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Polo-Megías D, Cano-Muñoz M, Berruezo AG, Laumond G, Moog C, Conejero-Lara F. Exploring Highly Conserved Regions of SARS-CoV-2 Spike S2 Subunit as Targets for Fusion Inhibition Using Chimeric Proteins. Int J Mol Sci 2022; 23:ijms232415511. [PMID: 36555153 PMCID: PMC9778920 DOI: 10.3390/ijms232415511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 11/23/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
Since the beginning of the COVID-19 pandemic, considerable efforts have been made to develop protective vaccines against SARS-CoV-2 infection. However, immunity tends to decline within a few months, and new virus variants are emerging with increased transmissibility and capacity to evade natural or vaccine-acquired immunity. Therefore, new robust strategies are needed to combat SARS-CoV-2 infection. The viral spike composed of S1 and S2 subunits mediates viral attachment and membrane fusion to infect the host cell. In this process, interaction between the highly conserved heptad repeat 1 and 2 regions (HR1 and HR2) of S2 is crucial and for this reason; these regions are promising targets to fight SARS-CoV-2. Here, we describe the design and characterization of chimeric proteins that structurally imitate the S2 HR1 region in a trimeric coiled-coil conformation. We biophysically characterized the proteins and determined their capacity to bind the HR2 region, as well as their inhibitory activity of SARS-CoV-2 infection in vitro. HR1 mimetic proteins showed conformational heterogeneity and a propensity to form oligomers. Moreover, their structure is composed of subdomains with varied stability. Interestingly, the full HR1 proteins showed high affinity for HR2-derived peptides and SARS-CoV-2 inhibitory activity, whereas smaller proteins mimicking HR1 subdomains had a decreased affinity for their complementary HR2 region and did not inhibit the virus. The results provide insight into effective strategies to create mimetic proteins with broad inhibitory activity and therapeutic potential against SARS-CoV-2.
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Affiliation(s)
- Daniel Polo-Megías
- Departamento de Química Física, Instituto de Biotecnología y Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Mario Cano-Muñoz
- Departamento de Química Física, Instituto de Biotecnología y Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Alberto G Berruezo
- Departamento de Química Física, Instituto de Biotecnología y Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Géraldine Laumond
- Laboratoire d'ImmunoRhumatologie Moléculaire, Institut National de la Santé et de la Recherche Médicale (INSERM) UMR_S 1109, Institut Thématique Interdisciplinaire (ITI) de Médecine de Précision de Strasbourg, Transplantex NG, Faculté de Médecine, Fédération Hospitalo-Universitaire OMICARE, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, F-67000 Strasbourg, France
| | - Christiane Moog
- Laboratoire d'ImmunoRhumatologie Moléculaire, Institut National de la Santé et de la Recherche Médicale (INSERM) UMR_S 1109, Institut Thématique Interdisciplinaire (ITI) de Médecine de Précision de Strasbourg, Transplantex NG, Faculté de Médecine, Fédération Hospitalo-Universitaire OMICARE, Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, F-67000 Strasbourg, France
- Vaccine Research Institute (VRI), F-94000 Créteil, France
| | - Francisco Conejero-Lara
- Departamento de Química Física, Instituto de Biotecnología y Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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2
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Slow and bimolecular folding of a de novo designed monomeric protein DS119. Biophys J 2014; 105:2141-8. [PMID: 24209859 DOI: 10.1016/j.bpj.2013.09.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 09/03/2013] [Accepted: 09/13/2013] [Indexed: 11/22/2022] Open
Abstract
De novo protein design offers a unique means to test and advance our understanding of how proteins fold. However, most current design methods are native structure eccentric and folding kinetics has rarely been considered in the design process. Here, we show that a de novo designed mini-protein DS119, which folds into a βαβ structure, exhibits unusually slow and concentration-dependent folding kinetics. For example, the folding time for 50 μM of DS119 was estimated to be ~2 s. Stopped-flow fluorescence resonance energy transfer experiments further suggested that its folding was likely facilitated by a transient dimerization process. Taken together, these results highlight the need for consideration of the entire folding energy landscape in de novo protein design and provide evidence suggesting nonnative interactions can play a key role in protein folding.
