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Ó'Fágáin C. Protein Stability: Enhancement and Measurement. Methods Mol Biol 2023; 2699:369-419. [PMID: 37647007 DOI: 10.1007/978-1-0716-3362-5_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
This chapter defines protein stability, emphasizes its importance, and surveys the field of protein stabilization, with summary reference to a selection of 2014-2021 publications. One can enhance stability, particularly by protein engineering strategies but also by chemical modification and by other means. General protocols are set out on how to measure a given protein's (i) kinetic thermal stability and (ii) oxidative stability and (iii) how to undertake chemical modification of a protein in solution.
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Affiliation(s)
- Ciarán Ó'Fágáin
- School of Biotechnology, Dublin City University, Dublin, Ireland.
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2
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The Thermodynamic Stability of Membrane Proteins in Micelles and Lipid Bilayers Investigated with the Ferrichrom Receptor FhuA. J Membr Biol 2022; 255:485-502. [PMID: 35552784 PMCID: PMC9581862 DOI: 10.1007/s00232-022-00238-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/05/2022] [Indexed: 12/03/2022]
Abstract
Extraction of integral membrane proteins into detergents for structural and functional studies often leads to a strong loss in protein stability. The impact of the lipid bilayer on the thermodynamic stability of an integral membrane protein in comparison to its solubilized form in detergent was examined and compared for FhuA from Escherichia coli and for a mutant, FhuAΔ5-160, lacking the N-terminal cork domain. Urea-induced unfolding was monitored by fluorescence spectroscopy to determine the effective free energies \documentclass[12pt]{minimal}
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\begin{document}$$ \Delta G{^\text{o}_{\rm u}} $$\end{document}ΔGuo of unfolding. To obtain enthalpic and entropic contributions of unfolding of FhuA, \documentclass[12pt]{minimal}
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\begin{document}$$ \Delta G{^\text{o}_{\rm u}} $$\end{document}ΔGuo were determined at various temperatures. When solubilized in LDAO detergent, wt-FhuA and FhuAΔ5-160 unfolded in a single step. The 155-residue cork domain stabilized wt-FhuA by \documentclass[12pt]{minimal}
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\begin{document}$$ \Delta\Delta G{^\text{o}_{\rm u}} $$\end{document}ΔΔGuo~ 40 kJ/mol. Reconstituted into lipid bilayers, wt-FhuA unfolded in two steps, while FhuAΔ5-160 unfolded in a single step, indicating an uncoupled unfolding of the cork domain. For FhuAΔ5-160 at 35 °C, \documentclass[12pt]{minimal}
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\begin{document}$$ \Delta G{^\text{o}_{\rm u}} $$\end{document}ΔGuo increased from ~ 5 kJ/mol in LDAO micelles to about ~ 20 kJ/mol in lipid bilayers, while the temperature of unfolding increased from TM ~ 49 °C in LDAO micelles to TM ~ 75 °C in lipid bilayers. Enthalpies \documentclass[12pt]{minimal}
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\begin{document}$$\Delta H{_{\rm M}^\text{o}}$$\end{document}ΔHMowere much larger than free energies \documentclass[12pt]{minimal}
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\begin{document}$$ \Delta G{^\text{o}_{\rm u}} $$\end{document}ΔGuo, for FhuAΔ5-160 and for wt-FhuA, and compensated by a large gain of entropy upon unfolding. The gain in conformational entropy is expected to be similar for unfolding of FhuA from micelles or bilayers. The strongly increased TM and \documentclass[12pt]{minimal}
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\begin{document}$$\Delta H{_{\rm M}^\text{o}}$$\end{document}ΔHMo observed for the lipid bilayer-reconstituted FhuA in comparison to the LDAO-solubilized forms, therefore, very likely arise from a much-increased solvation entropy of FhuA in bilayers.
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Evolution of Protein Structure and Stability in Global Warming. Int J Mol Sci 2020; 21:ijms21249662. [PMID: 33352933 PMCID: PMC7767258 DOI: 10.3390/ijms21249662] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/12/2022] Open
Abstract
This review focuses on the molecular signatures of protein structures in relation to evolution and survival in global warming. It is based on the premise that the power of evolutionary selection may lead to thermotolerant organisms that will repopulate the planet and continue life in general, but perhaps with different kinds of flora and fauna. Our focus is on molecular mechanisms, whereby known examples of thermoresistance and their physicochemical characteristics were noted. A comparison of interactions of diverse residues in proteins from thermophilic and mesophilic organisms, as well as reverse genetic studies, revealed a set of imprecise molecular signatures that pointed to major roles of hydrophobicity, solvent accessibility, disulfide bonds, hydrogen bonds, ionic and π-electron interactions, and an overall condensed packing of the higher-order structure, especially in the hydrophobic regions. Regardless of mutations, specialized protein chaperones may play a cardinal role. In evolutionary terms, thermoresistance to global warming will likely occur in stepwise mutational changes, conforming to the molecular signatures, such that each "intermediate" fits a temporary niche through punctuated equilibrium, while maintaining protein functionality. Finally, the population response of different species to global warming may vary substantially, and, as such, some may evolve while others will undergo catastrophic mass extinction.
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Yang G, Yu K, Kaitatzi CS, Singh A, Labahn J. Influence of solubilization and AD-mutations on stability and structure of human presenilins. Sci Rep 2017; 7:17970. [PMID: 29269939 PMCID: PMC5740079 DOI: 10.1038/s41598-017-18313-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 12/08/2017] [Indexed: 12/23/2022] Open
Abstract
Presenilin (PS1 or PS2) functions as the catalytic subunit of γ-secretase, which produces the toxic amyloid beta peptides in Alzheimer’s disease (AD). The dependence of folding and structural stability of PSs on the lipophilic environment and mutation were investigated by far UV CD spectroscopy. The secondary structure content and stability of PS2 depended on the lipophilic environment. PS2 undergoes a temperature-dependent structural transition from α-helical to β-structure at 331 K. The restructured protein formed structures which tested positive in spectroscopic amyloid fibrils assays. The AD mutant PS1L266F, PS1L424V and PS1ΔE9 displayed reduced stability which supports a proposed ‘loss of function’ mechanism of AD based on protein instability. The exon 9 coded sequence in the inhibitory loop of the zymogen was found to be required for the modulation of the thermal stability of PS1 by the lipophilic environment.
