1
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Grosskopf JD, Sidabras JW, Altenbach C, Anderson JR, Mett RR, Strangeway RA, Hyde JS, Hubbell WL, Lerch MT. A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins. Protein Sci 2024; 33:e5220. [PMID: 39565088 PMCID: PMC11577460 DOI: 10.1002/pro.5220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 10/24/2024] [Accepted: 10/25/2024] [Indexed: 11/21/2024]
Abstract
Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the timescale of ps-μs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of μs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and ms-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the ms timescale.
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Affiliation(s)
| | - Jason W. Sidabras
- Department of BiophysicsMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Christian Altenbach
- Department of Chemistry and Biochemistry and Stein Eye InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Jim R. Anderson
- Department of BiophysicsMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Richard R. Mett
- Department of BiophysicsMedical College of WisconsinMilwaukeeWisconsinUSA
| | | | - James S. Hyde
- Department of BiophysicsMedical College of WisconsinMilwaukeeWisconsinUSA
| | - Wayne L. Hubbell
- Department of Chemistry and Biochemistry and Stein Eye InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Michael T. Lerch
- Department of BiophysicsMedical College of WisconsinMilwaukeeWisconsinUSA
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2
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Grosskopf JD, Sidabras JW, Altenbach C, Anderson JR, Mett RR, Strangeway RA, Hyde JS, Hubbell WL, Lerch MT. A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.593074. [PMID: 38766191 PMCID: PMC11100676 DOI: 10.1101/2024.05.07.593074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the time scale of ps-µs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of µs-ms, corresponding to large-scale protein motions, is inaccessible to those methods. To extend SDSL-EPR to the longer time domain, the perturbation method of pressure-jump relaxation is implemented. Here, we describe a complete high-pressure EPR system at Q-band for both static pressure and millisecond-timescale pressure-jump measurements on spin-labeled proteins. The instrument enables pressure jumps both up and down from any holding pressure, ranging from atmospheric pressure to the maximum pressure capacity of the system components (~3500 bar). To demonstrate the utility of the system, we characterize a local folding-unfolding equilibrium of T4 lysozyme. The results illustrate the ability of the system to measure thermodynamic and kinetic parameters of protein conformational exchange on the millisecond timescale.
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Affiliation(s)
- Julian D Grosskopf
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Jason W Sidabras
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Christian Altenbach
- Department of Chemistry and Biochemistry and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - Jim R Anderson
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Richard R Mett
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Robert A Strangeway
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - James S Hyde
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Wayne L Hubbell
- Department of Chemistry and Biochemistry and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - Michael T Lerch
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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3
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Grünbein ML, Gorel A, Foucar L, Carbajo S, Colocho W, Gilevich S, Hartmann E, Hilpert M, Hunter M, Kloos M, Koglin JE, Lane TJ, Lewandowski J, Lutman A, Nass K, Nass Kovacs G, Roome CM, Sheppard J, Shoeman RL, Stricker M, van Driel T, Vetter S, Doak RB, Boutet S, Aquila A, Decker FJ, Barends TRM, Stan CA, Schlichting I. Effect of X-ray free-electron laser-induced shockwaves on haemoglobin microcrystals delivered in a liquid jet. Nat Commun 2021; 12:1672. [PMID: 33723266 PMCID: PMC7960726 DOI: 10.1038/s41467-021-21819-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 02/15/2021] [Indexed: 01/31/2023] Open
Abstract
X-ray free-electron lasers (XFELs) enable obtaining novel insights in structural biology. The recently available MHz repetition rate XFELs allow full data sets to be collected in shorter time and can also decrease sample consumption. However, the microsecond spacing of MHz XFEL pulses raises new challenges, including possible sample damage induced by shock waves that are launched by preceding pulses in the sample-carrying jet. We explored this matter with an X-ray-pump/X-ray-probe experiment employing haemoglobin microcrystals transported via a liquid jet into the XFEL beam. Diffraction data were collected using a shock-wave-free single-pulse scheme as well as the dual-pulse pump-probe scheme. The latter, relative to the former, reveals significant degradation of crystal hit rate, diffraction resolution and data quality. Crystal structures extracted from the two data sets also differ. Since our pump-probe attributes were chosen to emulate EuXFEL operation at its 4.5 MHz maximum pulse rate, this prompts concern about such data collection.
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Affiliation(s)
- Marie Luise Grünbein
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Alexander Gorel
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Lutz Foucar
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Sergio Carbajo
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - William Colocho
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Sasha Gilevich
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Elisabeth Hartmann
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Mario Hilpert
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Mark Hunter
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Marco Kloos
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany ,grid.434729.f0000 0004 0590 2900Present Address: European XFEL GmbH, Schenefeld, Germany
| | - Jason E. Koglin
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA ,grid.148313.c0000 0004 0428 3079Present Address: Los Alamos National Laboratory, Los Alamos, NM USA
| | - Thomas J. Lane
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA ,grid.466493.a0000 0004 0390 1787Present Address: Center for Free-Electron Laser Science, DESY, Hamburg, Germany
| | - Jim Lewandowski
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Alberto Lutman
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Karol Nass
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany ,grid.5991.40000 0001 1090 7501Present Address: Paul Scherrer Institut, Villigen, Switzerland
| | - Gabriela Nass Kovacs
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Christopher M. Roome
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - John Sheppard
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Robert L. Shoeman
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Miriam Stricker
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany ,grid.4991.50000 0004 1936 8948Present Address: Department of Statistics, University of Oxford, Oxford, UK
| | - Tim van Driel
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Sharon Vetter
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - R. Bruce Doak
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Sébastien Boutet
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Andrew Aquila
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Franz Josef Decker
- grid.445003.60000 0001 0725 7771SLAC National Accelerator Laboratory, Menlo Park, CA USA
| | - Thomas R. M. Barends
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
| | - Claudiu Andrei Stan
- grid.430387.b0000 0004 1936 8796Department of Physics, Rutgers University Newark, Newark, NJ USA
| | - Ilme Schlichting
- grid.414703.50000 0001 2202 0959Max Planck Institute for Medical Research, Jahnstrasse 29, Heidelberg, Germany
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4
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Ando N, Barquera B, Bartlett DH, Boyd E, Burnim AA, Byer AS, Colman D, Gillilan RE, Gruebele M, Makhatadze G, Royer CA, Shock E, Wand AJ, Watkins MB. The Molecular Basis for Life in Extreme Environments. Annu Rev Biophys 2021; 50:343-372. [PMID: 33637008 DOI: 10.1146/annurev-biophys-100120-072804] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sampling and genomic efforts over the past decade have revealed an enormous quantity and diversity of life in Earth's extreme environments. This new knowledge of life on Earth poses the challenge of understandingits molecular basis in such inhospitable conditions, given that such conditions lead to loss of structure and of function in biomolecules from mesophiles. In this review, we discuss the physicochemical properties of extreme environments. We present the state of recent progress in extreme environmental genomics. We then present an overview of our current understanding of the biomolecular adaptation to extreme conditions. As our current and future understanding of biomolecular structure-function relationships in extremophiles requires methodologies adapted to extremes of pressure, temperature, and chemical composition, advances in instrumentation for probing biophysical properties under extreme conditions are presented. Finally, we briefly discuss possible future directions in extreme biophysics.
