how those nonequilibrium states may influence the misfolding/folding process and the efficiency of the molecular engine cycle. Here, I discuss luminescence thermometry as a possible way to measure those temperature fluctuations from a single-molecule experimental perspective with its current technical limitations and challenges.
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Affiliation(s)
- Glauco S Maciel
- Instituto de Física, Universidade Federal Fluminense, Niterói, RJ, 24210-346, Brazil.
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21
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Dingfelder F, Macocco I, Benke S, Nettels D, Faccioli P, Schuler B. Slow Escape from a Helical Misfolded State of the Pore-Forming Toxin Cytolysin A. JACS AU 2021; 1:1217-1230. [PMID: 34467360 PMCID: PMC8397351 DOI: 10.1021/jacsau.1c00175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Indexed: 05/12/2023]
Abstract
The pore-forming toxin cytolysin A (ClyA) is expressed as a large α-helical monomer that, upon interaction with membranes, undergoes a major conformational rearrangement into the protomer conformation, which then assembles into a cytolytic pore. Here, we investigate the folding kinetics of the ClyA monomer with single-molecule Förster resonance energy transfer spectroscopy in combination with microfluidic mixing, stopped-flow circular dichroism experiments, and molecular simulations. The complex folding process occurs over a broad range of time scales, from hundreds of nanoseconds to minutes. The very slow formation of the native state occurs from a rapidly formed and highly collapsed intermediate with large helical content and nonnative topology. Molecular dynamics simulations suggest pronounced non-native interactions as the origin of the slow escape from this deep trap in the free-energy surface, and a variational enhanced path-sampling approach enables a glimpse of the folding process that is supported by the experimental data.
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Affiliation(s)
- Fabian Dingfelder
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Iuri Macocco
- Department
of Physics, Trento University, Via Sommarive 14, 38123 Povo (Trento), Italy
- SISSA, Via Bonomea 265, 34136 Trieste, Italy
| | - Stephan Benke
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Daniel Nettels
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Pietro Faccioli
- Department
of Physics, Trento University, Via Sommarive 14, 38123 Povo (Trento), Italy
- INFN-TIFPA, Via Sommarive 14, 38123 Povo (Trento), Italy
| | - Benjamin Schuler
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department
of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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22
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Ghosh A, Enderlein J. Advanced fluorescence correlation spectroscopy for studying biomolecular conformation. Curr Opin Struct Biol 2021; 70:123-131. [PMID: 34371261 DOI: 10.1016/j.sbi.2021.06.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/22/2021] [Accepted: 06/25/2021] [Indexed: 10/20/2022]
Abstract
We present the recent developments and advances in fluorescence correlation spectroscopy (FCS) and their application to the investigation of biomolecular conformations. In particular, we present and discuss three techniques: multichannel nanosecond FCS, photo-induced electron transfer FCS, and fluorescence lifetime correlation spectroscopy. We briefly describe each method and discuss recent applications to diverse biophysical studies of biomolecular conformation.
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Affiliation(s)
- Arindam Ghosh
- Third Institute of Physics, Biophysics, University of Göttingen, Friedrich Hund Platz 1 Göttingen, 37077, Germany
| | - Jörg Enderlein
- Third Institute of Physics, Biophysics, University of Göttingen, Friedrich Hund Platz 1 Göttingen, 37077, Germany; Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg August University, Göttingen, 37077, Germany.
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23
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Sanders JC, Holmstrom ED. Integrating single-molecule FRET and biomolecular simulations to study diverse interactions between nucleic acids and proteins. Essays Biochem 2021; 65:37-49. [PMID: 33600559 PMCID: PMC8052285 DOI: 10.1042/ebc20200022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/17/2021] [Accepted: 01/26/2021] [Indexed: 12/12/2022]
Abstract
The conformations of biological macromolecules are intimately related to their cellular functions. Conveniently, the well-characterized dipole-dipole distance-dependence of Förster resonance energy transfer (FRET) makes it possible to measure and monitor the nanoscale spatial dimensions of these conformations using fluorescence spectroscopy. For this reason, FRET is often used in conjunction with single-molecule detection to study a wide range of conformationally dynamic biochemical processes. Written for those not yet familiar with the subject, this review aims to introduce biochemists to the methodology associated with single-molecule FRET, with a particular emphasis on how it can be combined with biomolecular simulations to study diverse interactions between nucleic acids and proteins. In the first section, we highlight several conceptual and practical considerations related to this integrative approach. In the second section, we review a few recent research efforts wherein various combinations of single-molecule FRET and biomolecular simulations were used to study the structural and dynamic properties of biochemical systems involving different types of nucleic acids (e.g., DNA and RNA) and proteins (e.g., folded and disordered).
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Affiliation(s)
- Joshua C Sanders
- Department of Chemistry, University of Kansas, Lawrence, KS, U.S.A
| | - Erik D Holmstrom
- Department of Chemistry, University of Kansas, Lawrence, KS, U.S.A
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, U.S.A
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24
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Lerner E, Barth A, Hendrix J, Ambrose B, Birkedal V, Blanchard SC, Börner R, Sung Chung H, Cordes T, Craggs TD, Deniz AA, Diao J, Fei J, Gonzalez RL, Gopich IV, Ha T, Hanke CA, Haran G, Hatzakis NS, Hohng S, Hong SC, Hugel T, Ingargiola A, Joo C, Kapanidis AN, Kim HD, Laurence T, Lee NK, Lee TH, Lemke EA, Margeat E, Michaelis J, Michalet X, Myong S, Nettels D, Peulen TO, Ploetz E, Razvag Y, Robb NC, Schuler B, Soleimaninejad H, Tang C, Vafabakhsh R, Lamb DC, Seidel CAM, Weiss S. FRET-based dynamic structural biology: Challenges, perspectives and an appeal for open-science practices. eLife 2021; 10:e60416. [PMID: 33779550 PMCID: PMC8007216 DOI: 10.7554/elife.60416] [Citation(s) in RCA: 135] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/09/2021] [Indexed: 12/18/2022] Open
Abstract
Single-molecule FRET (smFRET) has become a mainstream technique for studying biomolecular structural dynamics. The rapid and wide adoption of smFRET experiments by an ever-increasing number of groups has generated significant progress in sample preparation, measurement procedures, data analysis, algorithms and documentation. Several labs that employ smFRET approaches have joined forces to inform the smFRET community about streamlining how to perform experiments and analyze results for obtaining quantitative information on biomolecular structure and dynamics. The recent efforts include blind tests to assess the accuracy and the precision of smFRET experiments among different labs using various procedures. These multi-lab studies have led to the development of smFRET procedures and documentation, which are important when submitting entries into the archiving system for integrative structure models, PDB-Dev. This position paper describes the current 'state of the art' from different perspectives, points to unresolved methodological issues for quantitative structural studies, provides a set of 'soft recommendations' about which an emerging consensus exists, and lists openly available resources for newcomers and seasoned practitioners. To make further progress, we strongly encourage 'open science' practices.
