1
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Knop JM, Mukherjee S, Jaworek MW, Kriegler S, Manisegaran M, Fetahaj Z, Ostermeier L, Oliva R, Gault S, Cockell CS, Winter R. Life in Multi-Extreme Environments: Brines, Osmotic and Hydrostatic Pressure─A Physicochemical View. Chem Rev 2023; 123:73-104. [PMID: 36260784 DOI: 10.1021/acs.chemrev.2c00491] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Elucidating the details of the formation, stability, interactions, and reactivity of biomolecular systems under extreme environmental conditions, including high salt concentrations in brines and high osmotic and high hydrostatic pressures, is of fundamental biological, astrobiological, and biotechnological importance. Bacteria and archaea are able to survive in the deep ocean or subsurface of Earth, where pressures of up to 1 kbar are reached. The deep subsurface of Mars may host high concentrations of ions in brines, such as perchlorates, but we know little about how these conditions and the resulting osmotic stress conditions would affect the habitability of such environments for cellular life. We discuss the combined effects of osmotic (salts, organic cosolvents) and hydrostatic pressures on the structure, stability, and reactivity of biomolecular systems, including membranes, proteins, and nucleic acids. To this end, a variety of biophysical techniques have been applied, including calorimetry, UV/vis, FTIR and fluorescence spectroscopy, and neutron and X-ray scattering, in conjunction with high pressure techniques. Knowledge of these effects is essential to our understanding of life exposed to such harsh conditions, and of the physical limits of life in general. Finally, we discuss strategies that not only help us understand the adaptive mechanisms of organisms that thrive in such harsh geological settings but could also have important ramifications in biotechnological and pharmaceutical applications.
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Affiliation(s)
- Jim-Marcel Knop
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Sanjib Mukherjee
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Michel W Jaworek
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Simon Kriegler
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Magiliny Manisegaran
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Zamira Fetahaj
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Lena Ostermeier
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
| | - Rosario Oliva
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany.,Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126Naples, Italy
| | - Stewart Gault
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, EH9 3FDEdinburgh, United Kingdom
| | - Charles S Cockell
- UK Centre for Astrobiology, SUPA School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, EH9 3FDEdinburgh, United Kingdom
| | - Roland Winter
- Department of Chemistry and Chemical Biology, Biophysical Chemistry, TU Dortmund University, D-44221Dortmund, Germany
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2
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Arsiccio A, Shea JE. Pressure Unfolding of Proteins: New Insights into the Role of Bound Water. J Phys Chem B 2021; 125:8431-8442. [PMID: 34310136 DOI: 10.1021/acs.jpcb.1c04398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
High pressures can be detrimental for protein stability, resulting in unfolding and loss of function. This phenomenon occurs because the unfolding transition is accompanied by a decrease in volume, which is typically attributed to the elimination of cavities that are present within the native state as a result of packing defects. We present a novel computational approach that enables the study of pressure unfolding in atomistically detailed protein models in implicit solvent. We include the effect of pressure using a transfer free energy term that allows us to decouple the effect of protein residues and bound water molecules on the volume change upon unfolding. We discuss molecular dynamics simulations results using this protocol for two model proteins, Trp-cage and staphylococcal nuclease (SNase). We find that the volume reduction of bound water is the key energetic term that drives protein denaturation under the effect of pressure, for both Trp-cage and SNase. However, we note differences in unfolding mechanisms between the smaller Trp-cage and the larger SNase protein. Indeed, the unfolding of SNase, but not Trp-cage, is seen to be further accompanied by a reduction in the volume of internal cavities. Our results indicate that, for small peptides, like Trp-cage, pressure denaturation is driven by the increase in solvent accessibility upon unfolding, and the subsequent increase in the number of bound water molecules. For larger proteins, like SNase, the cavities within the native fold act as weak spots, determining the overall resistance to pressure denaturation. Our simulations display a striking agreement with the pressure-unfolding profile experimentally obtained for SNase and represent a promising approach for a computationally efficient and accurate exploration of pressure-induced denaturation of proteins.
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Affiliation(s)
- Andrea Arsiccio
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.,Department of Physics, University of California, Santa Barbara, California 93106, United States
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3
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Skvarnavičius G, Toleikis Z, Michailovienė V, Roumestand C, Matulis D, Petrauskas V. Protein-Ligand Binding Volume Determined from a Single 2D NMR Spectrum with Increasing Pressure. J Phys Chem B 2021; 125:5823-5831. [PMID: 34032445 PMCID: PMC8279561 DOI: 10.1021/acs.jpcb.1c02917] [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
![]()
Proteins
undergo changes in their partial volumes in numerous biological
processes such as enzymatic catalysis, unfolding–refolding,
and ligand binding. The change in the protein volume upon ligand binding—a
parameter termed the protein–ligand binding volume—can
be extensively studied by high-pressure NMR spectroscopy. In this
study, we developed a method to determine the protein–ligand
binding volume from a single two-dimensional (2D) 1H–15N heteronuclear single quantum coherence (HSQC) spectrum
at different pressures, if the exchange between ligand-free and ligand-bound
states of a protein is slow in the NMR time-scale. This approach required
a significantly lower amount of protein and NMR time to determine
the protein–ligand binding volume of two carbonic anhydrase
isozymes upon binding their ligands. The proposed method can be used
in other protein–ligand systems and expand the knowledge about
protein volume changes upon small-molecule binding.