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Affiliation(s)
- Nozomi Ando
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14853, USA.,Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - Blanca Barquera
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, USA;
| | - Douglas H Bartlett
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0202, USA
| | - Eric Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana 59717, USA
| | - Audrey A Burnim
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Amanda S Byer
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Daniel Colman
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana 59717, USA
| | - Richard E Gillilan
- Center for High Energy X-ray Sciences (CHEXS), Ithaca, New York 14853, USA
| | - Martin Gruebele
- Department of Chemistry, University of Illinois, Urbana-Champaign, Illinois 61801, USA.,Department of Physics, University of Illinois, Urbana-Champaign, Illinois 61801, USA.,Center for Biophysics and Quantitative Biology, University of Illinois, Urbana-Champaign, Illinois 61801, USA
| | - George Makhatadze
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, USA;
| | - Catherine A Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York 12180, USA;
| | - Everett Shock
- GEOPIG, School of Earth & Space Exploration, School of Molecular Sciences, Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, Arizona 85287, USA
| | - A Joshua Wand
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas 77845, USA.,Department of Chemistry, Texas A&M University, College Station, Texas 77845, USA.,Department of Molecular & Cellular Medicine, Texas A&M University, College Station, Texas 77845, USA
| | - Maxwell B Watkins
- Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York 14853, USA.,Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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5
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Hofmann SM, Frost CV, Podewin T, Gailer M, Weber E, Zacharias M, Zinth W, Hoffmann-Röder A. Folding and Unfolding of the Short Light-Triggered β-Hairpin Peptide AzoChignolin Occurs within 100 ns. J Phys Chem B 2020; 124:5113-5121. [PMID: 32479079 DOI: 10.1021/acs.jpcb.0c02021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To map the underlying molecular mechanisms of folding dynamics in proteins, light-operated peptides have emerged as promising tools. In this study, we reveal the complete sequence of light-induced structural changes of AzoChignolin, a short β-hairpin peptide containing an azobenzene photoswitch in its loop region. Light-triggered structural changes were monitored by time-resolved IR spectroscopy. Formation and destruction of the hairpin structure is very fast and occurs within 100 ns for AzoChignolin in methanol. Atomistic molecular dynamics simulations using two explicit solvents, methanol and water, revealed the underlying molecular processes and allowed us to gain further insight into the reaction mechanism. Despite its rapid reaction time, hairpin formation in these solvents is not force-driven by the molecular switch but proceeded via formation of interstrand hydrogen bonds and contacts between aromatic residues. Moreover, the combined experimental and theoretical study demonstrates that the solvent (methanol vs water) does not dictate the velocity of β-hairpin formation in the AzoChignolin peptide comprising only a few hydrophobic residues in the strands.
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Affiliation(s)
- Stefan M Hofmann
- BioMolecular Optics and Center for Integrated Protein Science, Faculty of Physics, Ludwig-Maximilians-Universität München, Oettingenstr. 67, München 80538, Germany
| | - Christina V Frost
- TUM Department of Physics T38, Technical University of Munich, James-Franck-Str. 1, Garching 85748, Germany
| | - Tom Podewin
- Department of Organic Chemistry and Center for Integrated Protein Science, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, München 81377, Germany
| | - Manuel Gailer
- Department of Organic Chemistry and Center for Integrated Protein Science, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, München 81377, Germany
| | - Elisa Weber
- BioMolecular Optics and Center for Integrated Protein Science, Faculty of Physics, Ludwig-Maximilians-Universität München, Oettingenstr. 67, München 80538, Germany
| | - Martin Zacharias
- TUM Department of Physics T38, Technical University of Munich, James-Franck-Str. 1, Garching 85748, Germany
| | - Wolfgang Zinth
- BioMolecular Optics and Center for Integrated Protein Science, Faculty of Physics, Ludwig-Maximilians-Universität München, Oettingenstr. 67, München 80538, Germany
| | - Anja Hoffmann-Röder
- Department of Organic Chemistry and Center for Integrated Protein Science, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, München 81377, Germany
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6
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Jiang X, Wu Z, Fan Z, Yin J, Zheng L. A new way to recognize downhill folding based on generalized path length. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2020. [DOI: 10.1142/s0219633620400052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The protein folding is an important scientific problem and many methods were designed to elucidate the protein folding and obtain insight into the molecular mechanism. A novel means is presented to identify the downhill pathways of protein folding in this paper. This method is based on barrier energy profile projected onto the generalized path length (GPL) with Breadth-first searching (BFS) algorithm. We show the effectiveness of this approach by constructing the barrier energy profile of trpzip2 and comparing with other methods.
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Affiliation(s)
- Xuewei Jiang
- Wuhan Textile and Apparel Digital Engineering Technology Research Center, Wuhan Textile University, Wuhan, Hubei 430073, P. R. China
| | - Zhengwu Wu
- School of Computer Science, Wuhan University, Wuhan, Hubei 430072, P. R. China
| | - Zhenyuan Fan
- Wuhan Textile and Apparel Digital Engineering Technology Research Center, Wuhan Textile University, Wuhan, Hubei 430073, P. R. China
| | - Junhua Yin
- Wuhan Textile and Apparel Digital Engineering Technology Research Center, Wuhan Textile University, Wuhan, Hubei 430073, P. R. China
| | - Lu Zheng
- Wuhan Textile and Apparel Digital Engineering Technology Research Center, Wuhan Textile University, Wuhan, Hubei 430073, P. R. China
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7
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Syzonenko I, Phillips JL. Accelerated Protein Folding Using Greedy-Proximal A*. J Chem Inf Model 2020; 60:3093-3104. [DOI: 10.1021/acs.jcim.9b01194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ivan Syzonenko
- Computational Sciences PhD Program, Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States
- Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States
| | - Joshua L. Phillips
- Department of Computer Science, Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States
- Middle Tennessee State University, Murfreesboro, Tennessee 37132, United States
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8
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Winogradoff D, John S, Aksimentiev A. Protein unfolding by SDS: the microscopic mechanisms and the properties of the SDS-protein assembly. NANOSCALE 2020; 12:5422-5434. [PMID: 32080694 PMCID: PMC7291819 DOI: 10.1039/c9nr09135a] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The effects of detergent sodium dodecyl sulfate (SDS) on protein structure and dynamics are fundamental to the most common laboratory technique used to separate proteins and determine their molecular weights: polyacrylamide gel electrophoresis. However, the mechanism by which SDS induces protein unfolding and the microstructure of protein-SDS complexes remain largely unknown. Here, we report a detailed account of SDS-induced unfolding of two proteins-I27 domain of titin and β-amylase-obtained through all-atom molecular dynamics simulations. Both proteins were found to spontaneously unfold in the presence of SDS at boiling water temperature on the time scale of several microseconds. The protein unfolding was found to occur via two distinct mechanisms in which specific interactions of individual SDS molecules disrupt the protein's secondary structure. In the final state of the unfolding process, the proteins are found to wrap around SDS micelles in a fluid necklace-and-beads configuration, where the number and location of bound micelles changes dynamically. The global conformation of the protein was found to correlate with the number of SDS micelles bound to it, whereas the number of SDS molecules directly bound to the protein was found to define the relaxation time scale of the unfolded protein. Our microscopic characterization of SDS-protein interactions sets the stage for future refinement of SDS-enabled protein characterization methods, including protein fingerprinting and sequencing using a solid-state nanopore.
