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Katina N, Marchenkov V, Ryabova N, Ilyina N, Marchenko N, Balobanov V, Finkelstein A. Influence of Amino Acid Substitutions in ApoMb on Different Stages of Unfolding of Amyloids. Molecules 2023; 28:7736. [PMID: 38067466 PMCID: PMC10707739 DOI: 10.3390/molecules28237736] [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: 10/31/2023] [Revised: 11/19/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
To date, most research on amyloid aggregation has focused on describing the structure of amyloids and the kinetics of their formation, while the conformational stability of fibrils remains insufficiently explored. The aim of this work was to investigate the effect of amino acid substitutions on the stability of apomyoglobin (ApoMb) amyloids. A study of the amyloid unfolding of ApoMb and its six mutant variants by urea has been carried out. Changes in the structural features of aggregates during unfolding were recorded by far-UV CD and native electrophoresis. It was shown that during the initial stage of denaturation, amyloids' secondary structure partially unfolds. Then, the fibrils undergo dissociation and form intermediate aggregates weighing approximately 1 MDa, which at the last stage of unfolding decompose into 18 kDa monomeric unfolded molecules. The results of unfolding transitions suggest that the stability of the studied amyloids relative to the intermediate aggregates and of the latter relative to unfolded monomers is higher for ApoMb variants with substitutions that increase the hydrophobicity of the residues. The results presented provide a new insight into the mechanism of stabilization of protein aggregates and can serve as a base for further investigations of the amyloids' stability.
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Affiliation(s)
- Natalya Katina
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, 142290 Pushchino, Russia
| | - Victor Marchenkov
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
| | - Natalya Ryabova
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
| | - Nelly Ilyina
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
| | - Natalia Marchenko
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
| | - Vitalii Balobanov
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
| | - Alexey Finkelstein
- Institute of Protein Research RAS, 142290 Pushchino, Russia; (V.M.); (N.R.); (N.I.); (N.M.)
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2
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Sorokina J, Sokolova I, Majorina M, Ungur A, Troitskiy V, Tukhvatulin A, Melnik B, Belyi Y. Oligomerization and Adjuvant Activity of Peptides Derived from the VirB4-like ATPase of Clostridioides difficile. Biomolecules 2023; 13:1012. [PMID: 37371592 DOI: 10.3390/biom13061012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 06/13/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
In a previous study, we demonstrated that the Clostridioides difficile VirB4-like ATPase forms oligomers in vitro. In the current investigation, to study the observed phenomenon in more detail, we prepared a library of VirB4-derived peptides (delVirB4s) fused to a carrier maltose-binding protein (MBP). Using gel chromatography and polyacrylamide gel electrophoresis, we found a set of overlapping fragments that contribute most significantly to protein aggregation, which were represented as water-soluble oligomers with molecular masses ranging from ~300 kD to several megadaltons. Membrane filtration experiments, sucrose gradient ultracentrifugation, and dynamic light scattering measurements indicated the size of the soluble complex to be 15-100 nm. It was sufficiently stable to withstand treatment with 1 M urea; however, it dissociated in a 6 M urea solution. As shown by the changes in GFP fluorescence and the circular dichroism spectra, the attachment of the delVirB4 peptide significantly altered the structure of the partner MBP. The immunization of mice with the hybrid consisting of the selected VirB4-derived peptide and MBP, GST, or GFP resulted in increased production of specific antibodies compared to the peptide-free carrier proteins, suggesting significant adjuvant activity of the VirB4 fragment. This feature could be useful for the development of new vaccines, especially in the case of "weak" antigens that are unable to elicit a strong immune response by themselves.