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3
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Ruzafa D, Conejero-Lara F, Morel B. Modulation of the stability of amyloidogenic precursors by anion binding strongly influences the rate of amyloid nucleation. Phys Chem Chem Phys 2014; 15:15508-17. [PMID: 23942905 DOI: 10.1039/c3cp52313f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A deep understanding of the physicochemical factors modulating amyloid aggregation of proteins is crucial to develop therapeutic and preventive approaches for amyloid-related diseases. The earliest molecular events of the aggregation cascade represent some of the main targets as indicated by the toxic nature of certain early oligomers. Here, we study how different types of salt ions influence the kinetics of amyloid assembly of the N47A mutant α-spectrin SH3 domain using a battery of techniques. The salts influenced aggregation rates to different extents without altering the overall mechanism and the high apparent order of the experimental kinetics. A quantitative analysis of the initial aggregation rates measured by thioflavine-T fluorescence using a simple nucleation model allowed us to estimate the kinetic and thermodynamic magnitudes of crucial aggregation precursors, as well as to evaluate the impact of each type of ion on the earliest amyloid nucleation stages. Whilst cations did not have any noticeable effect under our experimental conditions, anions stabilized an amyloidogenic intermediate state and also increased the rate of the conformational conversion from dynamic oligomers to amyloid nuclei, resulting in a strong acceleration of the nucleation process. Anions appear to act by preferential binding to the amyloidogenic intermediate state, thus enhancing its population and subsequent oligomerization. Overall, our results contribute to the rationalization of the effect of ions on the amyloid nucleation stage and give insight into the properties of the crucial intermediate precursors of amyloid aggregation.
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Affiliation(s)
- David Ruzafa
- Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
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4
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Ruzafa D, Varela L, Azuaga AI, Conejero-Lara F, Morel B. Mapping the structure of amyloid nucleation precursors by protein engineering kinetic analysis. Phys Chem Chem Phys 2014; 16:2989-3000. [PMID: 24394436 DOI: 10.1039/c3cp54383h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Understanding the early molecular mechanisms governing amyloid aggregation is crucial to learn how to prevent it. Here, we used a site-directed mutagenesis approach to explore the molecular mechanism of nucleation of amyloid structure in the N47A Spc-SH3 domain. The changes in the native state stability produced by a series of mutations on each structural element of the domain were uncorrelated with the changes in the aggregation rates, although the overall aggregation mechanism was not altered. Analysis of the thioflavin T initial rates based on a simple kinetic model allowed us to extract thermodynamic magnitudes of the precursor states of nucleation and map the regions of the protein participating in the structure of the amyloidogenic precursors. This structure differs from that of the folding transition state of the SH3 domains, strongly suggesting that the regions of the conformational landscape leading to amyloid formation are divergent from those leading to the native fold.
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Affiliation(s)
- David Ruzafa
- Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
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5
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Doménech R, Hernández-Cifre JG, Bacarizo J, Díez-Peña AI, Martínez-Rodríguez S, Cavasotto CN, de la Torre JG, Cámara-Artigás A, Velázquez-Campoy A, Neira JL. The histidine-phosphocarrier protein of the phosphoenolpyruvate: sugar phosphotransferase system of Bacillus sphaericus self-associates. PLoS One 2013; 8:e69307. [PMID: 23922699 PMCID: PMC3724859 DOI: 10.1371/journal.pone.0069307] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 06/12/2013] [Indexed: 12/12/2022] Open
Abstract
The phosphotransferase system (PTS) is involved in the use of carbon sources in bacteria. Bacillus sphaericus, a bacterium with the ability to produce insecticidal proteins, is unable to use hexoses and pentoses as the sole carbon source, but it has ptsHI genes encoding the two general proteins of the PTS: enzyme I (EI) and the histidine phosphocarrier (HPr). In this work, we describe the biophysical and structural properties of HPr from B. sphaericus, HPrbs, and its affinity towards EI of other species to find out whether there is inter-species binding. Conversely to what happens to other members of the HPr family, HPrbs forms several self-associated species. The conformational stability of the protein is low, and it unfolds irreversibly during heating. The protein binds to the N-terminal domain of EI from Streptomyces coelicolor, EINsc, with a higher affinity than that of the natural partner of EINsc, HPrsc. Modelling of the complex between EINsc and HPrbs suggests that binding occurs similarly to that observed in other HPr species. We discuss the functional implications of the oligomeric states of HPrbs for the glycolytic activity of B. sphaericus, as well as a strategy to inhibit binding between HPrsc and EINsc.
