51
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Wang Z, Mothi N, Muñoz V. Single-Molecule Fluorescence Spectroscopy Approaches for Probing Fast Biomolecular Dynamics and Interactions. Methods Mol Biol 2022; 2376:235-246. [PMID: 34845613 DOI: 10.1007/978-1-0716-1716-8_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: 06/13/2023]
Abstract
Single-molecule fluorescence spectroscopy, and particularly its Förster resonance energy transfer implementation (SM-FRET), provides the opportunity to resolve the stochastic conformational fluctuations undergone by individual protein molecules while they fold-unfold, bind to their partners, or carry out catalysis. Such information is key to resolve the microscopic pathways and mechanisms underlying such processes, and cannot be obtained from bulk experiments. To fully resolve protein conformational dynamics, SM-FRET experiments need to reach microsecond, and even sub-microsecond, time resolutions. The key to reach such resolution lies in increasing the efficiency at which photons emitted by a single molecule are collected and detected by the instrument (photon count rates). In this chapter, we describe basic procedures that an end user can follow to optimize the confocal microscope optics in order to maximize the photon count rates. We also discuss the use of photoprotection cocktails specifically designed to reduce fluorophore triplet buildup at high irradiance (the major cause of limiting photon emission rates) while improving the mid-term photostability of the fluorophores. Complementary strategies based on the data analysis are discussed in depth by other authors in Chap. 14 .
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Affiliation(s)
- Zifan Wang
- Department of Bioengineering, University of California at Merced, Merced, CA, USA
- NSF CREST Center for Cellular and Biomolecular Machines (CCBM), University of California at Merced, Merced, CA, USA
| | - Nivin Mothi
- Chemistry and Chemical Biology Graduate Program, University of California at Merced, Merced, CA, USA
- NSF CREST Center for Cellular and Biomolecular Machines (CCBM), University of California at Merced, Merced, CA, USA
| | - Victor Muñoz
- Department of Bioengineering and Center for Cellular and Biomolecular Machines, University of California Merced, Merced, CA, USA.
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52
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Berezhkovskii AM, Makarov DE. On distributions of barrier crossing times as observed in single-molecule studies of biomolecules. BIOPHYSICAL REPORTS 2021; 1:100029. [PMID: 36425456 PMCID: PMC9680812 DOI: 10.1016/j.bpr.2021.100029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 10/19/2021] [Indexed: 06/16/2023]
Abstract
Single-molecule experiments that monitor time evolution of molecular observables in real time have expanded beyond measuring transition rates toward measuring distributions of times of various molecular events. Of particular interest is the first-passage time for making a transition from one molecular configuration ( a ) to another ( b ) and conditional first-passage times such as the transition path time, which is the first-passage time from a to b conditional upon not leaving the transition region intervening between a and b . Another experimentally accessible (but not yet studied experimentally) observable is the conditional exit time, i.e., the time to leave the transition region through a specified boundary. The distributions of such times contain a wealth of mechanistic information about the transitions in question. Here, we use the first and the second (and, if desired, higher) moments of these distributions to characterize their relative width for the model in which the experimental observable undergoes Brownian motion in a potential of mean force. We show that although the distributions of transition path times are always narrower than exponential (in that the ratio of the standard deviation to the distribution's mean is always less than 1), distributions of first-passage times and of conditional exit times can be either narrow or broad, in some cases displaying long power-law tails. The conditional exit time studied here provides a generalization of the transition path time that also allows one to characterize the temporal scales of failed barrier crossing attempts.
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Affiliation(s)
- Alexander M. Berezhkovskii
- Mathematical and Statistical Computing Laboratory, Office of Intramural Research, Center for Information Technology, National Institutes of Health, Bethesda, Maryland
| | - Dmitrii E. Makarov
- Department of Chemistry and Biochemistry and Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas
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53
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Naudi-Fabra S, Tengo M, Jensen MR, Blackledge M, Milles S. Quantitative Description of Intrinsically Disordered Proteins Using Single-Molecule FRET, NMR, and SAXS. J Am Chem Soc 2021; 143:20109-20121. [PMID: 34817999 PMCID: PMC8662727 DOI: 10.1021/jacs.1c06264] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Indexed: 12/18/2022]
Abstract
Studying the conformational landscape of intrinsically disordered and partially folded proteins is challenging and only accessible to a few solution state techniques, such as nuclear magnetic resonance (NMR), small-angle scattering techniques, and single-molecule Förster resonance energy transfer (smFRET). While each of the techniques is sensitive to different properties of the disordered chain, such as local structural propensities, overall dimension, or intermediate- and long-range contacts, conformational ensembles describing intrinsically disordered proteins (IDPs) accurately should ideally respect all of these properties. Here we develop an integrated approach using a large set of FRET efficiencies and fluorescence lifetimes, NMR chemical shifts, and paramagnetic relaxation enhancements (PREs), as well as small-angle X-ray scattering (SAXS) to derive quantitative conformational ensembles in agreement with all parameters. Our approach is tested using simulated data (five sets of PREs and 15 FRET efficiencies) and validated experimentally on the example of the disordered domain of measles virus phosphoprotein, providing new insights into the conformational landscape of this viral protein that comprises transient structural elements and is more compact than an unfolded chain throughout its length. Rigorous cross-validation using FRET efficiencies, fluorescence lifetimes, and SAXS demonstrates the predictive nature of the calculated conformational ensembles and underlines the potential of this strategy in integrative dynamic structural biology.
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Affiliation(s)
- Samuel Naudi-Fabra
- Institut de Biologie Structurale,
Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38044 Grenoble, France
| | - Maud Tengo
- Institut de Biologie Structurale,
Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38044 Grenoble, France
| | - Malene Ringkjøbing Jensen
- Institut de Biologie Structurale,
Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38044 Grenoble, France
| | - Martin Blackledge
- Institut de Biologie Structurale,
Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38044 Grenoble, France
| | - Sigrid Milles
- Institut de Biologie Structurale,
Université Grenoble Alpes-CEA-CNRS, 71, Avenue des Martyrs, 38044 Grenoble, France
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54
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Qin M, Denesyuk N, Liu Z, Wang W, Thirumalai D. Temperature and Guanidine Hydrochloride Effects on the Folding Thermodynamics of WW Domain and Variants. J Phys Chem B 2021; 125:11386-11391. [PMID: 34612657 DOI: 10.1021/acs.jpcb.1c06340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We used simulations based on an all-atom Go model to calculate the folding temperatures (Tfs) and free energies (ΔGs) of two variants of the WW domain, which is a small all-β-sheet protein. The results, without adjusting any parameter, are in good agreement with experiments, thus validating the simulations. We then used the molecular transfer model to predict the changes in the ΔGs and Tfs as the guanidine hydrochloride concentration is varied. The predictions can be readily tested in experiments.
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Affiliation(s)
- Meng Qin
- Biophysics Program, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States.,National Laboratory of Solid State Microstructure and Department of Physics, Nanjing University, and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Natalia Denesyuk
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zhenxing Liu
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Wei Wang
- School of Physics, Nanjing University, Nanjing 210093, China
| | - D Thirumalai
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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55
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Talele S, King JT. Fast and robust two-dimensional inverse Laplace transformation of single-molecule fluorescence lifetime data. Biophys J 2021; 120:4590-4599. [PMID: 34461104 DOI: 10.1016/j.bpj.2021.08.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 05/08/2021] [Accepted: 08/25/2021] [Indexed: 10/20/2022] Open
Abstract
Fluorescence spectroscopy at the single-molecule scale has been indispensable for studying conformational dynamics and rare states of biological macromolecules. Single-molecule two-dimensional (2D) fluorescence lifetime correlation spectroscopy is an emerging technique that holds promise for the study of protein and nucleic acid dynamics, as the technique is 1) capable of resolving conformational dynamics using a single chromophore, 2) resolves forward and reverse transitions independently, and 3) has a dynamic window ranging from microseconds to seconds. However, the calculation of a 2D fluorescence relaxation spectrum requires an inverse Laplace transform (ILT), which is an ill-conditioned inversion that must be estimated numerically through a regularized minimization. Current methods for performing ILTs of fluorescence relaxation can be computationally inefficient, sensitive to noise corruption, and difficult to implement. Here, we adopt an approach developed for NMR spectroscopy (T1-T2 relaxometry) to perform one-dimensional (1D) and 2D-ILTs on single-molecule fluorescence spectroscopy data using singular-valued decomposition and Tikhonov regularization. This approach provides fast, robust, and easy to implement Laplace inversions of single-molecule fluorescence data. We compare this approach to the widely used maximal entropy method.
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Affiliation(s)
- Saurabh Talele
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, Republic of Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - John T King
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, Republic of Korea.
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56
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Bartels K, Lasitza‐Male T, Hofmann H, Löw C. Single-Molecule FRET of Membrane Transport Proteins. Chembiochem 2021; 22:2657-2671. [PMID: 33945656 PMCID: PMC8453700 DOI: 10.1002/cbic.202100106] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/03/2021] [Indexed: 12/31/2022]
Abstract
Uncovering the structure and function of biomolecules is a fundamental goal in structural biology. Membrane-embedded transport proteins are ubiquitous in all kingdoms of life. Despite structural flexibility, their mechanisms are typically studied by ensemble biochemical methods or by static high-resolution structures, which complicate a detailed understanding of their dynamics. Here, we review the recent progress of single molecule Förster Resonance Energy Transfer (smFRET) in determining mechanisms and timescales of substrate transport across membranes. These studies do not only demonstrate the versatility and suitability of state-of-the-art smFRET tools for studying membrane transport proteins but they also highlight the importance of membrane mimicking environments in preserving the function of these proteins. The current achievements advance our understanding of transport mechanisms and have the potential to facilitate future progress in drug design.