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Affiliation(s)
- Ge Yang
- Centre for Structural Systems Biology (CSSB), CSSB-FZJ, Notkestr. 85, 22607, Hamburg, Germany.,Institute of Complex Systems-Structural Biochemistry (ICS-6), Forschungszentrum Jülich, Wilhelm-Johnen-Str., 52425, Jülich, Germany
| | - Kun Yu
- Centre for Structural Systems Biology (CSSB), CSSB-FZJ, Notkestr. 85, 22607, Hamburg, Germany.,Institute of Complex Systems-Structural Biochemistry (ICS-6), Forschungszentrum Jülich, Wilhelm-Johnen-Str., 52425, Jülich, Germany
| | - Christina-Symina Kaitatzi
- Centre for Structural Systems Biology (CSSB), CSSB-FZJ, Notkestr. 85, 22607, Hamburg, Germany.,Physics Department, University of Patras, University Campus, 26504, Rio Achaia, Greece
| | - Abhilasha Singh
- Centre for Structural Systems Biology (CSSB), CSSB-FZJ, Notkestr. 85, 22607, Hamburg, Germany.,Institute of Complex Systems-Structural Biochemistry (ICS-6), Forschungszentrum Jülich, Wilhelm-Johnen-Str., 52425, Jülich, Germany
| | - Jörg Labahn
- Centre for Structural Systems Biology (CSSB), CSSB-FZJ, Notkestr. 85, 22607, Hamburg, Germany. .,Institute of Complex Systems-Structural Biochemistry (ICS-6), Forschungszentrum Jülich, Wilhelm-Johnen-Str., 52425, Jülich, Germany. .,Institut für Physikalische Biologie, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, 40225, Düsseldorf, Germany.
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5
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Blahovec J, Kouřím P. DMA and DETA thermal analysis of carrot during its drying at different air humidity. J FOOD ENG 2017. [DOI: 10.1016/j.jfoodeng.2016.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
This article defines protein stability, emphasizes its importance and surveys the field of protein stabilization, with summary reference to a selection of 2009-2015 publications. One can enhance stability by, in particular, protein engineering strategies and by chemical modification (including conjugation) in solution. General protocols are set out on how to measure a given protein's (1) kinetic thermal stability, and (2) oxidative stability, and (3) how to undertake chemical modification of a protein in solution.
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Affiliation(s)
- Ciarán Ó'Fágáin
- School of Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
- National Centre for Sensor Research, Dublin City University, Glasnevin, Dublin 9, Ireland.
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Blahovec J, Kouřím P. Combined mechanical (DMA) and dielectric (DETA) thermal analysis of carrot at temperatures 30–90°C. J FOOD ENG 2016. [DOI: 10.1016/j.jfoodeng.2015.07.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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8
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Yang Z, Brouillette CG. A Guide to Differential Scanning Calorimetry of Membrane and Soluble Proteins in Detergents. Methods Enzymol 2016; 567:319-58. [DOI: 10.1016/bs.mie.2015.08.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Maurya SR, Mahalakshmi R. N-helix and Cysteines Inter-regulate Human Mitochondrial VDAC-2 Function and Biochemistry. J Biol Chem 2015; 290:30240-52. [PMID: 26487717 PMCID: PMC4683249 DOI: 10.1074/jbc.m115.693978] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Indexed: 12/25/2022] Open
Abstract
Human voltage-dependent anion channel-2 (hVDAC-2) functions primarily as the crucial anti-apoptotic protein in the outer mitochondrial membrane, and additionally as a gated bidirectional metabolite transporter. The N-terminal helix (NTH), involved in voltage sensing, bears an additional 11-residue extension (NTE) only in hVDAC-2. In this study, we assign a unique role for the NTE as influencing the chaperone-independent refolding kinetics and overall thermodynamic stability of hVDAC-2. Our electrophysiology data shows that the N-helix is crucial for channel activity, whereas NTE sensitizes this isoform to voltage gating. Additionally, hVDAC-2 possesses the highest cysteine content, possibly for regulating reactive oxygen species content. We identify interdependent contributions of the N-helix and cysteines to channel function, and the measured stability in micellar environments with differing physicochemical properties. The evolutionary demand for the NTE in the presence of cysteines clearly emerges from our biochemical and functional studies, providing insight into factors that functionally demarcate hVDAC-2 from the other VDACs.
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Affiliation(s)
- Svetlana Rajkumar Maurya
- From the Department of Biological Sciences, Molecular Biophysics Laboratory, Indian Institute of Science Education and Research, Bhopal 462023, India
| | - Radhakrishnan Mahalakshmi
- From the Department of Biological Sciences, Molecular Biophysics Laboratory, Indian Institute of Science Education and Research, Bhopal 462023, India
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Baturin S, Galka JJ, Piyadasa H, Gajjeraman S, O'Neil JD. The effects of a protein osmolyte on the stability of the integral membrane protein glycerol facilitator. Biochem Cell Biol 2014; 92:564-75. [PMID: 25387032 DOI: 10.1139/bcb-2014-0076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Osmolytes are naturally occurring molecules used by a wide variety of organisms to stabilize proteins under extreme conditions of temperature, salinity, hydrostatic pressure, denaturant concentration, and desiccation. The effects of the osmolyte trimethylamine N-oxide (TMAO) as well as the influence of detergent head group and acyl chain length on the stability of the Escherichia coli integral membrane protein glycerol facilitator (GF) tetramer to thermal and chemical denaturation by sodium dodecyl sulphate (SDS) are reported. TMAO promotes the association of the normally tetrameric α-helical protein into higher order oligomers in dodecyl-maltoside (DDM), but not in tetradecyl-maltoside (TDM), lyso-lauroylphosphatidyl choline (LLPC), or lyso-myristoylphosphatidyl choline (LMPC), as determined by dynamic light scattering (DLS); an octameric complex is particularly stable as indicated by SDS polyacrylamide gel electrophoresis. TMAO increases the heat stability of the GF tetramer an average of 10 °C in the 4 detergents and also protects the protein from denaturation by SDS. However, it did not promote re-association to the tetramer when added to SDS-dissociated protein. TMAO also promotes the formation of rod-like detergent micelles, and DLS was found to be useful for monitoring the structure of the protein and the redistribution of detergent during thermal dissociation of the protein. The protein is more thermally stable in detergents with the phosphatidylcholine head group (LLPC and LMPC) than in the maltoside detergents. The implications of the results for osmolyte mechanism, membrane protein stability, and protein-protein interactions are discussed.