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Affiliation(s)
- Rosa Doménech
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
| | | | - Julio Bacarizo
- Departamento de Química y Física, Campus de Excelencia Internacional Agroalimentario, Universidad de Almería, Almería, Spain
| | - Ana I. Díez-Peña
- Departamento de Química Física, Universidad de Murcia, Murcia, Spain
| | - Sergio Martínez-Rodríguez
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
- Departamento de Química y Física, Campus de Excelencia Internacional Agroalimentario, Universidad de Almería, Almería, Spain
| | - Claudio N. Cavasotto
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET- Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | | | - Ana Cámara-Artigás
- Departamento de Química y Física, Campus de Excelencia Internacional Agroalimentario, Universidad de Almería, Almería, Spain
| | - Adrián Velázquez-Campoy
- Instituto de Biocomputación y Física de Sistemas Complejos, Unidad Asociada IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- Fundación ARAID, Diputación General de Aragón, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
| | - José L. Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
- Instituto de Biocomputación y Física de Sistemas Complejos, Unidad Asociada IQFR-CSIC-BIFI, Universidad de Zaragoza, Zaragoza, Spain
- * E-mail:
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6
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Adhikary R, Zimmermann J, Liu J, Dawson PE, Romesberg FE. Experimental characterization of electrostatic and conformational heterogeneity in an SH3 domain. J Phys Chem B 2013; 117:13082-9. [PMID: 23834285 DOI: 10.1021/jp402772x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electrostatic and conformational heterogeneity make central contributions to protein function, but their experimental characterization requires a combination of spatial and temporal resolution that is challenging to achieve. Src homology 3 (SH3) domains mediate protein-protein interactions, and NMR studies have demonstrated that most possess conformational heterogeneity, which could be critical for their function. Here, we use the IR absorptions of carbon-deuterium (C-D) bonds site-selectively incorporated throughout the N-terminal SH3 domain from the murine adapter protein Crk-II to characterize its different microenvironments with high spatial and temporal resolution. The C-D absorptions are only differentiated in the folded state of the protein where they show evidence of significant environmental heterogeneity. However, the spectra of the folded state are independent of temperature, and upon thermal denaturation the protein undergoes a single, global unfolding transition. While some evidence of conformational heterogeneity is found within the peptide backbone, the majority of the environmental heterogeneity appears to result from electrostatics.
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Affiliation(s)
- Ramkrishna Adhikary
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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7
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Vega S, Neira JL, Marcuello C, Lostao A, Abian O, Velazquez-Campoy A. NS3 protease from hepatitis C virus: biophysical studies on an intrinsically disordered protein domain. Int J Mol Sci 2013; 14:13282-306. [PMID: 23803659 PMCID: PMC3742187 DOI: 10.3390/ijms140713282] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/04/2013] [Accepted: 06/13/2013] [Indexed: 12/14/2022] Open
Abstract
The nonstructural protein 3 (NS3) from the hepatitis C virus (HCV) is responsible for processing the non-structural region of the viral precursor polyprotein in infected hepatic cells. NS3 protease activity, located at the N-terminal domain, is a zinc-dependent serine protease. A zinc ion, required for the hydrolytic activity, has been considered as a structural metal ion essential for the structural integrity of the protein. In addition, NS3 interacts with another cofactor, NS4A, an accessory viral protein that induces a conformational change enhancing the hydrolytic activity. Biophysical studies on the isolated protease domain, whose behavior is similar to that of the full-length protein (e.g., catalytic activity, allosteric mechanism and susceptibility to inhibitors), suggest that a considerable global conformational change in the protein is coupled to zinc binding. Zinc binding to NS3 protease can be considered as a folding event, an extreme case of induced-fit binding. Therefore, NS3 protease is an intrinsically (partially) disordered protein with a complex conformational landscape due to its inherent plasticity and to the interaction with its different effectors. Here we summarize the results from a detailed biophysical characterization of this enzyme and present new experimental data.
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Affiliation(s)
- Sonia Vega
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
| | - Jose L. Neira
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- Institute of Molecular and Cell Biology, Miguel Hernandez University, Elche (Alicante) 03202, Spain
| | - Carlos Marcuello
- Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragon (INA), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (C.M.); (A.L.)
| | - Anabel Lostao
- Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragon (INA), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (C.M.); (A.L.)