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Affiliation(s)
- Kim Bartels
- Centre for Structural Systems Biology (CSSB)DESY and European Molecular Biology Laboratory HamburgNotkestrasse 8522607HamburgGermany
| | - Tanya Lasitza‐Male
- Department of Structural BiologyWeizmann Institute of ScienceHerzl St. 2347610001RehovotIsrael
| | - Hagen Hofmann
- Department of Structural BiologyWeizmann Institute of ScienceHerzl St. 2347610001RehovotIsrael
| | - Christian Löw
- Centre for Structural Systems Biology (CSSB)DESY and European Molecular Biology Laboratory HamburgNotkestrasse 8522607HamburgGermany
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57
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Lee DC, Guye KN, Paranji RK, Lachowski K, Pozzo LD, Ginger DS, Pun SH. Dual-Stimuli Responsive Single-Chain Polymer Folding via Intrachain Complexation of Tetramethoxyazobenzene and β-Cyclodextrin. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10126-10134. [PMID: 34369796 DOI: 10.1021/acs.langmuir.1c01442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We synthesize and characterize a triblock polymer with asymmetric tetramethoxyazobenzene (TMAB) and β-cyclodextrin functionalization, taking advantage of the well-characterized azobenzene derivative-cyclodextrin inclusion complex to promote photoresponsive, self-contained folding of the polymer in an aqueous system. We use 1H NMR to show the reversibility of (E)-to-(Z) and (Z)-to-(E) TMAB photoisomerization, and evaluate the thermal stability of (Z)-TMAB and the comparatively rapid acid-catalyzed thermal (Z)-to-(E) isomerization. Important for its potential use as a functional material, we show the photoisomerization cyclability of the polymeric TMAB chromophore and calculate isomerization quantum yields by extinction spectroscopy. To verify self-inclusion of the polymeric TMAB and cyclodextrin, we use two-dimensional 1H NOESY NMR data to show proximity of TMAB and cyclodextrin in the (E)-state only; however, (Z)-TMAB is not locally correlated with cyclodextrin. Finally, the observed decrease in photoisomerization quantum yield for the dual-functionalized polymer compared to the isolated chromophore in an aqueous solution confirms TMAB and β-cyclodextrin not only are in proximity to one another, but also form the inclusion complex.
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Affiliation(s)
- Daniel C Lee
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States
| | - Kathryn N Guye
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Rajan K Paranji
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Kacper Lachowski
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Lilo D Pozzo
- Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Suzie H Pun
- Molecular Engineering & Sciences Institute, University of Washington, Seattle, Washington 98195, United States
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, United States
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58
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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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59
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Abstract
Protein-folding kinetics is often described as Markovian (i.e., memoryless) diffusion in a one-dimensional free energy landscape, governed by an instantaneous friction coefficient that is fitted to reproduce experimental or simulated folding times. For the α-helix forming polypeptide alanine9 and a specific reaction coordinate that consists of the summed native hydrogen-bond lengths, we demonstrate that the friction extracted from molecular dynamics simulations exhibits significant memory with a decay time that is in the nanosecond range and thus, of the same order as the folding and unfolding times. Our non-Markovian modeling not only reproduces the molecular dynamics simulations accurately but also demonstrates that memory friction effects lead to anomalous and drastically accelerated protein kinetics. We extract the folding free energy landscape and the time-dependent friction function, the two ingredients of the generalized Langevin equation (GLE), from explicit-water molecular dynamics (MD) simulations of the α-helix forming polypeptide alanine9 for a one-dimensional reaction coordinate based on the sum of the native H-bond distances. Folding and unfolding times from numerical integration of the GLE agree accurately with MD results, which demonstrate the robustness of our GLE-based non-Markovian model. In contrast, Markovian models do not accurately describe the peptide kinetics and in particular, cannot reproduce the folding and unfolding kinetics simultaneously, even if a spatially dependent friction profile is used. Analysis of the GLE demonstrates that memory effects in the friction significantly speed up peptide folding and unfolding kinetics, as predicted by the Grote–Hynes theory, and are the cause of anomalous diffusion in configuration space. Our methods are applicable to any reaction coordinate and in principle, also to experimental trajectories from single-molecule experiments. Our results demonstrate that a consistent description of protein-folding dynamics must account for memory friction effects.
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60
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Ki H, Jo J, Kim Y, Kim TW, Kim C, Kim Y, Kim CW, Muniyappan S, Lee SJ, Kim Y, Kim HM, Yang Y, Rhee YM, Ihee H. Uncovering the Conformational Distribution of a Small Protein with Nanoparticle-Aided Cryo-Electron Microscopy Sampling. J Phys Chem Lett 2021; 12:6565-6573. [PMID: 34251825 DOI: 10.1021/acs.jpclett.1c01277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Here, we introduce the nanoparticle-aided cryo-electron microscopy sampling (NACS) method to access the conformational distribution of a protein molecule. Two nanogold particles are labeled at two target sites, and the interparticle distance is measured as a structural parameter via cryo-electron microscopy (cryo-EM). The key aspect of NACS is that the projected distance information instead of the global conformational information is extracted from each protein molecule. This is possible because the contrast provided by the nanogold particles is strong enough to provide the projected distance, while the protein itself is invisible due to its low contrast. We successfully demonstrate that various protein conformations, even for small or disordered proteins, which generally cannot be accessed via cryo-EM, can be captured. The demonstrated method with the potential to directly observe the conformational distribution of such systems may open up new possibilities in studying their dynamics at a single-molecule level.
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Affiliation(s)
- Hosung Ki
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Junbeom Jo
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Youngmin Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Tae Wu Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Changin Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Yeeun Kim
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Chang Woo Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Srinivasan Muniyappan
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Sang Jin Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Yonggwan Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
| | - Ho Min Kim
- Center for Biomolecular & Cellular Structure, Institute for Basic Science (IBS), Daejeon 34126, Republic of Korea
- Graduate School of Medical Science & Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Yongsoo Yang
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Young Min Rhee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, Republic of Korea
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61
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Bergkamp MH, IJzendoorn LJV, Prins MW. Real-Time Detection of State Transitions in Stochastic Signals from Biological Systems. ACS OMEGA 2021; 6:17726-17733. [PMID: 34278158 PMCID: PMC8280633 DOI: 10.1021/acsomega.1c02498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/16/2021] [Indexed: 05/27/2023]
Abstract
Robust analysis of signals from stochastic biomolecular processes is critical for understanding the dynamics of biological systems. Measured signals typically show multiple states with heterogeneities and a wide range of state lifetimes. Here, we present an algorithm for robust detection of state transitions in experimental time traces where the properties of the underlying states are a priori unknown. The method implements a maximum-likelihood approach to fit models in neighboring windows of data points. Multiple windows are combined to achieve a high sensitivity for state transitions with a wide range of lifetimes. The proposed maximum-likelihood multiple-windows change point detection (MM-CPD) algorithm is computationally extremely efficient and enables real-time signal analysis. By analyzing both simulated and experimental data, we demonstrate that the algorithm provides accurate change point detection in time traces with multiple heterogeneous states that are a priori unknown. A high sensitivity for a wide range of state lifetimes is achieved.
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Affiliation(s)
- Max H. Bergkamp
- Department
of Biomedical Engineering, Eindhoven University
of Technology, Eindhoven 5612, The Netherlands
- Institute
for Complex Molecular Systems (ICMS), Eindhoven
University of Technology, Eindhoven 5612, The Netherlands
| | - Leo J. van IJzendoorn
- Department
of Applied Physics, Eindhoven University
of Technology, Eindhoven 5612, The Netherlands
- Institute
for Complex Molecular Systems (ICMS), Eindhoven
University of Technology, Eindhoven 5612, The Netherlands
| | - Menno W.J. Prins
- Department
of Biomedical Engineering, Eindhoven University
of Technology, Eindhoven 5612, The Netherlands
- Department
of Applied Physics, Eindhoven University
of Technology, Eindhoven 5612, The Netherlands
- Institute
for Complex Molecular Systems (ICMS), Eindhoven
University of Technology, Eindhoven 5612, The Netherlands
- Helia
BioMonitoring, Eindhoven 5612, The Netherlands
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62
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Xu L, Kuan SL, Weil T. Contemporary Approaches for Site-Selective Dual Functionalization of Proteins. Angew Chem Int Ed Engl 2021; 60:13757-13777. [PMID: 33258535 PMCID: PMC8248073 DOI: 10.1002/anie.202012034] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Indexed: 12/16/2022]
Abstract
Site-selective protein functionalization serves as an invaluable tool for investigating protein structures and functions in complicated cellular environments and accomplishing semi-synthetic protein conjugates such as traceable therapeutics with improved features. Dual functionalization of proteins allows the incorporation of two different types of functionalities at distinct location(s), which greatly expands the features of native proteins. The attachment and crosstalk of a fluorescence donor and an acceptor dye provides fundamental insights into the folding and structural changes of proteins upon ligand binding in their native cellular environments. Moreover, the combination of drug molecules with different modes of action, imaging agents or stabilizing polymers provides new avenues to design precision protein therapeutics in a reproducible and well-characterizable fashion. This review aims to give a timely overview of the recent advancements and a future perspective of this relatively new research area. First, the chemical toolbox for dual functionalization of proteins is discussed and compared. The strengths and limitations of each strategy are summarized in order to enable readers to select the most appropriate method for their envisaged applications. Thereafter, representative applications of these dual-modified protein bioconjugates benefiting from the synergistic/additive properties of the two synthetic moieties are highlighted.