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Affiliation(s)
- Simon Baturin
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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11
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Pogozheva ID, Mosberg HI, Lomize AL. Life at the border: adaptation of proteins to anisotropic membrane environment. Protein Sci 2014; 23:1165-96. [PMID: 24947665 DOI: 10.1002/pro.2508] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 12/25/2022]
Abstract
This review discusses main features of transmembrane (TM) proteins which distinguish them from water-soluble proteins and allow their adaptation to the anisotropic membrane environment. We overview the structural limitations on membrane protein architecture, spatial arrangement of proteins in membranes and their intrinsic hydrophobic thickness, co-translational and post-translational folding and insertion into lipid bilayers, topogenesis, high propensity to form oligomers, and large-scale conformational transitions during membrane insertion and transport function. Special attention is paid to the polarity of TM protein surfaces described by profiles of dipolarity/polarizability and hydrogen-bonding capacity parameters that match polarity of the lipid environment. Analysis of distributions of Trp resides on surfaces of TM proteins from different biological membranes indicates that interfacial membrane regions with preferential accumulation of Trp indole rings correspond to the outer part of the lipid acyl chain region-between double bonds and carbonyl groups of lipids. These "midpolar" regions are not always symmetric in proteins from natural membranes. We also examined the hydrophobic effect that drives insertion of proteins into lipid bilayer and different free energy contributions to TM protein stability, including attractive van der Waals forces and hydrogen bonds, side-chain conformational entropy, the hydrophobic mismatch, membrane deformations, and specific protein-lipid binding.
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Affiliation(s)
- Irina D Pogozheva
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, 48109-1065
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12
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Thermal stress induced aggregation of aquaporin 0 (AQP0) and protection by α-crystallin via its chaperone function. PLoS One 2013; 8:e80404. [PMID: 24312215 PMCID: PMC3842347 DOI: 10.1371/journal.pone.0080404] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/02/2013] [Indexed: 11/22/2022] Open
Abstract
Aquaporin 0 (AQP0) formerly known as membrane intrinsic protein (MIP), is expressed exclusively in the lens during terminal differentiation of fiber cells. AQP0 plays an important role not only in the regulation of water content but also in cell-to-cell adhesion of the lens fiber cells. We have investigated the thermal stress-induced structural alterations of detergent (octyl glucoside)-solubilized calf lens AQP0. The results show an increase in the amount of AQP0 that aggregated as the temperature increased from 40°C to 65°C. α-Crystallin, molecular chaperone abundantly present in the eye lens, completely prevented the AQP0 aggregation at a 1∶1 (weight/weight) ratio. Since α-crystallin consists of two gene products namely αA- and αB-crystallins, we have tested the recombinant proteins on their ability to prevent thermal-stress induced AQP0 aggregation. In contrast to the general observation made with other target proteins, αA-crystallin exhibited better chaperone-like activity towards AQP0 compared to αB-crystallin. Neither post-translational modifications (glycation) nor C-terminus truncation of AQP0 have any appreciable effect on its thermal aggregation properties. α-Crystallin offers similar protection against thermal aggregation as in the case of the unmodified AQP0, suggesting that αcrystallin may bind to either intracellular loops or other residues of AQP0 that become exposed during thermal stress. Far-UV circular dichroism studies indicated a loss of αhelical structures when AQP0 was subjected to temperatures above 45°C, and the presence of α-crystallin stabilized these secondary structures. We report here, for the first time, that α-crystallin protects AQP0 from thermal aggregation. Since stress-induced structural perturbations of AQP0 may affect the integrity of the lens, presence of the molecular chaperone, α-crystallin (particularly αA-crystallin) in close proximity to the lens membrane is physiologically relevant.
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Methionine mutations of outer membrane protein X influence structural stability and beta-barrel unfolding. PLoS One 2013; 8:e79351. [PMID: 24265768 PMCID: PMC3827151 DOI: 10.1371/journal.pone.0079351] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 09/26/2013] [Indexed: 12/24/2022] Open
Abstract
We report the biochemical and biophysical characterization of outer membrane protein X (OmpX), an eight-stranded transmembrane β-barrel from E. coli, and compare the barrel behavior with a mutant devoid of methionine residues. Transmembrane outer membrane proteins of bacterial origin are known to display high tolerance to sequence rearrangements and mutations. Our studies with the triple mutant of OmpX that is devoid of all internal methionine residues (M18L; M21L; M118L) indicate that Met replacement has no influence on the refolding efficiency and structural characteristics of the protein. Surprisingly, the conserved substitution of Met→Leu leads to barrel destabilization and causes a lowering of the unfolding free energy by a factor of ∼8.5 kJ/mol, despite the mutations occurring at the loop regions. We report that the barrel destabilization is accompanied by a loss in cooperativity of unfolding in the presence of chemical denaturants. Furthermore, we are able to detect an unfolding intermediate in the Met-less barrel, whereas the parent protein exhibits a classic two-state unfolding. Thermal denaturation measurements also suggest a greater susceptibility of the OmpX barrel to heat, in the Met-less construct. Our studies reveal that even subtle variations in the extra-membrane region of rigid barrel structures such as OmpX, may bear severe implications on barrel stability. We propose that methionines contribute to efficient barrel structuring and protein-lipid interactions, and are therefore important elements of OmpX stability.
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15
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Tol MB, Deluz C, Hassaine G, Graff A, Stahlberg H, Vogel H. Thermal unfolding of a mammalian pentameric ligand-gated ion channel proceeds at consecutive, distinct steps. J Biol Chem 2012; 288:5756-69. [PMID: 23275379 DOI: 10.1074/jbc.m112.422287] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Pentameric ligand-gated ion channels (LGICs) play an important role in fast synaptic signal transduction. Binding of agonists to the β-sheet-structured extracellular domain opens an ion channel in the transmembrane α-helical region of the LGIC. How the structurally distinct and distant domains are functionally coupled for such central transmembrane signaling processes remains an open question. To obtain detailed information about the stability of and the coupling between these different functional domains, we analyzed the thermal unfolding of a homopentameric LGIC, the 5-hydroxytryptamine receptor (ligand binding, secondary structure, accessibility of Trp and Cys residues, and aggregation), in plasma membranes as well as during detergent extraction, purification, and reconstitution into artificial lipid bilayers. We found a large loss in thermostability correlating with the loss of the lipid bilayer during membrane solubilization and purification. Thermal unfolding of the 5-hydroxytryptamine receptor occurred in consecutive steps at distinct protein locations. A loss of ligand binding was detected first, followed by formation of different transient low oligomeric states of receptor pentamers, followed by partial unfolding of helical parts of the protein, which finally lead to the formation receptor aggregates. Structural destabilization of the receptor in detergents could be partially reversed by reconstituting the receptor into lipid bilayers. Our results are important because they quantify the stability of LGICs during detergent extraction and purification and can be used to create stabilized receptor proteins for structural and functional studies.