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Affiliation(s)
- Gediminas Skvarnavičius
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, 10257 Vilnius, Lithuania
| | - Zigmantas Toleikis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, 10257 Vilnius, Lithuania.,Latvian Institute of Organic Synthesis, Aizkraukles 21, 1006 Riga, Latvia
| | - Vilma Michailovienė
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, 10257 Vilnius, Lithuania
| | - Christian Roumestand
- Centre de Biochimie Structurale, INSERM U1054, CNRS UMR 5048, Université s de Montpellier, 34000 Montpellier, France
| | - Daumantas Matulis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, 10257 Vilnius, Lithuania
| | - Vytautas Petrauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, 10257 Vilnius, Lithuania
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4
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Pal S, Banerjee S, Prabhakaran EN. Helix-Coil Transition at a Glycine Following a Nascent α-Helix: A Synergetic Guidance Mechanism for Helix Growth. J Phys Chem A 2020; 124:7478-7490. [PMID: 32877193 DOI: 10.1021/acs.jpca.0c05489] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A detailed understanding of forces guiding the rapid folding of a polypeptide from an apparently random coil state to an ordered α-helical structure following the rate-limiting preorganization of the initial three residue backbones into helical conformation is imperative to comprehending and regulating protein folding and for the rational design of biological mimetics. However, several details of this process are still unknown. First, although the helix-coil transition was proposed to originate at the residue level (J. Chem. Phys. 1959, 31, 526-535; J. Chem. Phys. 1961, 34, 1963-1974), all helix-folding studies have only established it between time-averaged bulk states of a long-lived helix and several transiently populated random coils, along the whole helix model sequence. Second, the predominant thermodynamic forces driving either this two-state transition or the faster helix growth following helix nucleation are still unclear. Third, the conformational space of the random coil state is not well-defined unlike its corresponding α-helix. Here we investigate the restrictions placed on the conformational space of a Gly residue backbone, as a result of it immediately succeeding a nascent α-helical turn. Analyses of the temperature-dependent 1D-, 2D-NMR, FT-IR, and CD spectra and GROMACS MD simulation trajectory of a Gly residue backbone following a model α-helical turn, which is artificially rigidified by a covalent hydrogen bond surrogate, reveal that: (i) the α-helical turn guides the ϕ torsion of the Gly exclusively into either a predominantly populated entropically favored α-helical (α-ϕ) state or a scarcely populated random coil (RC-ϕ) state; (ii) the α-ϕ state of Gly in turn favors the stability of the preceding α-helical turn, while the RC-ϕ state disrupts it, revealing an entropy-driven synergetic guidance for helix growth in the residue following helix nucleation. The applicability of a current synergetic guidance mechanism to explain rapid helix growth in folded and unfolded states of proteins and helical peptides is discussed.
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Affiliation(s)
- Sunit Pal
- Department of Chemistry, Indian Institute of Science, Bangalore, Karnataka-560012, India
| | - Shreya Banerjee
- Department of Chemistry, Indian Institute of Science, Bangalore, Karnataka-560012, India
| | - Erode N Prabhakaran
- Department of Chemistry, Indian Institute of Science, Bangalore, Karnataka-560012, India
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5
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Roche J, Royer CA. Lessons from pressure denaturation of proteins. J R Soc Interface 2018; 15:rsif.2018.0244. [PMID: 30282759 DOI: 10.1098/rsif.2018.0244] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 09/13/2018] [Indexed: 12/26/2022] Open
Abstract
Although it is now relatively well understood how sequence defines and impacts global protein stability in specific structural contexts, the question of how sequence modulates the configurational landscape of proteins remains to be defined. Protein configurational equilibria are generally characterized by using various chemical denaturants or by changing temperature or pH. Another thermodynamic parameter which is less often used in such studies is high hydrostatic pressure. This review discusses the basis for pressure effects on protein structure and stability, and describes how the unique mechanisms of pressure-induced unfolding can provide unique insights into protein conformational landscapes.