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Affiliation(s)
- Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, and The Center for Nanoscience and Nanotechnology, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of JerusalemJerusalemIsrael
| | - Anders Barth
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-UniversitätDüsseldorfGermany
| | - Jelle Hendrix
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute (BIOMED), Hasselt UniversityDiepenbeekBelgium
| | - Benjamin Ambrose
- Department of Chemistry, University of SheffieldSheffieldUnited Kingdom
| | - Victoria Birkedal
- Department of Chemistry and iNANO center, Aarhus UniversityAarhusDenmark
| | - Scott C Blanchard
- Department of Structural Biology, St. Jude Children's Research HospitalMemphisUnited States
| | - Richard Börner
- Laserinstitut HS Mittweida, University of Applied Science MittweidaMittweidaGermany
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität MünchenPlanegg-MartinsriedGermany
| | - Timothy D Craggs
- Department of Chemistry, University of SheffieldSheffieldUnited Kingdom
| | - Ashok A Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research InstituteLa JollaUnited States
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati School of MedicineCincinnatiUnited States
| | - Jingyi Fei
- Department of Biochemistry and Molecular Biology and The Institute for Biophysical Dynamics, University of ChicagoChicagoUnited States
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia UniversityNew YorkUnited States
| | - Irina V Gopich
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaUnited States
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Howard Hughes Medical InstituteBaltimoreUnited States
| | - Christian A Hanke
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-UniversitätDüsseldorfGermany
| | - Gilad Haran
- Department of Chemical and Biological Physics, Weizmann Institute of ScienceRehovotIsrael
| | - Nikos S Hatzakis
- Department of Chemistry & Nanoscience Centre, University of CopenhagenCopenhagenDenmark
- Denmark Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | - Sungchul Hohng
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National UniversitySeoulRepublic of Korea
| | - Seok-Cheol Hong
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science and Department of Physics, Korea UniversitySeoulRepublic of Korea
| | - Thorsten Hugel
- Institute of Physical Chemistry and Signalling Research Centres BIOSS and CIBSS, University of FreiburgFreiburgGermany
| | - Antonino Ingargiola
- Department of Chemistry and Biochemistry, and Department of Physiology, University of California, Los AngelesLos AngelesUnited States
| | - Chirlmin Joo
- Department of BioNanoScience, Kavli Institute of Nanoscience, Delft University of TechnologyDelftNetherlands
| | - Achillefs N Kapanidis
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of OxfordOxfordUnited Kingdom
| | - Harold D Kim
- School of Physics, Georgia Institute of TechnologyAtlantaUnited States
| | - Ted Laurence
- Physical and Life Sciences Directorate, Lawrence Livermore National LaboratoryLivermoreUnited States
| | - Nam Ki Lee
- School of Chemistry, Seoul National UniversitySeoulRepublic of Korea
| | - Tae-Hee Lee
- Department of Chemistry, Pennsylvania State UniversityUniversity ParkUnited States
| | - Edward A Lemke
- Departments of Biology and Chemistry, Johannes Gutenberg UniversityMainzGermany
- Institute of Molecular Biology (IMB)MainzGermany
| | - Emmanuel Margeat
- Centre de Biologie Structurale (CBS), CNRS, INSERM, Universitié de MontpellierMontpellierFrance
| | | | - Xavier Michalet
- Department of Chemistry and Biochemistry, and Department of Physiology, University of California, Los AngelesLos AngelesUnited States
| | - Sua Myong
- Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Daniel Nettels
- Department of Biochemistry and Department of Physics, University of ZurichZurichSwitzerland
| | - Thomas-Otavio Peulen
- Department of Bioengineering and Therapeutic Sciences, University of California, San FranciscoSan FranciscoUnited States
| | - Evelyn Ploetz
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-UniversitätMünchenGermany
| | - Yair Razvag
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, and The Center for Nanoscience and Nanotechnology, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of JerusalemJerusalemIsrael
| | - Nicole C Robb
- Warwick Medical School, University of WarwickCoventryUnited Kingdom
| | - Benjamin Schuler
- Department of Biochemistry and Department of Physics, University of ZurichZurichSwitzerland
| | - Hamid Soleimaninejad
- Biological Optical Microscopy Platform (BOMP), University of MelbourneParkvilleAustralia
| | - Chun Tang
- College of Chemistry and Molecular Engineering, PKU-Tsinghua Center for Life Sciences, Beijing National Laboratory for Molecular Sciences, Peking UniversityBeijingChina
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM), Ludwig-Maximilians-UniversitätMünchenGermany
| | - Claus AM Seidel
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-UniversitätDüsseldorfGermany
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, and Department of Physiology, University of California, Los AngelesLos AngelesUnited States
- Department of Physiology, CaliforniaNanoSystems Institute, University of California, Los AngelesLos AngelesUnited States
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25
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Durham RJ, Latham DR, Sanabria H, Jayaraman V. Structural Dynamics of Glutamate Signaling Systems by smFRET. Biophys J 2020; 119:1929-1936. [PMID: 33096078 PMCID: PMC7732771 DOI: 10.1016/j.bpj.2020.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/06/2020] [Accepted: 10/13/2020] [Indexed: 12/19/2022] Open
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is a powerful technique for investigating the structural dynamics of biological macromolecules. smFRET reveals the conformational landscape and dynamic changes of proteins by building on the static structures found using cryo-electron microscopy, x-ray crystallography, and other methods. Combining smFRET with static structures allows for a direct correlation between dynamic conformation and function. Here, we discuss the different experimental setups, fluorescence detection schemes, and data analysis strategies that enable the study of structural dynamics of glutamate signaling across various timescales. We illustrate the versatility of smFRET by highlighting studies of a wide range of questions, including the mechanism of activation and transport, the role of intrinsically disordered segments, and allostery and cooperativity between subunits in biological systems responsible for glutamate signaling.