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Affiliation(s)
- David Winogradoff
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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9
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Fast pressure-jump all-atom simulations and experiments reveal site-specific protein dehydration-folding dynamics. Proc Natl Acad Sci U S A 2019; 116:5356-5361. [PMID: 30837309 DOI: 10.1073/pnas.1814927116] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As theory and experiment have shown, protein dehydration is a major contributor to protein folding. Dehydration upon folding can be characterized directly by all-atom simulations of fast pressure drops, which create desolvated pockets inside the nascent hydrophobic core. Here, we study pressure-drop refolding of three λ-repressor fragment (λ6-85) mutants computationally and experimentally. The three mutants report on tertiary structure formation via different fluorescent helix-helix contact pairs. All-atom simulations of pressure drops capture refolding and unfolding of all three mutants by a similar mechanism, thus validating the nonperturbative nature of the fluorescent contact probes. Analysis of simulated interprobe distances shows that the α-helix 1-3 pair distance displays a slower characteristic time scale than the 1-2 or 3-2 pair distance. To see whether slow packing of α-helices 1 and 3 is reflected in the rate-limiting folding step, fast pressure-drop relaxation experiments captured refolding on a millisecond time scale. These experiments reveal that refolding monitored by 1-3 contact formation indeed is much slower than when monitored by 1-2 or 3-2 contact formation. Unlike the case of the two-state folder [three-α-helix bundle (α3D)], whose drying and core formation proceed in concert, λ6-85 repeatedly dries and rewets different local tertiary contacts before finally forming a solvent-excluded core, explaining the non-two-state behavior observed during refolding in molecular dynamics simulations. This work demonstrates that proteins can explore desolvated pockets and dry globular states numerous times before reaching the native conformation.
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10
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Röder K, Joseph JA, Husic BE, Wales DJ. Energy Landscapes for Proteins: From Single Funnels to Multifunctional Systems. ADVANCED THEORY AND SIMULATIONS 2019. [DOI: 10.1002/adts.201800175] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Konstantin Röder
- Department of ChemistryUniversity of CambridgeLensfield Road CB2 1EW Cambridge UK
| | - Jerelle A. Joseph
- Department of ChemistryUniversity of CambridgeLensfield Road CB2 1EW Cambridge UK
| | - Brooke E. Husic
- Department of ChemistryUniversity of CambridgeLensfield Road CB2 1EW Cambridge UK
| | - David J. Wales
- Department of ChemistryUniversity of CambridgeLensfield Road CB2 1EW Cambridge UK
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11
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Charlier C, Courtney JM, Anfinrud P, Bax A. Interrupted Pressure-Jump NMR Experiments Reveal Resonances of On-Pathway Protein Folding Intermediate. J Phys Chem B 2018; 122:11792-11799. [PMID: 30256104 DOI: 10.1021/acs.jpcb.8b08456] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Previous pressure-jump NMR experiments on a pressure-sensitized double mutant of ubiquitin showed evidence that its folding occurs via two parallel, comparably efficient pathways: a single barrier and a two-barrier pathway. An interrupted folding NMR experiment is introduced, where for a brief period the pressure is dropped to atmospheric conditions (1 bar), followed by a jump back to high pressure for signal detection. Conventional, forward sampling of the indirect dimension during the low-pressure period correlates the 15N or 13C' chemical shifts of the unfolded protein at 1 bar to the 1H frequencies of both the unfolded and folded proteins at high pressure. Remarkably, sampling the data of the same experiment in the reverse direction yields the frequencies of proteins present at the end of the low-pressure interval, which include unfolded, intermediate, and folded species. Although the folding intermediate 15N shifts differ strongly from natively folded protein, its 13C' chemical shifts, which are more sensitive probes for secondary structure, closely match those of the folded protein and indicate that the folding intermediate must have a structure that is quite similar to the native state.
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Affiliation(s)
- Cyril Charlier
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Joseph M Courtney
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Philip Anfinrud
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Ad Bax
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
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12
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Dupuis NF, Holmstrom ED, Nesbitt DJ. Tests of Kramers’ Theory at the Single-Molecule Level: Evidence for Folding of an Isolated RNA Tertiary Interaction at the Viscous Speed Limit. J Phys Chem B 2018; 122:8796-8804. [DOI: 10.1021/acs.jpcb.8b04014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nicholas F. Dupuis
- JILA, University of Colorado and National Institute of Standards and Technology, Department of Chemistry and Biochemistry, and Department of Physics, University of Colorado, Boulder, Boulder, Colorado 80309, United States
| | - Erik D. Holmstrom
- JILA, University of Colorado and National Institute of Standards and Technology, Department of Chemistry and Biochemistry, and Department of Physics, University of Colorado, Boulder, Boulder, Colorado 80309, United States
| | - David J. Nesbitt
- JILA, University of Colorado and National Institute of Standards and Technology, Department of Chemistry and Biochemistry, and Department of Physics, University of Colorado, Boulder, Boulder, Colorado 80309, United States
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13
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Charlier C, Courtney JM, Alderson TR, Anfinrud P, Bax A. Monitoring 15N Chemical Shifts During Protein Folding by Pressure-Jump NMR. J Am Chem Soc 2018; 140:8096-8099. [PMID: 29923716 DOI: 10.1021/jacs.8b04833] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pressure-jump hardware permits direct observation of protein NMR spectra during a cyclically repeated protein folding process. For a two-state folding protein, the change in resonance frequency will occur nearly instantaneously when the protein clears the transition state barrier, resulting in a monoexponential change of the ensemble-averaged chemical shift. However, protein folding pathways can be more complex and contain metastable intermediates. With a pseudo-3D NMR experiment that utilizes stroboscopic observation, we measure the ensemble-averaged chemical shifts, including those of exchange-broadened intermediates, during the folding process. Such measurements for a pressure-sensitized mutant of ubiquitin show an on-pathway kinetic intermediate whose 15N chemical shifts differ most from the natively folded protein for strands β5, its preceding turn, and the two strands that pair with β5 in the native structure.
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Affiliation(s)
- Cyril Charlier
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Joseph M Courtney
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - T Reid Alderson
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Philip Anfinrud
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Ad Bax
- Laboratory of Chemical Physics, NIDDK , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
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14
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Kraack JP. Ultrafast structural molecular dynamics investigated with 2D infrared spectroscopy methods. Top Curr Chem (Cham) 2017; 375:86. [PMID: 29071445 DOI: 10.1007/s41061-017-0172-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 10/02/2017] [Indexed: 12/23/2022]
Abstract
Ultrafast, multi-dimensional infrared (IR) spectroscopy has been advanced in recent years to a versatile analytical tool with a broad range of applications to elucidate molecular structure on ultrafast timescales, and it can be used for samples in a many different environments. Following a short and general introduction on the benefits of 2D IR spectroscopy, the first part of this chapter contains a brief discussion on basic descriptions and conceptual considerations of 2D IR spectroscopy. Outstanding classical applications of 2D IR are used afterwards to highlight the strengths and basic applicability of the method. This includes the identification of vibrational coupling in molecules, characterization of spectral diffusion dynamics, chemical exchange of chemical bond formation and breaking, as well as dynamics of intra- and intermolecular energy transfer for molecules in bulk solution and thin films. In the second part, several important, recently developed variants and new applications of 2D IR spectroscopy are introduced. These methods focus on (i) applications to molecules under two- and three-dimensional confinement, (ii) the combination of 2D IR with electrochemistry, (iii) ultrafast 2D IR in conjunction with diffraction-limited microscopy, (iv) several variants of non-equilibrium 2D IR spectroscopy such as transient 2D IR and 3D IR, and (v) extensions of the pump and probe spectral regions for multi-dimensional vibrational spectroscopy towards mixed vibrational-electronic spectroscopies. In light of these examples, the important open scientific and conceptual questions with regard to intra- and intermolecular dynamics are highlighted. Such questions can be tackled with the existing arsenal of experimental variants of 2D IR spectroscopy to promote the understanding of fundamentally new aspects in chemistry, biology and materials science. The final part of the chapter introduces several concepts of currently performed technical developments, which aim at exploiting 2D IR spectroscopy as an analytical tool. Such developments embrace the combination of 2D IR spectroscopy and plasmonic spectroscopy for ultrasensitive analytics, merging 2D IR spectroscopy with ultra-high-resolution microscopy (nanoscopy), future variants of transient 2D IR methods, or 2D IR in conjunction with microfluidics. It is expected that these techniques will allow for groundbreaking research in many new areas of natural sciences.
