1
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Zheng N, Long M, Zhang Z, Du S, Huang X, Osire T, Xia X. Behavior of enzymes under high pressure in food processing: mechanisms, applications, and developments. Crit Rev Food Sci Nutr 2023:1-15. [PMID: 37243343 DOI: 10.1080/10408398.2023.2217268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
High pressure processing (HPP) offers the benefits of safety, uniformity, energy-efficient, and low waste, which is widely applied for microbial inactivation and shelf-life extension for foods. Over the past forty years, HPP has been extensively researched in the food industry, enabling the inactivation or activation of different enzymes in future food by altering their molecular structure and active site conformation. Such activation or inactivation of enzymes effectively hinders the spoilage of food and the production of beneficial substances, which is crucial for improving food quality. This paper reviews the mechanism in which high pressure affects the stability and activity of enzymes, concludes the roles of key enzymes in the future food processed using high pressure technologies. Moreover, we discuss the application of modified enzymes based on high pressure, providing insights into the future direction of enzyme evolution under complex food processing conditions (e.g. high temperature, high pressure, high shear, and multiple elements). Finally, we conclude with prospects of high pressure technology and research directions in the future. Although HPP has shown positive effects in improving the future food quality, there is still a pressing need to develop new and effective combined processing methods, upgrade processing modes, and promote sustainable lifestyles.
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Affiliation(s)
- Nan Zheng
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Mengfei Long
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zehua Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Shuang Du
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Xinlei Huang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Tolbert Osire
- Faculty of Biology, Shenzhen MSU-BIT University, Shenzhen, China
| | - Xiaole Xia
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
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2
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Zheng N, Gao L, Long M, Zhang Z, Zhu C, Lv X, Zhou Q, Xia X. Isothermal Compressibility Perturbation as a Protein Design Principle for T1 Lipase Stability-Activity Trade-Off Counteracting. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:6681-6690. [PMID: 37083407 DOI: 10.1021/acs.jafc.3c01684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Given the widely existing stability-activity trade-off in enzyme evolution, it is still a goal to obtain enzymes embracing both high activity and stability. Herein, we employed an isothermal compressibility (βT) perturbation engineering (ICPE) strategy to comprehensively understand the stability-activity seesaw-like mechanism. The stability and activity of mutants derived from ICPE uncovered a high Pearson correlation (r = 0.93) in a prototypical enzyme T1 lipase. The best variant A186L/L188M/A190Y exhibited a high Tm value up to 78.70 °C, catalytic activity of 474.04 U/mg, and a 73.33% increase in dimethyl sulfoxide resistance compared to the wild type, one of the highest comprehensive performances reported to date. The elastic activation mechanism mediated by conformational change with a ΔβT range of -6.81 × 10-6 to -1.90 × 10-6 bar-1 may account for the balancing of stability and activity to achieve better performing enzymes. The ICPE strategy deepens our understanding of stability-activity trade-off and boosts its applications in enzyme engineering.
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Affiliation(s)
- Nan Zheng
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Ling Gao
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Mengfei Long
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Zehua Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Cailin Zhu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Xiang Lv
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Qingtong Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Xiaole Xia
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
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3
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Fernández Del Río B, Rey A. Behavior of Proteins under Pressure from Experimental Pressure-Dependent Structures. J Phys Chem B 2021; 125:6179-6191. [PMID: 34100621 PMCID: PMC8478274 DOI: 10.1021/acs.jpcb.1c03313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structure-based models are coarse-grained representations of the interactions responsible for the protein folding process. In their simplest form, they use only the native contact map of a given protein to predict the main features of its folding process by computer simulation. Given their limitations, these models are frequently complemented with sequence-dependent contributions or additional information. Specifically, to analyze the effect of pressure on the folding/unfolding transition, special forms of these interaction potentials are employed, which may a priori determine the outcome of the simulations. In this work, we have tried to keep the original simplicity of structure-based models. Therefore, we have used folded structures that have been experimentally determined at different pressures to define native contact maps and thus interactions dependent on pressure. Despite the apparently tiny structural differences induced by pressure, our simulation results provide different thermodynamic and kinetic behaviors, which roughly correspond to experimental observations (when there is a possible comparison) of two proteins used as benchmarks, hen egg-white lysozyme and dihydrofolate reductase. Therefore, this work shows the feasibility of using experimental native structures at different pressures to analyze the global effects of this physical property on the protein folding process.
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Affiliation(s)
- Beatriz Fernández Del Río
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
| | - Antonio Rey
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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4
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Implicit water model within the Zimm-Bragg approach to analyze experimental data for heat and cold denaturation of proteins. Commun Chem 2021; 4:57. [PMID: 36697562 PMCID: PMC9814862 DOI: 10.1038/s42004-021-00499-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 03/16/2021] [Indexed: 02/02/2023] Open
Abstract
Studies of biopolymer conformations essentially rely on theoretical models that are routinely used to process and analyze experimental data. While modern experiments allow study of single molecules in vivo, corresponding theories date back to the early 1950s and require an essential update to include the recent significant progress in the description of water. The Hamiltonian formulation of the Zimm-Bragg model we propose includes a simplified, yet explicit model of water-polypeptide interactions that transforms into the equivalent implicit description after performing the summation of solvent degrees of freedom in the partition function. Here we show that our model fits very well to the circular dichroism experimental data for both heat and cold denaturation and provides the energies of inter- and intra-molecular H-bonds, unavailable with other processing methods. The revealed delicate balance between these energies determines the conditions for the existence of cold denaturation and thus clarifies its absence in some proteins.
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5
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Su Z, Alavi S, Ripmeester JA, Wolosh G, Dias CL. Methane Clathrate Formation is Catalyzed and Kinetically Inhibited by the Same Molecule: Two Facets of Methanol. J Phys Chem B 2021; 125:4162-4168. [PMID: 33861613 DOI: 10.1021/acs.jpcb.1c01274] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here, we perform molecular dynamics simulations to provide atomic-level insights into the dual roles of methanol in enhancing and delaying the rate of methane clathrate hydrate nucleation. Consistent with experiments, we find that methanol slows clathrate hydrate nucleation above 250 K but promotes clathrate formation at temperatures below 250 K. We show that this behavior can be rationalized by the unusual temperature dependence of the methane-methanol interaction in an aqueous solution, which emerges due to the hydrophobic effect. In addition to its antifreeze properties at temperatures above 250 K, methanol competes with water to interact with methane prior to the formation of clathrate nuclei. Below 250 K, methanol encourages water to occupy the space between methane molecules favoring clathrate formation and it may additionally promote water mobility.