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Affiliation(s)
- Julien Roche
- Department of Biochemistry, Biophysics and Molecular Biology Iowa State University, Ames, IA 50011, USA
| | - Catherine A Royer
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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6
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Zhang Y, Berghaus M, Klein S, Jenkins K, Zhang S, McCallum SA, Morgan JE, Winter R, Barrick D, Royer CA. High-Pressure NMR and SAXS Reveals How Capping Modulates Folding Cooperativity of the pp32 Leucine-rich Repeat Protein. J Mol Biol 2018; 430:1336-1349. [DOI: 10.1016/j.jmb.2018.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 03/03/2018] [Accepted: 03/06/2018] [Indexed: 12/18/2022]
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7
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Baweja L, Roche J. Pushing the Limits of Structure-Based Models: Prediction of Nonglobular Protein Folding and Fibrils Formation with Go-Model Simulations. J Phys Chem B 2018; 122:2525-2535. [DOI: 10.1021/acs.jpcb.7b12129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lokesh Baweja
- Department of Biochemistry, Molecular Biology and Biophysics, Iowa State University, Ames, Iowa 50011, United States
| | - Julien Roche
- Department of Biochemistry, Molecular Biology and Biophysics, Iowa State University, Ames, Iowa 50011, United States
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8
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Molecular determinant of the effects of hydrostatic pressure on protein folding stability. Nat Commun 2017; 8:14561. [PMID: 28169271 PMCID: PMC5309723 DOI: 10.1038/ncomms14561] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/09/2017] [Indexed: 11/14/2022] Open
Abstract
Hydrostatic pressure is an important environmental variable that plays an essential role in biological adaptation for many extremophilic organisms (for example, piezophiles). Increase in hydrostatic pressure, much like increase in temperature, perturbs the thermodynamic equilibrium between native and unfolded states of proteins. Experimentally, it has been observed that increase in hydrostatic pressure can both increase and decrease protein stability. These observations suggest that volume changes upon protein unfolding can be both positive and negative. The molecular details of this difference in sign of volume changes have been puzzling the field for the past 50 years. Here we present a comprehensive thermodynamic model that provides in-depth analysis of the contribution of various molecular determinants to the volume changes upon protein unfolding. Comparison with experimental data shows that the model allows quantitative predictions of volume changes upon protein unfolding, thus paving the way to proteome-wide computational comparison of proteins from different extremophilic organisms. Proteins can be both stabilized and destabilized by pressure. Here the authors analyse the factors contributing to both negative and positive protein volume change upon denaturation, and shed light on the molecular determinants allowing proteins to be stable at high pressures.
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9
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Zhang Y, Kitazawa S, Peran I, Stenzoski N, McCallum SA, Raleigh DP, Royer CA. High Pressure ZZ-Exchange NMR Reveals Key Features of Protein Folding Transition States. J Am Chem Soc 2016; 138:15260-15266. [PMID: 27781428 DOI: 10.1021/jacs.6b09887] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding protein folding mechanisms and their sequence dependence requires the determination of residue-specific apparent kinetic rate constants for the folding and unfolding reactions. Conventional two-dimensional NMR, such as HSQC experiments, can provide residue-specific information for proteins. However, folding is generally too fast for such experiments. ZZ-exchange NMR spectroscopy allows determination of folding and unfolding rates on much faster time scales, yet even this regime is not fast enough for many protein folding reactions. The application of high hydrostatic pressure slows folding by orders of magnitude due to positive activation volumes for the folding reaction. We combined high pressure perturbation with ZZ-exchange spectroscopy on two autonomously folding protein domains derived from the ribosomal protein, L9. We obtained residue-specific apparent rates at 2500 bar for the N-terminal domain of L9 (NTL9), and rates at atmospheric pressure for a mutant of the C-terminal domain (CTL9) from pressure dependent ZZ-exchange measurements. Our results revealed that NTL9 folding is almost perfectly two-state, while small deviations from two-state behavior were observed for CTL9. Both domains exhibited large positive activation volumes for folding. The volumetric properties of these domains reveal that their transition states contain most of the internal solvent excluded voids that are found in the hydrophobic cores of the respective native states. These results demonstrate that by coupling it with high pressure, ZZ-exchange can be extended to investigate a large number of protein conformational transitions.
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Affiliation(s)
- Yi Zhang
- Department of Chemistry & Chemical Biology, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Soichiro Kitazawa
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Ivan Peran
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States
| | - Natalie Stenzoski
- Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York 11794, United States
| | - Scott A McCallum
- NMR Core Facility, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794, United States
| | - Catherine A Royer
- Department of Chemistry & Chemical Biology, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.,Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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10
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Ingr M, Kutálková E, Hrnčiřík J, Lange R. Equilibria of oligomeric proteins under high pressure - A theoretical description. J Theor Biol 2016; 411:16-26. [PMID: 27717844 DOI: 10.1016/j.jtbi.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 09/14/2016] [Accepted: 10/03/2016] [Indexed: 01/18/2023]
Abstract
High pressure methods have become a useful tool for studying protein structure and stability. Using them, various physico-chemical processes including protein unfolding, aggregation, oligomer dissociation or enzyme-activity decrease were studied on many different proteins. Oligomeric protein dissociation is a process that can perfectly utilize the potential of high-pressure techniques, as the high pressure shifts the equilibria to higher concentrations making them better observable by spectroscopic methods. This can be especially useful when the oligomeric form is highly stable at atmospheric pressure. These applications may be, however, hindered by less intensive experimental response as well as interference of the oligomerization equilibria with unfolding or aggregation of the subunits, but also by more complex theoretical description. In this study we develop mathematical models describing different kinds of oligomerization equilibria, both closed (equilibrium of monomer and the highest possible oligomer without any intermediates) and consecutive. Closed homooligomer equilibria are discussed for any oligomerization degree, while the more complex heterooligomer equilibria and the consecutive equilibria in both homo- and heterooligomers are taken into account only for dimers and trimers. In all the cases, fractions of all the relevant forms are evaluated as functions of pressure and concentration. Significant points (inflection points and extremes) of the resulting transition curves, that can be determined experimentally, are evaluated as functions of pressure and/or concentration. These functions can be further used in order to evaluate the thermodynamic parameters of the system, i.e. atmospheric-pressure equilibrium constants and volume changes of the individual steps of the oligomer-dissociation processes.