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Affiliation(s)
- Menno B Tol
- Laboratory of Physical Chemistry of Polymers and Membranes, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Karabadzhak AG, Weerakkody D, Wijesinghe D, Thakur MS, Engelman DM, Andreev OA, Markin VS, Reshetnyak YK. Modulation of the pHLIP transmembrane helix insertion pathway. Biophys J 2012; 102:1846-55. [PMID: 22768940 DOI: 10.1016/j.bpj.2012.03.021] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 02/24/2012] [Accepted: 03/12/2012] [Indexed: 12/15/2022] Open
Abstract
The membrane-associated folding/unfolding of pH (low) insertion peptide (pHLIP) provides an opportunity to study how sequence variations influence the kinetics and pathway of peptide insertion into bilayers. Here, we present the results of steady-state and kinetics investigations of several pHLIP variants with different numbers of charged residues, with attached polar cargoes at the peptide's membrane-inserting end, and with three single-Trp variants placed at the beginning, middle, and end of the transmembrane helix. Each pHLIP variant exhibits a pH-dependent interaction with a lipid bilayer. Although the number of protonatable residues at the inserting end does not affect the ultimate formation of helical structure across a membrane, it correlates with the time for peptide insertion, the number of intermediate states on the folding pathway, and the rates of unfolding and exit. The presence of polar cargoes at the peptide's inserting end leads to the appearance of intermediate states on the insertion pathway. Cargo polarity correlates with a decrease of the insertion rate. We conclude that the existence of intermediate states on the folding and unfolding pathways is not mandatory and, in the simple case of a polypeptide with a noncharged and nonpolar inserting end, the folding and unfolding appears as an all-or-none transition. We propose a model for membrane-associated insertion/folding and exit/unfolding and discuss the importance of these observations for the design of new delivery agents for direct translocation of polar therapeutic and diagnostic cargo molecules across cellular membranes.
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17
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Effect of temperature on the formation of liquid phase-separating giant unilamellar vesicles (GUV). Chem Phys Lipids 2012; 165:630-7. [DOI: 10.1016/j.chemphyslip.2012.06.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/12/2012] [Accepted: 06/13/2012] [Indexed: 11/21/2022]
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18
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Chiu MH, Prenner EJ. Differential scanning calorimetry: An invaluable tool for a detailed thermodynamic characterization of macromolecules and their interactions. J Pharm Bioallied Sci 2011; 3:39-59. [PMID: 21430954 PMCID: PMC3053520 DOI: 10.4103/0975-7406.76463] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 10/05/2010] [Accepted: 10/19/2010] [Indexed: 11/04/2022] Open
Abstract
Differential Scanning Calorimetry (DSC) is a highly sensitive technique to study the thermotropic properties of many different biological macromolecules and extracts. Since its early development, DSC has been applied to the pharmaceutical field with excipient studies and DNA drugs. In recent times, more attention has been applied to lipid-based drug delivery systems and drug interactions with biomimetic membranes. Highly reproducible phase transitions have been used to determine values, such as, the type of binding interaction, purity, stability, and release from a drug delivery mechanism. This review focuses on the use of DSC for biochemical and pharmaceutical applications.
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Affiliation(s)
- Michael H Chiu
- Department of Biological Sciences, University of Calgary, T2N 1N4 Calgary, AB, Canada
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Samuli Ollila OH, Louhivuori M, Marrink SJ, Vattulainen I. Protein shape change has a major effect on the gating energy of a mechanosensitive channel. Biophys J 2011; 100:1651-9. [PMID: 21463578 PMCID: PMC3072608 DOI: 10.1016/j.bpj.2011.02.027] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 01/18/2011] [Accepted: 02/02/2011] [Indexed: 10/18/2022] Open
Abstract
Increasing experimental evidence has shown that membrane protein functionality depends on molecular composition of cell membranes. However, the origin of this dependence is not fully understood. It is reasonable to assume that specific lipid-protein interactions are important, yet more generic effects due to mechanical properties of lipid bilayers likely play a significant role too. Previously it has been demonstrated using models for elastic properties of membranes and lateral pressure profiles of lipid bilayers that the mechanical properties of a lipid bilayer can contribute as much as ∼10 k(B)T to the free energy difference associated with a change in protein conformational state. Here, we extend those previous approaches to a more realistic model for a large mechanosensitive channel (MscL). We use molecular dynamics together with the MARTINI model to simulate the open and closed states of MscL embedded in a DOPC bilayer. We introduce a procedure to calculate the mechanical energy change in the channel gating using a three-dimensional pressure distribution inside a membrane, computed from the molecular dynamics simulations. We decompose the mechanical energy to terms associated with area dilation and shape contribution. Our results highlight that the lateral pressure profile of a lipid bilayer together with the shape change in gating can induce a contribution of ∼30 k(B)T on the gating energy of MscL. This contribution arises largely from the interfacial tension between hydrophobic and hydrophilic regions in a lipid bilayer.
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Affiliation(s)
- O H Samuli Ollila
- Department of Physics, Tampere University of Technology, Tampere, Finland.
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Plasencia I, Survery S, Ibragimova S, Hansen JS, Kjellbom P, Helix-Nielsen C, Johanson U, Mouritsen OG. Structure and stability of the spinach aquaporin SoPIP2;1 in detergent micelles and lipid membranes. PLoS One 2011; 6:e14674. [PMID: 21339815 PMCID: PMC3038850 DOI: 10.1371/journal.pone.0014674] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 12/23/2010] [Indexed: 12/13/2022] Open
Abstract
Background SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. Methodology/Principal Finding We have characterized the protein structural stability after purification and after reconstitution into detergent micelles and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-β-D-glucopyranoside (OG) or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPhPC), or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE), 1-palmitoyl-2oleoyl-phosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS), and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly α-helical in accordance with crystallographic data. The protein has a high thermal structural stability in detergent solutions, with an irreversible thermal unfolding occurring at a melting temperature of 58°C. Incorporation of the protein into lipid membranes increases the structural stability as evidenced by an increased melting temperature of up to 70°C. Conclusion/Significance The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes for biotechnological applications.