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Affiliation(s)
- Ryan J Durham
- University of Texas Health Science Center at Houston, Houston, Texas
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26
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Fujiwara S, Matsuo T, Sugimoto Y, Shibata K. Segmental Motions of Proteins under Non-native States Evaluated Using Quasielastic Neutron Scattering. J Phys Chem Lett 2019; 10:7505-7509. [PMID: 31743029 DOI: 10.1021/acs.jpclett.9b03196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Characterization of the dynamics of disordered polypeptide chains is required to elucidate the behavior of intrinsically disordered proteins and proteins under non-native states related to the folding process. Here we develop a method using quasielastic neutron scattering, combined with small-angle X-ray scattering and dynamic light scattering, to evaluate segmental motions of proteins as well as diffusion of the entire molecules and local side-chain motions. We apply this method to RNase A under the unfolded and molten-globule (MG) states. The diffusion coefficients arising from the segmental motions are evaluated and found to be different between the unfolded and MG states. The values obtained here are consistent with those obtained using the fluorescence-based techniques. These results demonstrate not only feasibility of this method but also usefulness to characterize the behavior of proteins under various disordered states.
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Affiliation(s)
- Satoru Fujiwara
- Institute for Quantum Life Science , National Institutes for Quantum and Radiological Science and Technology , 2-4 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Tatsuhito Matsuo
- Institute for Quantum Life Science , National Institutes for Quantum and Radiological Science and Technology , 2-4 Shirakata , Tokai , Ibaraki 319-1106 , Japan
| | - Yasunobu Sugimoto
- Nagoya University Synchrotron Radiation Research Center , Furo-cho, Chikusa-ku, Nagoya , Aichi 464-8603 , Japan
| | - Kaoru Shibata
- Neutron Science Section, Materials and Life Science Division, J-PARC Center , Japan Atomic Energy Agency , 2-4 Shirakata , Tokai , Ibaraki 319-1195 , Japan
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27
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Krainer G, Keller S, Schlierf M. Structural dynamics of membrane-protein folding from single-molecule FRET. Curr Opin Struct Biol 2019; 58:124-137. [DOI: 10.1016/j.sbi.2019.05.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 05/27/2019] [Indexed: 12/15/2022]
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28
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Disordered RNA chaperones can enhance nucleic acid folding via local charge screening. Nat Commun 2019; 10:2453. [PMID: 31165735 PMCID: PMC6549165 DOI: 10.1038/s41467-019-10356-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/06/2019] [Indexed: 01/14/2023] Open
Abstract
RNA chaperones are proteins that aid in the folding of nucleic acids, but remarkably, many of these proteins are intrinsically disordered. How can these proteins function without a well-defined three-dimensional structure? Here, we address this question by studying the hepatitis C virus core protein, a chaperone that promotes viral genome dimerization. Using single-molecule fluorescence spectroscopy, we find that this positively charged disordered protein facilitates the formation of compact nucleic acid conformations by acting as a flexible macromolecular counterion that locally screens repulsive electrostatic interactions with an efficiency equivalent to molar salt concentrations. The resulting compaction can bias unfolded nucleic acids towards folding, resulting in faster folding kinetics. This potentially widespread mechanism is supported by molecular simulations that rationalize the experimental findings by describing the chaperone as an unstructured polyelectrolyte. RNA chaperones, such as the hepatitic C virus (HCV) core protein, are proteins that aid in the folding of nucleic acids. Here authors use single‐molecule spectroscopy and simulation to show that the HCV core protein acts as a flexible macromolecular counterion which facilitates nucleic acid folding.
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29
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Meng F, Bellaiche MMJ, Kim JY, Zerze GH, Best RB, Chung HS. Highly Disordered Amyloid-β Monomer Probed by Single-Molecule FRET and MD Simulation. Biophys J 2019; 114:870-884. [PMID: 29490247 DOI: 10.1016/j.bpj.2017.12.025] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 12/12/2017] [Accepted: 12/18/2017] [Indexed: 12/13/2022] Open
Abstract
Monomers of amyloid-β (Aβ) protein are known to be disordered, but there is considerable controversy over the existence of residual or transient conformations that can potentially promote oligomerization and fibril formation. We employed single-molecule Förster resonance energy transfer (FRET) spectroscopy with site-specific dye labeling using an unnatural amino acid and molecular dynamics simulations to investigate conformations and dynamics of Aβ isoforms with 40 (Aβ40) and 42 residues (Aβ42). The FRET efficiency distributions of both proteins measured in phosphate-buffered saline at room temperature show a single peak with very similar FRET efficiencies, indicating there is apparently only one state. 2D FRET efficiency-donor lifetime analysis reveals, however, that there is a broad distribution of rapidly interconverting conformations. Using nanosecond fluorescence correlation spectroscopy, we measured the timescale of the fluctuations between these conformations to be ∼35 ns, similar to that of disordered proteins. These results suggest that both Aβ40 and Aβ42 populate an ensemble of rapidly reconfiguring unfolded states, with no long-lived conformational state distinguishable from that of the disordered ensemble. To gain molecular-level insights into these observations, we performed molecular dynamics simulations with a force field optimized to describe disordered proteins. We find, as in experiments, that both peptides populate configurations consistent with random polymer chains, with the vast majority of conformations lacking significant secondary structure, giving rise to very similar ensemble-averaged FRET efficiencies.
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Affiliation(s)
- Fanjie Meng
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Mathias M J Bellaiche
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland; Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Jae-Yeol Kim
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Gül H Zerze
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania
| | - Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland.
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland.