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Affiliation(s)
- Jan Philip Kraack
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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15
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Abstract
In this review, I discuss the various methods researchers use to unfold proteins in the lab in order to understand protein folding both
in vitro and
in vivo. The four main techniques, chemical-, heat-, pressure- and force-denaturation, produce distinctly different unfolded conformational ensembles. Recent measurements have revealed different folding kinetics from different unfolding mechanisms. Thus, comparing these distinct unfolded ensembles sheds light on the underlying free energy landscape of folding.
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Affiliation(s)
- Lisa J Lapidus
- Department of Physics and Astronomy, Michigan State University, East Lansing, USA
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16
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Directly monitor protein rearrangement on a nanosecond-to-millisecond time-scale. Sci Rep 2017; 7:8691. [PMID: 28821738 PMCID: PMC5562898 DOI: 10.1038/s41598-017-08385-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 07/10/2017] [Indexed: 11/09/2022] Open
Abstract
In order to directly observe the refolding kinetics from a partially misfolded state to a native state in the bottom of the protein-folding funnel, we used a "caging" strategy to trap the β-sheet structure of ubiquitin in a misfolded conformation. We used molecular dynamics simulation to generate the cage-induced, misfolded structure and compared the structure of the misfolded ubiquitin with native ubiquitin. Using laser flash irradiation, the cage can be cleaved from the misfolded structure within one nanosecond, and we monitored the refolding kinetics of ubiquitin from this misfolded state to the native state by photoacoustic calorimetry and photothermal beam deflection techniques on nanosecond to millisecond timescales. Our results showed two refolding events in this refolding process. The fast event is shorter than 20 ns and corresponds to the instant collapse of ubiquitin upon cage release initiated by laser irradiation. The slow event is ~60 μs, derived from a structural rearrangement in β-sheet refolding. The event lasts 10 times longer than the timescale of β-hairpin formation for short peptides as monitored by temperature jump, suggesting that rearrangement of a β-sheet structure from a misfolded state to its native state requires more time than ab initio folding of a β-sheet.
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17
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Abstract
Single-molecule studies of protein folding hold keys to unveiling protein folding pathways and elusive intermediate folding states-attractive pharmaceutical targets. Although conventional single-molecule approaches can detect folding intermediates, they presently lack throughput and require elaborate labeling. Here, we theoretically show that measurements of ionic current through a nanopore containing a protein can report on the protein's folding state. Our all-atom molecular dynamics (MD) simulations show that the unfolding of a protein lowers the nanopore ionic current, an effect that originates from the reduction of ion mobility in proximity to a protein. Using a theoretical model, we show that the average change in ionic current produced by a folding-unfolding transition is detectable despite the orientational and conformational heterogeneity of the folded and unfolded states. By analyzing millisecond-long all-atom MD simulations of multiple protein transitions, we show that a nanopore ionic current recording can detect folding-unfolding transitions in real time and report on the structure of folding intermediates.
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Affiliation(s)
- Wei Si
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments and School of Mechanical Engineering, Southeast University, Nanjing, 210096, China
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- To whom correspondence should be addressed:
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18
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When fast is better: protein folding fundamentals and mechanisms from ultrafast approaches. Biochem J 2017; 473:2545-59. [PMID: 27574021 PMCID: PMC5003694 DOI: 10.1042/bcj20160107] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/18/2016] [Indexed: 11/19/2022]
Abstract
Protein folding research stalled for decades because conventional experiments indicated that proteins fold slowly and in single strokes, whereas theory predicted a complex interplay between dynamics and energetics resulting in myriad microscopic pathways. Ultrafast kinetic methods turned the field upside down by providing the means to probe fundamental aspects of folding, test theoretical predictions and benchmark simulations. Accordingly, experimentalists could measure the timescales for all relevant folding motions, determine the folding speed limit and confirm that folding barriers are entropic bottlenecks. Moreover, a catalogue of proteins that fold extremely fast (microseconds) could be identified. Such fast-folding proteins cross shallow free energy barriers or fold downhill, and thus unfold with minimal co-operativity (gradually). A new generation of thermodynamic methods has exploited this property to map folding landscapes, interaction networks and mechanisms at nearly atomic resolution. In parallel, modern molecular dynamics simulations have finally reached the timescales required to watch fast-folding proteins fold and unfold in silico. All of these findings have buttressed the fundamentals of protein folding predicted by theory, and are now offering the first glimpses at the underlying mechanisms. Fast folding appears to also have functional implications as recent results connect downhill folding with intrinsically disordered proteins, their complex binding modes and ability to moonlight. These connections suggest that the coupling between downhill (un)folding and binding enables such protein domains to operate analogically as conformational rheostats.
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19
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Jiao J, Rebane AA, Ma L, Zhang Y. Single-Molecule Protein Folding Experiments Using High-Precision Optical Tweezers. Methods Mol Biol 2017; 1486:357-390. [PMID: 27844436 DOI: 10.1007/978-1-4939-6421-5_14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
How proteins fold from linear chains of amino acids to delicate three-dimensional structures remains a fundamental biological problem. Single-molecule manipulation based on high-resolution optical tweezers (OT) provides a powerful approach to study protein folding with unprecedented spatiotemporal resolution. In this method, a single protein or protein complex is tethered between two beads confined in optical traps and pulled. Protein unfolding induced by the mechanical force is counteracted by the spontaneous folding of the protein, reaching a dynamic equilibrium at a characteristic force and rate. The transition is monitored by the accompanying extension change of the protein and used to derive conformations and energies of folding intermediates and their associated transition kinetics. Here, we provide general strategies and detailed protocols to study folding of proteins and protein complexes using optical tweezers, including sample preparation, DNA-protein conjugation and methods of data analysis to extract folding energies and rates from the single-molecule measurements.
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Affiliation(s)
- Junyi Jiao
- Department of Cell Biology, School of Medicine and Integrated Graduate Program in Physical and Engineering Biology, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA
| | - Aleksander A Rebane
- Department of Cell Biology, School of Medicine and Integrated Graduate Program in Physical and Engineering Biology, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA
| | - Lu Ma
- Department of Cell Biology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA
| | - Yongli Zhang
- Department of Cell Biology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT, 06520, USA.