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Affiliation(s)
- Marek Ingr
- Tomas Bata University in Zlín, Faculty of Technology, Department of Physics and Materials Engineering, nám. T. G. Masaryka 5555, 76001 Zlín, Czechia; Charles University in Prague, Faculty of Science, Department of Biochemistry, Hlavova 2030, 12843 Prague 2, Czechia.
| | - Eva Kutálková
- Tomas Bata University in Zlín, Faculty of Technology, Department of Physics and Materials Engineering, nám. T. G. Masaryka 5555, 76001 Zlín, Czechia
| | - Josef Hrnčiřík
- Tomas Bata University in Zlín, Faculty of Technology, Department of Physics and Materials Engineering, nám. T. G. Masaryka 5555, 76001 Zlín, Czechia
| | - Reinhard Lange
- Université Montpellier, INRA UMR IATE, Biochimie et Technologie Alimentaires, cc023, Place Eugene Bataillon, 34095 Montpellier Cedex 05, France
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11
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Pandharipande PP, Makhatadze GI. Applications of pressure perturbation calorimetry to study factors contributing to the volume changes upon protein unfolding. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1860:1036-1042. [PMID: 26341789 DOI: 10.1016/j.bbagen.2015.08.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 08/28/2015] [Accepted: 08/30/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Pressure perturbation calorimetry (PPC) is a biophysical method that allows direct determination of the volume changes upon conformational transitions in macromolecules. SCOPE OF THIS REVIEW This review provides novel details of the use of PPC to analyze unfolding transitions in proteins. The emphasis is made on the data analysis as well as on the validation of different structural factors that define the volume changes upon unfolding. Four case studies are presented that show the application of these concepts to various protein systems. MAJOR CONCLUSIONS The major conclusions are: 1. Knowledge of the thermodynamic parameters for heat induced unfolding facilitates the analysis of the PPC profiles. 2. The changes in the thermal expansion coefficient upon unfolding appear to be temperature dependent.3.Substitutions on the protein surface have negligible effects on the volume changes upon protein unfolding. 4. Structural plasticity of proteins defines the position dependent effect of amino acid substitutions of the residues buried in the native state. 5. Small proteins have positive volume changes upon unfolding which suggests difference in balance between the cavity/void volume in the native state and the hydration volume changes upon unfolding as compared to the large proteins that have negative volume changes. GENERAL SIGNIFICANCE The information provided here gives a better understanding and deeper insight into the role played by various factors in defining the volume changes upon protein unfolding.
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Affiliation(s)
- Pranav P Pandharipande
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA; Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - George I Makhatadze
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA; Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
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12
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Dave K, Gelman H, Thu CTH, Guin D, Gruebele M. The Effect of Fluorescent Protein Tags on Phosphoglycerate Kinase Stability Is Nonadditive. J Phys Chem B 2016; 120:2878-85. [PMID: 26923443 DOI: 10.1021/acs.jpcb.5b11915] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is frequently assumed that fluorescent protein tags used in biological imaging experiments are minimally perturbing to their host protein. As in-cell experiments become more quantitative and measure rates and equilibrium constants, rather than just "on-off" activity or the presence of a protein, it becomes more important to understand such perturbations. One criterion for a protein modification to be a perturbation is additivity of two perturbations (a linear effect on the protein free energy). Here we show that adding fluorescent protein tags to a host protein in vitro has a large nonadditive effect on its folding free energy. We compare an unlabeled, three singly labeled, and a doubly labeled enzyme (phosphoglycerate kinase). We propose two mechanisms for nonadditivity. In the "quinary interaction" mechanism, two tags interact transiently with one another, relieving the host protein from unfavorable tag-protein interactions. In the "crowding" mechanism, adding two tags provides the minimal crowding necessary to overcome destabilizing interactions of individual tags with the host protein. Both of these mechanisms affect protein stability in cells; we show here that they must also be considered for tagged proteins used for reference in vitro.