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30
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Ingargiola A, Weiss S, Lerner E. Monte Carlo Diffusion-Enhanced Photon Inference: Distance Distributions and Conformational Dynamics in Single-Molecule FRET. J Phys Chem B 2018; 122:11598-11615. [PMID: 30252475 DOI: 10.1021/acs.jpcb.8b07608] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is utilized to study the structure and dynamics of many biomolecules, such as proteins, DNA, and their various complexes. The structural assessment is based on the well-known Förster relationship between the measured efficiency of energy transfer between a donor (D) and an acceptor (A) dye and the distance between them. Classical smFRET analysis methods called photon distribution analysis (PDA) take into account photon shot-noise, D-A distance distribution, and, more recently, interconversion between states in order to extract accurate distance information. It is known that rapid D-A distance fluctuations on the order of the D lifetime (or shorter) can increase the measured mean FRET efficiency and thus decrease the estimated D-A distance. Nonetheless, this effect has been so far neglected in smFRET experiments, potentially leading to biases in estimated distances. Here we introduce a PDA approach dubbed Monte Carlo diffusion-enhanced photon inference (MC-DEPI). MC-DEPI recolor detected photons of smFRET experiments taking into account dynamics of D-A distance fluctuations, multiple interconverting states, and photoblinking. Using this approach, we show how different underlying conditions may yield identical FRET histograms and how the additional information from fluorescence decays helps in distinguishing between the different conditions. We also introduce a machine learning fitting approach for retrieving the D-A distance distribution, decoupled from the above-mentioned effects. We show that distance interpretation of smFRET experiments of even the simplest dsDNA is nontrivial and requires decoupling the effects of rapid D-A distance fluctuations on FRET in order to avoid systematic biases in the estimation of the D-A distance distribution.
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Affiliation(s)
- Antonino Ingargiola
- Department of Chemistry and Biochemistry , University of California Los Angeles , Los Angeles , California , United States
| | - Shimon Weiss
- Department of Chemistry and Biochemistry , University of California Los Angeles , Los Angeles , California , United States
| | - Eitan Lerner
- Department of Chemistry and Biochemistry , University of California Los Angeles , Los Angeles , California , United States.,Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences , The Hebrew University , Jerusalem , Israel
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31
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Otosu T, Yamaguchi S. Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy: Concepts and Applications. Molecules 2018; 23:E2972. [PMID: 30441830 PMCID: PMC6278346 DOI: 10.3390/molecules23112972] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/07/2018] [Accepted: 11/13/2018] [Indexed: 01/03/2023] Open
Abstract
We review the basic concepts and recent applications of two-dimensional fluorescence lifetime correlation spectroscopy (2D FLCS), which is the extension of fluorescence correlation spectroscopy (FCS) to analyze the correlation of fluorescence lifetime in addition to fluorescence intensity. Fluorescence lifetime is sensitive to the microenvironment and can be a "molecular ruler" when combined with FRET. Utilization of fluorescence lifetime in 2D FLCS thus enables us to quantify the inhomogeneity of the system and the interconversion dynamics among different species with a higher time resolution than other single-molecule techniques. Recent applications of 2D FLCS to various biological systems demonstrate that 2D FLCS is a unique and promising tool to quantitatively analyze the microsecond conformational dynamics of macromolecules at the single-molecule level.
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Affiliation(s)
- Takuhiro Otosu
- Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan.
| | - Shoichi Yamaguchi
- Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan.
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32
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LeBlanc SJ, Kulkarni P, Weninger KR. Single Molecule FRET: A Powerful Tool to Study Intrinsically Disordered Proteins. Biomolecules 2018; 8:biom8040140. [PMID: 30413085 PMCID: PMC6315554 DOI: 10.3390/biom8040140] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/02/2018] [Accepted: 11/06/2018] [Indexed: 12/22/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are often modeled using ideas from polymer physics that suggest they smoothly explore all corners of configuration space. Experimental verification of this random, dynamic behavior is difficult as random fluctuations of IDPs cannot be synchronized across an ensemble. Single molecule fluorescence (or Förster) resonance energy transfer (smFRET) is one of the few approaches that are sensitive to transient populations of sub-states within molecular ensembles. In some implementations, smFRET has sufficient time resolution to resolve transitions in IDP behaviors. Here we present experimental issues to consider when applying smFRET to study IDP configuration. We illustrate the power of applying smFRET to IDPs by discussing two cases in the literature of protein systems for which smFRET has successfully reported phosphorylation-induced modification (but not elimination) of the disordered properties that have been connected to impacts on the related biological function. The examples we discuss, PAGE4 and a disordered segment of the GluN2B subunit of the NMDA receptor, illustrate the great potential of smFRET to inform how IDP function can be regulated by controlling the detailed ensemble of disordered states within biological networks.
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Affiliation(s)
- Sharonda J LeBlanc
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, CA 91010, USA.
| | - Keith R Weninger
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA.
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33
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Grotz KK, Nueesch MF, Holmstrom ED, Heinz M, Stelzl LS, Schuler B, Hummer G. Dispersion Correction Alleviates Dye Stacking of Single-Stranded DNA and RNA in Simulations of Single-Molecule Fluorescence Experiments. J Phys Chem B 2018; 122:11626-11639. [PMID: 30285443 DOI: 10.1021/acs.jpcb.8b07537] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We combine single-molecule Förster resonance energy transfer (single-molecule FRET) experiments with extensive all-atom molecular dynamics (MD) simulations (>100 μs) to characterize the conformational ensembles of single-stranded (ss) DNA and RNA in solution. From MD simulations with explicit dyes attached to single-stranded nucleic acids via flexible linkers, we calculate FRET efficiencies and fluorescence anisotropy decays. We find that dispersion-corrected water models alleviate the problem of overly abundant interactions between fluorescent dyes and the aromatic ring systems of nucleobases. To model dye motions in a computationally efficient and conformationally exhaustive manner, we introduce a dye-conformer library, built from simulations of dinucleotides with covalently attached dye molecules. We use this library to calculate FRET efficiencies for dT19, dA19, and rA19 simulated without explicit labels over a wide range of salt concentrations. For end-labeled homopolymeric pyrimidine ssDNA, MD simulations with the parmBSC1 force field capture the overall trend in salt-dependence of single-molecule FRET based distance measurements. For homopolymeric purine ssRNA and ssDNA, the DESRES and parmBSC1 force fields, respectively, provide useful starting points, even though our comparison also identifies clear deviations from experiment.