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Affiliation(s)
- Lujuan Xu
- Max Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
- Institute of Inorganic Chemistry IUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
| | - Seah Ling Kuan
- Max Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
- Institute of Inorganic Chemistry IUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
| | - Tanja Weil
- Max Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
- Institute of Inorganic Chemistry IUlm UniversityAlbert-Einstein-Allee 1189081UlmGermany
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63
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Chakraborty D, Banerjee A, Wales DJ. Side-Chain Polarity Modulates the Intrinsic Conformational Landscape of Model Dipeptides. J Phys Chem B 2021; 125:5809-5822. [PMID: 34037392 PMCID: PMC8279551 DOI: 10.1021/acs.jpcb.1c02412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The
intrinsic conformational preferences of small peptides may
provide additional insight into the thermodynamics and kinetics of
protein folding. In this study, we explore the underlying energy landscapes
of two model peptides, namely, Ac-Ala-NH2 and Ac-Ser-NH2, using geometry-optimization-based tools developed within
the context of energy landscape theory. We analyze not only how side-chain
polarity influences the structural preferences of the dipeptides,
but also other emergent properties of the landscape, including heat
capacity profiles, and kinetics of conformational rearrangements.
The contrasting topographies of the free energy landscape agree with
recent results from Fourier transform microwave spectroscopy experiments,
where Ac-Ala-NH2 was found to exist as a mixture of two
conformers, while Ac-Ser-NH2 remained structurally locked,
despite exhibiting an apparently rich conformational landscape.
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Affiliation(s)
- Debayan Chakraborty
- Department of Chemistry, The University of Texas at Austin, 24th Street Stop A5300, Austin, Texas 78712, United States
| | - Atreyee Banerjee
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.,Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - David J Wales
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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64
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Mondal S, Mondal S, Seki K, Bagchi B. An exact solution in the theory of fluorescence resonance energy transfer with vibrational relaxation. J Chem Phys 2021; 154:134104. [PMID: 33832249 DOI: 10.1063/5.0045008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The elegant expression of Förster that predicts the well-known 1/R6 distance (R) dependence of the rate of energy transfer, although widely used, was derived using several approximations. Notable among them is the neglect of the vibrational relaxation in the reactant (donor) and product (acceptor) manifolds. Vibrational relaxation can play an important role when the energy transfer rate is faster than the vibrational relaxation rate. Under such conditions, donor to acceptor energy transfer can occur from the excited vibrational states. This phenomenon is not captured by the usual formulation based on the overlap of donor emission and acceptor absorption spectra. Here, we develop a Green's function-based generalized formalism and obtain an exact solution for the excited state population relaxation and the rate of energy transfer in the presence of vibrational relaxation. We find that the application of the well-known Förster's expression might lead to overestimation of R.
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Affiliation(s)
- Sangita Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, India
| | - Sayantan Mondal
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, India
| | - Kazuhiko Seki
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Biman Bagchi
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru, India
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65
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Hsu DJ, Leshchev D, Kosheleva I, Kohlstedt KL, Chen LX. Unfolding bovine α-lactalbumin with T-jump: Characterizing disordered intermediates via time-resolved x-ray solution scattering and molecular dynamics simulations. J Chem Phys 2021; 154:105101. [PMID: 33722011 PMCID: PMC7943248 DOI: 10.1063/5.0039194] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/04/2021] [Indexed: 02/07/2023] Open
Abstract
The protein folding process often proceeds through partially folded transient states. Therefore, a structural understanding of these disordered states is crucial for developing mechanistic models of the folding process. Characterization of unfolded states remains challenging due to their disordered nature, and incorporating multiple methods is necessary. Combining the time-resolved x-ray solution scattering (TRXSS) signal with molecular dynamics (MD), we are able to characterize transient partially folded states of bovine α-lactalbumin, a model system widely used for investigation of molten globule states, during its unfolding triggered by a temperature jump. We track the unfolding process between 20 µs and 70 ms and demonstrate that it passes through three distinct kinetic states. The scattering signals associated with these transient species are then analyzed with TRXSS constrained MD simulations to produce protein structures that are compatible with the input signals. Without utilizing any experimentally extracted kinetic information, the constrained MD simulation successfully drove the protein to an intermediate molten globule state; signals for two later disordered states are refined to terminal unfolded states. From our examination of the structural characteristics of these disordered states, we discuss the implications disordered states have on the folding process, especially on the folding pathway. Finally, we discuss the potential applications and limitations of this method.
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Affiliation(s)
- Darren J. Hsu
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Denis Leshchev
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Irina Kosheleva
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - Kevin L. Kohlstedt
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Lin X. Chen
- Authors to whom correspondence should be addressed: and
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66
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Xu L, Kuan SL, Weil T. Contemporary Approaches for Site‐Selective Dual Functionalization of Proteins. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202012034] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Lujuan Xu
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Seah Ling Kuan
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Tanja Weil
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
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67
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Li J, Zhang L, Johnson-Buck A, Walter NG. Automatic classification and segmentation of single-molecule fluorescence time traces with deep learning. Nat Commun 2020; 11:5833. [PMID: 33203879 PMCID: PMC7673028 DOI: 10.1038/s41467-020-19673-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 10/20/2020] [Indexed: 01/19/2023] Open
Abstract
Traces from single-molecule fluorescence microscopy (SMFM) experiments exhibit photophysical artifacts that typically necessitate human expert screening, which is time-consuming and introduces potential for user-dependent expectation bias. Here, we use deep learning to develop a rapid, automatic SMFM trace selector, termed AutoSiM, that improves the sensitivity and specificity of an assay for a DNA point mutation based on single-molecule recognition through equilibrium Poisson sampling (SiMREPS). The improved performance of AutoSiM is based on accepting both more true positives and fewer false positives than the conventional approach of hidden Markov modeling (HMM) followed by hard thresholding. As a second application, the selector is used for automated screening of single-molecule Förster resonance energy transfer (smFRET) data to identify high-quality traces for further analysis, and achieves ~90% concordance with manual selection while requiring less processing time. Finally, we show that AutoSiM can be adapted readily to novel datasets, requiring only modest Transfer Learning.
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Affiliation(s)
- Jieming Li
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, The University of Michigan, Ann Arbor, MI, USA
- Bristol-Myers Squibb Company, New Brunswick, NJ, USA
| | - Leyou Zhang
- Department of Physics, The University of Michigan, Ann Arbor, MI, USA
- Google, Pittsburgh, PA, USA
| | - Alexander Johnson-Buck
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, The University of Michigan, Ann Arbor, MI, USA.
- Department of Internal Medicine, Division of Hematology/Oncology, University of Michigan, Ann Arbor, MI, USA.
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry and Center for RNA Biomedicine, The University of Michigan, Ann Arbor, MI, USA.
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68
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Single-molecule studies of amyloid proteins: from biophysical properties to diagnostic perspectives. Q Rev Biophys 2020; 53:e12. [PMID: 33148356 DOI: 10.1017/s0033583520000086] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In neurodegenerative diseases, a wide range of amyloid proteins or peptides such as amyloid-beta and α-synuclein fail to keep native functional conformations, followed by misfolding and self-assembling into a diverse array of aggregates. The aggregates further exert toxicity leading to the dysfunction, degeneration and loss of cells in the affected organs. Due to the disordered structure of the amyloid proteins, endogenous molecules, such as lipids, are prone to interact with amyloid proteins at a low concentration and influence amyloid cytotoxicity. The heterogeneity of amyloid proteinscomplicates the understanding of the amyloid cytotoxicity when relying only on conventional bulk and ensemble techniques. As complementary tools, single-molecule techniques (SMTs) provide novel insights into the different subpopulations of a heterogeneous amyloid mixture as well as the cytotoxicity, in particular as involved in lipid membranes. This review focuses on the recent advances of a series of SMTs, including single-molecule fluorescence imaging, single-molecule force spectroscopy and single-nanopore electrical recording, for the understanding of the amyloid molecular mechanism. The working principles, benefits and limitations of each technique are discussed and compared in amyloid protein related studies.. We also discuss why SMTs show great potential and are worthy of further investigation with feasibility studies as diagnostic tools of neurodegenerative diseases and which limitations are to be addressed.
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69
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Thomsen J, Sletfjerding MB, Jensen SB, Stella S, Paul B, Malle MG, Montoya G, Petersen TC, Hatzakis NS. DeepFRET, a software for rapid and automated single-molecule FRET data classification using deep learning. eLife 2020; 9:e60404. [PMID: 33138911 PMCID: PMC7609065 DOI: 10.7554/elife.60404] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/02/2020] [Indexed: 12/20/2022] Open
Abstract
Single-molecule Förster Resonance energy transfer (smFRET) is an adaptable method for studying the structure and dynamics of biomolecules. The development of high throughput methodologies and the growth of commercial instrumentation have outpaced the development of rapid, standardized, and automated methodologies to objectively analyze the wealth of produced data. Here we present DeepFRET, an automated, open-source standalone solution based on deep learning, where the only crucial human intervention in transiting from raw microscope images to histograms of biomolecule behavior, is a user-adjustable quality threshold. Integrating standard features of smFRET analysis, DeepFRET consequently outputs the common kinetic information metrics. Its classification accuracy on ground truth data reached >95% outperforming human operators and commonly used threshold, only requiring ~1% of the time. Its precise and rapid operation on real data demonstrates DeepFRET's capacity to objectively quantify biomolecular dynamics and the potential to contribute to benchmarking smFRET for dynamic structural biology.