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Affiliation(s)
- Zhaoqian Su
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Saman Alavi
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - John A Ripmeester
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - Gedaliah Wolosh
- New Jersey Institute of Technology, Academic and Research Computing Systems, University Heights, Newark, New Jersey 07102, United States
| | - Cristiano L Dias
- New Jersey Institute of Technology, Department of Physics, University Heights, Newark, New Jersey 07102, United States
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6
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Fetahaj Z, Ostermeier L, Cinar H, Oliva R, Winter R. Biomolecular Condensates under Extreme Martian Salt Conditions. J Am Chem Soc 2021; 143:5247-5259. [PMID: 33755443 DOI: 10.1021/jacs.1c01832] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Biomolecular condensates formed by liquid-liquid phase separation (LLPS) are considered one of the early compartmentalization strategies of cells, which still prevail today forming nonmembranous compartments in biological cells. Studies of the effect of high pressures, such as those encountered in the subsurface salt lakes of Mars or in the depths of the subseafloor on Earth, on biomolecular LLPS will contribute to questions of protocell formation under prebiotic conditions. We investigated the effects of extreme environmental conditions, focusing on highly aggressive Martian salts (perchlorate and sulfate) and high pressure, on the formation of biomolecular condensates of proteins. Our data show that the driving force for phase separation of proteins is not only sensitively dictated by their amino acid sequence but also strongly influenced by the type of salt and its concentration. At high salinity, as encountered in Martian soil and similar harsh environments on Earth, attractive short-range interactions, ion correlation effects, hydrophobic, and π-driven interactions can sustain LLPS for suitable polypeptide sequences. Our results also show that salts across the Hofmeister series have a differential effect on shifting the boundary of immiscibility that determines phase separation. In addition, we show that confinement mimicking cracks in sediments and subsurface saline water pools in the Antarctica or on Mars can dramatically stabilize liquid phase droplets, leading to an increase in the temperature and pressure stability of the droplet phase.
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Affiliation(s)
- Zamira Fetahaj
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Street 4a, 44227 Dortmund, Germany
| | - Lena Ostermeier
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Street 4a, 44227 Dortmund, Germany
| | - Hasan Cinar
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Street 4a, 44227 Dortmund, Germany
| | - Rosario Oliva
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Street 4a, 44227 Dortmund, Germany
| | - Roland Winter
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Street 4a, 44227 Dortmund, Germany
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7
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Bogunia M, Makowski M. Influence of Ionic Strength on Hydrophobic Interactions in Water: Dependence on Solute Size and Shape. J Phys Chem B 2020; 124:10326-10336. [PMID: 33147018 PMCID: PMC7681779 DOI: 10.1021/acs.jpcb.0c06399] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
Hydrophobicity is a phenomenon of
great importance in biology,
chemistry, and biochemistry. It is defined as the interaction between
nonpolar molecules or groups in water and their low solubility. Hydrophobic
interactions affect many processes in water, for example, complexation,
surfactant aggregation, and coagulation. These interactions play a
pivotal role in the formation and stability of proteins or biological
membranes. In the present study, we assessed the effect of ionic strength,
solute size, and shape on hydrophobic interactions between pairs of
nonpolar particles. Pairs of methane, neopentane, adamantane, fullerene,
ethane, propane, butane, hexane, octane, and decane were simulated
by molecular dynamics in AMBER 16.0 force field. As a solvent, TIP3P
and TIP4PEW water models were used. Potential of mean force (PMF)
plots of these dimers were determined at four values of ionic strength,
0, 0.04, 0.08, and 0.40 mol/dm3, to observe its impact
on hydrophobic interactions. The characteristic shape of PMFs with
three extrema (contact minimum, solvent-separated minimum, and desolvation
maximum) was observed for most of the compounds for hydrophobic interactions.
Ionic strength affected hydrophobic interactions. We observed a tendency
to deepen contact minima with an increase in ionic strength value
in the case of spherical and spheroidal molecules. Additionally, two-dimensional
distribution functions describing water density and average number
of hydrogen bonds between water molecules were calculated in both
water models for adamantane and hexane. It was observed that the density
of water did not significantly change with the increase in ionic strength,
but the average number of hydrogen bonds changed. The latter tendency
strongly depends on the water model used for simulations.
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Affiliation(s)
- Małgorzata Bogunia
- Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Mariusz Makowski
- Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland
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8
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The effects of cosolutes and crowding on the kinetics of protein condensate formation based on liquid-liquid phase separation: a pressure-jump relaxation study. Sci Rep 2020; 10:17245. [PMID: 33057154 PMCID: PMC7566631 DOI: 10.1038/s41598-020-74271-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/15/2020] [Indexed: 01/21/2023] Open
Abstract
Biomolecular assembly processes based on liquid-liquid phase separation (LLPS) are ubiquitous in the biological cell. To fully understand the role of LLPS in biological self-assembly, it is necessary to characterize also their kinetics of formation and dissolution. Here, we introduce the pressure-jump relaxation technique in concert with UV/Vis and FTIR spectroscopy as well as light microscopy to characterize the evolution of LLPS formation and dissolution in a time-dependent manner. As a model system undergoing LLPS we used the globular eye-lens protein γD-crystallin. As cosolutes and macromolecular crowding are known to affect the stability and dynamics of biomolecular condensates in cellulo, we extended our kinetic study by addressing also the impact of urea, the deep-sea osmolyte trimethylamine-N-oxide (TMAO) and a crowding agent on the transformation kinetics of the LLPS system. As a prerequisite for the kinetic studies, the phase diagram of γD-crystallin at the different solution conditions also had to be determined. The formation of the droplet phase was found to be a very rapid process and can be switched on and off on the 1-4 s timescale. Theoretical treatment using the Johnson-Mehl-Avrami-Kolmogorov model indicates that the LLPS proceeds via a diffusion-limited nucleation and growth mechanism at subcritical protein concentrations, a scenario which is also expected to prevail within biologically relevant crowded systems. Compared to the marked effect the cosolutes take on the stability of the LLPS region, their effect at biologically relevant concentrations on the phase transformation kinetics is very small, which might be a particular advantage in the cellular context, as a fast switching capability of the transition should not be compromised by the presence of cellular cosolutes.
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9
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Stenzoski NE, Zou J, Piserchio A, Ghose R, Holehouse AS, Raleigh DP. The Cold-Unfolded State Is Expanded but Contains Long- and Medium-Range Contacts and Is Poorly Described by Homopolymer Models. Biochemistry 2020; 59:3290-3299. [PMID: 32786415 DOI: 10.1021/acs.biochem.0c00469] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cold unfolding of proteins is predicted by the Gibbs-Helmholtz equation and is thought to be driven by a strongly temperature-dependent interaction of protein nonpolar groups with water. Studies of the cold-unfolded state provide insight into protein energetics, partially structured states, and folding cooperativity and are of practical interest in biotechnology. However, structural characterization of the cold-unfolded state is much less extensive than studies of thermally or chemically denatured unfolded states, in large part because the midpoint of the cold unfolding transition is usually below freezing. We exploit a rationally designed point mutation (I98A) in the hydrophobic core of the C-terminal domain of the ribosomal protein L9 that allows the cold denatured state ensemble to be observed above 0 °C at near neutral pH and ambient pressure in the absence of added denaturants. A combined approach consisting of paramagnetic relaxation enhancement measurements, analysis of small-angle X-ray scattering data, all-atom simulations, and polymer theory provides a detailed description of the cold-unfolded state. Despite a globally expanded ensemble, as determined by small-angle X-ray scattering, sequence-specific medium- and long-range interactions in the cold-unfolded state give rise to deviations from homopolymer-like behavior. Our results reveal that the cold-denatured state is heterogeneous with local and long-range intramolecular interactions that may prime the folded state and also demonstrate that significant long-range interactions are compatible with expanded unfolded ensembles. The work also highlights the limitations of homopolymer-based descriptions of unfolded states of proteins.