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Affiliation(s)
- Kara K Grotz
- Department of Theoretical Biophysics , Max Planck Institute of Biophysics , 60438 Frankfurt am Main , Germany
| | - Mark F Nueesch
- Department of Biochemistry , University of Zurich , 8057 Zurich , Switzerland
| | - Erik D Holmstrom
- Department of Biochemistry , University of Zurich , 8057 Zurich , Switzerland
| | - Marcel Heinz
- Department of Theoretical Biophysics , Max Planck Institute of Biophysics , 60438 Frankfurt am Main , Germany
| | - Lukas S Stelzl
- Department of Theoretical Biophysics , Max Planck Institute of Biophysics , 60438 Frankfurt am Main , Germany
| | - Benjamin Schuler
- Department of Biochemistry , University of Zurich , 8057 Zurich , Switzerland.,Department of Physics , University of Zurich , 8057 Zurich , Switzerland
| | - Gerhard Hummer
- Department of Theoretical Biophysics , Max Planck Institute of Biophysics , 60438 Frankfurt am Main , Germany.,Institute of Biophysics , Goethe University Frankfurt , 60438 Frankfurt am Main , Germany
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34
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Jacob MH, Ghosh I, D'Souza RN, Nau WM. Two Orders of Magnitude Variation of Diffusion-Enhanced Förster Resonance Energy Transfer in Polypeptide Chains. Polymers (Basel) 2018; 10:E1079. [PMID: 30961004 PMCID: PMC6403563 DOI: 10.3390/polym10101079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 09/20/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022] Open
Abstract
A flexible peptide chain displays structural and dynamic properties that correspond to its folding and biological activity. These properties are mirrored in intrachain site-to-site distances and diffusion coefficients of mutual site-to-site motion. Both distance distribution and diffusion determine the extent of Förster resonance energy transfer (FRET) between two sites labeled with a FRET donor and acceptor. The relatively large Förster radii of traditional FRET methods (R₀ > 20 Å) lead to a fairly low contribution of diffusion. We introduced short-distance FRET (sdFRET) where Dbo, an asparagine residue conjugated to 2,3-diazabicyclo[2.2.2]octane, acts as acceptor paired with donors, such as naphtylalanine (NAla), tryptophan, 5-l-fluorotryptophan, or tyrosine. The Förster radii are always close to 10 Å, which makes sdFRET highly sensitive to diffusional motion. We recently found indications that the FRET enhancement caused by diffusion depends symmetrically on the product of the radiative fluorescence lifetime of the donor and the diffusion coefficient. In this study, we varied this product by two orders of magnitude, using both donors of different lifetime, NAla and FTrp, as well as a varying viscogen concentration, to corroborate this statement. We demonstrate the consequences of this relationship in evaluating the impact of viscogenic coadditives on peptide dimensions.
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Affiliation(s)
- Maik H Jacob
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Indrajit Ghosh
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Roy N D'Souza
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Werner M Nau
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
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35
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Dingfelder F, Benke S, Nettels D, Schuler B. Mapping an Equilibrium Folding Intermediate of the Cytolytic Pore Toxin ClyA with Single-Molecule FRET. J Phys Chem B 2018; 122:11251-11261. [PMID: 30156409 DOI: 10.1021/acs.jpcb.8b07026] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The 303-residue cytolytic toxin ClyA forms a stable α-helical monomer. In the presence of detergents or membranes, however, the protein makes a large conformational transition to the protomer state, which is competent for assembly into a dodecameric cytolytic pore. In this study, we map the structure of the ClyA monomer during denaturant-induced unfolding with single-molecule Förster resonance energy transfer (FRET) spectroscopy. To this end, we probe intramolecular distances of six different segments of ClyA by placing donor and acceptor fluorophores at corresponding positions along the chain. We identify an intermediate state that contains the folded core consisting of three of the α-helices that make up the helical bundle present in the structure of both the monomer and the protomer, but with the C- and N-terminal helices unfolded, in accord with the secondary structure content estimated from circular dichroism (CD) spectroscopy. The existence of this intermediate is likely to be a consequence of the structural bistability underlying the biological function of ClyA: The terminal helices are part of the largest rearrangements during protomer formation, and the local differences in stability we detect may prime the protein for the required conformational transition.
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Affiliation(s)
- Fabian Dingfelder
- Department of Biochemistry , University of Zurich , Winterthurerstrasse 190 , 8057 Zurich , Switzerland
| | - Stephan Benke
- Department of Biochemistry , University of Zurich , Winterthurerstrasse 190 , 8057 Zurich , Switzerland
| | - Daniel Nettels
- Department of Biochemistry , University of Zurich , Winterthurerstrasse 190 , 8057 Zurich , Switzerland
| | - Benjamin Schuler
- Department of Biochemistry , University of Zurich , Winterthurerstrasse 190 , 8057 Zurich , Switzerland.,Department of Physics , University of Zurich , Winterthurerstrasse 190 , 8057 Zurich , Switzerland
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36
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Woodard J, Srivastava KR, Rahamim G, Grupi A, Hogan S, Witalka DJ, Nawrocki G, Haas E, Feig M, Lapidus LJ. Intramolecular Diffusion in α-Synuclein: It Depends on How You Measure It. Biophys J 2018; 115:1190-1199. [PMID: 30224053 DOI: 10.1016/j.bpj.2018.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 08/09/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022] Open
Abstract
Intramolecular protein diffusion, the motion of one part of the polypeptide chain relative to another part, is a fundamental aspect of protein folding and may modulate amyloidogenesis of disease-associated intrinsically disordered proteins. Much work has determined such diffusion coefficients using a variety of probes, but there has been an apparent discrepancy between measurements using long-range probes, such as fluorescence resonance energy transfer, and short-range probes, such as Trp-Cys quenching. In this work, we make both such measurements on the same protein, α-synuclein, and confirm that such discrepancy exists. Molecular dynamics simulations suggest that such differences result from a diffusion coefficient that depends on the spatial distance between probes. Diffusional estimates in good quantitative agreement with experiment are obtained by accounting for the distinct distance ranges probed by fluorescence resonance energy transfer and Trp-Cys quenching.
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Affiliation(s)
- Jaie Woodard
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Kinshuk R Srivastava
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - Gil Rahamim
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Asaf Grupi
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Steven Hogan
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - David J Witalka
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - Grzegorz Nawrocki
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Elisha Haas
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Lisa J Lapidus
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan.