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Affiliation(s)
- Julya Sorokina
- Gamaleya Research Centre for Epidemiology and Microbiology, Moscow 123098, Russia
| | - Irina Sokolova
- Gamaleya Research Centre for Epidemiology and Microbiology, Moscow 123098, Russia
| | - Mariya Majorina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino 142290, Russia
| | - Anastasia Ungur
- Gamaleya Research Centre for Epidemiology and Microbiology, Moscow 123098, Russia
| | - Vasiliy Troitskiy
- Department of Infectious Diseases, Institute of Clinical Medicine, I.M. Sechenov First Moscow State Medical University (Sechenov University), 2 Bolshaya Pirogovskaya St., Moscow 119435, Russia
| | - Amir Tukhvatulin
- Gamaleya Research Centre for Epidemiology and Microbiology, Moscow 123098, Russia
| | - Bogdan Melnik
- Institute of Protein Research, Russian Academy of Sciences, Pushchino 142290, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, Pushchino 142290, Russia
| | - Yury Belyi
- Gamaleya Research Centre for Epidemiology and Microbiology, Moscow 123098, Russia
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3
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Bychkova VE, Dolgikh DA, Balobanov VA, Finkelstein AV. The Molten Globule State of a Globular Protein in a Cell Is More or Less Frequent Case Rather than an Exception. Molecules 2022; 27:molecules27144361. [PMID: 35889244 PMCID: PMC9319461 DOI: 10.3390/molecules27144361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/01/2022] [Accepted: 07/03/2022] [Indexed: 02/01/2023] Open
Abstract
Quite a long time ago, Oleg B. Ptitsyn put forward a hypothesis about the possible functional significance of the molten globule (MG) state for the functioning of proteins. MG is an intermediate between the unfolded and the native state of a protein. Its experimental detection and investigation in a cell are extremely difficult. In the last decades, intensive studies have demonstrated that the MG-like state of some globular proteins arises from either their modifications or interactions with protein partners or other cell components. This review summarizes such reports. In many cases, MG was evidenced to be functionally important. Thus, the MG state is quite common for functional cellular proteins. This supports Ptitsyn’s hypothesis that some globular proteins may switch between two active states, rigid (N) and soft (MG), to work in solution or interact with partners.
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Affiliation(s)
- Valentina E. Bychkova
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (V.E.B.); (A.V.F.)
| | - Dmitry A. Dolgikh
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117871 Moscow, Russia;
| | - Vitalii A. Balobanov
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (V.E.B.); (A.V.F.)
- Correspondence:
| | - Alexei V. Finkelstein
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; (V.E.B.); (A.V.F.)
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4
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Majorina MA, Balobanov VA, Uversky VN, Melnik BS. Loops linking secondary structure elements affect the stability of the molten globule intermediate state of apomyoglobin. FEBS Lett 2020; 594:3293-3304. [PMID: 32770670 DOI: 10.1002/1873-3468.13905] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 07/29/2020] [Accepted: 08/06/2020] [Indexed: 11/11/2022]
Abstract
Apomyoglobin is a widely used model for studying the molecular mechanisms of globular protein folding. This work aimed to analyze the effects of rigidity and length of loops linking protein secondary structure elements on the stability of the molten globule intermediate state. For this purpose, we studied folding/unfolding of mutant apomyoglobin forms with substitutions of loop-located proline residues to glycine and with loop extension by three or six glycine residues. The kinetic and equilibrium experiments performed gave an opportunity to calculate free energies of different apomyoglobin states. Our analysis revealed that the mutations introduced into the apomyoglobin loops have a noticeable effect on the stability of the intermediate state compared to the unfolded state.
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Affiliation(s)
| | | | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Pushchino, Moscow region, Russia
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5
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Uversky VN, Finkelstein AV. Life in Phases: Intra- and Inter- Molecular Phase Transitions in Protein Solutions. Biomolecules 2019; 9:E842. [PMID: 31817975 PMCID: PMC6995567 DOI: 10.3390/biom9120842] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 02/06/2023] Open
Abstract
Proteins, these evolutionarily-edited biological polymers, are able to undergo intramolecular and intermolecular phase transitions. Spontaneous intramolecular phase transitions define the folding of globular proteins, whereas binding-induced, intra- and inter- molecular phase transitions play a crucial role in the functionality of many intrinsically-disordered proteins. On the other hand, intermolecular phase transitions are the behind-the-scenes players in a diverse set of macrosystemic phenomena taking place in protein solutions, such as new phase nucleation in bulk, on the interface, and on the impurities, protein crystallization, protein aggregation, the formation of amyloid fibrils, and intermolecular liquid-liquid or liquid-gel phase transitions associated with the biogenesis of membraneless organelles in the cells. This review is dedicated to the systematic analysis of the phase behavior of protein molecules and their ensembles, and provides a description of the major physical principles governing intramolecular and intermolecular phase transitions in protein solutions.