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Affiliation(s)
- Inés Plasencia
- Department of Physics and Chemistry, MEMPHYS-Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark.
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21
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Opposing structural changes in two symmetrical polypeptides bring about opposing changes to the thermal stability of a complex integral membrane protein. Arch Biochem Biophys 2011; 505:160-70. [DOI: 10.1016/j.abb.2010.09.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 09/29/2010] [Accepted: 09/30/2010] [Indexed: 11/23/2022]
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Abstract
This article defines protein stability, emphasizes its importance and surveys some notable recent publications (2004-2008) in the field of protein stability/stabilization. Knowledge of the factors stabilizing proteins has emerged from denaturation studies and from study of thermophilic (and other extremophilic) proteins. One can enhance stability by protein engineering strategies, the judicious use of solutes and additives, immobilization, and chemical modification in solution. General protocols are set out on how to measure the kinetic thermal stability of a given protein and how to undertake chemical modification of a protein in solution.
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Affiliation(s)
- Ciarán O'Fágáin
- School of Biotechnology and National Centre for Sensor Research, Dublin City University, Dublin, Ireland.
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23
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Thibodeau PH, Richardson JM, Wang W, Millen L, Watson J, Mendoza JL, Du K, Fischman S, Senderowitz H, Lukacs GL, Kirk K, Thomas PJ. The cystic fibrosis-causing mutation deltaF508 affects multiple steps in cystic fibrosis transmembrane conductance regulator biogenesis. J Biol Chem 2010; 285:35825-35. [PMID: 20667826 DOI: 10.1074/jbc.m110.131623] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The deletion of phenylalanine 508 in the first nucleotide binding domain of the cystic fibrosis transmembrane conductance regulator is directly associated with >90% of cystic fibrosis cases. This mutant protein fails to traffic out of the endoplasmic reticulum and is subsequently degraded by the proteasome. The effects of this mutation may be partially reversed by the application of exogenous osmolytes, expression at low temperature, and the introduction of second site suppressor mutations. However, the specific steps of folding and assembly of full-length cystic fibrosis transmembrane conductance regulator (CFTR) directly altered by the disease-causing mutation are unclear. To elucidate the effects of the ΔF508 mutation, on various steps in CFTR folding, a series of misfolding and suppressor mutations in the nucleotide binding and transmembrane domains were evaluated for effects on the folding and maturation of the protein. The results indicate that the isolated NBD1 responds to both the ΔF508 mutation and intradomain suppressors of this mutation. In addition, identification of a novel second site suppressor of the defect within the second transmembrane domain suggests that ΔF508 also effects interdomain interactions critical for later steps in the biosynthesis of CFTR.
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Affiliation(s)
- Patrick H Thibodeau
- Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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24
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Huang T, Shi XH, Wang P, He Z, Feng KY, Hu L, Kong X, Li YX, Cai YD, Chou KC. Analysis and prediction of the metabolic stability of proteins based on their sequential features, subcellular locations and interaction networks. PLoS One 2010; 5:e10972. [PMID: 20532046 PMCID: PMC2881046 DOI: 10.1371/journal.pone.0010972] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 05/14/2010] [Indexed: 11/19/2022] Open
Abstract
The metabolic stability is a very important idiosyncracy of proteins that is related to their global flexibility, intramolecular fluctuations, various internal dynamic processes, as well as many marvelous biological functions. Determination of protein's metabolic stability would provide us with useful information for in-depth understanding of the dynamic action mechanisms of proteins. Although several experimental methods have been developed to measure protein's metabolic stability, they are time-consuming and more expensive. Reported in this paper is a computational method, which is featured by (1) integrating various properties of proteins, such as biochemical and physicochemical properties, subcellular locations, network properties and protein complex property, (2) using the mRMR (Maximum Relevance & Minimum Redundancy) principle and the IFS (Incremental Feature Selection) procedure to optimize the prediction engine, and (3) being able to identify proteins among the four types: “short”, “medium”, “long”, and “extra-long” half-life spans. It was revealed through our analysis that the following seven characters played major roles in determining the stability of proteins: (1) KEGG enrichment scores of the protein and its neighbors in network, (2) subcellular locations, (3) polarity, (4) amino acids composition, (5) hydrophobicity, (6) secondary structure propensity, and (7) the number of protein complexes the protein involved. It was observed that there was an intriguing correlation between the predicted metabolic stability of some proteins and the real half-life of the drugs designed to target them. These findings might provide useful insights for designing protein-stability-relevant drugs. The computational method can also be used as a large-scale tool for annotating the metabolic stability for the avalanche of protein sequences generated in the post-genomic age.