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Affiliation(s)
- Natalie E Stenzoski
- Graduate Program in Biochemistry & Structural Biology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Junjie Zou
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York 10031, United States
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York 10031, United States.,Graduate Programs in Biochemistry, Chemistry and Physics, The Graduate Center of CUNY, New York, New York 10016, United States
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, United States.,Center for Science and Engineering of Living Systems, Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Daniel P Raleigh
- Graduate Program in Biochemistry & Structural Biology, Stony Brook University, Stony Brook, New York 11794-3400, United States.,Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.,Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
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10
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Cinar H, Oliva R, Lin Y, Chen X, Zhang M, Chan HS, Winter R. Pressure Sensitivity of SynGAP/PSD-95 Condensates as a Model for Postsynaptic Densities and Its Biophysical and Neurological Ramifications. Chemistry 2020; 26:11024-11031. [PMID: 31910298 PMCID: PMC7496680 DOI: 10.1002/chem.201905269] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Indexed: 12/11/2022]
Abstract
Biomolecular condensates consisting of proteins and nucleic acids can serve critical biological functions, so that some condensates are referred as membraneless organelles. They can also be disease-causing, if their assembly is misregulated. A major physicochemical basis of the formation of biomolecular condensates is liquid-liquid phase separation (LLPS). In general, LLPS depends on environmental variables, such as temperature and hydrostatic pressure. The effects of pressure on the LLPS of a binary SynGAP/PSD-95 protein system mimicking postsynaptic densities, which are protein assemblies underneath the plasma membrane of excitatory synapses, were investigated. Quite unexpectedly, the model system LLPS is much more sensitive to pressure than the folded states of typical globular proteins. Phase-separated droplets of SynGAP/PSD-95 were found to dissolve into a homogeneous solution already at ten-to-hundred bar levels. The pressure sensitivity of SynGAP/PSD-95 is seen here as a consequence of both pressure-dependent multivalent interaction strength and void volume effects. Considering that organisms in the deep sea are under pressures up to about 1 kbar, this implies that deep-sea organisms have to devise means to counteract this high pressure sensitivity of biomolecular condensates to avoid harm. Intriguingly, these findings may shed light on the biophysical underpinning of pressure-related neurological disorders in terrestrial vertebrates.
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Affiliation(s)
- Hasan Cinar
- Physical Chemistry I—Biophysical ChemistryFaculty of Chemistry and Chemical BiologyTU DortmundOtto-Hahn-Strasse 4a44227DortmundGermany
| | - Rosario Oliva
- Physical Chemistry I—Biophysical ChemistryFaculty of Chemistry and Chemical BiologyTU DortmundOtto-Hahn-Strasse 4a44227DortmundGermany
| | - Yi‐Hsuan Lin
- Department of BiochemistryFaculty of MedicineUniversity of TorontoTorontoOntarioM5S 1A8Canada
- Molecular MedicineHospital for Sick ChildrenTorontoOntarioM5G 0A4Canada
| | - Xudong Chen
- Division of Life ScienceState Key Laboratory of Molecular NeuroscienceHong Kong University of Science and TechnologyClear Water BayKowloon, Hong KongChina
| | - Mingjie Zhang
- Division of Life ScienceState Key Laboratory of Molecular NeuroscienceHong Kong University of Science and TechnologyClear Water BayKowloon, Hong KongChina
| | - Hue Sun Chan
- Department of BiochemistryFaculty of MedicineUniversity of TorontoTorontoOntarioM5S 1A8Canada
| | - Roland Winter
- Physical Chemistry I—Biophysical ChemistryFaculty of Chemistry and Chemical BiologyTU DortmundOtto-Hahn-Strasse 4a44227DortmundGermany
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11
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Abstract
Biological phase separation is known to be important for cellular organization, which has recently been extended to a new class of biomolecules that form liquid-like droplets coexisting with the surrounding cellular or extracellular environment. These droplets are termed membraneless organelles, as they lack a dividing lipid membrane, and are formed through liquid-liquid phase separation (LLPS). Elucidating the molecular determinants of phase separation is a critical challenge for the field, as we are still at the early stages of understanding how cells may promote and regulate functions that are driven by LLPS. In this review, we discuss the role that disorder, perturbations to molecular interactions resulting from sequence, posttranslational modifications, and various regulatory stimuli play on protein LLPS, with a particular focus on insights that may be obtained from simulation and theory. We finally discuss how these molecular driving forces alter multicomponent phase separation and selectivity.
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Affiliation(s)
- Gregory L Dignon
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA;
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, USA;
| | - Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Jeetain Mittal
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA;
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12
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Gasic AG, Cheung MS. A Tale of Two Desolvation Potentials: An Investigation of Protein Behavior under High Hydrostatic Pressure. J Phys Chem B 2020; 124:1619-1627. [DOI: 10.1021/acs.jpcb.9b10734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Andrei G. Gasic
- Department of Physics, University of Houston, Houston, Texas 77204, United States
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Margaret S. Cheung
- Department of Physics, University of Houston, Houston, Texas 77204, United States
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
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13
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Bianco V, Franzese G, Coluzza I. In Silico Evidence That Protein Unfolding is a Precursor of Protein Aggregation. Chemphyschem 2020; 21:377-384. [DOI: 10.1002/cphc.201900904] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/01/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Valentino Bianco
- Faculty of Chemistry, Chemical Physics Department, Universidad Complutense de Madrid, Plaza de las Ciencias Ciudad Universitaria Madrid 28040 Spain
| | - Giancarlo Franzese
- Secció de Física Estadística i Interdisciplinària-Departament de Física de la Matèria Condensada, Facultat de Física & Institute of Nanoscience and Nanotechnology (IN2UB) Universitat de Barcelona Martí i Franquès 1 08028 Barcelona Spain
| | - Ivan Coluzza
- CIC biomaGUNE Paseo Miramon 182 20014 San Sebastian Spain
- IKERBASQUE, Basque Foundation for Science 48013 Bilbao Spain
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14
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Parui S, Jana B. Relative Solvent Exposure of the Alpha-Helix and Beta-Sheet in Water Determines the Initial Stages of Urea and Guanidinium Chloride-Induced Denaturation of Alpha/Beta Proteins. J Phys Chem B 2019; 123:8889-8900. [DOI: 10.1021/acs.jpcb.9b06859] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Sridip Parui
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Biman Jana
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
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15
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Gasic AG, Boob MM, Prigozhin MB, Homouz D, Wirth AJ, Daugherty CM, Gruebele M, Cheung MS. Critical phenomena in the temperature-pressure-crowding phase diagram of a protein. PHYSICAL REVIEW. X 2019; 9:041035. [PMID: 32642303 PMCID: PMC7343146 DOI: 10.1103/physrevx.9.041035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In the cell, proteins fold and perform complex functions through global structural rearrangements. Function requires a protein to be at the brink of stability to be susceptible to small environmental fluctuations, yet stable enough to maintain structural integrity. These apparently conflicting behaviors are exhibited by systems near a critical point, where distinct phases merge-a concept beyond previous studies indicating proteins have a well-defined folded/unfolded phase boundary in the pressure-temperature plane. Here, by modeling the protein phosphoglycerate kinase (PGK) on the temperature (T), pressure (P), and crowding volume-fraction (ϕ) phase diagram, we demonstrate a critical transition where phases merge, and PGK exhibits large structural fluctuations. Above the critical point, the difference between the intermediate and unfolded phases disappears. When ϕ increases, the critical point moves to lower T c. We verify the calculations with experiments mapping the T-P-ϕ space, which likewise reveal a critical point at 305 K and 170 MPa that moves to lower T c as ϕ increases. Crowding places PGK near a critical line in its natural parameter space, where large conformational changes can occur without costly free energy barriers. Specific structures are proposed for each phase based on simulation.