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Affiliation(s)
- Johannes Thomsen
- Department of Chemistry and Nanoscience Centre, University of CopenhagenCopenhagenDenmark
| | | | - Simon Bo Jensen
- Department of Chemistry and Nanoscience Centre, University of CopenhagenCopenhagenDenmark
| | - Stefano Stella
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | - Bijoya Paul
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | - Mette Galsgaard Malle
- Department of Chemistry and Nanoscience Centre, University of CopenhagenCopenhagenDenmark
| | - Guillermo Montoya
- Structural Molecular Biology Group, Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
| | | | - Nikos S Hatzakis
- Department of Chemistry and Nanoscience Centre, University of CopenhagenCopenhagenDenmark
- Novo Nordisk Foundation Centre for Protein Research, Faculty of Health and Medical Sciences, University of CopenhagenCopenhagenDenmark
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70
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Liutkute M, Maiti M, Samatova E, Enderlein J, Rodnina MV. Gradual compaction of the nascent peptide during cotranslational folding on the ribosome. eLife 2020; 9:60895. [PMID: 33112737 PMCID: PMC7593090 DOI: 10.7554/elife.60895] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/16/2020] [Indexed: 12/21/2022] Open
Abstract
Nascent polypeptides begin to fold in the constrained space of the ribosomal peptide exit tunnel. Here we use force-profile analysis (FPA) and photo-induced energy-transfer fluorescence correlation spectroscopy (PET-FCS) to show how a small α-helical domain, the N-terminal domain of HemK, folds cotranslationally. Compaction starts vectorially as soon as the first α-helical segments are synthesized. As nascent chain grows, emerging helical segments dock onto each other and continue to rearrange at the vicinity of the ribosome. Inside or in the proximity of the ribosome, the nascent peptide undergoes structural fluctuations on the µs time scale. The fluctuations slow down as the domain moves away from the ribosome. Mutations that destabilize the packing of the domain's hydrophobic core have little effect on folding within the exit tunnel, but abolish the final domain stabilization. The results show the power of FPA and PET-FCS in solving the trajectory of cotranslational protein folding and in characterizing the dynamic properties of folding intermediates.
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Affiliation(s)
- Marija Liutkute
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Manisankar Maiti
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Ekaterina Samatova
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jörg Enderlein
- III. Institute of Physics - Biophysics, Georg August University, Göttingen, Germany
| | - Marina V Rodnina
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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71
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Yang L, Jang SJ. Theoretical investigation of non-Förster exciton transfer mechanisms in perylene diimide donor, phenylene bridge, and terrylene diimide acceptor systems. J Chem Phys 2020; 153:144305. [PMID: 33086841 DOI: 10.1063/5.0023709] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rates of exciton transfer within dyads of perylene diimide and terrylene diimide connected by oligophenylene bridge units have been shown to deviate significantly from those of Förster's resonance energy transfer theory, according to single molecule spectroscopy experiments. The present work provides a detailed computational and theoretical study investigating the source of such a discrepancy. Electronic spectroscopy data are calculated by time-dependent density functional theory and then compared with experimental results. Electronic couplings between the exciton donor and the acceptor are estimated based on both the transition density cube method and transition dipole approximation. These results confirm that the delocalization of the exciton to the bridge parts contributes to significant enhancement of donor-acceptor electronic coupling. Mechanistic details of exciton transfer are examined by estimating the contributions of the bridge electronic states, vibrational modes of the dyads commonly coupled to both donor and acceptor, inelastic resonance energy transfer mechanism, and dark exciton states. These analyses suggest that the contribution of common vibrational modes serves as the main source of deviation from Förster's spectral overlap expression.
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Affiliation(s)
- Lei Yang
- Center for Molecular Systems and Organic Devices, Key Laboratory for Organic Electronics and Information Displays and Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, China
| | - Seogjoo J Jang
- Department of Chemistry and Biochemistry, Queens College, City University of New York, 65-30 Kissena Boulevard, Queens, New York 11367, USA and PhD Programs in Chemistry and Physics, and Initiative for the Theoretical Sciences, Graduate Center, City University of New York, 365 Fifth Avenue, New York, New York 10016, USA
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72
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Kirmizialtin S, Pitici F, Cardenas AE, Elber R, Thirumalai D. Dramatic Shape Changes Occur as Cytochrome c Folds. J Phys Chem B 2020; 124:8240-8248. [PMID: 32840372 DOI: 10.1021/acs.jpcb.0c05802] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Extensive experimental studies on the folding of cytochrome c (Cyt c) make this small protein an ideal target for atomic detailed simulations for the purposes of quantitatively characterizing the structural transitions and the associated time scales for folding to the native state from an ensemble of unfolded states. We use previously generated atomically detailed folding trajectories by the stochastic difference equation in length to calculate the time-dependent changes in the small-angle X-ray scattering (SAXS) profiles. Excellent agreement is obtained between experiments and simulations for the time-dependent SAXS spectra, allowing us to identify the structures of the folding intermediates, which shows that Cyt c reaches the native state by a sequential folding mechanism. Using the ensembles of structures along the folding pathways, we show that compaction and the sphericity of Cyt c change dramatically from the prolate ellipsoid shape in the unfolded state to the spherical native state. Our data, which are in unprecedented quantitative agreement with all aspects of time-resolved SAXS experiments, show that hydrophobic collapse and amide group protection coincide on the 100 microseconds time scale, which is in accordance with ultrafast hydrogen/deuterium exchange studies. Based on these results, we propose that compaction of polypeptide chains, accompanied by dramatic shape changes, is a universal characteristic of globular proteins, regardless of the underlying folding mechanism.
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Affiliation(s)
- Serdal Kirmizialtin
- Chemistry Program, Math and Sciences, New York University Abu Dhabi, P.O. Box 129188, Abu Dhabi, UAE
| | | | - Alfredo E Cardenas
- Institute for Computational Science and Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Ron Elber
- Institute for Computational Science and Engineering, The University of Texas at Austin, Austin, Texas 78712, United States.,Department of Chemistry, University of Texas, Austin Texas, 78712, United States
| | - D Thirumalai
- Department of Chemistry, University of Texas, Austin Texas, 78712, United States
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73
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Henry L, Panman MR, Isaksson L, Claesson E, Kosheleva I, Henning R, Westenhoff S, Berntsson O. Real-time tracking of protein unfolding with time-resolved x-ray solution scattering. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:054702. [PMID: 32984436 PMCID: PMC7511240 DOI: 10.1063/4.0000013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Accepted: 08/17/2020] [Indexed: 05/14/2023]
Abstract
The correct folding of proteins is of paramount importance for their function, and protein misfolding is believed to be the primary cause of a wide range of diseases. Protein folding has been investigated with time-averaged methods and time-resolved spectroscopy, but observing the structural dynamics of the unfolding process in real-time is challenging. Here, we demonstrate an approach to directly reveal the structural changes in the unfolding reaction. We use nano- to millisecond time-resolved x-ray solution scattering to probe the unfolding of apomyoglobin. The unfolding reaction was triggered using a temperature jump, which was induced by a nanosecond laser pulse. We demonstrate a new strategy to interpret time-resolved x-ray solution scattering data, which evaluates ensembles of structures obtained from molecular dynamics simulations. We find that apomyoglobin passes three states when unfolding, which we characterize as native, molten globule, and unfolded. The molten globule dominates the population under the conditions investigated herein, whereas native and unfolded structures primarily contribute before the laser jump and 30 μs after it, respectively. The molten globule retains much of the native structure but shows a dynamic pattern of inter-residue contacts. Our study demonstrates a new strategy to directly observe structural changes over the cause of the unfolding reaction, providing time- and spatially resolved atomic details of the folding mechanism of globular proteins.
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Affiliation(s)
- L. Henry
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - M. R. Panman
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - L. Isaksson
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - E. Claesson
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - I. Kosheleva
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - R. Henning
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, Illinois 60637, USA
| | - S. Westenhoff
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden
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74
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Smith Z, Ravindra P, Wang Y, Cooley R, Tiwary P. Discovering Protein Conformational Flexibility through Artificial-Intelligence-Aided Molecular Dynamics. J Phys Chem B 2020; 124:8221-8229. [DOI: 10.1021/acs.jpcb.0c03985] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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75
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Dou S, Wang Y, Zhang X. Amphiphilic Fluorescence Resonance Energy‐Transfer Dyes: Synthesis, Fluorescence, and Aggregation Behavior in Water. Chemistry 2020; 26:11503-11510. [DOI: 10.1002/chem.202000107] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Shilei Dou
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Chemical Engineering (Tianjin) Tianjin University Tianjin 300072 P.R. China
| | - Ying Wang
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Chemical Engineering (Tianjin) Tianjin University Tianjin 300072 P.R. China
| | - Xin Zhang
- School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Chemical Engineering (Tianjin) Tianjin University Tianjin 300072 P.R. China
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76
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Fast three-color single-molecule FRET using statistical inference. Nat Commun 2020; 11:3336. [PMID: 32620782 PMCID: PMC7335206 DOI: 10.1038/s41467-020-17149-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 06/11/2020] [Indexed: 12/21/2022] Open
Abstract
We describe theory, experiments, and analyses of three-color Förster resonance energy transfer (FRET) spectroscopy for probing sub-millisecond conformational dynamics of protein folding and binding of disordered proteins. We devise a scheme that uses single continuous-wave laser excitation of the donor instead of alternating excitation of the donor and one of the acceptors. This scheme alleviates photophysical problems of acceptors such as rapid photobleaching, which is crucial for high time resolution experiments with elevated illumination intensity. Our method exploits the molecular species with one of the acceptors absent or photobleached, from which two-color FRET data is collected in the same experiment. We show that three FRET efficiencies and kinetic parameters can be determined without alternating excitation from a global maximum likelihood analysis of two-color and three-color photon trajectories. We implement co-parallelization of CPU-GPU processing, which leads to a significant reduction of the likelihood calculation time for efficient parameter determination.