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Affiliation(s)
- Tao Huang
- Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
- Shanghai Center for Bioinformation Technology, Shanghai, People's Republic of China
| | - Xiao-He Shi
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Ping Wang
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
| | - Zhisong He
- CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
| | - Kai-Yan Feng
- Shanghai Center for Bioinformation Technology, Shanghai, People's Republic of China
| | - LeLe Hu
- Institute of Systems Biology, Shanghai University, Shanghai, People's Republic of China
| | - Xiangyin Kong
- Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
- State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, People's Republic of China
- * E-mail: (XYK); (YXL); (YDC); (KCC)
| | - Yi-Xue Li
- Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
- Shanghai Center for Bioinformation Technology, Shanghai, People's Republic of China
- * E-mail: (XYK); (YXL); (YDC); (KCC)
| | - Yu-Dong Cai
- Institute of Systems Biology, Shanghai University, Shanghai, People's Republic of China
- Centre for Computational Systems Biology, Fudan University, Shanghai, People's Republic of China
- Gordon Life Science Institute, San Diego, California, United States of America
- * E-mail: (XYK); (YXL); (YDC); (KCC)
| | - Kuo-Chen Chou
- Gordon Life Science Institute, San Diego, California, United States of America
- * E-mail: (XYK); (YXL); (YDC); (KCC)
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25
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Palazzo G, Lopez F, Mallardi A. Effect of detergent concentration on the thermal stability of a membrane protein: The case study of bacterial reaction center solubilized by N,N-dimethyldodecylamine-N-oxide. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:137-46. [DOI: 10.1016/j.bbapap.2009.09.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 09/17/2009] [Accepted: 09/21/2009] [Indexed: 11/29/2022]
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26
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Sedlák E, Robinson NC. Sequential dissociation of subunits from bovine heart cytochrome C oxidase by urea. Biochemistry 2009; 48:8143-50. [PMID: 19663452 DOI: 10.1021/bi900773r] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The quaternary stability of purified, detergent-solubilized, cytochrome c oxidase (CcO) was probed using two chemical denaturants, urea and guanidinium chloride (GdmCl). Each chaotrope induces dissociation of five subunits in a concentration-dependent manner. These five subunits are not scattered over the surface of CcO but are clustered together in close contact at the dimer interface. Increasing the concentration of urea selectively dissociates subunits from CcO in the following order: VIa and VIb, followed by III and VIIa, and finally Vb. After incubation in urea for 10 min at room temperature, the sigmoidal dissociation transitions were centered at 3.7, 4.6, and 7.0 M urea, respectively. The secondary structure of CcO was only minimally perturbed, indicating that urea causes disruption of subunit interactions without urea-induced conformational changes. Incubation of CcO in urea for 120 min produced similar results but shifted the sigmoidal dissociation curves to lower urea concentrations. Incubation of CcO with increasing concentrations of GdmCl produces an analogous effect; however, the GdmCl-induced dissociation of subunits occurs at lower concentrations and with a narrower concentration range. Thermodynamic parameters for each subunit dissociation were evaluated from the sigmoidal dissociation data by assuming a single transition from bound to dissociated subunit. The free energy change accompanying urea-induced dissociation of each subunit ranged from 18.0 to 29.7 kJ/mol, which corresponds to 0.32-0.59 kJ/mol per 100 A(2) of newly exposed solvent-accessible surface area. These values are 30-50-fold smaller than previously reported for the unfolding of soluble or membrane proteins.
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Affiliation(s)
- Erik Sedlák
- Department of Biochemistry, The University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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27
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Gopee NV, Roberts DW, Webb P, Cozart CR, Siitonen PH, Latendresse JR, Warbitton AR, Yu WW, Colvin VL, Walker NJ, Howard PC. Quantitative determination of skin penetration of PEG-coated CdSe quantum dots in dermabraded but not intact SKH-1 hairless mouse skin. Toxicol Sci 2009; 111:37-48. [PMID: 19574408 DOI: 10.1093/toxsci/kfp139] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Many cosmetics, sunscreens, and other consumer products are reported to contain nanoscale materials. The possible transdermal absorption of nanoscale materials and the long-term consequences of the absorption have not been determined. We used polyethylene glycol coated cadmium selenide (CdSe) core quantum dots (QD; 37 nm diameter) to evaluate the penetration of nanoscale material into intact, tape stripped, acetone treated, or dermabraded mouse skin. QD were suspended in an oil-in-water emulsion (approximately 9 microM) and the emulsion was applied at 2 mg/cm(2) to mouse dorsal skin pretreated as follows: intact; tape stripped to remove the stratum corneum; acetone pretreated; dermabraded to remove stratum corneum and epidermis. QD penetration into the skin was monitored in sentinel organs (liver and regional draining lymph nodes) using inductively coupled plasma mass spectrometry analysis of cadmium (from the CdSe QD). No consistent cadmium elevation was detected in the sentinel organs of mice with intact, acetone pretreated, or tape-stripped skin at 24- and 48-h post-QD application; however, in dermabraded mice, cadmium elevations were detected in the lymph nodes and liver. QD accumulation (as cadmium) in the liver was approximately 2.0% of the applied dose. The passing of QD through the dermabraded skin was confirmed using confocal fluorescence microscopy. These results suggest that transdermal absorption of nanoscale materials depends on skin barrier quality, and that the lack of an epidermis provided access to QD penetration. Future dermal risk assessments of nanoscale materials should consider key barrier aspects of skin and its overall physiologic integrity.
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Affiliation(s)
- Neera V Gopee
- National Center for Toxicological Research, US Food & Drug Administration, Jefferson, Arkansas 72079, USA
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28
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Kimura Y, Yu LJ, Hirano Y, Suzuki H, Wang ZY. Calcium ions are required for the enhanced thermal stability of the light-harvesting-reaction center core complex from thermophilic purple sulfur bacterium Thermochromatium tepidum. J Biol Chem 2008; 284:93-99. [PMID: 18977753 DOI: 10.1074/jbc.m806840200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thermochromatium tepidum is a thermophilic purple sulfur photosynthetic bacterium collected from the Mammoth Hot Springs, Yellowstone National Park. A previous study showed that the light-harvesting-reaction center core complex (LH1-RC) purified from this bacterium is highly stable at room temperature (Suzuki, H., Hirano, Y., Kimura, Y., Takaichi, S., Kobayashi, M., Miki, K., and Wang, Z.-Y. (2007) Biochim. Biophys. Acta 1767, 1057-1063). In this work, we demonstrate that thermal stability of the Tch. tepidum LH1-RC is much higher than that of its mesophilic counterparts, and the enhanced thermal stability requires Ca2+ as a cofactor. Removal of the Ca2+ from Tch. tepidum LH1-RC resulted in a complex with the same degree of thermal stability as that of the LH1-RCs purified from mesophilic bacteria. The enhanced thermal stability can be restored by addition of Ca2+ to the Ca2+-depleted LH1-RC, and this process is fully reversible. Interchange of the thermal stability between the two forms is accompanied by a shift of the LH1 Qy transition between 915 nm for the native and 880 nm for the Ca2+-depleted LH1-RC. Differential scanning calorimetry measurements reveal that degradation temperature of the native LH1-RC is 15 degrees C higher and the enthalpy change is about 28% larger than the Ca2+-depleted LH1-RC. Substitution of the Ca2+ with other metal cations caused a decrease in thermal stability of an extent depending on the properties of the cations. These results indicate that Ca2+ ions play a dual role in stabilizing the structure of the pigment-membrane protein complex and in altering its spectroscopic properties, and hence provide insight into the adaptive strategy of this photosynthetic organism to survive in extreme environments using natural resources.
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Affiliation(s)
- Yukihiro Kimura
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan
| | - Long-Jiang Yu
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan
| | - Yu Hirano
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan
| | - Hiroaki Suzuki
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan
| | - Zheng-Yu Wang
- Faculty of Science, Ibaraki University, Mito 310-8512, Japan.