- ARAID Foundation, Government of Aragon, Zaragoza 50018, Spain
| | - Olga Abian
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- IIS Aragon–Aragon Health Science Institute (I+CS), Zaragoza 50009, Spain
- Network Biomedical Research Center on Hepatic and Digestive Diseases (CIBERehd), Barcelona 08036, Spain
- Authors to whom correspondence should be addressed; E-Mails: (O.A.); (A.V.-C.); Tel.: +34-976-761-000 (ext. 5417) (O.A.); +34-976-762-996 (A.V.-C.); Fax: +34-976-762-990 (O.A. & A.V.-C.)
| | - Adrian Velazquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Unit BIFI-IQFR (CSIC), University of Zaragoza, Zaragoza 50018, Spain; E-Mails: (S.V.); (J.L.N.)
- ARAID Foundation, Government of Aragon, Zaragoza 50018, Spain
- Department of Biochemistry and Cellular and Molecular Biology, Faculty of Sciences, University of Zaragoza, Zaragoza 50009, Spain
- Authors to whom correspondence should be addressed; E-Mails: (O.A.); (A.V.-C.); Tel.: +34-976-761-000 (ext. 5417) (O.A.); +34-976-762-996 (A.V.-C.); Fax: +34-976-762-990 (O.A. & A.V.-C.)
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8
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Navarro A, Encinar JA, López-Méndez B, Aguado-Llera D, Prieto J, Gómez J, Martínez-Cruz LA, Millet O, González-Ros JM, Fernández-Ballester G, Neira JL, Ferrer-Montiel A. Mutation of Ser-50 and Cys-66 in Snapin Modulates Protein Structure and Stability. Biochemistry 2012; 51:3470-84. [DOI: 10.1021/bi201574t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron Navarro
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | - José A. Encinar
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | | | - David Aguado-Llera
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | - Jesús Prieto
- Departamento de Biología
Estructural y Biocomputación, CNIO, 28029 Madrid, Spain
| | - Javier Gómez
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | | | - Oscar Millet
- Structural
Biology Unit, CIC bioGUNE, 48160 Derio,
Spain
| | | | | | - José L. Neira
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
- Complex Systems Physics Institute, 50009
Zaragoza, Spain
| | - Antonio Ferrer-Montiel
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
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9
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Varela L, Morel B, Azuaga AI, Conejero-Lara F. A single mutation in an SH3 domain increases amyloid aggregation by accelerating nucleation, but not by destabilizing thermodynamically the native state. FEBS Lett 2009; 583:801-6. [PMID: 19183554 DOI: 10.1016/j.febslet.2009.01.033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 01/10/2009] [Accepted: 01/19/2009] [Indexed: 10/21/2022]
Abstract
We investigated the relationship between thermodynamic stability and amyloid aggregation propensity for a set of single mutants of the alpha-spectrin SH3 domain (Spc-SH3). Whilst mutations destabilizing the domain at position 56 did not enhance fibrillation, the N47A mutation increased the rate of amyloid fibril formation by 10-fold. Even under conditions of identical thermodynamic stability, the aggregation rate was much higher for the N47A mutant than for the WT domain. We conclude that the N47A mutation does not change the apparent mechanism of fibrillation or the morphology of the amyloid fibrils, and that its amyloidogenic property is due to its effect upon the rate of the conformational events leading to nucleation and not to its overall destabilizing effect.
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Affiliation(s)
- Lorena Varela
- Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva, 18071 Granada, Spain
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10
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Frembgen-Kesner T, Elcock AH. Striking Effects of Hydrodynamic Interactions on the Simulated Diffusion and Folding of Proteins. J Chem Theory Comput 2009; 5:242-56. [DOI: 10.1021/ct800499p] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
| | - Adrian H. Elcock
- Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242
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11
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Gushchina LV, Gabdulkhakov AG, Nikonov SV, Mateo PL, Filimonov VV. Structural and thermodynamic studies of Bergerac-SH3 chimeras. Biophys Chem 2008; 139:106-15. [PMID: 19042078 DOI: 10.1016/j.bpc.2008.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 10/24/2008] [Accepted: 10/24/2008] [Indexed: 11/18/2022]
Abstract
Bergerac-type chimeras of spectrin SH3 were designed by extending a beta-hairpin by eight amino acids so that the extension protruded from the domain body like a "nose" being exposed to the solvent. A calorimetric study of several Bergerac-SH3 variants was carried out over a wide range of pH values and protein concentrations and the three-dimensional structure of one of them, SHH, was determined. X-ray studies confirmed that the nose had a well defined beta-structure whilst the chimera formed a stable tetramer within the crystal unit because of four tightly packed noses. In the pH range of 4-7 the heat-induced unfolding of some chimeras was complex and concentration dependent, whilst at pH values below 3.5, low protein concentrations of all the chimeras studied, including SHH, seemed to obey a monomolecular two-state unfolding model. The best set of data was obtained for the SHA variant, the unfolding heat effects of which were systematically higher than those of the WT protein (about 16.4 kJ/mol at 323 K), which may be close to the upper limit of the enthalpy gain due to 10 residue beta-hairpin folding. At the same time, the chimeras with high nose stability, which, like SHH, have a hydrophobic (IVY) cluster on their surface, showed a lower apparent unfolding heat effect, much closer to that of the WT protein. The possible reasons for this difference are discussed.