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Affiliation(s)
- Andrei G. Gasic
- University of Houston, Department of Physics, Houston, Texas, 77204, United States
- Center for Theoretical Biological Physics, Rice University, 77005, United States
| | - Mayank M. Boob
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Champaign, IL 61801, United States
| | - Maxim B. Prigozhin
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, IL, 61801, United States
| | - Dirar Homouz
- University of Houston, Department of Physics, Houston, Texas, 77204, United States
- Center for Theoretical Biological Physics, Rice University, 77005, United States
- Khalifa University of Science and Technology, Department of Physics, P.O. Box 127788, Abu Dhabi, United Arab Emirates
| | - Anna Jean Wirth
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, IL, 61801, United States
| | - Caleb M. Daugherty
- University of Houston, Department of Physics, Houston, Texas, 77204, United States
- Center for Theoretical Biological Physics, Rice University, 77005, United States
| | - Martin Gruebele
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Champaign, IL 61801, United States
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, IL, 61801, United States
- Department of Physics and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Champaign, IL 61801, United States
| | - Margaret S. Cheung
- University of Houston, Department of Physics, Houston, Texas, 77204, United States
- Center for Theoretical Biological Physics, Rice University, 77005, United States
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16
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Cinar H, Fetahaj Z, Cinar S, Vernon RM, Chan HS, Winter RHA. Temperature, Hydrostatic Pressure, and Osmolyte Effects on Liquid-Liquid Phase Separation in Protein Condensates: Physical Chemistry and Biological Implications. Chemistry 2019; 25:13049-13069. [PMID: 31237369 DOI: 10.1002/chem.201902210] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/23/2019] [Indexed: 01/04/2023]
Abstract
Liquid-liquid phase separation (LLPS) of proteins and other biomolecules play a critical role in the organization of extracellular materials and membrane-less compartmentalization of intra-organismal spaces through the formation of condensates. Structural properties of such mesoscopic droplet-like states were studied by spectroscopy, microscopy, and other biophysical techniques. The temperature dependence of biomolecular LLPS has been studied extensively, indicating that phase-separated condensed states of proteins can be stabilized or destabilized by increasing temperature. In contrast, the physical and biological significance of hydrostatic pressure on LLPS is less appreciated. Summarized here are recent investigations of protein LLPS under pressures up to the kbar-regime. Strikingly, for the cases studied thus far, LLPSs of both globular proteins and intrinsically disordered proteins/regions are typically more sensitive to pressure than the folding of proteins, suggesting that organisms inhabiting the deep sea and sub-seafloor sediments, under pressures up to 1 kbar and beyond, have to mitigate this pressure-sensitivity to avoid unwanted destabilization of their functional biomolecular condensates. Interestingly, we found that trimethylamine-N-oxide (TMAO), an osmolyte upregulated in deep-sea fish, can significantly stabilize protein droplets under pressure, pointing to another adaptive advantage for increased TMAO concentrations in deep-sea organisms besides the osmolyte's stabilizing effect against protein unfolding. As life on Earth might have originated in the deep sea, pressure-dependent LLPS is pertinent to questions regarding prebiotic proto-cells. Herein, we offer a conceptual framework for rationalizing the recent experimental findings and present an outline of the basic thermodynamics of temperature-, pressure-, and osmolyte-dependent LLPS as well as a molecular-level statistical mechanics picture in terms of solvent-mediated interactions and void volumes.
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Affiliation(s)
- Hasan Cinar
- Physical Chemistry I-Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Strasse 4a, 44227, Dortmund, Germany
| | - Zamira Fetahaj
- Physical Chemistry I-Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Strasse 4a, 44227, Dortmund, Germany
| | - Süleyman Cinar
- Physical Chemistry I-Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Strasse 4a, 44227, Dortmund, Germany
| | - Robert M Vernon
- Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, M5G 0A4, Canada
| | - Hue Sun Chan
- Department of Biochemistry, Faculty of Medicine, University of Toronto, Ontario, M5S 1A8, Canada.,Department of Molecular Genetics, Faculty of Medicine, University of Toronto, Ontario, M5S 1A8, Canada
| | - Roland H A Winter
- Physical Chemistry I-Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Strasse 4a, 44227, Dortmund, Germany
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17
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Peterson KI, Pullman DP, Lin W, Minei AJ, Arsenault EA, Novick SE. Structure and Dynamics of the Methane-Propane van der Waals Complex. J Phys Chem A 2019; 123:5274-5282. [DOI: 10.1021/acs.jpca.9b02486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karen I. Peterson
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Road, San Diego, California 92182-1030, United States
| | - D. P. Pullman
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Road, San Diego, California 92182-1030, United States
| | - Wei Lin
- Department of Chemistry, University of Texas Rio Grande Valley, Brownsville, Texas, United States
| | - Andrea J. Minei
- Department of Chemistry and Biochemistry, Division of Natural Sciences, College of Mount Saint Vincent, 6301 Riverdale Avenue, Riverdale, New York 10471, United States
| | - Eric A. Arsenault
- Department of Chemistry, Wesleyan University, 52 Lawn Avenue, Middletown, Connecticut 06459, United States
| | - Stewart E. Novick
- Department of Chemistry, Wesleyan University, 52 Lawn Avenue, Middletown, Connecticut 06459, United States
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18
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Dignon G, Zheng W, Kim YC, Mittal J. Temperature-Controlled Liquid-Liquid Phase Separation of Disordered Proteins. ACS CENTRAL SCIENCE 2019; 5:821-830. [PMID: 31139718 PMCID: PMC6535772 DOI: 10.1021/acscentsci.9b00102] [Citation(s) in RCA: 150] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Indexed: 05/18/2023]
Abstract
The liquid-liquid phase separation (LLPS) of intrinsically disordered proteins (IDPs) is a commonly observed phenomenon within the cell, and such condensates are also highly attractive for applications in biomaterials and drug delivery. A better understanding of the sequence-dependent thermoresponsive behavior is of immense interest as it will aid in the design of protein sequences with desirable properties and in the understanding of cellular response to heat stress. In this work, we use a transferable coarse-grained model to directly probe the sequence-dependent thermoresponsive phase behavior of IDPs. To achieve this goal, we develop a unique knowledge-based amino acid potential that accounts for the temperature-dependent effects on solvent-mediated interactions for different types of amino acids. Remarkably, we are able to distinguish between more than 35 IDPs with upper or lower critical solution temperatures at experimental conditions, thus providing direct evidence that incorporating the temperature-dependent solvent-mediated interactions to IDP assemblies can capture the difference in the shape of the resulting phase diagrams. Given the success of the model in predicting experimental behavior, we use it as a high-throughput screening framework to scan through millions of disordered sequences to characterize the composition dependence of protein phase separation.