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20
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Möller J, Léonardon J, Gorini J, Dattani R, Narayanan T. A sub-ms pressure jump setup for time-resolved X-ray scattering. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:125116. [PMID: 28040915 DOI: 10.1063/1.4972296] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a new experimental setup for time-resolved solution small-angle X-ray scattering (SAXS) studies of kinetic processes induced by sub-ms hydrostatic pressure jumps. It is based on a high-force piezo-stack actuator, with which the volume of the sample can be dynamically compressed. The presented setup has been designed and optimized for SAXS experiments with absolute pressures of up to 1000 bars, using transparent diamond windows and an easy-to-change sample capillary. The pressure in the cell can be changed in less than 1 ms, which is about an order of magnitude faster jump than previously obtained by dynamic pressure setups for SAXS. An additional temperature control offers the possibility for automated mapping of p-T phase diagrams. Here we present the technical specifications and first experimental data taken together with a preview of new research opportunities enabled by this setup.
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21
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Quérard J, Le Saux T, Gautier A, Alcor D, Croquette V, Lemarchand A, Gosse C, Jullien L. Kinetics of Reactive Modules Adds Discriminative Dimensions for Selective Cell Imaging. Chemphyschem 2016; 17:1396-413. [PMID: 26833808 DOI: 10.1002/cphc.201500987] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Indexed: 11/07/2022]
Abstract
Living cells are chemical mixtures of exceptional interest and significance, whose investigation requires the development of powerful analytical tools fulfilling the demanding constraints resulting from their singular features. In particular, multiplexed observation of a large number of molecular targets with high spatiotemporal resolution appears highly desirable. One attractive road to address this analytical challenge relies on engaging the targets in reactions and exploiting the rich kinetic signature of the resulting reactive module, which originates from its topology and its rate constants. This review explores the various facets of this promising strategy. We first emphasize the singularity of the content of a living cell as a chemical mixture and suggest that its multiplexed observation is significant and timely. Then, we show that exploiting the kinetics of analytical processes is relevant to selectively detect a given analyte: upon perturbing the system, the kinetic window associated to response read-out has to be matched with that of the targeted reactive module. Eventually, we introduce the state-of-the-art of cell imaging exploiting protocols based on reaction kinetics and draw some promising perspectives.
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Affiliation(s)
- Jérôme Quérard
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
| | - Thomas Le Saux
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
| | - Arnaud Gautier
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
| | - Damien Alcor
- INSERM U1065, C3M; 151 route Saint Antoine de Ginestière, BP 2 3194 F-06204 Nice Cedex 3 France
| | - Vincent Croquette
- Ecole Normale Supérieure; Département de Physique and Département de Biologie, Laboratoire de Physique Statistique UMR CNRS-ENS 8550; 24 rue Lhomond F-75005 Paris France
| | - Annie Lemarchand
- Sorbonne Universités; UPMC Univ Paris 06, Laboratoire de Physique Théorique de la Matière Condensée; 4 place Jussieu, case courrier 121 75252 Paris cedex 05 France
- CNRS, UMR 7600 LPTMC; 75005 Paris France
| | - Charlie Gosse
- Laboratoire de Photonique et de Nanostructures, LPN-CNRS; route de Nozay 91460 Marcoussis France
| | - Ludovic Jullien
- Ecole Normale Supérieure-PSL Research University; Département de Chimie; 24, rue Lhomond F-75005 Paris France
- Sorbonne Universités; UPMC Univ Paris 06, PASTEUR; F-75005 Paris France
- CNRS, UMR 8640 PASTEUR; F-75005 Paris France
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22
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Gianni S, Dogan J, Jemth P. Coupled binding and folding of intrinsically disordered proteins: what can we learn from kinetics? Curr Opin Struct Biol 2016; 36:18-24. [DOI: 10.1016/j.sbi.2015.11.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/13/2015] [Accepted: 11/26/2015] [Indexed: 12/16/2022]
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23
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McCarthy N, Brooks N. Using High Pressure to Modulate Lateral Structuring in Model Lipid Membranes. ADVANCES IN BIOMEMBRANES AND LIPID SELF-ASSEMBLY 2016. [DOI: 10.1016/bs.abl.2016.04.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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24
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van Wilderen LJGW, Bredenbeck J. Von ultraschnellen Strukturbestimmungen bis zum Steuern von Reaktionen: mehrdimensionale gemischte IR/nicht-IR-Schwingungsspektroskopie. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201503155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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van Wilderen LJGW, Bredenbeck J. From Ultrafast Structure Determination to Steering Reactions: Mixed IR/Non-IR Multidimensional Vibrational Spectroscopies. Angew Chem Int Ed Engl 2015; 54:11624-40. [PMID: 26394274 DOI: 10.1002/anie.201503155] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Indexed: 12/27/2022]
Abstract
Ultrafast multidimensional infrared spectroscopy is a powerful method for resolving features of molecular structure and dynamics that are difficult or impossible to address with linear spectroscopy. Augmenting the IR pulse sequences by resonant or nonresonant UV, Vis, or NIR pulses considerably extends the range of application and creates techniques with possibilities far beyond a pure multidimensional IR experiment. These include surface-specific 2D-IR spectroscopy with sub-monolayer sensitivity, ultrafast structure determination in non-equilibrium systems, triggered exchange spectroscopy to correlate reactant and product bands, exploring the interplay of electronic and nuclear degrees of freedom, investigation of interactions between Raman- and IR-active modes, imaging with chemical contrast, sub-ensemble-selective photochemistry, and even steering a reaction by selective IR excitation. We give an overview of useful mixed IR/non-IR pulse sequences, discuss their differences, and illustrate their application potential.
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Affiliation(s)
| | - Jens Bredenbeck
- Institute of Biophysics, Johann Wolfgang Goethe-University, Frankfurt am Main (Germany).
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26
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Best RB, Miller C, Mittal J. Role of solvation in pressure-induced helix stabilization. J Chem Phys 2015; 141:22D522. [PMID: 25494793 DOI: 10.1063/1.4901112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In contrast to the well-known destabilization of globular proteins by high pressure, recent work has shown that pressure stabilizes the formation of isolated α-helices. However, all simulations to date have obtained a qualitatively opposite result within the experimental pressure range. We show that using a protein force field (Amber03w) parametrized in conjunction with an accurate water model (TIP4P/2005) recovers the correct pressure-dependence and an overall stability diagram for helix formation similar to that from experiment; on the other hand, we confirm that using TIP3P water results in a very weak pressure destabilization of helices. By carefully analyzing the contributing factors, we show that this is not merely a consequence of different peptide conformations sampled using TIP3P. Rather, there is a critical role for the solvent itself in determining the dependence of total system volume (peptide and solvent) on helix content. Helical peptide structures exclude a smaller volume to water, relative to non-helical structures with both the water models, but the total system volume for helical conformations is higher than non-helical conformations with TIP3P water at low to intermediate pressures, in contrast to TIP4P/2005 water. Our results further emphasize the importance of using an accurate water model to study protein folding under conditions away from standard temperature and pressure.
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Affiliation(s)
- Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, USA
| | - Cayla Miller
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Jeetain Mittal
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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27
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Fast-folding proteins under stress. Cell Mol Life Sci 2015; 72:4273-85. [PMID: 26231095 DOI: 10.1007/s00018-015-2002-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/07/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
Proteins are subject to a variety of stresses in biological organisms, including pressure and temperature, which are the easiest stresses to simulate by molecular dynamics. We discuss the effect of pressure and thermal stress on very-fast-folding model proteins, whose in vitro folding can be fully simulated on computers and compared with experiments. We then discuss experiments that can be used to subject proteins to low- and high-temperature unfolding, as well as low- and high-pressure unfolding. Pressure and temperature are prototypical perturbations that illustrate how close many proteins are to instability, a property that cells can exploit to control protein function. We conclude by reviewing some recent in-cell experiments, and progress being made in simulating and measuring protein stability and function inside live cells.