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Affiliation(s)
- Liubov' V Gushchina
- Institute of Protein Research of the Russian Academy of Sciences, Pushchino, Russia
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12
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Petzold K, Öhman A, Backman L. Folding of the αΙΙ-spectrin SH3 domain under physiological salt conditions. Arch Biochem Biophys 2008; 474:39-47. [PMID: 18358826 DOI: 10.1016/j.abb.2008.02.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 02/27/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
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13
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Lee HJ, Jang DS, Cha HJ, Moon HS, Hong BH, Choi KY, Lee HC. NMR studies on the equilibrium unfolding of ketosteroid isomerase by urea. J Biochem 2008; 144:215-21. [PMID: 18442985 DOI: 10.1093/jb/mvn058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Multidimensional NMR was employed to investigate the structural changes in the urea-induced equilibrium unfolding of the dimeric ketosteroid isomerase (KSI) from Pseudomonas putida biotype B. Sequence specific backbone assignments for the native KSI and the protein with 3.5 M urea were carried out using various 3D NMR experiments. Hydrogen exchange measurements indicated that the secondary structures of KSI were not affected significantly by urea up to 3.5 M. However, the chemical shift analysis of 1H-(15)N HSQC spectra at various urea concentrations revealed that the residues in the dimeric interface region, particularly around the beta5-strand, were significantly perturbed by urea at low concentrations, while the line-width analysis indicated the possibility of conformational exchange at the interface region around the beta6-strand. The results thus suggest that the interface region primarily around the beta5- and beta6-strands could play an important role as the starting positions in the unfolding process of KSI.
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Affiliation(s)
- Hyeong Ju Lee
- Department of Chemistry; and Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, Republic of Korea, 790-784
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14
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Alcaraz LA, del Alamo M, Barrera FN, Mateu MG, Neira JL. Flexibility in HIV-1 assembly subunits: solution structure of the monomeric C-terminal domain of the capsid protein. Biophys J 2007; 93:1264-76. [PMID: 17526561 PMCID: PMC1929042 DOI: 10.1529/biophysj.106.101089] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The protein CA forms the mature capsid of human immunodeficiency virus. Hexamerization of the N-terminal domain and dimerization of the C-terminal domain, CAC, occur during capsid assembly, and both domains constitute potential targets for anti-HIV inhibitors. CAC homodimerization occurs mainly through its second helix, and is abolished when its sole tryptophan is mutated to alanine. Previous thermodynamic data obtained with the dimeric and monomeric forms of CAC indicate that the structure of the mutant resembles that of a monomeric intermediate found in the folding and association reactions of CAC. We have solved the three-dimensional structure in aqueous solution of the monomeric mutant. The structure is similar to that of the subunits in the dimeric, nonmutated CAC, except the segment corresponding to the second helix, which is highly dynamic. At the end of this region, the polypeptide chain is bent to bury several hydrophobic residues and, as a consequence, the last two helices are rotated 90 degrees when compared to their position in dimeric CAC. The previously obtained thermodynamic data are consistent with the determined structure of the monomeric mutant. This extraordinary ability of CAC to change its structure may contribute to the different modes of association of CA during HIV assembly, and should be taken into account in the design of new drugs against this virus.