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Affiliation(s)
- Gregory
L. Dignon
- Department
of Chemical and Biomolecular Engineering, Lehigh University, 111 Research Drive, Bethlehem, Pennsylvania 18015, United States
| | - Wenwei Zheng
- College
of Integrative Sciences and Arts, Arizona
State University, Mesa, Arizona 85212, United
States
| | - Young C. Kim
- Center
for Materials Physics and Technology, Naval
Research Laboratory, Washington, D.C. 20375, United States
| | - Jeetain Mittal
- Department
of Chemical and Biomolecular Engineering, Lehigh University, 111 Research Drive, Bethlehem, Pennsylvania 18015, United States
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19
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Cinar S, Cinar H, Chan HS, Winter R. Pressure-Sensitive and Osmolyte-Modulated Liquid–Liquid Phase Separation of Eye-Lens γ-Crystallins. J Am Chem Soc 2019; 141:7347-7354. [DOI: 10.1021/jacs.8b13636] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Süleyman Cinar
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Strasse 4a, 44227 Dortmund, Germany
| | - Hasan Cinar
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Strasse 4a, 44227 Dortmund, Germany
| | - Hue Sun Chan
- Departments of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Roland Winter
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Strasse 4a, 44227 Dortmund, Germany
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20
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Lin Y, McCarty J, Rauch JN, Delaney KT, Kosik KS, Fredrickson GH, Shea JE, Han S. Narrow equilibrium window for complex coacervation of tau and RNA under cellular conditions. eLife 2019; 8:e42571. [PMID: 30950394 PMCID: PMC6450672 DOI: 10.7554/elife.42571] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 03/06/2019] [Indexed: 12/28/2022] Open
Abstract
The mechanism that leads to liquid-liquid phase separation (LLPS) of the tau protein, whose pathological aggregation is implicated in neurodegenerative disorders, is not well understood. Establishing a phase diagram that delineates the boundaries of phase co-existence is key to understanding whether LLPS is an equilibrium or intermediate state. We demonstrate that tau and RNA reversibly form complex coacervates. While the equilibrium phase diagram can be fit to an analytical theory, a more advanced model is investigated through field theoretic simulations (FTS) that provided direct insight into the thermodynamic driving forces of tau LLPS. Together, experiment and simulation reveal that tau-RNA LLPS is stable within a narrow equilibrium window near physiological conditions over experimentally tunable parameters including temperature, salt and tau concentrations, and is entropy-driven. Guided by our phase diagram, we show that tau can be driven toward LLPS under live cell coculturing conditions with rationally chosen experimental parameters.
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Affiliation(s)
- Yanxian Lin
- Biomolecular Science and EngineeringUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - James McCarty
- Department of Chemistry and BiochemistryUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - Jennifer N Rauch
- Department of Molecular, Cellular and Developmental BiologyUniversity of California Santa BarbaraSanta BarbaraUnited States
- Neuroscience Research InstituteUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - Kris T Delaney
- Materials Research LaboratoryUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - Kenneth S Kosik
- Department of Molecular, Cellular and Developmental BiologyUniversity of California Santa BarbaraSanta BarbaraUnited States
- Neuroscience Research InstituteUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - Glenn H Fredrickson
- Materials Research LaboratoryUniversity of California Santa BarbaraSanta BarbaraUnited States
- Department of Chemical EngineeringUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - Joan-Emma Shea
- Department of Chemistry and BiochemistryUniversity of California Santa BarbaraSanta BarbaraUnited States
- Department of PhysicsUniversity of California Santa BarbaraSanta BarbaraUnited States
| | - Songi Han
- Department of Chemistry and BiochemistryUniversity of California Santa BarbaraSanta BarbaraUnited States
- Department of Chemical EngineeringUniversity of California Santa BarbaraSanta BarbaraUnited States
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21
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Parui S, Jana B. Factors Promoting the Formation of Clathrate-Like Ordering of Water in Biomolecular Structure at Ambient Temperature and Pressure. J Phys Chem B 2019; 123:811-824. [PMID: 30605607 DOI: 10.1021/acs.jpcb.8b11172] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Clathrate hydrate forms when a hydrophobic molecule is entrapped inside a water cage or cavity. Although biomolecular structures also have hydrophobic patches, clathrate-like water is found in only a limited number of biomolecules. Also, while clathrate hydrates form at low temperature and moderately higher pressure, clathrate-like water is observed in biomolecular structure at ambient temperature and pressure. These indicate presence of other factors along with hydrophobic environment behind the formation of clathrate-like water in biomolecules. In the current study, we presented a systematic approach to explore the factors behind the formation of clathrate-like water in biomolecules by means of molecular dynamics simulation of a model protein, maxi, which is a naturally occurring nanopore and has clathrate-like water inside the pore. Removal of either confinement or hydrophobic environment results in the disappearance of clathrate-like water ordering, indicating a coupled role of these two factors. Apart from these two factors, clathrate-like water ordering also requires anchoring groups that can stabilize the clathrate-like water through hydrogen bonding. Our results uncover crucial factors for the stabilization of clathrate-like ordering in biomolecular structure which can be used for the development of new biomolecular structure promoting clathrate formation.
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Affiliation(s)
- Sridip Parui
- School of Chemical Sciences , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India
| | - Biman Jana
- School of Chemical Sciences , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India
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22
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Das S, Amin AN, Lin YH, Chan HS. Coarse-grained residue-based models of disordered protein condensates: utility and limitations of simple charge pattern parameters. Phys Chem Chem Phys 2018; 20:28558-28574. [PMID: 30397688 DOI: 10.1039/c8cp05095c] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Biomolecular condensates undergirded by phase separations of proteins and nucleic acids serve crucial biological functions. To gain physical insights into their genetic basis, we study how liquid-liquid phase separation (LLPS) of intrinsically disordered proteins (IDPs) depends on their sequence charge patterns using a continuum Langevin chain model wherein each amino acid residue is represented by a single bead. Charge patterns are characterized by the "blockiness" measure κ and the "sequence charge decoration" (SCD) parameter. Consistent with random phase approximation (RPA) theory and lattice simulations, LLPS propensity as characterized by critical temperature Tcr* increases with increasingly negative SCD for a set of sequences showing a positive correlation between κ and -SCD. Relative to RPA, the simulated sequence-dependent variation in Tcr* is often-though not always-smaller, whereas the simulated critical volume fractions are higher. However, for a set of sequences exhibiting an anti-correlation between κ and -SCD, the simulated Tcr*'s are quite insensitive to either parameter. Additionally, we find that blocky sequences that allow for strong electrostatic repulsion can lead to coexistence curves with upward concavity as stipulated by RPA, but the LLPS propensity of a strictly alternating charge sequence was likely overestimated by RPA and lattice models because interchain stabilization of this sequence requires spatial alignments that are difficult to achieve in real space. These results help delineate the utility and limitations of the charge pattern parameters and of RPA, pointing to further efforts necessary for rationalizing the newly observed subtleties.