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Affiliation(s)
- Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
- Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, 142290 Pushchino, Moscow, Russia
| | - Alexei V. Finkelstein
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow, Russia
- Biology Department, Lomonosov Moscow State University, 119192 Moscow, Russia
- Bioltechnogy Department, Lomonosov Moscow State University, 142290 Pushchino, Moscow, Russia
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6
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Majorina MA, Glukhova KA, Marchenkov VV, Melnik BS. Effect of Substitutions in Surface Amino Acid on Energy Profile of Apomyoglobin. Mol Biol 2018. [DOI: 10.1134/s0026893318010119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Katina NS, Suvorina MY, Grigorashvili EI, Marchenkov VV, Ryabova NA, Nikulin AD, Surin AK. Identification of Regions in Apomyoglobin that Form Intermolecular Interactions in Amyloid Aggregates Using High-Performance Mass Spectrometry. JOURNAL OF ANALYTICAL CHEMISTRY 2018. [DOI: 10.1134/s1061934817130056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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8
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Bychkova VE, Semisotnov GV, Balobanov VA, Finkelstein AV. The Molten Globule Concept: 45 Years Later. BIOCHEMISTRY (MOSCOW) 2018; 83:S33-S47. [DOI: 10.1134/s0006297918140043] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Katina NS, Balobanov VA, Ilyina NB, Vasiliev VD, Marchenkov VV, Glukhov AS, Nikulin AD, Bychkova VE. sw ApoMb Amyloid Aggregation under Nondenaturing Conditions: The Role of Native Structure Stability. Biophys J 2017; 113:991-1001. [PMID: 28877500 DOI: 10.1016/j.bpj.2017.07.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 07/19/2017] [Accepted: 07/20/2017] [Indexed: 12/17/2022] Open
Abstract
Investigation of the molecular mechanisms underlying amyloid-related human diseases attracts close attention. These diseases, the number of which currently is above 40, are characterized by formation of peptide or protein aggregates containing a cross-β structure. Most of the amyloidogenesis mechanisms described so far are based on experimental studies of aggregation of short peptides, intrinsically disordered proteins, or proteins under denaturing conditions, and studies of amyloid aggregate formations by structured globular proteins under conditions close to physiological ones are still in the initial stage. We investigated the effect of amino acid substitutions on propensity of the completely helical protein sperm whale apomyoglobin (sw ApoMb) for amyloid formation from its structured state in the absence of denaturing agents. Stability and aggregation of mutated sw ApoMb were studied using circular dichroism, Fourier transform infrared spectroscopy, x-ray diffraction, native electrophoresis, and electron microscopy techniques. Here, we demonstrate that stability of the protein native state determines both protein aggregation propensity and structural peculiarities of formed aggregates. Specifically, structurally stable mutants show low aggregation propensity and moderately destabilized sw ApoMb variants form amyloids, whereas their strongly destabilized mutants form both amyloids and nonamyloid aggregates.