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29
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Prudovsky I, Tarantini F, Landriscina M, Neivandt D, Soldi R, Kirov A, Small D, Kathir KM, Rajalingam D, Kumar TKS. Secretion without Golgi. J Cell Biochem 2008; 103:1327-43. [PMID: 17786931 PMCID: PMC2613191 DOI: 10.1002/jcb.21513] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A growing number of proteins devoid of signal peptides have been demonstrated to be released through the non-classical pathways independent of endoplasmic reticulum and Golgi. Among them are two potent proangiogenic cytokines FGF1 and IL1alpha. Stress-induced transmembrane translocation of these proteins requires the assembly of copper-dependent multiprotein release complexes. It involves the interaction of exported proteins with the acidic phospholipids of the inner leaflet of the cell membrane and membrane destabilization. Not only stress, but also thrombin treatment and inhibition of Notch signaling stimulate the export of FGF1. Non-classical release of FGF1 and IL1alpha presents a promising target for treatment of cardiovascular, oncologic, and inflammatory disorders.
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Affiliation(s)
- Igor Prudovsky
- Maine Medical Center Research Institute, Maine Medical Center, Scarborough, Maine 04074, USA.
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30
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Thermal stability of CopA, a polytopic membrane protein from the hyperthermophile Archaeoglobus fulgidus. Arch Biochem Biophys 2008; 471:198-206. [DOI: 10.1016/j.abb.2007.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2007] [Revised: 12/19/2007] [Accepted: 12/20/2007] [Indexed: 11/21/2022]
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31
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Ghosh D, Beavis RC, Wilkins JA. The Identification and Characterization of Membranome Components. J Proteome Res 2008; 7:1572-83. [DOI: 10.1021/pr070509u] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dhimankrishna Ghosh
- Manitoba Centre for Proteomics and Systems Biology, Departments of Internal Medicine, Biochemistry and Medical Genetics, and Immunology, University of Manitoba, Winnipeg, Manitoba R3E 3P4, Canada
| | - Ron C. Beavis
- Manitoba Centre for Proteomics and Systems Biology, Departments of Internal Medicine, Biochemistry and Medical Genetics, and Immunology, University of Manitoba, Winnipeg, Manitoba R3E 3P4, Canada
| | - John A. Wilkins
- Manitoba Centre for Proteomics and Systems Biology, Departments of Internal Medicine, Biochemistry and Medical Genetics, and Immunology, University of Manitoba, Winnipeg, Manitoba R3E 3P4, Canada
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32
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Galka JJ, Baturin SJ, Manley DM, Kehler AJ, O’Neil JD. Stability of the Glycerol Facilitator in Detergent Solutions. Biochemistry 2008; 47:3513-24. [DOI: 10.1021/bi7021409] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Jamie J. Galka
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada
| | - Simon J. Baturin
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada
| | - Darren M. Manley
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada
| | - Angela J. Kehler
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada
| | - Joe D. O’Neil
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada
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33
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Escribá PV, González-Ros JM, Goñi FM, Kinnunen PKJ, Vigh L, Sánchez-Magraner L, Fernández AM, Busquets X, Horváth I, Barceló-Coblijn G. Membranes: a meeting point for lipids, proteins and therapies. J Cell Mol Med 2008; 12:829-75. [PMID: 18266954 PMCID: PMC4401130 DOI: 10.1111/j.1582-4934.2008.00281.x] [Citation(s) in RCA: 276] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Membranes constitute a meeting point for lipids and proteins. Not only do they define the entity of cells and cytosolic organelles but they also display a wide variety of important functions previously ascribed to the activity of proteins alone. Indeed, lipids have commonly been considered a mere support for the transient or permanent association of membrane proteins, while acting as a selective cell/organelle barrier. However, mounting evidence demonstrates that lipids themselves regulate the location and activity of many membrane proteins, as well as defining membrane microdomains that serve as spatio-temporal platforms for interacting signalling proteins. Membrane lipids are crucial in the fission and fusion of lipid bilayers and they also act as sensors to control environmental or physiological conditions. Lipids and lipid structures participate directly as messengers or regulators of signal transduction. Moreover, their alteration has been associated with the development of numerous diseases. Proteins can interact with membranes through lipid co-/post-translational modifications, and electrostatic and hydrophobic interactions, van der Waals forces and hydrogen bonding are all involved in the associations among membrane proteins and lipids. The present study reviews these interactions from the molecular and biomedical point of view, and the effects of their modulation on the physiological activity of cells, the aetiology of human diseases and the design of clinical drugs. In fact, the influence of lipids on protein function is reflected in the possibility to use these molecular species as targets for therapies against cancer, obesity, neurodegenerative disorders, cardiovascular pathologies and other diseases, using a new approach called membrane-lipid therapy.
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Affiliation(s)
- Pablo V Escribá
- Laboratory of Molecular Cell Biomedicine, Dept of Biology-IUNICS, University of the Balearic Islands, Palma de Mallorca, Spain.
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Dell'Orco D, De Benedetti PG, Fanelli F. In Silico Screening of Mutational Effects on Transmembrane Helix Dimerization: Insights from Rigid-Body Docking and Molecular Dynamics Simulations. J Phys Chem B 2007; 111:9114-24. [PMID: 17602582 DOI: 10.1021/jp071383r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, a docking-based protocol has been probed for its ability to predict the effects of 32 single and double mutations on glycophorin A (GpA) homodimerization. Rigid-body docking simulations have been paralleled by molecular dynamics (MD) simulations in implicit membrane. The rigid-body docking-based approach proved effective in reconstituting the native architecture of the GpA dimer for the wild type and the wild-type-like mutants. The good correlative models between the intermolecular interaction descriptors derived both by rigid-body docking simulations and by MD simulations and experimental relative free energies support the assumption that the mutation-induced changes in the association free energy of GpA helices are essentially ascribed to differences in the packing interactions, whereas almost all the variations in the entropic contributions to the association free energy are constant and/or negligible. The MD-based models achieved provide insights into the structural determinants for disruptive and restoring mutational effects. The computational approaches presented in this study are fast and effective, and constitute simple and promising tools for in silico screening of mutational effects on the association properties of integral membrane proteins.