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Affiliation(s)
- Suman Das
- Department of Biochemistry, University of Toronto, Medical Sciences Building - 5th Fl., 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
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23
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Parui S, Jana B. Molecular Insights into the Unusual Structure of an Antifreeze Protein with a Hydrated Core. J Phys Chem B 2018; 122:9827-9839. [PMID: 30286600 DOI: 10.1021/acs.jpcb.8b05350] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The primary driving force for protein folding is the formation of a well-packed, anhydrous core. However, recently, the crystal structure of an antifreeze protein, maxi, has been resolved where the core of the protein is filled with water, which apparently contradicts the existing notion of protein folding. Here, we have performed standard molecular dynamics (MD) simulation, replica exchange MD (REMD) simulation, and umbrella sampling using TIP4P water at various temperatures (300, 260, and 240 K) to explore the origin of this unusual structural feature. It is evident from standard MD and REMD simulations that the protein is found to be stable at 240 K in its unusual state. The core of protein has two layers of semi-clathrate water separating the methyl groups of alanine residues from different helical strands. However, with increasing temperature (260 and 300 K), the stability decreases as the core becomes dehydrated, and methyl groups of alanine are tightly packed driven by hydrophobic interactions. Calculation of the potential of mean force by an umbrella sampling technique between a pair of model hydrophobes resembling maxi protein at 240 K shows the stabilization of second solvent-separated minima (SSM), which provides a thermodynamic rationale of the unusual structural feature in terms of weakening of the hydrophobic interaction. Because the stabilization of SSMs is implicated for cold denaturation, it suggests that the maxi protein is so designed by nature where the cold denatured-like state becomes the biologically active form as it works near or below the freezing point of water.
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Affiliation(s)
- Sridip Parui
- Department of Physical Chemistry , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India
| | - Biman Jana
- Department of Physical Chemistry , Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032 , India
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24
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Cinar H, Cinar S, Chan HS, Winter R. Pressure-Induced Dissolution and Reentrant Formation of Condensed, Liquid-Liquid Phase-Separated Elastomeric α-Elastin. Chemistry 2018; 24:8286-8291. [PMID: 29738068 DOI: 10.1002/chem.201801643] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/07/2018] [Indexed: 02/05/2023]
Abstract
We investigated the combined effects of temperature and pressure on liquid-liquid phase separation (LLPS) phenomena of α-elastin up to the multi-kbar regime. FT-IR spectroscopy, CD, UV/Vis absorption, phase-contrast light and fluorescence microscopy techniques were employed to reveal structural changes and mesoscopic phase states of the system. A novel pressure-induced reentrant LLPS was observed in the intermediate temperature range. A molecular-level picture, in particular on the role of hydrophobic interactions, hydration, and void volume in controlling LLPS phenomena is presented. The potential role of the LLPS phenomena in the development of early cellular compartmentalization is discussed, which might have started in the deep sea, where pressures up to the kbar level are encountered.
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Affiliation(s)
- Hasan Cinar
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
| | - Süleyman Cinar
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
| | - Hue Sun Chan
- Departments of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Roland Winter
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn-Strasse 4a, 44227, Dortmund, Germany
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25
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Su Z, Ravindhran G, Dias CL. Effects of Trimethylamine-N-oxide (TMAO) on Hydrophobic and Charged Interactions. J Phys Chem B 2018; 122:5557-5566. [DOI: 10.1021/acs.jpcb.7b11847] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Zhaoqian Su
- Department of Physics, New Jersey Institute of Technology, University Heights Newark, New Jersey 07102-1982, United States
| | - Gopal Ravindhran
- Department of Physics, New Jersey Institute of Technology, University Heights Newark, New Jersey 07102-1982, United States
| | - Cristiano L. Dias
- Department of Physics, New Jersey Institute of Technology, University Heights Newark, New Jersey 07102-1982, United States
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26
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Huynh L, Neale C, Pomès R, Chan HS. Molecular recognition and packing frustration in a helical protein. PLoS Comput Biol 2017; 13:e1005909. [PMID: 29261665 PMCID: PMC5757960 DOI: 10.1371/journal.pcbi.1005909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/08/2018] [Accepted: 11/28/2017] [Indexed: 01/25/2023] Open
Abstract
Biomolecular recognition entails attractive forces for the functional native states and discrimination against potential nonnative interactions that favor alternate stable configurations. The challenge posed by the competition of nonnative stabilization against native-centric forces is conceptualized as frustration. Experiment indicates that frustration is often minimal in evolved biological systems although nonnative possibilities are intuitively abundant. Much of the physical basis of minimal frustration in protein folding thus remains to be elucidated. Here we make progress by studying the colicin immunity protein Im9. To assess the energetic favorability of nonnative versus native interactions, we compute free energies of association of various combinations of the four helices in Im9 (referred to as H1, H2, H3, and H4) by extensive explicit-water molecular dynamics simulations (total simulated time > 300 μs), focusing primarily on the pairs with the largest native contact surfaces, H1-H2 and H1-H4. Frustration is detected in H1-H2 packing in that a nonnative packing orientation is significantly stabilized relative to native, whereas such a prominent nonnative effect is not observed for H1-H4 packing. However, in contrast to the favored nonnative H1-H2 packing in isolation, the native H1-H2 packing orientation is stabilized by H3 and loop residues surrounding H4. Taken together, these results showcase the contextual nature of molecular recognition, and suggest further that nonnative effects in H1-H2 packing may be largely avoided by the experimentally inferred Im9 folding transition state with native packing most developed at the H1-H4 rather than the H1-H2 interface. Biomolecules need to recognize one another with high specificity: promoting “native” functional intermolecular binding events while avoiding detrimental “nonnative” bound configurations; i.e., “frustration”—the tendency for nonnative interactions—has to be minimized. Folding of globular proteins entails a similar discrimination. To gain physical insight, we computed the binding affinities of helical structures of the protein Im9 in various native or nonnative configurations by atomic simulations, discovering that partial packing of the Im9 core is frustrated. This frustration is overcome when the entire core of the protein is assembled, consistent with experiment indicating no significant kinetic trapping in Im9 folding. Our systematic analysis thus reveals a subtle, contextual aspect of biomolecular recognition and provides a general approach to characterize folding frustration.