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Affiliation(s)
- Natalya S Katina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Vitalii A Balobanov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Nelly B Ilyina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Victor D Vasiliev
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Victor V Marchenkov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Anatoly S Glukhov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Alexey D Nikulin
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
| | - Valentina E Bychkova
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
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10
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Balobanov VA, Katina NS, Finkelstein AV, Bychkova VE. Intermediate states of apomyoglobin: Are they parts of the same area of conformations diagram? BIOCHEMISTRY (MOSCOW) 2017; 82:625-631. [DOI: 10.1134/s0006297917050108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Bychkova VE, Basova LV, Balobanov VA. How membrane surface affects protein structure. BIOCHEMISTRY (MOSCOW) 2015; 79:1483-514. [DOI: 10.1134/s0006297914130045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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12
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Melnik TN, Majorina MA, Larina DS, Kashparov IA, Samatova EN, Glukhov AS, Melnik BS. Independent of their localization in protein the hydrophobic amino acid residues have no effect on the molten globule state of apomyoglobin and the disulfide bond on the surface of apomyoglobin stabilizes this intermediate state. PLoS One 2014; 9:e98645. [PMID: 24892675 PMCID: PMC4043776 DOI: 10.1371/journal.pone.0098645] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 05/06/2014] [Indexed: 01/07/2023] Open
Abstract
At present it is unclear which interactions in proteins reveal the presence of intermediate states, their stability and formation rate. In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin. It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin. It has been shown also that introduction of a disulfide bond on the protein surface can stabilize the molten globule state. However in the case of apomyoglobin, stabilization of the intermediate state leads to relative destabilization of the native state of apomyoglobin. The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to “strengthen” the protein) can result in destabilization of the protein native state of apomyoglobin.
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Affiliation(s)
- Tatiana N. Melnik
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
| | - Maria A. Majorina
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
| | - Daria S. Larina
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
| | - Ivan A. Kashparov
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
| | - Ekaterina N. Samatova
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
- Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | - Bogdan S. Melnik
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
- * E-mail:
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13
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Orevi T, Rahamim G, Hazan G, Amir D, Haas E. The loop hypothesis: contribution of early formed specific non-local interactions to the determination of protein folding pathways. Biophys Rev 2013; 5:85-98. [PMID: 28510159 DOI: 10.1007/s12551-013-0113-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/01/2013] [Indexed: 12/12/2022] Open
Abstract
The extremely fast and efficient folding transition (in seconds) of globular proteins led to the search for some unifying principles embedded in the physics of the folding polypeptides. Most of the proposed mechanisms highlight the role of local interactions that stabilize secondary structure elements or a folding nucleus as the starting point of the folding pathways, i.e., a "bottom-up" mechanism. Non-local interactions were assumed either to stabilize the nucleus or lead to the later steps of coalescence of the secondary structure elements. An alternative mechanism was proposed, an "up-down" mechanism in which it was assumed that folding starts with the formation of very few non-local interactions which form closed long loops at the initiation of folding. The possible biological advantage of this mechanism, the "loop hypothesis", is that the hydrophobic collapse is associated with ordered compactization which reduces the chance for degradation and misfolding. In the present review the experiments, simulations and theoretical consideration that either directly or indirectly support this mechanism are summarized. It is argued that experiments monitoring the time-dependent development of the formation of specifically targeted early-formed sub-domain structural elements, either long loops or secondary structure elements, are necessary. This can be achieved by the time-resolved FRET-based "double kinetics" method in combination with mutational studies. Yet, attempts to improve the time resolution of the folding initiation should be extended down to the sub-microsecond time regime in order to design experiments that would resolve the classes of proteins which first fold by local or non-local interactions.
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Affiliation(s)
- Tomer Orevi
- The Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel, 52900
| | - Gil Rahamim
- The Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel, 52900
| | - Gershon Hazan
- The Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel, 52900
| | - Dan Amir
- The Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel, 52900
| | - Elisha Haas
- The Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel, 52900.