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37
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Das A, Makarov DE. Dynamics of Disordered Proteins under Confinement: Memory Effects and Internal Friction. J Phys Chem B 2018; 122:9049-9060. [PMID: 30092636 DOI: 10.1021/acs.jpcb.8b06112] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Many proteins are disordered under physiological conditions. How efficiently they can search for their cellular targets and how fast they can fold upon target binding is determined by their intrinsic dynamics, which have thus attracted much recent attention. Experiments and molecular simulations show that the inherent reconfiguration timescale for unfolded proteins has a solvent friction component and an internal friction component, and the microscopic origin of the latter, along with its proper mathematical description, has been a topic of considerable debate. Internal friction varies across different proteins of comparable length and increases with decreasing denaturant concentration, showing that it depends on how compact the protein is. Here we report on a systematic atomistic simulation study of how confinement, which induces a more compact unfolded state, affects dynamics and friction in disordered peptides. We find that the average reconfiguration timescales increase exponentially as the peptide's spatial dimensions are reduced; at the same time, confinement broadens the spectrum of relaxation timescales exhibited by the peptide. There are two important implications of this broadening: First, it limits applicability of the common Rouse and Zimm models with internal friction, as those models attempt to capture internal friction effects by introducing a single internal friction timescale. Second, the long-tailed distribution of relaxation times leads to anomalous diffusion effects in the dynamics of intramolecular distances. Analysis and interpretation of experimental signals from various measurements that probe intramolecular protein dynamics (such as single-molecule fluorescence correlation spectroscopy and single-molecule force spectroscopy) rely on the assumption of diffusive dynamics along the distances being probed; hence, our results suggest the need for more general models allowing for anomalous diffusion effects.
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Affiliation(s)
- Atanu Das
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Dmitrii E Makarov
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States.,Institute for Computational Engineering and Sciences , University of Texas at Austin , Austin , Texas 78712 , United States
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38
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Schuler B. Perspective: Chain dynamics of unfolded and intrinsically disordered proteins from nanosecond fluorescence correlation spectroscopy combined with single-molecule FRET. J Chem Phys 2018; 149:010901. [PMID: 29981536 DOI: 10.1063/1.5037683] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The dynamics of unfolded proteins are important both for the process of protein folding and for the behavior of intrinsically disordered proteins. However, methods for investigating the global chain dynamics of these structurally diverse systems have been limited. A versatile experimental approach is single-molecule spectroscopy in combination with Förster resonance energy transfer and nanosecond fluorescence correlation spectroscopy. The concepts of polymer physics offer a powerful framework both for interpreting the results and for understanding and classifying the properties of unfolded and intrinsically disordered proteins. This information on long-range chain dynamics can be complemented with spectroscopic techniques that probe different length scales and time scales, and integration of these results greatly benefits from recent advances in molecular simulations. This increasing convergence between the experiment, theory, and simulation is thus starting to enable an increasingly detailed view of the dynamics of disordered proteins.
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Affiliation(s)
- Benjamin Schuler
- Department of Biochemistry and Department of Physics, University of Zurich, Winterthurerstrasse 190, Zurich, Switzerland
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39
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Maity BK, Vishvakarma V, Surendran D, Rawat A, Das A, Pramanik S, Arfin N, Maiti S. Spontaneous Fluctuations Can Guide Drug Design Strategies for Structurally Disordered Proteins. Biochemistry 2018; 57:4206-4213. [PMID: 29928798 DOI: 10.1021/acs.biochem.8b00504] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Structure-based "rational" drug design strategies fail for diseases associated with intrinsically disordered proteins (IDPs). However, structural disorder allows large-amplitude spontaneous intramolecular dynamics in a protein. We demonstrate a method that exploits this dynamics to provide quantitative information about the degree of interaction of an IDP with other molecules. A candidate ligand molecule may not bind strongly, but even momentary interactions can be expected to perturb the fluctuations. We measure the amplitude and frequency of the equilibrium fluctuations of fluorescently labeled small oligomers of hIAPP (an IDP associated with type II diabetes) in a physiological solution, using nanosecond fluorescence cross-correlation spectroscopy. We show that the interterminal distance fluctuates at a characteristic time scale of 134 ± 10 ns, and 6.4 ± 0.2% of the population is in the "closed" (quenched) state at equilibrium. These fluctuations are affected in a dose-dependent manner by a series of small molecules known to reduce the toxicity of various amyloid peptides. The degree of interaction increases in the following order: resveratrol < epicatechin ∼ quercetin < Congo red < epigallocatechin 3-gallate. Such ordering can provide a direction for exploring the chemical space for finding stronger-binding ligands. We test the biological relevance of these measurements by measuring the effect of these molecules on the affinity of hIAPP for lipid vesicles and cell membranes. We find that the ability of a molecule to modulate intramolecular fluctuations correlates well with its ability to lower membrane affinity. We conclude that structural disorder may provide new avenues for rational drug design for IDPs.
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Affiliation(s)
- Barun Kumar Maity
- Department of Chemical Sciences , Tata Institute of Fundamental Research , Homi Bhabha Road , Colaba, Mumbai 400005 , India
| | - Vicky Vishvakarma
- Department of Chemical Sciences , Tata Institute of Fundamental Research , Homi Bhabha Road , Colaba, Mumbai 400005 , India
| | - Dayana Surendran
- Department of Chemical Sciences , Tata Institute of Fundamental Research , Homi Bhabha Road , Colaba, Mumbai 400005 , India
| | - Anoop Rawat
- Department of Chemical Sciences , Tata Institute of Fundamental Research , Homi Bhabha Road , Colaba, Mumbai 400005 , India
| | - Anirban Das
- Department of Chemical Sciences , Tata Institute of Fundamental Research , Homi Bhabha Road , Colaba, Mumbai 400005 , India
| | - Shreya Pramanik
- UM-DAE Centre for Excellence in Basic Sciences , University of Mumbai , Kalina, Mumbai 400098 , India
| | - Najmul Arfin
- Center for Interdisciplinary Research in Basic Sciences , Jamia Milia Islamia , New Delhi 110025 , India
| | - Sudipta Maiti
- Department of Chemical Sciences , Tata Institute of Fundamental Research , Homi Bhabha Road , Colaba, Mumbai 400005 , India
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40
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Satija R, Das A, Makarov DE. Transition path times reveal memory effects and anomalous diffusion in the dynamics of protein folding. J Chem Phys 2018; 147:152707. [PMID: 29055292 DOI: 10.1063/1.4993228] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Recent single-molecule experiments probed transition paths of biomolecular folding and, in particular, measured the time biomolecules spend while crossing their free energy barriers. A surprising finding from these studies is that the transition barriers crossed by transition paths, as inferred from experimentally observed transition path times, are often lower than the independently determined free energy barriers. Here we explore memory effects leading to anomalous diffusion as a possible origin of this discrepancy. Our analysis of several molecular dynamics trajectories shows that the dynamics of common reaction coordinates used to describe protein folding is subdiffusive, at least at sufficiently short times. We capture this effect using a one-dimensional fractional Brownian motion (FBM) model, in which the system undergoes a subdiffusive process in the presence of a potential of mean force, and show that this model yields much broader distributions of transition path times with stretched exponential long-time tails. Without any adjustable parameters, these distributions agree well with the transition path times computed directly from protein trajectories. We further discuss how the FBM model can be tested experimentally.