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Affiliation(s)
- Luis A Alcaraz
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche (Alicante), Spain
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15
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Shen VK, Cheung JK, Errington JR, Truskett TM. Coarse-grained strategy for modeling protein stability in concentrated solutions. II: phase behavior. Biophys J 2006; 90:1949-60. [PMID: 16387768 PMCID: PMC1386775 DOI: 10.1529/biophysj.105.076497] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Accepted: 12/08/2005] [Indexed: 11/18/2022] Open
Abstract
We use highly efficient transition-matrix Monte Carlo simulations to determine equilibrium unfolding curves and fluid phase boundaries for solutions of coarse-grained globular proteins. The model we analyze derives the intrinsic stability of the native state and protein-protein interactions from basic information about protein sequence using heteropolymer collapse theory. It predicts that solutions of low hydrophobicity proteins generally exhibit a single liquid phase near their midpoint temperatures for unfolding, while solutions of proteins with high sequence hydrophobicity display the type of temperature-inverted, liquid-liquid transition associated with aggregation processes of proteins and other amphiphilic molecules. The phase transition occurring in solutions of the most hydrophobic protein we study extends below the unfolding curve, creating an immiscibility gap between a dilute, mostly native phase and a concentrated, mostly denatured phase. The results are qualitatively consistent with the solution behavior of hemoglobin (HbA) and its sickle variant (HbS), and they suggest that a liquid-liquid transition resulting in significant protein denaturation should generally be expected on the phase diagram of high-hydrophobicity protein solutions. The concentration fluctuations associated with this transition could be a driving force for the nonnative aggregation that can occur below the midpoint temperature.
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Affiliation(s)
- Vincent K Shen
- Physical and Chemical Properties Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
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Morel B, Casares S, Conejero-Lara F. A single mutation induces amyloid aggregation in the alpha-spectrin SH3 domain: analysis of the early stages of fibril formation. J Mol Biol 2005; 356:453-68. [PMID: 16375922 DOI: 10.1016/j.jmb.2005.11.062] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 10/13/2005] [Accepted: 11/21/2005] [Indexed: 10/25/2022]
Abstract
The Src-homology region 3 domain of chicken alpha-spectrin (Spc-SH3) is a small two-state folding protein, which has never been described to form amyloid fibrils under any condition investigated so far. We show here that the mutation of asparagine 47 to alanine at the distal loop, which destabilises similarly the native and folding transition states of the domain, induces the formation of amyloid fibrils under mild acid conditions. Amyloid aggregation of the mutant is enhanced by the increase in temperature, protein concentration and NaCl concentration. The early stages of amyloid formation have been monitored as a function of time and temperature using a variety of biophysical methods. Differential scanning calorimetry experiments under conditions of amyloid formation have allowed the identification of different thermal transitions corresponding to conformational and aggregation processes as well as to the high-temperature disaggregation and unfolding of the amyloid fibrils. Aggregation is preceded by a rapid conformational change in the monomeric domain involving about 40% of the global unfolding enthalpy, considerable change in secondary structure, large loss of tertiary structure and exposure of hydrophobic patches to the solvent. The conformational change is followed by formation of a majority of oligomeric species with apparent hydrodynamic radius between 2.5 nm and 10nm, depending on temperature, together with the appearance and progressive growth of protofibrillar aggregates. After these early aggregation stages, long and curved fibrils of up to several micrometers start to develop by elongation of the protofibrils. The calorimetric data indicate that the specific enthalpy of fibril disaggregation and unfolding is relatively low, suggesting a low density of interactions within the fibril structure as compared to the native protein and a main entropy contribution to the stability of the amyloid fibrils.
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Affiliation(s)
- Bertrand Morel
- Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, Spain
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Cheung JK, Truskett TM. Coarse-grained strategy for modeling protein stability in concentrated solutions. Biophys J 2005; 89:2372-84. [PMID: 16040749 PMCID: PMC1366737 DOI: 10.1529/biophysj.105.062067] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a coarse-grained approach for modeling the thermodynamic stability of single-domain globular proteins in concentrated aqueous solutions. Our treatment derives effective protein-protein interactions from basic structural and energetic characteristics of the native and denatured states. These characteristics, along with the intrinsic (i.e., infinite dilution) thermodynamics of folding, are calculated from elementary sequence information using a heteropolymer collapse theory. We integrate this information into Reactive Canonical Monte Carlo simulations to investigate the connections between protein sequence hydrophobicity, protein-protein interactions, protein concentration, and the thermodynamic stability of the native state. The model predicts that sequence hydrophobicity can affect how protein concentration impacts native-state stability in solution. In particular, low hydrophobicity proteins are primarily stabilized by increases in protein concentration, whereas high hydrophobicity proteins exhibit richer nonmonotonic behavior. These trends appear qualitatively consistent with the available experimental data. Although factors such as pH, salt concentration, and protein charge are also important for protein stability, our analysis suggests that some of the nontrivial experimental trends may be driven by a competition between destabilizing hydrophobic protein-protein attractions and entropic crowding effects.
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Affiliation(s)
- Jason K Cheung
- Department of Chemical Engineering, and Institute of Theoretical Chemistry, The University of Texas at Austin, Austin, TX 78712, USA
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