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28
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Wirth AJ, Liu Y, Prigozhin MB, Schulten K, Gruebele M. Comparing Fast Pressure Jump and Temperature Jump Protein Folding Experiments and Simulations. J Am Chem Soc 2015; 137:7152-7159. [PMID: 25988868 DOI: 10.1021/jacs.5b02474] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The unimolecular folding reaction of small proteins is now amenable to a very direct mechanistic comparison between experiment and simulation. We present such a comparison of microsecond pressure and temperature jump refolding kinetics of the engineered WW domain FiP35, a model system for β-sheet folding. Both perturbations produce experimentally a faster and a slower kinetic phase, and the "slow" microsecond phase is activated. The fast phase shows differences between perturbation methods and is closer to the downhill limit by temperature jump, but closer to the transiently populated intermediate limit by pressure jump. These observations make more demands on simulations of the folding process than just a rough comparison of time scales. To complement experiments, we carried out several pressure jump and temperature jump all-atom molecular dynamics trajectories in explicit solvent, where FiP35 folded in five of the six simulations. We analyzed our pressure jump simulations by kinetic modeling and found that the pressure jump experiments and MD simulations are most consistent with a 4-state kinetic mechanism. Together, our experimental and computational data highlight FiP35's position at the boundary where activated intermediates and downhill folding meet, and we show that this model protein is an excellent candidate for further pressure jump molecular dynamics studies to compare experiment and modeling at the folding mechanism level.
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Affiliation(s)
- Anna Jean Wirth
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
| | - Yanxin Liu
- Department of Physics, and Beckman Institute, University of Illinois, Urbana, Illinois 61801, United States
| | - Maxim B Prigozhin
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
| | - Klaus Schulten
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States.,Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, United States.,Department of Physics, and Beckman Institute, University of Illinois, Urbana, Illinois 61801, United States
| | - Martin Gruebele
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States.,Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, United States.,Department of Physics, and Beckman Institute, University of Illinois, Urbana, Illinois 61801, United States
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29
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Brooks NJ. Pressure effects on lipids and bio-membrane assemblies. IUCRJ 2014; 1:470-7. [PMID: 25485127 PMCID: PMC4224465 DOI: 10.1107/s2052252514019551] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/28/2014] [Indexed: 05/06/2023]
Abstract
Membranes are amongst the most important biological structures; they maintain the fundamental integrity of cells, compartmentalize regions within them and play an active role in a wide range of cellular processes. Pressure can play a key role in probing the structure and dynamics of membrane assemblies, and is also critical to the biology and adaptation of deep-sea organisms. This article presents an overview of the effect of pressure on the mesostructure of lipid membranes, bilayer organization and lipid-protein assemblies. It also summarizes recent developments in high-pressure structural instrumentation suitable for experiments on membranes.
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Affiliation(s)
- Nicholas J. Brooks
- Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ, England
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30
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Affiliation(s)
- Irisbel Guzman
- Department
of Biochemistry, University of Illinois, Urbana, Illinois 61801, United States
| | - Martin Gruebele
- Department
of Chemistry, Department of Physics, Center for the Physics of Living
Cells, and Center for Biophysics and Quantitative Biology, University of Illinois, Urbana, Illinois 61801, United States
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31
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Liu Y, Prigozhin M, Schulten K, Gruebele M. Observation of complete pressure-jump protein refolding in molecular dynamics simulation and experiment. J Am Chem Soc 2014; 136:4265-72. [PMID: 24437525 PMCID: PMC3985862 DOI: 10.1021/ja412639u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Indexed: 11/29/2022]
Abstract
Density is an easily adjusted variable in molecular dynamics (MD) simulations. Thus, pressure-jump (P-jump)-induced protein refolding, if it could be made fast enough, would be ideally suited for comparison with MD. Although pressure denaturation perturbs secondary structure less than temperature denaturation, protein refolding after a fast P-jump is not necessarily faster than that after a temperature jump. Recent P-jump refolding experiments on the helix bundle λ-repressor have shown evidence of a <3 μs burst phase, but also of a ~1.5 ms "slow" phase of refolding, attributed to non-native helical structure frustrating microsecond refolding. Here we show that a λ-repressor mutant is nonetheless capable of refolding in a single explicit solvent MD trajectory in about 19 μs, indicating that the burst phase observed in experiments on the same mutant could produce native protein. The simulation reveals that after about 18.5 μs of conformational sampling, the productive structural rearrangement to the native state does not occur in a single swift step but is spread out over a brief series of helix and loop rearrangements that take about 0.9 μs. Our results support the molecular time scale inferred for λ-repressor from near-downhill folding experiments, where transition-state population can be seen experimentally, and also agrees with the transition-state transit time observed in slower folding proteins by single-molecule spectroscopy.
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Affiliation(s)
- Yanxin Liu
- Department of Physics,
Beckman Institute, Department of Chemistry, and Center for Biophysics
and Computational Biology, University of
Illinois, Urbana, Illinois 61801, United
States
| | - Maxim
B. Prigozhin
- Department of Physics,
Beckman Institute, Department of Chemistry, and Center for Biophysics
and Computational Biology, University of
Illinois, Urbana, Illinois 61801, United
States
| | - Klaus Schulten
- Department of Physics,
Beckman Institute, Department of Chemistry, and Center for Biophysics
and Computational Biology, University of
Illinois, Urbana, Illinois 61801, United
States
| | - Martin Gruebele
- Department of Physics,
Beckman Institute, Department of Chemistry, and Center for Biophysics
and Computational Biology, University of
Illinois, Urbana, Illinois 61801, United
States
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32
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Abstract
Fast-folding proteins have been a major focus of computational and experimental study because they are accessible to both techniques: they are small and fast enough to be reasonably simulated with current computational power, but have dynamics slow enough to be observed with specially developed experimental techniques. This coupled study of fast-folding proteins has provided insight into the mechanisms, which allow some proteins to find their native conformation well <1 ms and has uncovered examples of theoretically predicted phenomena such as downhill folding. The study of fast folders also informs our understanding of even 'slow' folding processes: fast folders are small; relatively simple protein domains and the principles that govern their folding also govern the folding of more complex systems. This review summarizes the major theoretical and experimental techniques used to study fast-folding proteins and provides an overview of the major findings of fast-folding research. Finally, we examine the themes that have emerged from studying fast folders and briefly summarize their application to protein folding in general, as well as some work that is left to do.
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Fazelinia H, Xu M, Cheng H, Roder H. Ultrafast hydrogen exchange reveals specific structural events during the initial stages of folding of cytochrome c. J Am Chem Soc 2013; 136:733-40. [PMID: 24364692 DOI: 10.1021/ja410437d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Many proteins undergo a sharp decrease in chain dimensions during early stages of folding, prior to the rate-limiting step in folding. However, it remains unclear whether compact states are the result of specific folding events or a general hydrophobic collapse of the poly peptide chain driven by the change in solvent conditions. To address this fundamental question, we extended the temporal resolution of NMR-detected H/D exchange labeling experiments into the microsecond regime by adopting a microfluidics approach. By observing the competition between H/D exchange and folding as a function of labeling pH, coupled with direct measurement of exchange rates in the unfolded state, we were able to monitor hydrogen-bond formation for over 50 individual backbone NH groups within the initial 140 microseconds of folding of horse cytochrome c. Clusters of solvent-shielded amide protons were observed in two α-helical segments in the C-terminal half of the protein, while the N-terminal helix remained largely unstructured, suggesting that proximity in the primary structure is a major factor in promoting helix formation and association at early stages of folding, while the entropically more costly long-range contacts between the N- and C-terminal helices are established only during later stages. Our findings clearly indicate that the initial chain condensation in cytochrome c is driven by specific interactions among a subset of α-helical segments rather than a general hydrophobic collapse.