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14
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Melnik TN, Povarnitsyna TV, Glukhov AS, Melnik BS. Multi-state proteins: approach allowing experimental determination of the formation order of structure elements in the green fluorescent protein. PLoS One 2012; 7:e48604. [PMID: 23155397 PMCID: PMC3498258 DOI: 10.1371/journal.pone.0048604] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 09/26/2012] [Indexed: 11/19/2022] Open
Abstract
The most complex problem in studying multi-state protein folding is the determination of the sequence of formation of protein intermediate states. A far more complex issue is to determine at what stages of protein folding its various parts (secondary structure elements) develop. The structure and properties of different intermediate states depend in particular on these parts. An experimental approach, named μ-analysis, which allows understanding the order of formation of structural elements upon folding of a multi-state protein was used in this study. In this approach the same elements of the protein secondary structure are “tested” by substitutions of single hydrophobic amino acids and by incorporation of cysteine bridges. Single substitutions of hydrophobic amino acids contribute to yielding information on the late stages of protein folding while incorporation of ss-bridges allows obtaining data on the initial stages of folding. As a result of such an μ-analysis, we have determined the order of formation of beta-hairpins upon folding of the green fluorescent protein.
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Affiliation(s)
- Tatiana N. Melnik
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
| | | | | | - Bogdan S. Melnik
- Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia
- * E-mail:
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15
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Katina NS, Ilyina NB, Kashparov IA, Balobanov VA, Vasiliev VD, Bychkova VE. Apomyoglobin mutants with single point mutations at val10 can form amyloid structures at permissive temperature. BIOCHEMISTRY. BIOKHIMIIA 2011; 76:555-563. [PMID: 21639835 DOI: 10.1134/s0006297911050051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Formation of amyloid-like protein aggregates in human organs and tissues underlies many serious diseases, therefore being in the focus of numerous biochemical, medical, and molecular biological studies. So far, formation of amyloids by globular proteins has been studied mostly under conditions that strongly destabilized their native structure. Here we present our results obtained at permissive temperature by thioflavin T fluorescence, far UV CD, IR spectroscopy, and electron microscopy. We used apomyoglobin and its mutants with Ala or Phe substituted for Val10 that are structurally close to wild type apomyoglobin. It is shown that at permissive temperature the ability of the protein to form amyloids depends on the extent of its structural destabilization, but not on hydrophobicity of the substituting residue. A possible difference between amyloids formed by strongly destabilized proteins and those yielded by proteins with a slightly fluctuating native structure, as well as the stroke and infarction effect on the ability of proteins to form amyloid structures, are discussed.
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Affiliation(s)
- N S Katina
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region
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16
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Samatova EN, Melnik BS, Balobanov VA, Katina NS, Dolgikh DA, Semisotnov GV, Finkelstein AV, Bychkova VE. Folding intermediate and folding nucleus for I-->N and U-->I-->N transitions in apomyoglobin: contributions by conserved and nonconserved residues. Biophys J 2010; 98:1694-702. [PMID: 20409491 DOI: 10.1016/j.bpj.2009.12.4326] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Revised: 12/22/2009] [Accepted: 12/30/2009] [Indexed: 11/19/2022] Open
Abstract
Kinetic investigation on the wild-type apomyoglobin and its 12 mutants with substitutions of hydrophobic residues by Ala was performed using stopped-flow fluorescence. Characteristics of the kinetic intermediate I and the folding nucleus were derived solely from kinetic data, namely, the slow-phase folding rate constants and the burst-phase amplitudes of Trp fluorescence intensity. This allowed us to pioneer the phi-analysis for apomyoglobin. As shown, these mutations drastically destabilized the native state N and produced minor (for conserved residues of G, H helices) or even negligible (for nonconserved residues of B, C, D, E helices) destabilizing effect on the state I. On the other hand, conserved residues of A, G, H helices made a smaller contribution to stability of the folding nucleus at the rate-limiting I-->N transition than nonconserved residues of B, D, E helices. Thus, conserved side chains of the A-, G-, H-residues become involved in the folding nucleus before crossing the main barrier, whereas nonconserved side chains of the B-, D-, E-residues join the nucleus in the course of the I-->N transition.
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Affiliation(s)
- Ekaterina N Samatova
- Institute of Protein Research, Russian Academy of Sciences, Moscow, Russian Federation
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