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Affiliation(s)
- Daniele Dell'Orco
- Department of Chemistry and Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy
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35
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Pastoriza-Gallego M, Oukhaled G, Mathé J, Thiebot B, Betton JM, Auvray L, Pelta J. Urea denaturation of α-hemolysin pore inserted in planar lipid bilayer detected by single nanopore recording: Loss of structural asymmetry. FEBS Lett 2007; 581:3371-6. [PMID: 17601577 DOI: 10.1016/j.febslet.2007.06.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 06/15/2007] [Indexed: 11/23/2022]
Abstract
The aim of this work is to study pore protein denaturation inside a lipid bilayer and to probe current asymmetry as a function of the channel conformation. We describe the urea denaturation of alpha-hemolysin channel and the channel formation of alpha-hemolysin monomer incubated with urea prior to insertion into a lipid bilayer. Analysis of single-channel recordings of current traces reveals a sigmoid curve of current intensity as a function of urea concentration. The normalized current asymmetry at 29+/-4% is observed between 0 and 3.56M concentrations and vanishes abruptly down to 0 concentration exceeds 4M. The loss of current asymmetry through alpha-hemolysin is due to the denaturation of the channel's cap. We also show that the alpha-hemolysin pore inserted into a lipid bilayer is much more resistant to urea denaturation than the alpha-hemolysin monomer in solution: The pore remains in the lipid bilayer up to 7.2M urea. The pore formation is possible up to 4.66M urea when protein monomers were previously incubated in urea.
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Affiliation(s)
- Manuela Pastoriza-Gallego
- Laboratoire de Recherche sur les Polymères, équipe Matériaux Polymères aux Interfaces, CNRS-UMR 7581, Université d'Evry, Boulevard F. Mitterrand, 91025 Evry, France
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36
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González-Díaz H, Vilar S, Santana L, Podda G, Uriarte E. On the applicability of QSAR for recognition of miRNA bioorganic structures at early stages of organism and cell development: Embryo and stem cells. Bioorg Med Chem 2007; 15:2544-50. [PMID: 17300944 DOI: 10.1016/j.bmc.2007.01.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 01/24/2007] [Accepted: 01/31/2007] [Indexed: 11/18/2022]
Abstract
Quantitative structure-activity-relationship (QSAR) models have application in bioorganic chemistry mainly to the study of small sized molecules while applications to biopolymers remain not very developed. MicroRNAs (miRNAs), which are non-coding small RNAs, regulate a variety of biological processes and constitute good candidates to scale up the application of QSAR to biopolymers. The propensity of a small RNA sequence to act as miRNA depends on its secondary structure, which one can explain in terms of folding thermodynamic parameters. Then, thermodynamic QSAR can be used, for instance, for fast identification of miRNAs at early stages of development such as embryos and stem cells (called here esmiRNAs), and gain clarity inside cellular differentiation processes and diseases such as cancer. First, we calculated folding free energies (DeltaG), enthalpies (DeltaH), and entropies (DeltaS) as well as melting temperatures (T(m)) for 2623 small RNA sequences (including 623 esmiRNAs and 2000 negative control sequences). Next, we seek a QSAR classification model: esmiRNA=0.035 x T(m)-0.078 x DeltaS-8.748. The model correctly recognized 543 (87.2%) of esmiRNAs and 935 (93.5%) of non-esmiRNAs divided into both training and validation series. The model also recognized 908 out of 1000 additional negative control sequences. ROC curve analysis (area=0.93) demonstrated that the present model significantly differentiates from a random classifier. In addition, we map the influence of thermodynamic parameters over esmiRNA activity. Last, a double ordinate Cartesian plot of cross-validated residuals (first ordinate), standard residuals (second ordinate), and leverages (abscissa) defined the domain of applicability of the model as a squared area within +/-2 band for residuals and a leverage threshold of h=0.0074. The present is the first QSAR model for quickly accurate selection of new esmiRNAs with potential use in bioorganic and medicinal chemistry.
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Affiliation(s)
- Humberto González-Díaz
- Faculty of Pharmacy, University of Santiago de Compostela, Santiago de Compostela 15782, Spain.
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Vucetic S, Xie H, Iakoucheva LM, Oldfield CJ, Dunker AK, Obradovic Z, Uversky VN. Functional anthology of intrinsic disorder. 2. Cellular components, domains, technical terms, developmental processes, and coding sequence diversities correlated with long disordered regions. J Proteome Res 2007; 6:1899-916. [PMID: 17391015 PMCID: PMC2588346 DOI: 10.1021/pr060393m] [Citation(s) in RCA: 193] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biologically active proteins without stable ordered structure (i.e., intrinsically disordered proteins) are attracting increased attention. Functional repertoires of ordered and disordered proteins are very different, and the ability to differentiate whether a given function is associated with intrinsic disorder or with a well-folded protein is crucial for modern protein science. However, there is a large gap between the number of proteins experimentally confirmed to be disordered and their actual number in nature. As a result, studies of functional properties of confirmed disordered proteins, while helpful in revealing the functional diversity of protein disorder, provide only a limited view. To overcome this problem, a bioinformatics approach for comprehensive study of functional roles of protein disorder was proposed in the first paper of this series (Xie, H.; Vucetic, S.; Iakoucheva, L. M.; Oldfield, C. J.; Dunker, A. K.; Obradovic, Z.; Uversky, V. N. Functional anthology of intrinsic disorder. 1. Biological processes and functions of proteins with long disordered regions. J. Proteome Res. 2007, 5, 1882-1898). Applying this novel approach to Swiss-Prot sequences and functional keywords, we found over 238 and 302 keywords to be strongly positively or negatively correlated, respectively, with long intrinsically disordered regions. This paper describes approximately 90 Swiss-Prot keywords attributed to the cellular components, domains, technical terms, developmental processes, and coding sequence diversities possessing strong positive and negative correlation with long disordered regions.
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Affiliation(s)
- Slobodan Vucetic
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122
| | - Hongbo Xie
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122
| | - Lilia M. Iakoucheva
- Laboratory of Statistical Genetics, The Rockefeller University, New York, NY 10021
| | - Christopher J. Oldfield
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, IN 46202
| | - A. Keith Dunker
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, IN 46202
| | - Zoran Obradovic
- Center for Information Science and Technology, Temple University, Philadelphia, PA 19122
| | - Vladimir N. Uversky
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University, School of Medicine, Indianapolis, IN 46202
- Institute for Biological Instrumentation, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
- CORRESPONDING AUTHOR FOOTNOTE: Correspondence should be addressed to: Vladimir N. Uversky, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS#4021, Indianapolis, IN 46202, USA; Phone: 317-278-9194; Fax: 317-274-4686; E-mail:
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