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77
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Ermolenko DN, Mathews DH. Making ends meet: New functions of mRNA secondary structure. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1611. [PMID: 32597020 DOI: 10.1002/wrna.1611] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 11/10/2022]
Abstract
The 5' cap and 3' poly(A) tail of mRNA are known to synergistically regulate mRNA translation and stability. Recent computational and experimental studies revealed that both protein-coding and non-coding RNAs will fold with extensive intramolecular secondary structure, which will result in close distances between the sequence ends. This proximity of the ends is a sequence-independent, universal property of most RNAs. Only low-complexity sequences without guanosines are without secondary structure and exhibit end-to-end distances expected for RNA random coils. The innate proximity of RNA ends might have important biological implications that remain unexplored. In particular, the inherent compactness of mRNA might regulate translation initiation by facilitating the formation of protein complexes that bridge mRNA 5' and 3' ends. Additionally, the proximity of mRNA ends might mediate coupling of 3' deadenylation to 5' end mRNA decay. This article is categorized under: RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems Translation > Translation Regulation.
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Affiliation(s)
- Dmitri N Ermolenko
- Department of Biochemistry & Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
| | - David H Mathews
- Department of Biochemistry & Biophysics and Center for RNA Biology, School of Medicine and Dentistry, University of Rochester, Rochester, New York, USA
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78
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Gleason PR, Kelly PI, Grisingher DW, Mills JH. An intrinsic FRET sensor of protein-ligand interactions. Org Biomol Chem 2020; 18:4079-4084. [PMID: 32427252 PMCID: PMC7313717 DOI: 10.1039/d0ob00793e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe an approach for the development of fluorescent sensors of metabolite binding in which a genetically encoded fluorescent non-canonical amino acid (fNCAA) containing a 7-hydroxycoumarin moiety (7-HCAA) forms a FRET pair with native tryptophan residues. Although previous studies demonstrated the potential for using 7-HCAA as an acceptor for tryptophan, this approach has not yet been explored within a single protein containing multiple tryptophan residues. A structure-based analysis of a hexokinase enzyme with multiple native tryptophan residues identified glutamate 50 as a potential site of 7-HCAA incorporation; Glu50 moves closer to the native tryptophans upon substrate binding. Substitution of 7-HCAA at residue 50 led to an increase in FRET efficiency in the presence of the substrate; this effect was not observed in a control protein where no change in distance between 7-HCAA and the native tryptophans occurs on substrate binding. This system was then used to directly observe differences in binding affinity of the hexokinase that occur at a number of pH values. Our approach builds on previous research in that it eliminates the need for the incorporation of multiple fNCAAs or fluorescent labels within a target protein and can be used to study substrate binding with native ligands. As such, it serves to expand the versatility of FRET-based techniques.
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Affiliation(s)
- Patrick R Gleason
- School of Molecular Sciences and The Biodesign Center for Molecular Design and Biomimetics, Arizona State University, Tempe, AZ 85287, USA.
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79
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Benjamin CE, Chen Z, Brohlin OR, Lee H, Shahrivarkevishahi A, Boyd S, Winkler DD, Gassensmith JJ. Using FRET to measure the time it takes for a cell to destroy a virus. NANOSCALE 2020; 12:9124-9132. [PMID: 32292962 DOI: 10.1039/c9nr09816j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The emergence of viral nanotechnology over the preceding two decades has created a number of intellectually captivating possible translational applications; however, the in vitro fate of the viral nanoparticles in cells remains an open question. Herein, we investigate the stability and lifetime of virus-like particle (VLP) Qβ-a representative and popular VLP for several applications-following cellular uptake. By exploiting the available functional handles on the viral surface, we have orthogonally installed the known FRET pair, FITC and Rhodamine B, to gain insight of the particle's behavior in vitro. Based on these data, we believe VLPs undergo aggregation in addition to the anticipated proteolysis within a few hours of cellular uptake.
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Affiliation(s)
- Candace E Benjamin
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas 75080, USA.
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80
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Matsunaga Y, Sugita Y. Use of single-molecule time-series data for refining conformational dynamics in molecular simulations. Curr Opin Struct Biol 2020; 61:153-159. [DOI: 10.1016/j.sbi.2019.12.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/24/2019] [Accepted: 12/27/2019] [Indexed: 12/18/2022]
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81
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Wang Y, Horáček M, Zijlstra P. Strong Plasmon Enhancement of the Saturation Photon Count Rate of Single Molecules. J Phys Chem Lett 2020; 11:1962-1969. [PMID: 32073865 PMCID: PMC7061331 DOI: 10.1021/acs.jpclett.0c00155] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/19/2020] [Indexed: 06/10/2023]
Abstract
Plasmon resonances have appeared as a promising method to boost the fluorescence intensity of single emitters. However, because research has focused on the enhancement at low excitation intensity, little is known about plasmon-fluorophore coupling near the point where the dye saturates. Here we study plasmon-enhanced fluorescence at a broad range of excitation intensities up to saturation. We adopt a novel DNA-mediated approach wherein dynamic single-molecule binding provides a controlled particle-fluorophore spacing, and dynamic rebinding circumvents artifacts due to photobleaching. We find that near saturation the maximum photon count rate is enhanced by more than 2 orders of magnitude at the optimal particle-fluorophore spacing, even for a dye with a high intrinsic quantum yield. We compare our results to a numerical model taking into account dye saturation. These experiments provide design rules to maximize the photon output of single emitters, which will open the door to studying fast dynamics in real time using single-molecule fluorescence.
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Affiliation(s)
- Yuyang Wang
- Department
of Applied Physics, Eindhoven University
of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
| | - Matěj Horáček
- Department
of Applied Physics, Eindhoven University
of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
| | - Peter Zijlstra
- Department
of Applied Physics, Eindhoven University
of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Postbus 513, 5600 MB Eindhoven, The Netherlands
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82
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Ernst P, Zosel F, Reichen C, Nettels D, Schuler B, Plückthun A. Structure-Guided Design of a Peptide Lock for Modular Peptide Binders. ACS Chem Biol 2020; 15:457-468. [PMID: 31985201 DOI: 10.1021/acschembio.9b00928] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Peptides play an important role in intermolecular interactions and are frequent analytes in diagnostic assays, also as unstructured, linear epitopes in whole proteins. Yet, due to the many different sequence possibilities even for short peptides, classical selection of binding proteins from a library, one at a time, is not scalable to proteomes. However, moving away from selection to a rational assembly of preselected modules binding to predefined linear epitopes would split the problem into smaller parts. These modules could then be reassembled in any desired order to bind to, in principle, arbitrary sequences, thereby circumventing any new rounds of selection. Designed Armadillo repeat proteins (dArmRPs) are modular, and they do bind elongated peptides in a modular way. Their consensus sequence carries pockets that prefer arginine and lysine. In our quest to select pockets for all amino acid side chains, we had discovered that repetitive sequences can lead to register shifts and peptide flipping during selections from libraries, hindering the selection of new binding specificities. To solve this problem, we now created an orthogonal binding specificity by a combination of grafting from β-catenin, computational design and mutual optimization of the pocket and the bound peptide. We have confirmed the design and the desired interactions by X-ray structure determination. Furthermore, we could confirm the absence of sliding in solution by a single-molecule Förster resonance energy transfer. The new pocket could be moved from the N-terminus of the protein to the middle, retaining its properties, further underlining the modularity of the system.
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Affiliation(s)
- Patrick Ernst
- Department of Biochemistry, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Franziska Zosel
- Department of Biochemistry, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Christian Reichen
- Department of Biochemistry, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Daniel Nettels
- Department of Biochemistry, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Benjamin Schuler
- Department of Biochemistry, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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83
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Vuorinen E, Valtonen S, Eskonen V, Kariniemi T, Jakovleva J, Kopra K, Härmä H. Sensitive Label-Free Thermal Stability Assay for Protein Denaturation and Protein-Ligand Interaction Studies. Anal Chem 2020; 92:3512-3516. [PMID: 32013400 PMCID: PMC7145280 DOI: 10.1021/acs.analchem.9b05712] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
In modern biochemistry,
protein stability and ligand interactions are of high interest. These
properties are often studied with methods requiring labeled biomolecules,
as the existing methods utilizing luminescent external probes suffer
from low sensitivity. Currently available label-free technologies,
e.g., thermal shift assays, circular dichroism, and differential scanning
calorimetry, enable studies on protein unfolding and protein–ligand
interactions (PLI). Unfortunately, the required micromolar protein
concentration increases the costs and predisposes these methods for
spontaneous protein aggregation. Here, we report a time-resolved luminescence
method for protein unfolding and PLI detection with nanomolar sensitivity.
The Protein-Probe method is based on highly luminescent europium chelate-conjugated
probe, which is the key component in sensing the hydrophobic regions
exposed to solution after protein unfolding. With the same Eu-probe,
we also demonstrate ligand-interaction induced thermal stabilization
with model proteins. The developed Protein-Probe method provides a
sensitive approach overcoming the problems of the current label-free
methodologies.