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Affiliation(s)
| | | | - Chu Thi Hien Thu
- Department of Chemistry, Hanoi University of Science, Vietnam National University , Hanoi, Vietnam
| | | | - Martin Gruebele
- Department of Chemistry, Hanoi University of Science, Vietnam National University , Hanoi, Vietnam
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13
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Schroer MA, Westermeier F, Lehmkühler F, Conrad H, Schavkan A, Zozulya AV, Fischer B, Roseker W, Sprung M, Gutt C, Grübel G. Colloidal crystallite suspensions studied by high pressure small angle x-ray scattering. J Chem Phys 2016; 144:084903. [PMID: 26931722 DOI: 10.1063/1.4941563] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on high pressure small angle x-ray scattering on suspensions of colloidal crystallites in water. The crystallites made out of charge-stabilized poly-acrylate particles exhibit a complex pressure dependence which is based on the specific pressure properties of the suspending medium water. The dominant effect is a compression of the crystallites caused by the compression of the water. In addition, we find indications that also the electrostatic properties of the system, i.e. the particle charge and the dissociation of ions, might play a role for the pressure dependence of the samples. The data further suggest that crystallites in a metastable state induced by shear-induced melting can relax to a similar structural state upon the application of pressure and dilution with water. X-ray cross correlation analysis of the two-dimensional scattering patterns indicates a pressure-dependent increase of the orientational order of the crystallites correlated with growth of these in the suspension. This study underlines the potential of pressure as a very relevant parameter to understand colloidal crystallite systems in aqueous suspension.
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Affiliation(s)
- M A Schroer
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - F Westermeier
- Max-Planck-Institut für Struktur und Dynamik der Materie, CFEL, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - F Lehmkühler
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - H Conrad
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - A Schavkan
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - A V Zozulya
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - B Fischer
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - W Roseker
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - M Sprung
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - C Gutt
- Department of Physics, University of Siegen, Walter-Flex-Str. 3, 57072 Siegen, Germany
| | - G Grübel
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
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14
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Abstract
This year, 2014, marks the 100th anniversary of the first publication reporting the denaturation of proteins by high hydrostatic pressure (Bridgman 1914). Since that time a large and recently increasing number of studies of pressure effects on protein stability have been published, yet the mechanism for the action of pressure on proteins remains subject to considerable debate. This review will present an overview from this author's perspective of where this debate stands today.
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Affiliation(s)
- Catherine A Royer
- Department of Biology, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA,
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15
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Meersman F, McMillan PF. High hydrostatic pressure: a probing tool and a necessary parameter in biophysical chemistry. Chem Commun (Camb) 2014; 50:766-75. [PMID: 24286104 DOI: 10.1039/c3cc45844j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High pressures extending up to several thousands of atmospheres provide extreme conditions for biological organisms to survive. Recent studies are investigating the survival mechanisms and biological function of microorganisms under natural and laboratory conditions extending into the GigaPascal range, with applications to understanding the Earth's deep biosphere and food technology. High pressure has also emerged as a useful tool and physical parameter for probing changes in the structure and functional properties of biologically important macromolecules and polymers encountered in soft matter science. Here we highlight some areas of current interest in high pressure biophysics and physical chemistry that are emerging at the frontier of this cross-disciplinary field.
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Affiliation(s)
- Filip Meersman
- Department of Chemistry, University College London, 20 Gordon St., London WC1H 0AJ, UK.
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16
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Dias CL, Chan HS. Pressure-Dependent Properties of Elementary Hydrophobic Interactions: Ramifications for Activation Properties of Protein Folding. J Phys Chem B 2014; 118:7488-7509. [DOI: 10.1021/jp501935f] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Cristiano L. Dias
- Department
of Physics, New Jersey Institute of Technology, University Heights, Tiernan Hall, Room 463, Newark, New Jersey 07102, United States
- Departments
of Biochemistry, Molecular Genetics, and Physics, University of Toronto, 1 King’s College Circle, Toronto, Ontario Canada M5S 1A8
| | - Hue Sun Chan
- Departments
of Biochemistry, Molecular Genetics, and Physics, University of Toronto, 1 King’s College Circle, Toronto, Ontario Canada M5S 1A8
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17
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Abstract
Fluorescence is the most widely used technique to study the effect of pressure on biochemical systems. The use of pressure as a physical variable sheds light into volumetric characteristics of reactions. Here we focus on the effect of pressure on protein solutions using a simple unfolding example in order to illustrate the applications of the methodology. Topics covered in this review include the relationships between practical aspects and technical limitations; the effect of pressure and the study of protein cavities; the interpretation of thermodynamic and relaxation kinetics; and the study of relaxation amplitudes. Finally, we discuss the insights available from the combination of fluorescence and other methods adapted to high pressure, such as SAXS or NMR. Because of the simplicity and accessibility of high-pressure fluorescence, the technique is a starting point that complements appropriately multi-methodological approaches related to understanding protein function, disfunction, and folding from the volumetric point of view.