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Affiliation(s)
- Loan Huynh
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Chris Neale
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York, United States of America
| | - Régis Pomès
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- * E-mail: (HSC); (RP)
| | - Hue Sun Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (HSC); (RP)
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27
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de Oliveira GA, Silva JL. The push-and-pull hypothesis in protein unfolding, misfolding and aggregation. Biophys Chem 2017; 231:20-26. [DOI: 10.1016/j.bpc.2017.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 03/25/2017] [Accepted: 03/27/2017] [Indexed: 01/17/2023]
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28
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Bianco V, Pagès-Gelabert N, Coluzza I, Franzese G. How the stability of a folded protein depends on interfacial water properties and residue-residue interactions. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.08.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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29
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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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30
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Parui S, Jana B. Pairwise Hydrophobicity at Low Temperature: Appearance of a Stable Second Solvent-Separated Minimum with Possible Implication in Cold Denaturation. J Phys Chem B 2017; 121:7016-7026. [DOI: 10.1021/acs.jpcb.7b02676] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Sridip Parui
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Biman Jana
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
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31
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Lin YH, Song J, Forman-Kay JD, Chan HS. Random-phase-approximation theory for sequence-dependent, biologically functional liquid-liquid phase separation of intrinsically disordered proteins. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2016.09.090] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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32
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Krobath H, Chen T, Chan HS. Volumetric Physics of Polypeptide Coil–Helix Transitions. Biochemistry 2016; 55:6269-6281. [DOI: 10.1021/acs.biochem.6b00802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Heinrich Krobath
- Departments of Biochemistry
and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Tao Chen
- Departments of Biochemistry
and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Hue Sun Chan
- Departments of Biochemistry
and Molecular Genetics, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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33
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Sikosek T, Krobath H, Chan HS. Theoretical Insights into the Biophysics of Protein Bi-stability and Evolutionary Switches. PLoS Comput Biol 2016; 12:e1004960. [PMID: 27253392 PMCID: PMC4890782 DOI: 10.1371/journal.pcbi.1004960] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/04/2016] [Indexed: 11/18/2022] Open
Abstract
Deciphering the effects of nonsynonymous mutations on protein structure is central to many areas of biomedical research and is of fundamental importance to the study of molecular evolution. Much of the investigation of protein evolution has focused on mutations that leave a protein’s folded structure essentially unchanged. However, to evolve novel folds of proteins, mutations that lead to large conformational modifications have to be involved. Unraveling the basic biophysics of such mutations is a challenge to theory, especially when only one or two amino acid substitutions cause a large-scale conformational switch. Among the few such mutational switches identified experimentally, the one between the GA all-α and GB α+β folds is extensively characterized; but all-atom simulations using fully transferrable potentials have not been able to account for this striking switching behavior. Here we introduce an explicit-chain model that combines structure-based native biases for multiple alternative structures with a general physical atomic force field, and apply this construct to twelve mutants spanning the sequence variation between GA and GB. In agreement with experiment, we observe conformational switching from GA to GB upon a single L45Y substitution in the GA98 mutant. In line with the latent evolutionary potential concept, our model shows a gradual sequence-dependent change in fold preference in the mutants before this switch. Our analysis also indicates that a sharp GA/GB switch may arise from the orientation dependence of aromatic π-interactions. These findings provide physical insights toward rationalizing, predicting and designing evolutionary conformational switches. The biological functions of globular proteins are intimately related to their folded structures and their associated conformational fluctuations. Evolution of new structures is an important avenue to new functions. Although many mutations do not change the folded state, experiments indicate that a single amino acid substitution can lead to a drastic change in the folded structure. The physics of this switch-like behavior remains to be elucidated. Here we develop a computational model for the relevant physical forces, showing that mutations can lead to new folds by passing through intermediate sequences where the old and new folds occur with varying probabilities. Our approach helps provide a general physical account of conformational switching in evolution and mutational effects on conformational dynamics.
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Affiliation(s)
- Tobias Sikosek
- Departments of Biochemistry and Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Heinrich Krobath
- Departments of Biochemistry and Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Hue Sun Chan
- Departments of Biochemistry and Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Abstract
AbstractA general theory of hydrophobic hydration and pairwise hydrophobic interaction has been developed in the last years. The main ingredient is the recognition that: (a) cavity creation (necessary to insert a solute molecule into water) causes a solvent-excluded volume effect that leads to a loss in the translational entropy of water molecules; (b) the merging of two cavities (necessary to form the contact minimum configuration of two nonpolar molecules) causes a decrease in the solvent-excluded volume effect and so an increase in the translational entropy of water molecules. The performance of the theoretical approach is tested by reproducing both the hydration thermodynamics of xenon and the thermodynamics associated with the formation of the contact minimum configuration of two xenon atoms, over a large temperature range.
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Affiliation(s)
- Giuseppe Graziano
- 1Dipartimento di Scienze e Tecnologie, Università del Sannio, Via Port’Arsa 11 – 82100 Benevento, Italy
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Nguyen K, Whitford PC. Steric interactions lead to collective tilting motion in the ribosome during mRNA-tRNA translocation. Nat Commun 2016; 7:10586. [PMID: 26838673 PMCID: PMC4742886 DOI: 10.1038/ncomms10586] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 12/31/2015] [Indexed: 12/01/2022] Open
Abstract
Translocation of mRNA and tRNA through the ribosome is associated with large-scale rearrangements of the head domain in the 30S ribosomal subunit. To elucidate the relationship between 30S head dynamics and mRNA–tRNA displacement, we apply molecular dynamics simulations using an all-atom structure-based model. Here we provide a statistical analysis of 250 spontaneous transitions between the A/P–P/E and P/P–E/E ensembles. Consistent with structural studies, the ribosome samples a chimeric ap/P–pe/E intermediate, where the 30S head is rotated ∼18°. It then transiently populates a previously unreported intermediate ensemble, which is characterized by a ∼10° tilt of the head. To identify the origins of head tilting, we analyse 781 additional simulations in which specific steric features are perturbed. These calculations show that head tilting may be attributed to specific steric interactions between tRNA and the 30S subunit (PE loop and protein S13). Taken together, this study demonstrates how molecular structure can give rise to large-scale collective rearrangements. During protein elongation, the translocation of mRNA and tRNA molecules across the 30S ribosomal subunit is associated with large-scale motions of the 30S head domain. Here the authors carry out MD simulations to probe the associated steric interactions and identify novel tilting motions during the late stages of translocation.