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Affiliation(s)
- Emmiliisa Vuorinen
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
| | - Salla Valtonen
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
| | - Ville Eskonen
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
| | - Taru Kariniemi
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
| | - Jelena Jakovleva
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
| | - Kari Kopra
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
| | - Harri Härmä
- Department of Chemistry, University of Turku, Vatselankatu 2, 20500 Turku, Finland
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84
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Cerminara M, Schöne A, Ritter I, Gabba M, Fitter J. Mapping Multiple Distances in a Multidomain Protein for the Identification of Folding Intermediates. Biophys J 2020; 118:688-697. [PMID: 31916943 PMCID: PMC7002912 DOI: 10.1016/j.bpj.2019.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/13/2019] [Accepted: 12/10/2019] [Indexed: 10/27/2022] Open
Abstract
The investigation and understanding of the folding mechanism of multidomain proteins is still a challenge in structural biology. The use of single-molecule Förster resonance energy transfer offers a unique tool to map conformational changes within the protein structure. Here, we present a study following denaturant-induced unfolding transitions of yeast phosphoglycerate kinase by mapping several inter- and intradomain distances of this two-domain protein, exhibiting a quite heterogeneous behavior. On the one hand, the development of the interdomain distance during the unfolding transition suggests a classical two-state unfolding behavior. On the other hand, the behavior of some intradomain distances indicates the formation of a compact and transient molten globule intermediate state. Furthermore, different intradomain distances measured within the same domain show pronounced differences in their unfolding behavior, underlining the fact that the choice of dye attachment positions within the polypeptide chain has a substantial impact on which unfolding properties are observed by single-molecule Förster resonance energy transfer measurements. Our results suggest that, to fully characterize the complex folding and unfolding mechanism of multidomain proteins, it is necessary to monitor multiple intra- and interdomain distances because a single reporter can lead to a misleading, partial, or oversimplified interpretation.
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Affiliation(s)
- Michele Cerminara
- Forschungszentrum Jülich, Institute of Complex Systems ICS-5, Jülich, Germany.
| | - Antonie Schöne
- Forschungszentrum Jülich, Institute of Complex Systems ICS-5, Jülich, Germany
| | - Ilona Ritter
- Forschungszentrum Jülich, Institute of Complex Systems ICS-5, Jülich, Germany
| | - Matteo Gabba
- Forschungszentrum Jülich, Institute of Complex Systems ICS-5, Jülich, Germany
| | - Jörg Fitter
- Forschungszentrum Jülich, Institute of Complex Systems ICS-5, Jülich, Germany; RWTH Aachen University, I. Physikalisches Institut (IA), Aachen, Germany.
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85
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Pisapati AV, Wang Y, Blauch ME, Wittenberg NJ, Cheng X, Zhang XF. Characterizing Single-Molecule Conformational Changes Under Shear Flow with Fluorescence Microscopy. J Vis Exp 2020:10.3791/60784. [PMID: 32065139 PMCID: PMC7205595 DOI: 10.3791/60784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Single-molecule behavior under mechanical perturbation has been characterized widely to understand many biological processes. However, methods such as atomic force microscopy have limited temporal resolution, while Förster resonance energy transfer (FRET) only allow conformations to be inferred. Fluorescence microscopy, on the other hand, allows real-time in situ visualization of single molecules in various flow conditions. Our protocol describes the steps to capture conformational changes of single biomolecules under different shear flow environments using fluorescence microscopy. The shear flow is created inside microfluidic channels and controlled by a syringe pump. As demonstrations of the method, von Willebrand factor (VWF) and lambda DNA are labeled with biotin and fluorophore and then immobilized on the channel surface. Their conformations are continuously monitored under variable shear flow using total internal reflection (TIRF) and confocal fluorescence microscopy. The reversible unraveling dynamics of VWF are useful for understanding how its function is regulated in human blood, while the conformation of lambda DNA offers insights into the biophysics of macromolecules. The protocol can also be widely applied to study the behavior of polymers, especially biopolymers, in varying flow conditions and to investigate the rheology of complex fluids.
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Affiliation(s)
| | - Yi Wang
- Department of Materials Science and Engineering, Lehigh University
| | | | | | - Xuanhong Cheng
- Department of Bioengineering, Lehigh University; Department of Materials Science and Engineering, Lehigh University;
| | - X Frank Zhang
- Department of Bioengineering, Lehigh University; Department of Mechanical Engineering and Mechanics, Lehigh University;
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86
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Reese HR, Shanahan CC, Proulx C, Menegatti S. Peptide science: A "rule model" for new generations of peptidomimetics. Acta Biomater 2020; 102:35-74. [PMID: 31698048 DOI: 10.1016/j.actbio.2019.10.045] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 10/17/2019] [Accepted: 10/30/2019] [Indexed: 02/07/2023]
Abstract
Peptides have been heavily investigated for their biocompatible and bioactive properties. Though a wide array of functionalities can be introduced by varying the amino acid sequence or by structural constraints, properties such as proteolytic stability, catalytic activity, and phase behavior in solution are difficult or impossible to impart upon naturally occurring α-L-peptides. To this end, sequence-controlled peptidomimetics exhibit new folds, morphologies, and chemical modifications that create new structures and functions. The study of these new classes of polymers, especially α-peptoids, has been highly influenced by the analysis, computational, and design techniques developed for peptides. This review examines techniques to determine primary, secondary, and tertiary structure of peptides, and how they have been adapted to investigate peptoid structure. Computational models developed for peptides have been modified to predict the morphologies of peptoids and have increased in accuracy in recent years. The combination of in vitro and in silico techniques have led to secondary and tertiary structure design principles that mirror those for peptides. We then examine several important developments in peptoid applications inspired by peptides such as pharmaceuticals, catalysis, and protein-binding. A brief survey of alternative backbone structures and research investigating these peptidomimetics shows how the advancement of peptide and peptoid science has influenced the growth of numerous fields of study. As peptide, peptoid, and other peptidomimetic studies continue to advance, we will expect to see higher throughput structural analyses, greater computational accuracy and functionality, and wider application space that can improve human health, solve environmental challenges, and meet industrial needs. STATEMENT OF SIGNIFICANCE: Many historical, chemical, and functional relations draw a thread connecting peptides to their recent cognates, the "peptidomimetics". This review presents a comprehensive survey of this field by highlighting the width and relevance of these familial connections. In the first section, we examine the experimental and computational techniques originally developed for peptides and their morphing into a broader analytical and predictive toolbox. The second section presents an excursus of the structures and properties of prominent peptidomimetics, and how the expansion of the chemical and structural diversity has returned new exciting properties. The third section presents an overview of technological applications and new families of peptidomimetics. As the field grows, new compounds emerge with clear potential in medicine and advanced manufacturing.
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87
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Birol M, Melo AM. Untangling the Conformational Polymorphism of Disordered Proteins Associated With Neurodegeneration at the Single-Molecule Level. Front Mol Neurosci 2020; 12:309. [PMID: 31998071 PMCID: PMC6965022 DOI: 10.3389/fnmol.2019.00309] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/29/2019] [Indexed: 12/15/2022] Open
Abstract
A large fraction of the human genome encodes intrinsically disordered proteins/regions (IDPs/IDRs) that are involved in diverse cellular functions/regulation and dysfunctions. Moreover, several neurodegenerative disorders are associated with the pathological self-assembly of neuronal IDPs, including tau [Alzheimer's disease (AD)], α-synuclein [Parkinson's disease (PD)], and huntingtin exon 1 [Huntington's disease (HD)]. Therefore, there is an urgent and emerging clinical interest in understanding the physical and structural features of their functional and disease states. However, their biophysical characterization is inherently challenging by traditional ensemble techniques. First, unlike globular proteins, IDPs lack stable secondary/tertiary structures under physiological conditions and may interact with multiple and distinct biological partners, subsequently folding differentially, thus contributing to the conformational polymorphism. Second, amyloidogenic IDPs display a high aggregation propensity, undergoing complex heterogeneous self-assembly mechanisms. In this review article, we discuss the advantages of employing cutting-edge single-molecule fluorescence (SMF) techniques to characterize the conformational ensemble of three selected neuronal IDPs (huntingtin exon 1, tau, and α-synuclein). Specifically, we survey the versatility of these powerful approaches to describe their monomeric conformational ensemble under functional and aggregation-prone conditions, and binding to biological partners. Together, the information gained from these studies provides unique insights into the role of gain or loss of function of these disordered proteins in neurodegeneration, which may assist the development of new therapeutic molecules to prevent and treat these devastating human disorders.
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Affiliation(s)
- Melissa Birol
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Ana M Melo
- Centro de Química-Física Molecular- IN and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
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88
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Mandal M, Das A, Mukhopadhyay C. Ubiquitin folds via a flip-twist-lock mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140299. [DOI: 10.1016/j.bbapap.2019.140299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/14/2019] [Accepted: 10/01/2019] [Indexed: 01/08/2023]
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89
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Zelger-Paulus S, Hadzic MCAS, Sigel RKO, Börner R. Encapsulation of Fluorescently Labeled RNAs into Surface-Tethered Vesicles for Single-Molecule FRET Studies in TIRF Microscopy. Methods Mol Biol 2020; 2113:1-16. [PMID: 32006303 DOI: 10.1007/978-1-0716-0278-2_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Imaging fluorescently labeled biomolecules on a single-molecule level is a well-established technique to follow intra- and intermolecular processes in time, usually hidden in the ensemble average. The classical approach comprises surface immobilization of the molecule of interest, which increases the risk of restricting the natural behavior due to surface interactions. Encapsulation of such biomolecules into surface-tethered phospholipid vesicles enables to follow one molecule at a time, freely diffusing and without disturbing surface interactions. Further, the encapsulation allows to keep reaction partners (reactants and products) in close proximity and enables higher temperatures otherwise leading to desorption of the direct immobilized biomolecules.Here, we describe a detailed protocol for the encapsulation of a catalytically active RNA starting from surface passivation over RNA encapsulation to data evaluation of single-molecule FRET experiments in TIRF microscopy. We present an optimized procedure that preserves RNA functionality and applies to investigations of, e.g., large ribozymes and RNAs, where direct immobilization is structurally not possible.