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18
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Transition state and ground state properties of the helix-coil transition in peptides deduced from high-pressure studies. Proc Natl Acad Sci U S A 2013; 110:20988-93. [PMID: 24324160 DOI: 10.1073/pnas.1317973110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Volume changes associated with protein folding reactions contain valuable information about the folding mechanism and the nature of the transition state. However, meaningful interpretation of such data requires that overall volume changes be deconvoluted into individual contributions from different structural components. Here we focus on one type of structural element, the α-helix, and measure triplet-triplet energy transfer at high pressure to determine volume changes associated with the helix-coil transition. Our results reveal that the volume of a 21-amino-acid alanine-based peptide shrinks upon helix formation. Thus, helices, in contrast with native proteins, become more stable with increasing pressure, explaining the frequently observed helical structures in pressure-unfolded proteins. Both helix folding and unfolding become slower with increasing pressure. The volume changes associated with the addition of a single helical residue to a preexisting helix were obtained by comparing the experimental results with Monte Carlo simulations based on a kinetic linear Ising model. The reaction volume for adding a single residue to a helix is small and negative (-0.23 cm(3) per mol = -0.38 Å(3) per molecule) implying that intrahelical hydrogen bonds have a smaller volume than peptide-water hydrogen bonds. In contrast, the transition state has a larger volume than either the helical or the coil state, with activation volumes of 2.2 cm(3)/mol (3.7 Å(3) per molecule) for adding and 2.4 cm(3)/mol (4.0 Å(3) per molecule) for removing one residue. Thus, addition or removal of a helical residue proceeds through a transitory high-energy state with a large volume, possibly due to the presence of unsatisfied hydrogen bonds, although steric effects may also contribute.
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19
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Landahl EC, Rice SE. Model-independent decomposition of two-state data. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062713. [PMID: 24483492 PMCID: PMC3955112 DOI: 10.1103/physreve.88.062713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Indexed: 06/03/2023]
Abstract
Two-state models often provide a reasonable approximation of protein behaviors such as partner binding, folding, and conformational changes. Many different techniques have been developed to determine the population ratio between two states as a function of different experimental conditions. Data analysis is accomplished either by fitting individual measured spectra to a linear combination of known basis spectra or alternatively by decomposing the entire set of spectra into two components using a least-squares optimization of free parameters within an assumed population model. Here we demonstrate that it is possible to determine the population ratio in a two-state system directly from data without an a priori model for basis spectra or populations by applying physical constraints iteratively to a singular value decomposition of optical fluorescence, x-ray-scattering, and electron paramagnetic resonance data.
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Affiliation(s)
| | - Sarah E. Rice
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
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20
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Roche J, Dellarole M, Caro JA, Norberto DR, Garcia AE, Garcia-Moreno B, Roumestand C, Royer CA. Effect of Internal Cavities on Folding Rates and Routes Revealed by Real-Time Pressure-Jump NMR Spectroscopy. J Am Chem Soc 2013; 135:14610-8. [DOI: 10.1021/ja406682e] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julien Roche
- Centre de Biochimie
Structurale, INSERM U554, CNRS UMR 5048, Universités de Montpellier, France
| | - Mariano Dellarole
- Centre de Biochimie
Structurale, INSERM U554, CNRS UMR 5048, Universités de Montpellier, France
| | - José A. Caro
- Department
of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Douglas R. Norberto
- Department
of Biochemistry, Institute of Biology, University of Campinas, Campinas, Brazil
| | - Angel E. Garcia
- Department
of Physics and Applied Physics and Center for Biotechnology and Interdisciplinary
Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Bertrand Garcia-Moreno
- Department
of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Christian Roumestand
- Centre de Biochimie
Structurale, INSERM U554, CNRS UMR 5048, Universités de Montpellier, France
| | - Catherine A. Royer
- Centre de Biochimie
Structurale, INSERM U554, CNRS UMR 5048, Universités de Montpellier, France
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21
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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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22
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Baldwin RL, Rose GD. Molten globules, entropy-driven conformational change and protein folding. Curr Opin Struct Biol 2013; 23:4-10. [DOI: 10.1016/j.sbi.2012.11.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/14/2012] [Accepted: 11/15/2012] [Indexed: 10/27/2022]
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23
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Volume of Hsp90 ligand binding and the unfolding phase diagram as a function of pressure and temperature. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2013; 42:355-62. [DOI: 10.1007/s00249-012-0884-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 11/15/2012] [Accepted: 12/13/2012] [Indexed: 12/14/2022]
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24
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High-pressure NMR reveals close similarity between cold and alcohol protein denaturation in ubiquitin. Proc Natl Acad Sci U S A 2013; 110:E368-76. [PMID: 23284170 DOI: 10.1073/pnas.1212222110] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteins denature not only at high, but also at low temperature as well as high pressure. These denatured states are not easily accessible for experiment, because usually heat denaturation causes aggregation, whereas cold or pressure denaturation occurs at temperatures well below the freezing point of water or pressures above 5 kbar, respectively. Here we have obtained atomic details of the pressure-assisted, cold-denatured state of ubiquitin at 2,500 bar and 258 K by high-resolution NMR techniques. Under these conditions, a folded, native-like and a disordered state exist in slow exchange. Secondary chemical shifts show that the disordered state has structural propensities for a native-like N-terminal β-hairpin and α-helix and a nonnative C-terminal α-helix. These propensities are very similar to the previously described alcohol-denatured (A-)state. Similar to the A-state, (15)N relaxation data indicate that the secondary structure elements move as independent segments. The close similarity of pressure-assisted, cold-denatured, and alcohol-denatured states with native and nonnative secondary elements supports a hierarchical mechanism of folding and supports the notion that similar to alcohol, pressure and cold reduce the hydrophobic effect. Indeed, at nondenaturing concentrations of methanol, a complete transition from the native to the A-state can be achieved at ambient temperature by varying the pressure from 1 to 2,500 bar. The methanol-assisted pressure transition is completely reversible and can also be induced in protein G. This method should allow highly detailed studies of protein-folding transitions in a continuous and reversible manner.