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Affiliation(s)
- Rohit Satija
- Department of Chemistry and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712, USA
| | - Atanu Das
- Department of Chemistry and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712, USA
| | - Dmitrii E Makarov
- Department of Chemistry and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712, USA
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41
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Wang Z, Lu HP. Single-Molecule Spectroscopy Study of Crowding-Induced Protein Spontaneous Denature and Crowding-Perturbed Unfolding–Folding Conformational Fluctuation Dynamics. J Phys Chem B 2018; 122:6724-6732. [DOI: 10.1021/acs.jpcb.8b03119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Zijiang Wang
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - H. Peter Lu
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
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42
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Reinartz I, Sinner C, Nettels D, Stucki-Buchli B, Stockmar F, Panek PT, Jacob CR, Nienhaus GU, Schuler B, Schug A. Simulation of FRET dyes allows quantitative comparison against experimental data. J Chem Phys 2018; 148:123321. [DOI: 10.1063/1.5010434] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Ines Reinartz
- Department of Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
- Steinbuch Centre for Computing, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Claude Sinner
- Department of Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
- Steinbuch Centre for Computing, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Brigitte Stucki-Buchli
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Florian Stockmar
- Institute of Applied Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
| | - Pawel T. Panek
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Christoph R. Jacob
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, Gaußstraße 17, 38106 Braunschweig, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
- HEiKA–Heidelberg Karlsruhe Research Partnership, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Nanotechnology and Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Alexander Schug
- Steinbuch Centre for Computing, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- John von Neumann Institute for Computing, Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425 Jülich, Germany
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43
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Moringo NA, Shen H, Bishop LDC, Wang W, Landes CF. Enhancing Analytical Separations Using Super-Resolution Microscopy. Annu Rev Phys Chem 2018; 69:353-375. [PMID: 29490205 DOI: 10.1146/annurev-physchem-052516-045018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Super-resolution microscopy is becoming an invaluable tool to investigate structure and dynamics driving protein interactions at interfaces. In this review, we highlight the applications of super-resolution microscopy for quantifying the physics and chemistry that occur between target proteins and stationary-phase supports during chromatographic separations. Our discussion concentrates on the newfound ability of super-resolved single-protein spectroscopy to inform theoretical parameters via quantification of adsorption-desorption dynamics, protein unfolding, and nanoconfined transport.
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Affiliation(s)
| | - Hao Shen
- Department of Chemistry, Rice University, Houston, Texas 77251, USA;
| | - Logan D C Bishop
- Department of Chemistry, Rice University, Houston, Texas 77251, USA;
| | - Wenxiao Wang
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77251, USA
| | - Christy F Landes
- Department of Chemistry, Rice University, Houston, Texas 77251, USA; .,Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77251, USA.,Smalley-Curl Institute, Rice University, Houston, Texas 77251, USA
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44
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Lerner E, Cordes T, Ingargiol A, Alhadid Y, Chung S, Michalet X, Weiss S. Toward dynamic structural biology: Two decades of single-molecule Förster resonance energy transfer. Science 2018; 359:eaan1133. [PMID: 29348210 PMCID: PMC6200918 DOI: 10.1126/science.aan1133] [Citation(s) in RCA: 323] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Classical structural biology can only provide static snapshots of biomacromolecules. Single-molecule Förster resonance energy transfer (smFRET) paved the way for studying dynamics in macromolecular structures under biologically relevant conditions. Since its first implementation in 1996, smFRET experiments have confirmed previously hypothesized mechanisms and provided new insights into many fundamental biological processes, such as DNA maintenance and repair, transcription, translation, and membrane transport. We review 22 years of contributions of smFRET to our understanding of basic mechanisms in biochemistry, molecular biology, and structural biology. Additionally, building on current state-of-the-art implementations of smFRET, we highlight possible future directions for smFRET in applications such as biosensing, high-throughput screening, and molecular diagnostics.
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Affiliation(s)
- Eitan Lerner
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Thorben Cordes
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, Netherlands
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Antonino Ingargiol
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Yazan Alhadid
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - SangYoon Chung
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Xavier Michalet
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Department of Physiology, University of California, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
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45
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Zosel F, Haenni D, Soranno A, Nettels D, Schuler B. Combining short- and long-range fluorescence reporters with simulations to explore the intramolecular dynamics of an intrinsically disordered protein. J Chem Phys 2017; 147:152708. [DOI: 10.1063/1.4992800] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Franziska Zosel
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Dominik Haenni
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Center for Microscopy and Image Analysis, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Andrea Soranno
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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46
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Holmstrom ED, Nettels D, Schuler B. Conformational Plasticity of Hepatitis C Virus Core Protein Enables RNA-Induced Formation of Nucleocapsid-like Particles. J Mol Biol 2017; 430:2453-2467. [PMID: 29045818 DOI: 10.1016/j.jmb.2017.10.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/29/2017] [Accepted: 10/02/2017] [Indexed: 02/08/2023]
Abstract
Many of the unanswered questions associated with hepatitis C virus assembly are related to the core protein (HCVcp), which forms an oligomeric nucleocapsid encompassing the viral genome. The structural properties of HCVcp have been difficult to quantify, at least in part because it is an intrinsically disordered protein. We have used single-molecule Förster Resonance Energy Transfer techniques to study the conformational dimensions and dynamics of the HCVcp nucleocapsid domain (HCVncd) at various stages during the RNA-induced formation of nucleocapsid-like particles. Our results indicate that HCVncd is a typical intrinsically disordered protein. When it forms small ribonucleoprotein complexes with various RNA hairpins from the 3' end of the HCV genome, it compacts but remains intrinsically disordered and conformationally dynamic. Above a critical RNA concentration, these ribonucleoprotein complexes rapidly and cooperatively assemble into large nucleocapsid-like particles, wherein the individual HCVncd subunits become substantially more extended.