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Affiliation(s)
| | | | - Roland K O Sigel
- Department of Chemistry, University of Zurich, Zurich, Switzerland.
| | - Richard Börner
- Department of Chemistry, University of Zurich, Zurich, Switzerland.
- Laserinstitut Hochschule Mittweida, University of Applied Sciences Mittweida, Mittweida, Germany.
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90
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Liu X, Chen J. Modulation of p53 Transactivation Domain Conformations by Ligand Binding and Cancer-Associated Mutations. PACIFIC SYMPOSIUM ON BIOCOMPUTING. PACIFIC SYMPOSIUM ON BIOCOMPUTING 2020; 25:195-206. [PMID: 31797597 PMCID: PMC6934143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Intrinsically disordered proteins (IDPs) are important functional proteins, and their deregulation are linked to numerous human diseases including cancers. Understanding how disease-associated mutations or drug molecules can perturb the sequence-disordered ensemble-function-disease relationship of IDPs remains challenging, because it requires detailed characterization of the heterogeneous structural ensembles of IDPs. In this work, we combine the latest atomistic force field a99SB-disp, enhanced sampling technique replica exchange with solute tempering, and GPU-accelerated molecular dynamics simulations to investigate how four cancer-associated mutations, K24N, N29K/N30D, D49Y, and W53G, and binding of an anti-cancer molecule, epigallocatechin gallate (EGCG), modulate the disordered ensemble of the transactivation domain (TAD) of tumor suppressor p53. Through extensive sampling, in excess of 1.0 μs per replica, well-converged structural ensembles of wild-type and mutant p53-TAD as well as WT p53-TAD in the presence of EGCG were generated. The results reveal that mutants could induce local structural changes and affect secondary structural properties. Interestingly, both EGCG binding and N29K/N30D could also induce long-range structural reorganizations and lead to more compact structures that could shield key binding sites of p53-TAD regulators. Further analysis reveals that the effects of EGCG binding are mainly achieved through nonspecific interactions. These observations are generally consistent with on-going NMR studies and binding assays. Our studies suggest that induced conformational collapse of IDPs may be a general mechanism for shielding functional sites, thus inhibiting recognition of their targets. The current study also demonstrates that atomistic simulations provide a viable approach for studying the sequence-disordered ensemble-function-disease relationships of IDPs and developing new drug design strategies targeting regulatory IDPs.
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Affiliation(s)
- Xiaorong Liu
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003, USA,Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA 01003, USA,
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91
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Troilo F, Malagrinò F, Visconti L, Toto A, Gianni S. The Effect of Proline cis- trans Isomerization on the Folding of the C-Terminal SH2 Domain from p85. Int J Mol Sci 2019; 21:E125. [PMID: 31878075 PMCID: PMC6982175 DOI: 10.3390/ijms21010125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/20/2019] [Accepted: 12/20/2019] [Indexed: 11/17/2022] Open
Abstract
SH2 domains are protein domains that modulate protein-protein interactions through a specific interaction with sequences containing phosphorylated tyrosines. In this work, we analyze the folding pathway of the C-terminal SH2 domain of the p85 regulatory subunit of the protein PI3K, which presents a proline residue in a cis configuration in the loop between the βE and βF strands. By employing single and double jump folding and unfolding experiments, we demonstrate the presence of an on-pathway intermediate that transiently accumulates during (un)folding. By comparing the kinetics of folding of the wild-type protein to that of a site-directed variant of C-SH2 in which the proline was replaced with an alanine, we demonstrate that this intermediate is dictated by the peptidyl prolyl cis-trans isomerization. The results are discussed in the light of previous work on the effect of peptidyl prolyl cis-trans isomerization on folding events.
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Affiliation(s)
- Francesca Troilo
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Francesca Malagrinò
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Lorenzo Visconti
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Angelo Toto
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
| | - Stefano Gianni
- Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, 00161 Roma, Italy; (F.T.); (F.M.); (L.V.); (A.T.)
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza Università di Roma, 00185 Rome, Italy
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92
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Gutiérrez-Mejía FA, Moerland CP, van IJzendoorn LJ, Prins MWJ. Conformation switching of single native proteins revealed by nanomechanical probing without a pulling force. NANOSCALE 2019; 11:19933-19942. [PMID: 31599908 DOI: 10.1039/c9nr01448a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Protein conformational changes are essential to biological function, and the heterogeneous nature of the corresponding protein states provokes an interest to measure conformational changes at the single molecule level. Here we demonstrate that conformational changes in single native proteins can be revealed by non-covalent antibody-targeting of specific domains within the protein, using nanomechanical probing without an applied pulling force. The protein of interest was captured between a particle and a substrate and three properties were quantified: the twist amplitude related to an applied torque, torsional compliance related to rotational Brownian motion, and translational Brownian displacement. Calcium-dependent conformation switching was studied in native human cardiac troponin, a heterotrimer protein complex that regulates the contraction and relaxation of heart muscle cells and is also a key biomarker for diagnosing myocardial infarction. The data reveal a change in mechanical properties upon conformation switching from the non-saturated to the calcium-saturated state, which in cardiomyocytes gives myosin motor proteins access to actin filaments. A clear increase was observed in the molecular stiffness for the calcium-saturated protein conformation. Using libraries of monoclonal antibodies, the nanomechanical probing of conformation by antibody targeting opens avenues for characterizing single native protein complexes for research as well as for diagnostic applications.
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Affiliation(s)
- Fabiola A Gutiérrez-Mejía
- Department of Applied Physics, Eindhoven University of Technology (TU/e), Eindhoven, The Netherlands. and Institute for Complex Molecular Systems (ICMS), TU/e, Eindhoven, The Netherlands
| | - Christian P Moerland
- Department of Applied Physics, Eindhoven University of Technology (TU/e), Eindhoven, The Netherlands. and Institute for Complex Molecular Systems (ICMS), TU/e, Eindhoven, The Netherlands
| | - Leo J van IJzendoorn
- Department of Applied Physics, Eindhoven University of Technology (TU/e), Eindhoven, The Netherlands. and Institute for Complex Molecular Systems (ICMS), TU/e, Eindhoven, The Netherlands
| | - Menno W J Prins
- Department of Applied Physics, Eindhoven University of Technology (TU/e), Eindhoven, The Netherlands. and Institute for Complex Molecular Systems (ICMS), TU/e, Eindhoven, The Netherlands and Department of Biomedical Engineering, TU/e, Eindhoven, The Netherlands
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93
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Kumari N, Ciuba MA, Levitus M. Photophysical properties of the hemicyanine Dy-630 and its potential as a single-molecule fluorescent probe for biophysical applications. Methods Appl Fluoresc 2019; 8:015004. [PMID: 31585443 DOI: 10.1088/2050-6120/ab4b0d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Protein-induced fluorescence enhancement (PIFE) is an increasingly used approach to investigate DNA-protein interactions at the single molecule level. The optimal probe for this type of application is highly photostable, has a high absorption extinction coefficient, and has a moderate fluorescence quantum yield that increases significantly when the dye is in close proximity to a large macromolecule such as a protein. So far, the green-absorbing symmetric cyanine known as Cy3 has been the probe of choice in this field because the magnitude of the increase observed upon protein binding (usually 2-4 -fold) is large enough to allow for the analysis of protein dynamics on the inherently noisy single-molecule signals. Here, we report the characterization of the photophysical properties of the red-absorbing hemicyanine dye Dy-630 in the context of its potential application as a single-molecule PIFE probe. The behavior of Dy-630 in solution is similar to that of Cy3; the fluorescence quantum yield and lifetime of Dy-630 increase with increasing viscosity, and decrease with increasing temperature indicating the existence of an activated nonradiative process that depopulates the singlet state of the dye. As in the case of Cy3, the results of transient spectroscopy experiments are consistent with the formation of a photoisomer that reverts to the ground state thermally in the microsecond timescale. Unfortunately, experiments with DNA samples paint a more complex scenario. As in the case of Cy3, the fluorescence quantum yield of Dy-630 increases significantly when the dye interacts with the DNA bases, but in the case of Dy-630 attachment to DNA results in an already long fluorescence lifetime that does not provide a significant window for the protein-induced enhancement observed with Cy3. Although we show that Dy-630 may not be well-suited for PIFE, our results shed light on the optimal design principles for probes for PIFE applications.
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94
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Breitgoff FD, Keller K, Qi M, Klose D, Yulikov M, Godt A, Jeschke G. UWB DEER and RIDME distance measurements in Cu(II)-Cu(II) spin pairs. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 308:106560. [PMID: 31377151 DOI: 10.1016/j.jmr.2019.07.047] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 06/10/2023]
Abstract
Distance determination by Electron Paramagnetic Resonance (EPR) based on measurements of the dipolar coupling are technically challenging for electron spin systems with broad spectra due to comparatively narrow microwave pulse excitation bandwidths. With Na4[{CuII(PyMTA)}-(stiff spacer)-{CuII(PyMTA)}] as a model compound, we compared DEER and RIDME measurements and investigated the use of frequency-swept pulses. We found very large improvements in sensitivity when substituting the monochromatic pump pulse by a frequency-swept one in DEER experiments with monochromatic observer pulses. This effect was especially strong in X band, where nearly the whole spectrum can be included in the experiment. The RIDME experiment is characterised by a trade-off in signal intensity and modulation depth. Optimal parameters are further influenced by varying steepness of the background decay. A simple 2-point optimization experiment was found to serve as good estimate to identify the mixing time of highest sensitivity. Using frequency-swept pulses in the observer sequences resulted in lower SNR in both the RIDME and the DEER experiment. Orientation selectivity was found to vary in both experiments with the detection position as well as with the settings of the pump pulse in DEER. In RIDME, orientation selection by relaxation anisotropy of the inverted spin appeared to be negligible as form factors remain relatively constant with varying mixing time. This reduces the overall observed orientation selection to the one given by the detection position. Field-averaged data from RIDME and DEER with a shaped pump pulse resulted in the same dipolar spectrum. We found that both methods have their advantages and disadvantages for given instrumental limitations and sample properties. Thus the choice of method depends on the situation at hand and we discuss which parameters should be considered for optimization.