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25
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Wu QY, Li F, Guo HY, Cao J, Chen C, Chen W, Zhao K, Zeng LY, Han ZX, Li ZY, Wang XY, Xu KL. Amino acid residue E543 in JAK2 C618R is a potential therapeutic target for myeloproliferative disorders caused by JAK2 C618R mutation. Arch Biochem Biophys 2012; 528:57-66. [DOI: 10.1016/j.abb.2012.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 08/20/2012] [Accepted: 08/20/2012] [Indexed: 01/05/2023]
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26
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Toleikis Z, Cimmperman P, Petrauskas V, Matulis D. Determination of the volume changes induced by ligand binding to heat shock protein 90 using high-pressure denaturation. Anal Biochem 2011; 413:171-8. [DOI: 10.1016/j.ab.2011.02.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 02/11/2011] [Accepted: 02/12/2011] [Indexed: 11/26/2022]
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27
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Rouget JB, Aksel T, Roche J, Saldana JL, Garcia AE, Barrick D, Royer CA. Size and sequence and the volume change of protein folding. J Am Chem Soc 2011; 133:6020-7. [PMID: 21446709 PMCID: PMC3151578 DOI: 10.1021/ja200228w] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The application of hydrostatic pressure generally leads to protein unfolding, implying, in accordance with Le Chatelier's principle, that the unfolded state has a smaller molar volume than the folded state. However, the origin of the volume change upon unfolding, ΔV(u), has yet to be determined. We have examined systematically the effects of protein size and sequence on the value of ΔV(u) using as a model system a series of deletion variants of the ankyrin repeat domain of the Notch receptor. The results provide strong evidence in support of the notion that the major contributing factor to pressure effects on proteins is their imperfect internal packing in the folded state. These packing defects appear to be specifically localized in the 3D structure, in contrast to the uniformly distributed effects of temperature and denaturants that depend upon hydration of exposed surface area upon unfolding. Given its local nature, the extent to which pressure globally affects protein structure can inform on the degree of cooperativity and long-range coupling intrinsic to the folded state. We also show that the energetics of the protein's conformations can significantly modulate their volumetric properties, providing further insight into protein stability.
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Affiliation(s)
- Jean-Baptiste Rouget
- Centre de Biochimie Structurale, INSERM U554, CNRS UMR5048, Université Montpellier 1&2, Montpellier France
| | - Tural Aksel
- T. C. Jenkins Department of Biophysics, The Johns Hopkins University, Baltimore MD USA
| | - Julien Roche
- Centre de Biochimie Structurale, INSERM U554, CNRS UMR5048, Université Montpellier 1&2, Montpellier France
- Department of Physics and Applied Physics and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy NY USA
| | - Jean-Louis Saldana
- Centre de Biochimie Structurale, INSERM U554, CNRS UMR5048, Université Montpellier 1&2, Montpellier France
| | - Angel E. Garcia
- Department of Physics and Applied Physics and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy NY USA
| | - Doug Barrick
- T. C. Jenkins Department of Biophysics, The Johns Hopkins University, Baltimore MD USA
| | - Catherine A. Royer
- Centre de Biochimie Structurale, INSERM U554, CNRS UMR5048, Université Montpellier 1&2, Montpellier France
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28
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Baldwin RL, Frieden C, Rose GD. Dry molten globule intermediates and the mechanism of protein unfolding. Proteins 2011; 78:2725-37. [PMID: 20635344 DOI: 10.1002/prot.22803] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
New experimental results show that either gain or loss of close packing can be observed as a discrete step in protein folding or unfolding reactions. This finding poses a significant challenge to the conventional two-state model of protein folding. Results of interest involve dry molten globule (DMG) intermediates, an expanded form of the protein that lacks appreciable solvent. When an unfolding protein expands to the DMG state, side chains unlock and gain conformational entropy, while liquid-like van der Waals interactions persist. Four unrelated proteins are now known to form DMGs as the first step of unfolding, suggesting that such an intermediate may well be commonplace in both folding and unfolding. Data from the literature show that peptide amide protons are protected in the DMG, indicating that backbone structure is intact despite loss of side-chain close packing. Other complementary evidence shows that secondary structure formation provides a major source of compaction during folding. In our model, the major free-energy barrier separating unfolded from native states usually occurs during the transition between the unfolded state and the DMG. The absence of close packing at this barrier provides an explanation for why phi-values, derived from a Brønsted-Leffler plot, depend primarily on structure at the mutational site and not on specific side-chain interactions. The conventional two-state folding model breaks down when there are DMG intermediates, a realization that has major implications for future experimental work on the mechanism of protein folding.