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Affiliation(s)
- Erik D Holmstrom
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland; Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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47
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Gomes GN, Gradinaru CC. Insights into the conformations and dynamics of intrinsically disordered proteins using single-molecule fluorescence. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017. [PMID: 28625737 DOI: 10.1016/j.bbapap.2017.06.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Most proteins are not static structures, but many of them are found in a dynamic state, exchanging conformations on various time scales as a key aspect of their biological function. An entire spectrum of structural disorder exists in proteins and obtaining a satisfactory quantitative description of these states remains a challenge. Single-molecule fluorescence spectroscopy techniques are uniquely suited for this task, by measuring conformations without ensemble averaging and kinetics without interference from asynchronous processes. In this paper we review some of the recent successes in applying single-molecule fluorescence to different disordered protein systems, including interactions with their cellular targets and self-aggregation processes. We also discuss the implementation of computational methods and polymer physics models that are essential for inferring global dimension parameters for these proteins from smFRET data. Regarding future directions; 3- or 4-color FRET methods can provide multiple distances within a disordered ensemble simultaneously. In addition, integrating complementary experimental data from smFRET, NMR and SAXS will provide meaningful constraints for molecular simulations and will lead to more accurate structural representations of disordered proteins. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman.
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Affiliation(s)
- Gregory-Neal Gomes
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Claudiu C Gradinaru
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
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48
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Krainer G, Gracia P, Frotscher E, Hartmann A, Gröger P, Keller S, Schlierf M. Slow Interconversion in a Heterogeneous Unfolded-State Ensemble of Outer-Membrane Phospholipase A. Biophys J 2017. [PMID: 28629619 DOI: 10.1016/j.bpj.2017.05.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Structural and dynamic investigations of unfolded proteins are important for understanding protein-folding mechanisms as well as the interactions of unfolded polypeptide chains with other cell components. In the case of outer-membrane proteins (OMPs), unfolded-state properties are of particular physiological relevance, because these proteins remain unfolded for extended periods of time during their biogenesis and rely on interactions with binding partners to support proper folding. Using a combination of ensemble and single-molecule spectroscopy, we have scrutinized the unfolded state of outer-membrane phospholipase A (OmpLA) to provide a detailed view of its structural dynamics on timescales from nanoseconds to milliseconds. We find that even under strongly denaturing conditions and in the absence of residual secondary structure, OmpLA populates an ensemble of slowly (>100 ms) interconverting and conformationally heterogeneous unfolded states that lack the fast chain-reconfiguration motions expected for an unstructured, fully unfolded chain. The drastically slowed sampling of potentially folding-competent states, as compared with a random-coil polypeptide, may contribute to the slow in vitro folding kinetics observed for many OMPs. In vivo, however, slow intramolecular long-range dynamics might be advantageous for entropically favored binding of unfolded OMPs to chaperones and, by facilitating conformational selection after release from chaperones, for preserving binding-competent conformations before insertion into the outer membrane.
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Affiliation(s)
- Georg Krainer
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany; Molecular Biophysics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Pablo Gracia
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany
| | - Erik Frotscher
- Molecular Biophysics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Andreas Hartmann
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany
| | - Philip Gröger
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany
| | - Sandro Keller
- Molecular Biophysics, University of Kaiserslautern, Kaiserslautern, Germany.
| | - Michael Schlierf
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Dresden, Germany.
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49
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Chung HS. Transition Path Times Measured by Single-Molecule Spectroscopy. J Mol Biol 2017; 430:409-423. [PMID: 28551335 DOI: 10.1016/j.jmb.2017.05.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Accepted: 05/18/2017] [Indexed: 11/28/2022]
Abstract
The transition path is a tiny fraction of a molecular trajectory during which the free-energy barrier is crossed. It is a single-molecule property and contains all mechanistic information of folding processes of biomolecules such as proteins and nucleic acids. However, the transition path has been difficult to probe because it is short and rarely visited when transitions actually occur. Recent technical advances in single-molecule spectroscopy have made it possible to directly probe transition paths, which has opened up new theoretical and experimental approaches to investigating folding mechanisms. This article reviews recent single-molecule fluorescence and force spectroscopic measurements of transition path times and their connection to both theory and simulations.
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Affiliation(s)
- Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 5 Memorial Dr., Bethesda, MD 20892-0520, USA.
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50
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Theoretical and computational validation of the Kuhn barrier friction mechanism in unfolded proteins. Sci Rep 2017; 7:269. [PMID: 28325911 PMCID: PMC5428071 DOI: 10.1038/s41598-017-00287-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 02/20/2017] [Indexed: 11/08/2022] Open
Abstract
A long time ago, Kuhn predicted that long polymers should approach a limit where their global motion is controlled by solvent friction alone, with ruggedness of their energy landscapes having no consequences for their dynamics. In contrast, internal friction effects are important for polymers of modest length. Internal friction in proteins, in particular, affects how fast they fold or find their binding targets and, as such, has attracted much recent attention. Here we explore the molecular origins of internal friction in unfolded proteins using atomistic simulations, coarse-grained models and analytic theory. We show that the characteristic internal friction timescale is directly proportional to the timescale of hindered dihedral rotations within the polypeptide chain, with a proportionality coefficient b that is independent of the chain length. Such chain length independence of b provides experimentally testable evidence that internal friction arises from concerted, crankshaft-like dihedral rearrangements. In accord with phenomenological models of internal friction, we find the global reconfiguration timescale of a polypeptide to be the sum of solvent friction and internal friction timescales. At the same time, the time evolution of inter-monomer distances within polypeptides deviates both from the predictions of those models and from a simple, one-dimensional diffusion model.
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