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Affiliation(s)
- Frauke D Breitgoff
- ETH Zürich, Lab. Phys. Chem., Vladimir-Prelog-Weg 2, 8063 Zürich 3 Switzerland.
| | - Katharina Keller
- ETH Zürich, Lab. Phys. Chem., Vladimir-Prelog-Weg 2, 8063 Zürich 3 Switzerland.
| | - Mian Qi
- Faculty of Chemistry and Center for Molecular Materials (CM(2)), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Daniel Klose
- ETH Zürich, Lab. Phys. Chem., Vladimir-Prelog-Weg 2, 8063 Zürich 3 Switzerland
| | - Maxim Yulikov
- ETH Zürich, Lab. Phys. Chem., Vladimir-Prelog-Weg 2, 8063 Zürich 3 Switzerland
| | - Adelheid Godt
- Faculty of Chemistry and Center for Molecular Materials (CM(2)), Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany.
| | - Gunnar Jeschke
- ETH Zürich, Lab. Phys. Chem., Vladimir-Prelog-Weg 2, 8063 Zürich 3 Switzerland
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95
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Gilboa B, Jing B, Cui TJ, Sow M, Plochowietz A, Mazumder A, Kapanidis AN. Confinement-Free Wide-Field Ratiometric Tracking of Single Fluorescent Molecules. Biophys J 2019; 117:2141-2153. [PMID: 31711608 PMCID: PMC6895709 DOI: 10.1016/j.bpj.2019.10.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 09/25/2019] [Accepted: 10/21/2019] [Indexed: 11/24/2022] Open
Abstract
Single-molecule fluorescence has been highly instrumental in elucidating interactions and dynamics of biological molecules in the past two decades. Single-molecule fluorescence experiments usually rely on one of two detection geometries, either confocal point-detection or wide-field area detection, typically in a total internal reflection fluorescence (TIRF) format. However, each of these techniques suffers from fundamental drawbacks that limit their application. In this work, we present a new technique, solution wide-field imaging (SWiFi) of diffusing molecules, as an alternative to the existing methods. SWiFi is a simple extension to existing objective-type TIRF microscopes that allows wide-field observations of fast-diffusing molecules down to single fluorophores without the need of tethering the molecules to the surface. We demonstrate that SWiFi enables high-throughput ratiometric measurements with several thousands of individual data points per minute on double-stranded DNA standard (dsDNA) samples containing Förster resonance energy transfer pairs. We further display the capabilities of SWiFi by reporting on mobility and ratiometric characterization of fluorescent nanodiamonds, DNA Holliday junctions, and protein-DNA interactions. The ability of SWiFi for high-throughput, ratiometric measurements of fast-diffusing species renders it a valuable tool for the single-molecule research community by bridging between confocal and TIRF detection geometries in a simple and efficient way.
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Affiliation(s)
- Barak Gilboa
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Bo Jing
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Tao J Cui
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Maabur Sow
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Anne Plochowietz
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Abhishek Mazumder
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Achillefs N Kapanidis
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom.
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96
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Faulón Marruecos D, Saleh LS, Kim HH, Bryant SJ, Schwartz DK, Kaar JL. Stabilization of Fibronectin by Random Copolymer Brushes Inhibits Macrophage Activation. ACS APPLIED BIO MATERIALS 2019; 2:4698-4702. [DOI: 10.1021/acsabm.9b00815] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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97
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Siefe C, Mehlenbacher RD, Peng CS, Zhang Y, Fischer S, Lay A, McLellan CA, Alivisatos AP, Chu S, Dionne JA. Sub-20 nm Core-Shell-Shell Nanoparticles for Bright Upconversion and Enhanced Förster Resonant Energy Transfer. J Am Chem Soc 2019; 141:16997-17005. [PMID: 31592655 PMCID: PMC8259630 DOI: 10.1021/jacs.9b09571] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Upconverting nanoparticles provide valuable benefits as optical probes for bioimaging and Förster resonant energy transfer (FRET) due to their high signal-to-noise ratio, photostability, and biocompatibility; yet, making nanoparticles small yields a significant decay in brightness due to increased surface quenching. Approaches to improve the brightness of UCNPs exist but often require increased nanoparticle size. Here we present a unique core-shell-shell nanoparticle architecture for small (sub-20 nm), bright upconversion with several key features: (1) maximal sensitizer concentration in the core for high near-infrared absorption, (2) efficient energy transfer between core and interior shell for strong emission, and (3) emitter localization near the nanoparticle surface for efficient FRET. This architecture consists of β-NaYbF4 (core) @NaY0.8-xErxGd0.2F4 (interior shell) @NaY0.8Gd0.2F4 (exterior shell), where sensitizer and emitter ions are partitioned into core and interior shell, respectively. Emitter concentration is varied (x = 1, 2, 5, 10, 20, 50, and 80%) to investigate influence on single particle brightness, upconversion quantum yield, decay lifetimes, and FRET coupling. We compare these seven samples with the field-standard core-shell architecture of β-NaY0.58Gd0.2Yb0.2Er0.02F4 (core) @NaY0.8Gd0.2F4 (shell), with sensitizer and emitter ions codoped in the core. At a single particle level, the core-shell-shell design was up to 2-fold brighter than the standard core-shell design. Further, by coupling a fluorescent dye to the surface of the two different architectures, we demonstrated up to 8-fold improved emission enhancement with the core-shell-shell compared to the core-shell design. We show how, given proper consideration for emitter concentration, we can design a unique nanoparticle architecture to yield comparable or improved brightness and FRET coupling within a small volume.
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Affiliation(s)
- Chris Siefe
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Randy D. Mehlenbacher
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Chunte Sam Peng
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, United States
| | - Yunxiang Zhang
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, United States
| | - Stefan Fischer
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - Alice Lay
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Claire A. McLellan
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
| | - A. Paul Alivisatos
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
| | - Steven Chu
- Department of Physics, Stanford University, Stanford, California 94305, United States
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, United States
| | - Jennifer A. Dionne
- Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States
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98
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Adamski W, Salvi N, Maurin D, Magnat J, Milles S, Jensen MR, Abyzov A, Moreau CJ, Blackledge M. A Unified Description of Intrinsically Disordered Protein Dynamics under Physiological Conditions Using NMR Spectroscopy. J Am Chem Soc 2019; 141:17817-17829. [PMID: 31591893 DOI: 10.1021/jacs.9b09002] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Intrinsically disordered proteins (IDPs) are flexible biomolecules whose essential functions are defined by their dynamic nature. Nuclear magnetic resonance (NMR) spectroscopy is ideally suited to the investigation of this behavior at atomic resolution. NMR relaxation is increasingly used to detect conformational dynamics in free and bound forms of IDPs under conditions approaching physiological, although a general framework providing a quantitative interpretation of these exquisitely sensitive probes as a function of experimental conditions is still lacking. Here, measuring an extensive set of relaxation rates sampling multiple-time-scale dynamics over a broad range of crowding conditions, we develop and test an integrated analytical description that accurately portrays the motion of IDPs as a function of the intrinsic properties of the crowded molecular environment. In particular we observe a strong dependence of both short-range and long-range motional time scales of the protein on the friction of the solvent. This tight coupling between the dynamic behavior of the IDP and its environment allows us to develop analytical expressions for protein motions and NMR relaxation properties that can be accurately applied over a vast range of experimental conditions. This unified dynamic description provides new insight into the physical behavior of IDPs, extending our ability to quantitatively investigate their conformational dynamics under complex environmental conditions, and accurately predicting relaxation rates reporting on motions on time scales up to tens of nanoseconds, both in vitro and in cellulo.
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Affiliation(s)
- Wiktor Adamski
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Nicola Salvi
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Damien Maurin
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Justine Magnat
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Sigrid Milles
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Malene Ringkjøbing Jensen
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Anton Abyzov
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Christophe J Moreau
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
| | - Martin Blackledge
- Institut de Biologie Structurale , Université Grenoble Alpes-CEA-CNRS , 71, Avenue des Martyrs , Grenoble , France
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99
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Xiao M, Lai W, Man T, Chang B, Li L, Chandrasekaran AR, Pei H. Rationally Engineered Nucleic Acid Architectures for Biosensing Applications. Chem Rev 2019; 119:11631-11717. [DOI: 10.1021/acs.chemrev.9b00121] [Citation(s) in RCA: 147] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Mingshu Xiao
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P. R. China
| | - Wei Lai
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P. R. China
| | - Tiantian Man
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P. R. China
| | - Binbin Chang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P. R. China
| | - Li Li
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P. R. China
| | - Arun Richard Chandrasekaran
- The RNA Institute, University at Albany, State University of New York, Albany, New York 12222, United States
| | - Hao Pei
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, P. R. China
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100
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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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