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Affiliation(s)
- Kien Nguyen
- Department of Physics, Northeastern University, Dana Research Center 111, 360 Huntington Avenue, Boston, Massachusetts 02115, USA
| | - Paul C Whitford
- Department of Physics, Northeastern University, Dana Research Center 111, 360 Huntington Avenue, Boston, Massachusetts 02115, USA
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Rao Jampani S, Mahmoudinobar F, Su Z, Dias CL. Thermodynamics of Aβ16-21 dissociation from a fibril: Enthalpy, entropy, and volumetric properties. Proteins 2015; 83:1963-72. [PMID: 26264694 DOI: 10.1002/prot.24875] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 07/22/2015] [Accepted: 08/02/2015] [Indexed: 11/10/2022]
Abstract
Here, we provide insights into the thermodynamic properties of A β16-21 dissociation from an amyloid fibril using all-atom molecular dynamics simulations in explicit water. An umbrella sampling protocol is used to compute potentials of mean force (PMF) as a function of the distance ξ between centers-of-mass of the A β16-21 peptide and the preformed fibril at nine temperatures. Changes in the enthalpy and the entropic energy are determined from the temperature dependence of these PMF(s) and the average volume of the simulation box is computed as a function of ξ. We find that the PMF at 310 K is dominated by enthalpy while the entropic energy does not change significantly during dissociation. The volume of the system decreases during dissociation. Moreover, the magnitude of this volume change also decreases with increasing temperature. By defining dock and lock states using the solvent accessible surface area (SASA), we find that the behavior of the electrostatic energy is different in these two states. It increases (unfavorable) and decreases (favorable) during dissociation in lock and dock states, respectively, while the energy due to Lennard-Jones interactions increases continuously in these states. Our simulations also highlight the importance of hydrophobic interactions in accounting for the stability of A β16-21.
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Affiliation(s)
- Srinivasa Rao Jampani
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey, 07102-1982
| | - Farbod Mahmoudinobar
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey, 07102-1982
| | - Zhaoqian Su
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey, 07102-1982
| | - Cristiano L Dias
- Department of Physics, New Jersey Institute of Technology, Newark, New Jersey, 07102-1982
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37
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On the effect of hydrostatic pressure on the conformational stability of globular proteins. Biopolymers 2015; 103:711-8. [DOI: 10.1002/bip.22736] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 07/20/2015] [Accepted: 08/17/2015] [Indexed: 11/07/2022]
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Bianco V, Franzese G. Contribution of Water to Pressure and Cold Denaturation of Proteins. PHYSICAL REVIEW LETTERS 2015; 115:108101. [PMID: 26382703 DOI: 10.1103/physrevlett.115.108101] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Indexed: 05/28/2023]
Abstract
The mechanisms of cold and pressure denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here, we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.
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Affiliation(s)
- Valentino Bianco
- Departament de Física Fonamental, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
| | - Giancarlo Franzese
- Departament de Física Fonamental, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
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Chen T, Chan HS. Native contact density and nonnative hydrophobic effects in the folding of bacterial immunity proteins. PLoS Comput Biol 2015; 11:e1004260. [PMID: 26016652 PMCID: PMC4446218 DOI: 10.1371/journal.pcbi.1004260] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 03/29/2015] [Indexed: 11/18/2022] Open
Abstract
The bacterial colicin-immunity proteins Im7 and Im9 fold by different mechanisms. Experimentally, at pH 7.0 and 10°C, Im7 folds in a three-state manner via an intermediate but Im9 folding is two-state-like. Accordingly, Im7 exhibits a chevron rollover, whereas the chevron arm for Im9 folding is linear. Here we address the biophysical basis of their different behaviors by using native-centric models with and without additional transferrable, sequence-dependent energies. The Im7 chevron rollover is not captured by either a pure native-centric model or a model augmented by nonnative hydrophobic interactions with a uniform strength irrespective of residue type. By contrast, a more realistic nonnative interaction scheme that accounts for the difference in hydrophobicity among residues leads simultaneously to a chevron rollover for Im7 and an essentially linear folding chevron arm for Im9. Hydrophobic residues identified by published experiments to be involved in nonnative interactions during Im7 folding are found to participate in the strongest nonnative contacts in this model. Thus our observations support the experimental perspective that the Im7 folding intermediate is largely underpinned by nonnative interactions involving large hydrophobics. Our simulation suggests further that nonnative effects in Im7 are facilitated by a lower local native contact density relative to that of Im9. In a one-dimensional diffusion picture of Im7 folding with a coordinate- and stability-dependent diffusion coefficient, a significant chevron rollover is consistent with a diffusion coefficient that depends strongly on native stability at the conformational position of the folding intermediate. In order to fold correctly, a globular protein must avoid being trapped in wrong, i.e., nonnative conformations. Thus a biophysical account of how attractive nonnative interactions are bypassed by some amino acid sequences but not others is key to deciphering protein structure and function. We examine two closely related bacterial immunity proteins, Im7 and Im9, that are experimentally known to fold very differently: Whereas Im9 folds directly, Im7 folds through a mispacked conformational intermediate. A simple model we developed accounts for their intriguingly different folding kinetics in terms of a balance between the density of native-promoting contacts and the hydrophobicity of local amino acid sequences. This emergent principle is extensible to other biomolecular recognition processes.
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Affiliation(s)
- Tao Chen
- Departments of Biochemistry, of Molecular Genetics, and of Physics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Hue Sun Chan
- Departments of Biochemistry, of Molecular Genetics, and of Physics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- * E-mail:
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40
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Ashbaugh HS, Weiss K, Williams SM, Meng B, Surampudi LN. Temperature and Pressure Dependence of Methane Correlations and Osmotic Second Virial Coefficients in Water. J Phys Chem B 2015; 119:6280-94. [DOI: 10.1021/acs.jpcb.5b02056] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Henry S. Ashbaugh
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Katie Weiss
- Alfred University, Alfred, New York 14802, United States
| | - Steven M. Williams
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Bin Meng
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
| | - Lalitanand N. Surampudi
- Department
of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana 70118, United States
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Chen T, Song J, Chan HS. Theoretical perspectives on nonnative interactions and intrinsic disorder in protein folding and binding. Curr Opin Struct Biol 2014; 30:32-42. [PMID: 25544254 DOI: 10.1016/j.sbi.2014.12.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 12/02/2014] [Accepted: 12/02/2014] [Indexed: 11/29/2022]
Abstract
The diverse biological functions of intrinsically disordered proteins (IDPs) have markedly raised our appreciation of protein conformational versatility, whereas the existence of energetically favorable yet functional detrimental nonnative interactions underscores the physical limitations of evolutionary optimization. Here we survey recent advances in using biophysical modeling to gain insight into experimentally observed nonnative behaviors and IDP properties. Simulations of IDP interactions to date focus mostly on coupled folding-binding, which follows essentially the same organizing principle as the local-nonlocal coupling mechanism in cooperative folding of monomeric globular proteins. By contrast, more innovative theories of electrostatic and aromatic interactions are needed for the conceptually novel but less-explored 'fuzzy' complexes in which the functionally bound IDPs remain largely disordered.
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Affiliation(s)
- Tao Chen
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Jianhui Song
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Hue Sun Chan
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada.
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43
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Affiliation(s)
- Zhaoqian Su
- Physics Department, New Jersey Institute of Technology, Newark, New Jersey 07102-1982, United States
| | - Cristiano L. Dias
- Physics Department, New Jersey Institute of Technology, Newark, New Jersey 07102-1982, United States
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