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Affiliation(s)
- Hossein Fazelinia
- Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, United States
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34
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Vahidi S, Stocks BB, Liaghati-Mobarhan Y, Konermann L. Submillisecond protein folding events monitored by rapid mixing and mass spectrometry-based oxidative labeling. Anal Chem 2013; 85:8618-25. [PMID: 23841479 DOI: 10.1021/ac401148z] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Kinetic measurements can provide insights into protein folding mechanisms. However, the initial (submillisecond) stages of folding still represent a formidable analytical challenge. A number of ultrarapid triggering techniques have been available for some time, but coupling of these techniques with detection methods that are capable of providing detailed structural information has proven to be difficult. The current work addresses this issue by combining submillisecond mixing with laser-induced oxidative labeling. Apomyoglobin (aMb) serves as a model system for our measurements. Exposure of the protein to a brief pulse of hydroxyl radical (·OH) at different time points during folding introduces covalent modifications at solvent accessible side chains. The extent of labeling is monitored using mass spectrometry-based peptide mapping, providing spatially resolved measurements of changes in solvent accessibility. The submillisecond mixer used here improves the time resolution by a factor of 50 compared to earlier ·OH labeling experiments from our laboratory. Data obtained in this way indicate that early aMb folding events are driven by both local and sequence-remote docking of hydrophobic side chains. Assembly of a partially formed A(E)G(H) scaffold after 0.2 ms is followed by stepwise consolidation that ultimately yields the native state. Major conformational changes go to completion within 0.1 s. The technique introduced here is capable of providing in-depth structural information on very short time scales that have thus far been dominated by low resolution (global) spectroscopic probes. By employing submillisecond mixing in conjunction with slower mixing techniques, it is possible to observe complete folding pathways, from fractions of a millisecond all the way to minutes.
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Affiliation(s)
- Siavash Vahidi
- Departments of Chemistry and Biochemistry, The University of Western Ontario , London, Ontario, N6A 5B7, Canada
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35
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Abstract
Using a newly developed microsecond pressure-jump apparatus, we monitor the refolding kinetics of the helix-stabilized five-helix bundle protein λ*YA, the Y22W/Q33Y/G46,48A mutant of λ-repressor fragment 6-85, from 3 μs to 5 ms after a 1,200-bar P-drop. In addition to a microsecond phase, we observe a slower 1.4-ms phase during refolding to the native state. Unlike temperature denaturation, pressure denaturation produces a highly reversible helix-coil-rich state. This difference highlights the importance of the denatured initial condition in folding experiments and leads us to assign a compact nonnative helical trap as the reason for slower P-jump-induced refolding. To complement the experiments, we performed over 50 μs of all-atom molecular dynamics P-drop refolding simulations with four different force fields. Two of the force fields yield compact nonnative states with misplaced α-helix content within a few microseconds of the P-drop. Our overall conclusion from experiment and simulation is that the pressure-denatured state of λ*YA contains mainly residual helix and little β-sheet; following a fast P-drop, at least some λ*YA forms misplaced helical structure within microseconds. We hypothesize that nonnative helix at helix-turn interfaces traps the protein in compact nonnative conformations. These traps delay the folding of at least some of the population for 1.4 ms en route to the native state. Based on molecular dynamics, we predict specific mutations at the helix-turn interfaces that should speed up refolding from the pressure-denatured state, if this hypothesis is correct.
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36
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Perezzan R, Rey A. Simulating protein unfolding under pressure with a coarse-grained model. J Chem Phys 2012; 137:185102. [DOI: 10.1063/1.4765057] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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37
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Clarke DT. Circular dichroism in protein folding studies. CURRENT PROTOCOLS IN PROTEIN SCIENCE 2012; Chapter 28:28.3.1-28.3.17. [PMID: 23151746 DOI: 10.1002/0471140864.ps2803s70] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Protein folding is a biological process of both fundamental significance and practical importance, and protein misfolding is implicated in a number of serious diseases of both humans and animals. The study of protein folding requires a technique that is able to monitor changes in protein structure in solution, with millisecond time resolution. Ultraviolet circular dichroism (CD) is such a technique, providing information on both secondary and tertiary protein structure. This unit describes the procedures for performing CD experiments for the study of protein folding, and identifies commonly encountered problems and their solutions.
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Affiliation(s)
- David T Clarke
- Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, United Kingdom
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38
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Senne M, Trendelkamp-Schroer B, Mey ASJS, Schütte C, Noé F. EMMA: A Software Package for Markov Model Building and Analysis. J Chem Theory Comput 2012; 8:2223-38. [PMID: 26588955 DOI: 10.1021/ct300274u] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The study of folding and conformational changes of macromolecules by molecular dynamics simulations often requires the generation of large amounts of simulation data that are difficult to analyze. Markov (state) models (MSMs) address this challenge by providing a systematic way to decompose the state space of the molecular system into substates and to estimate a transition matrix containing the transition probabilities between these substates. This transition matrix can be analyzed to reveal the metastable, i.e., long-living, states of the system, its slowest relaxation time scales, and transition pathways and rates, e.g., from unfolded to folded, or from dissociated to bound states. Markov models can also be used to calculate spectroscopic data and thus serve as a way to reconcile experimental and simulation data. To reduce the technical burden of constructing, validating, and analyzing such MSMs, we provide the software framework EMMA that is freely available at https://simtk.org/home/emma .
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Affiliation(s)
- Martin Senne
- Department for Mathematics and Computer Science, FU Berlin
| | | | | | | | - Frank Noé
- Department for Mathematics and Computer Science, FU Berlin
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39
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Gelman H, Platkov M, Gruebele M. Rapid Perturbation of Free-Energy Landscapes: From In Vitro to In Vivo. Chemistry 2012; 18:6420-7. [DOI: 10.1002/chem.201104047] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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40
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Keller BG, Prinz JH, Noé F. Markov models and dynamical fingerprints: Unraveling the complexity of molecular kinetics. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2011.08.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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41
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Denos S, Dhar A, Gruebele M. Crowding effects on the small, fast-folding protein lambda6-85. Faraday Discuss 2012; 157:451-500. [PMID: 23230782 PMCID: PMC3834863 DOI: 10.1039/c2fd20009k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
The microsecond folder lambda6-85 is a small (9.2 kDa = 9200 amu) five helix bundle protein. We investigated the stability of lambda6-85 in two different low-fluorescence crowding matrices: the large 70 kDa carbohydrate Ficoll 70, and the small 14 kDa thermophilic protein SubL. The same thermal stability of secondary structure was measured by circular dichroism in aqueous buffer, and at a crowding fraction phi = 15 +/- 1% of Ficoll 70. Tryptophan fluorescence detection (probing a tertiary contact) yielded the same thermal stability in Ficoll, but 4 degrees C lower in aqueous buffer. Temperature-jump kinetics revealed that the relaxation rate, corrected for bulk viscosity, was very similar in Ficoll and in aqueous buffer. Thus viscosity, hydrodynamics and crowding seem to compensate one another. However, a new fast phase was observed in Ficoll, attributed to crowding-induced downhill folding. We also measured the stability of lambda6-85 in phi = 14 +/- 1% SubL, which acts as a smaller more rigid crowder. Significantly greater stabilization (7 to 13 degrees C depending on probe) was observed than in the Ficoll matrix. The results highlight the importance of crowding agent choice for studies of small, fast-folding proteins amenable to comparison with molecular dynamics simulations.