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Affiliation(s)
- Robert L Baldwin
- Department of Biochemistry, Stanford University Medical Center, Beckman Center, School of Medicine, Stanford, California 94305-5307, USA.
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29
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Jeworrek C, Steitz R, Czeslik C, Winter R. High pressure cell for neutron reflectivity measurements up to 2500 bar. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:025106. [PMID: 21361632 DOI: 10.1063/1.3553392] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The design of a high pressure (HP) cell for neutron reflectivity experiments is described. The cell can be used to study solid-liquid interfaces under pressures up to 2500 bar (250 MPa). The sample interface is based on a thick silicon block with an area of about 14 cm(2). This area is in contact with the sample solution which has a volume of only 6 cm(3). The sample solution is separated from the pressure transmitting medium, water, by a thin flexible polymer membrane. In addition, the HP cell can be temperature-controlled by a water bath in the range 5-75°C. By using an aluminum alloy as window material, the assembled HP cell provides a neutron transmission as high as 41%. The maximum angle of incidence that can be used in reflectivity experiments is 7.5°. The large accessible pressure range and the low required volume of the sample solution make this HP cell highly suitable for studying pressure-induced structural changes of interfacial proteins, supported lipid membranes, and, in general, biomolecular systems that are available in small quantities, only. To illustrate the performance of the HP cell, we present neutron reflectivity data of a protein adsorbate under high pressure and a lipid film which undergoes several phase transitions upon pressurization.
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Affiliation(s)
- Christoph Jeworrek
- Physical Chemistry I-Biophysical Chemistry, Technische Universität Dortmund, Dortmund, Germany
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30
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Kitahara R, Hata K, Maeno A, Akasaka K, Chimenti MS, Garcia-Moreno E B, Schroer MA, Jeworrek C, Tolan M, Winter R, Roche J, Roumestand C, Montet de Guillen K, Royer CA. Structural plasticity of staphylococcal nuclease probed by perturbation with pressure and pH. Proteins 2011; 79:1293-305. [PMID: 21254234 DOI: 10.1002/prot.22966] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/01/2010] [Accepted: 11/29/2010] [Indexed: 11/11/2022]
Abstract
The ionization of internal groups in proteins can trigger conformational change. Despite this being the structural basis of most biological energy transduction, these processes are poorly understood. Small angle X-ray scattering (SAXS) and nuclear magnetic resonance (NMR) spectroscopy experiments at ambient and high hydrostatic pressure were used to examine how the presence and ionization of Lys-66, buried in the hydrophobic core of a stabilized variant of staphylococcal nuclease, affect conformation and dynamics. NMR spectroscopy at atmospheric pressure showed previously that the neutral Lys-66 affects slow conformational fluctuations globally, whereas the effects of the charged form are localized to the region immediately surrounding position 66. Ab initio models from SAXS data suggest that when Lys-66 is charged the protein expands, which is consistent with results from NMR spectroscopy. The application of moderate pressure (<2 kbar) at pH values where Lys-66 is normally neutral at ambient pressure left most of the structure unperturbed but produced significant nonlinear changes in chemical shifts in the helix where Lys-66 is located. Above 2 kbar pressure at these pH values the protein with Lys-66 unfolded cooperatively adopting a relatively compact, albeit random structure according to Kratky analysis of the SAXS data. In contrast, at low pH and high pressure the unfolded state of the variant with Lys-66 is more expanded than that of the reference protein. The combined global and local view of the structural reorganization triggered by ionization of the internal Lys-66 reveals more detectable changes than were previously suggested by NMR spectroscopy at ambient pressure.
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Affiliation(s)
- Ryo Kitahara
- College of Pharmaceutical Sciences, Ritsumeikan University, Shiga, Japan
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31
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Sosnick TR, Barrick D. The folding of single domain proteins--have we reached a consensus? Curr Opin Struct Biol 2010; 21:12-24. [PMID: 21144739 DOI: 10.1016/j.sbi.2010.11.002] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Revised: 11/03/2010] [Accepted: 11/04/2010] [Indexed: 10/18/2022]
Abstract
Rather than stressing the most recent advances in the field, this review highlights the fundamental topics where disagreement remains and where adequate experimental data are lacking. These topics include properties of the denatured state and the role of residual structure, the nature of the fundamental steps and barriers, the extent of pathway heterogeneity and non-native interactions, recent comparisons between theory and experiment, and finally, dynamical properties of the folding reaction.
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Affiliation(s)
- Tobin R Sosnick
- Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA.
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