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Affiliation(s)
- Sharlene Denos
- Center for Biophysics and Computational Biology, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| | - Apratim Dhar
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
| | - Martin Gruebele
- Center for Biophysics and Computational Biology, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
- Department of Chemistry, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
- Department of Physics, 600 South Mathews Avenue, University of Illinois, Urbana-Champaign, IL 61801
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42
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Chan HS, Zhang Z, Wallin S, Liu Z. Cooperativity, local-nonlocal coupling, and nonnative interactions: principles of protein folding from coarse-grained models. Annu Rev Phys Chem 2011; 62:301-26. [PMID: 21453060 DOI: 10.1146/annurev-physchem-032210-103405] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coarse-grained, self-contained polymer models are powerful tools in the study of protein folding. They are also essential to assess predictions from less rigorous theoretical approaches that lack an explicit-chain representation. Here we review advances in coarse-grained modeling of cooperative protein folding, noting in particular that the Levinthal paradox was raised in response to the experimental discovery of two-state-like folding in the late 1960s, rather than to the problem of conformational search per se. Comparisons between theory and experiment indicate a prominent role of desolvation barriers in cooperative folding, which likely emerges generally from a coupling between local conformational preferences and nonlocal packing interactions. Many of these principles have been elucidated by native-centric models, wherein nonnative interactions may be treated perturbatively. We discuss these developments as well as recent applications of coarse-grained chain modeling to knotted proteins and to intrinsically disordered proteins.
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Affiliation(s)
- Hue Sun Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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43
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Affiliation(s)
- Jose M. Sanchez-Ruiz
- Facultad de Ciencias, Departamento de Quimica Fisica, Universidad de Granada, 18071 Granada, Spain;
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44
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Noé F, Doose S, Daidone I, Löllmann M, Sauer M, Chodera JD, Smith JC. Dynamical fingerprints for probing individual relaxation processes in biomolecular dynamics with simulations and kinetic experiments. Proc Natl Acad Sci U S A 2011; 108:4822-7. [PMID: 21368203 PMCID: PMC3064371 DOI: 10.1073/pnas.1004646108] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There is a gap between kinetic experiment and simulation in their views of the dynamics of complex biomolecular systems. Whereas experiments typically reveal only a few readily discernible exponential relaxations, simulations often indicate complex multistate behavior. Here, a theoretical framework is presented that reconciles these two approaches. The central concept is "dynamical fingerprints" which contain peaks at the time scales of the dynamical processes involved with amplitudes determined by the experimental observable. Fingerprints can be generated from both experimental and simulation data, and their comparison by matching peaks permits assignment of structural changes present in the simulation to experimentally observed relaxation processes. The approach is applied here to a test case interpreting single molecule fluorescence correlation spectroscopy experiments on a set of fluorescent peptides with molecular dynamics simulations. The peptides exhibit complex kinetics shown to be consistent with the apparent simplicity of the experimental data. Moreover, the fingerprint approach can be used to design new experiments with site-specific labels that optimally probe specific dynamical processes in the molecule under investigation.
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Affiliation(s)
- Frank Noé
- Research Center Matheon, FU Berlin, Arnimallee 6, 14159 Berlin, Germany.
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45
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Chen HL, Hsu JCC, Viet MH, Li MS, Hu CK, Liu CH, Luh FY, Chen SSW, Chang ESH, Wang AHJ, Hsu MF, Fann W, Chen RPY. Studying submicrosecond protein folding kinetics using a photolabile caging strategy and time-resolved photoacoustic calorimetry. Proteins 2011; 78:2973-83. [PMID: 20737588 DOI: 10.1002/prot.22823] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Kinetic measurement of protein folding is limited by the method used to trigger folding. Traditional methods, such as stopped flow, have a long mixing dead time and cannot be used to monitor fast folding processes. Here, we report a compound, 4-(bromomethyl)-6,7-dimethoxycoumarin, that can be used as a "photolabile cage" to study the early stages of protein folding. The folding process of a protein, RD1, including kinetics, enthalpy, and volume change, was studied by the combined use of a phototriggered caging strategy and time-resolved photoacoustic calorimetry. The cage caused unfolding of the photolabile protein, and then a pulse UV laser (∼10(-9) s) was used to break the cage, leaving the protein free to refold and allowing the resolving of two folding events on a nanosecond time scale. This strategy is especially good for monitoring fast folding proteins that cannot be studied by traditional methods.
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Affiliation(s)
- Hsin-Liang Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
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46
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Brooks NJ, Ces O, Templer RH, Seddon JM. Pressure effects on lipid membrane structure and dynamics. Chem Phys Lipids 2010; 164:89-98. [PMID: 21172328 DOI: 10.1016/j.chemphyslip.2010.12.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 12/07/2010] [Accepted: 12/09/2010] [Indexed: 11/30/2022]
Abstract
The effect of hydrostatic pressure on lipid structure and dynamics is highly important as a tool in biophysics and bio-technology, and in the biology of deep sea organisms. Despite its importance, high hydrostatic pressure remains significantly less utilised than other thermodynamic variables such as temperature and chemical composition. Here, we give an overview of some of the theoretical aspects which determine lipid behaviour under pressure and the techniques and technology available to study these effects. We also summarise several recent experiments which highlight the information available from these approaches.
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Affiliation(s)
- Nicholas J Brooks
- Membrane Biophysics Platform and Institute of Chemical Biology, Department of Chemistry, Imperial College London, South Kensington Campus, UK
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47
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Best RB, Mittal J. Protein Simulations with an Optimized Water Model: Cooperative Helix Formation and Temperature-Induced Unfolded State Collapse. J Phys Chem B 2010; 114:14916-23. [DOI: 10.1021/jp108618d] [Citation(s) in RCA: 216] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert B. Best
- Cambridge University, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, United Kingdom, and Lehigh University, Department of Chemical Engineering, Bethlehem, Pennsylvania 18015, United States
| | - Jeetain Mittal
- Cambridge University, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, United Kingdom, and Lehigh University, Department of Chemical Engineering, Bethlehem, Pennsylvania 18015, United States
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48
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49
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Iwaoka M, Sano N, Hasegawa N, Yokokawa M, Kunigami S, Shirai H. Structural Transitions and Enzymatic Function of Ribonuclease A Encapsulated in Transparent Porous Silica Gel. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2010. [DOI: 10.1246/bcsj.20090337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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50
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Robinson D, Besley NA, O’Shea P, Hirst JD. Calculating the Fluorescence of 5-Hydroxytryptophan in Proteins. J Phys Chem B 2009; 113:14521-8. [DOI: 10.1021/jp9071108] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- David Robinson
- School of Chemistry, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom, and Cell Biophysics Group, School of Biology, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - Nicholas A. Besley
- School of Chemistry, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom, and Cell Biophysics Group, School of Biology, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - Paul O’Shea
- School of Chemistry, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom, and Cell Biophysics Group, School of Biology, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom
| | - Jonathan D. Hirst
- School of Chemistry, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom, and Cell Biophysics Group, School of Biology, University Park, The University of Nottingham, Nottingham, NG7 2RD, United Kingdom
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