1
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Graham KA, Byrne A, Son R, Andersen NH. Reversing the typical pH stability profile of the Trp-cage. Biopolymers 2019; 110:e23260. [PMID: 30779444 DOI: 10.1002/bip.23260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/14/2018] [Accepted: 01/07/2019] [Indexed: 12/18/2022]
Abstract
The Trp-cage, an 18-20 residue miniprotein, has emerged as a primary test system for evaluating computational fold prediction and folding rate determination efforts. As it turns out, a number of stabilizing interactions in the Trp-cage folded state have a strong pH dependence; all prior Trp-cage mutants have been destabilized under carboxylate-protonating conditions. Notable among the pH dependent stabilizing interactions within the Trp-cage are: (1) an Asp as the helix N-cap, (2) an H-bonded Asp9/Arg16 salt bridge, (3) an interaction between the chain termini which are in close spatial proximity, and (4) additional side chain interactions with Asp9. In the present study, we have prepared Trp-cage species that are significantly more stable at pH 2.5 (rather than 7) and quantitated the contribution of each interaction listed above. The Trp-cage structure remains constant with the pH change. The study has also provided measures of the stabilizing contribution of indole ring shielding from surface exposure and the destabilizing effects of an ionized Asp at the C-terminus of an α-helix.
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Affiliation(s)
| | - Aimee Byrne
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Ruth Son
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Niels H Andersen
- Department of Chemistry, University of Washington, Seattle, Washington
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2
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Gera J, Szögi T, Bozsó Z, Fülöp L, Barrera EE, Rodriguez AM, Méndez L, Delpiccolo CM, Mata EG, Cioffi F, Broersen K, Paragi G, Enriz RD. Searching for improved mimetic peptides inhibitors preventing conformational transition of amyloid-β42 monomer. Bioorg Chem 2018; 81:211-221. [DOI: 10.1016/j.bioorg.2018.08.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/10/2018] [Accepted: 08/13/2018] [Indexed: 01/14/2023]
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3
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Cote Y, Delarue P, Scheraga HA, Senet P, Maisuradze GG. From a Highly Disordered to a Metastable State: Uncovering Insights of α-Synuclein. ACS Chem Neurosci 2018; 9:1051-1065. [PMID: 29451381 DOI: 10.1021/acschemneuro.7b00446] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
α-Synuclein (αS) is a major constituent of Lewy bodies, the insoluble aggregates that are the hallmark of one of the most prevalent neurodegenerative disorders, Parkinson's disease (PD). The vast majority of experiments in vitro and in vivo provide extensive evidence that a disordered monomeric form is the predominant state of αS in water solution, and it undergoes a large-scale disorder-to-helix transition upon binding to vesicles of different types. Recently, another form, tetrameric, of αS with a stable helical structure was identified experimentally. It has been shown that a dynamic intracellular population of metastable αS tetramers and monomers coexists normally; and the tetramer plays an essential role in maintaining αS homeostasis. Therefore, it is of interest to know whether the tetramer can serve as a means of preventing or delaying the start of PD. Before answering this very important question, it is, first, necessary to find out, on an atomistic level, a correlation between tetramers and monomers; what mediates tetramer formation and what makes a tetramer stable. We address these questions here by investigating both monomeric and tetrameric forms of αS. In particular, by examining correlations between the motions of the side chains and the main chain, steric parameters along the amino-acid sequence, and one- and two-dimensional free-energy landscapes along the coarse-grained dihedral angles γ and δ and principal components, respectively, in monomeric and tetrameric αS, we were able to shed light on a fundamental relationship between monomers and tetramers, and the key residues involved in mediating formation of a tetramer. Also, the reasons for the stability of tetrameric αS and inability of monomeric αS to fold are elucidated here.
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Affiliation(s)
- Yoann Cote
- Department of
Integrative Structural Biology, Institut de Génétique
et de Biologie Moléculaire et Cellulaire, CNRS UMR 7104 - INSERM
U 964, Université de Strasbourg, 1 rue Laurent Fries, 67400 Illkirch-Graffenstaden, France
- Laboratoire Interdisciplinaire
Carnot de Bourgogne, UMR 6303 CNRS - Univ. Bourgogne Franche-Comté, 9 Av. Alain Savary, BP 47 870, F-21078 Dijon Cedex, France
| | - Patrice Delarue
- Laboratoire Interdisciplinaire
Carnot de Bourgogne, UMR 6303 CNRS - Univ. Bourgogne Franche-Comté, 9 Av. Alain Savary, BP 47 870, F-21078 Dijon Cedex, France
| | - Harold A. Scheraga
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States
| | - Patrick Senet
- Laboratoire Interdisciplinaire
Carnot de Bourgogne, UMR 6303 CNRS - Univ. Bourgogne Franche-Comté, 9 Av. Alain Savary, BP 47 870, F-21078 Dijon Cedex, France
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States
| | - Gia G. Maisuradze
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States
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4
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Narang SS, Shuaib S, Goyal B. Molecular insights into the inhibitory mechanism of rifamycin SV against β 2 –microglobulin aggregation: A molecular dynamics simulation study. Int J Biol Macromol 2017; 102:1025-1034. [DOI: 10.1016/j.ijbiomac.2017.04.086] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/24/2017] [Accepted: 04/24/2017] [Indexed: 01/30/2023]
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5
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Saini RK, Shuaib S, Goyal B. Molecular insights into Aβ42protofibril destabilization with a fluorinated compound D744: A molecular dynamics simulation study. J Mol Recognit 2017; 30. [DOI: 10.1002/jmr.2656] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 12/13/2022]
Affiliation(s)
- Rajneet Kaur Saini
- Department of Chemistry, School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib Punjab India
| | - Suniba Shuaib
- Department of Chemistry, School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib Punjab India
| | - Bhupesh Goyal
- Department of Chemistry, School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib Punjab India
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6
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Narang SS, Shuaib S, Goyal D, Goyal B. Assessing the effect of D59P mutation in the DE loop region in amyloid aggregation propensity of β2‐microglobulin: A molecular dynamics simulation study. J Cell Biochem 2017; 119:782-792. [DOI: 10.1002/jcb.26241] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 06/27/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Simranjeet S. Narang
- Department of Chemistry School of Basic and Applied Sciences Sri Guru Granth Sahib World University Punjab India
| | - Suniba Shuaib
- Department of Chemistry School of Basic and Applied Sciences Sri Guru Granth Sahib World University Punjab India
| | - Deepti Goyal
- Department of Chemistry School of Basic and Applied Sciences Sri Guru Granth Sahib World University Punjab India
| | - Bhupesh Goyal
- Department of Chemistry School of Basic and Applied Sciences Sri Guru Granth Sahib World University Punjab India
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7
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Goyal B, Srivastava KR, Durani S. N-terminal diproline and charge group effects on the stabilization of helical conformation in alanine-based short peptides: CD studies with water and methanol as solvent. J Pept Sci 2017; 23:431-437. [PMID: 28425159 DOI: 10.1002/psc.3005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 03/17/2017] [Accepted: 03/20/2017] [Indexed: 12/25/2022]
Abstract
Protein folding problem remains a formidable challenge as main chain, side chain and solvent interactions remain entangled and have been difficult to resolve. Alanine-based short peptides are promising models to dissect protein folding initiation and propagation structurally as well as energetically. The effect of N-terminal diproline and charged side chains is assessed on the stabilization of helical conformation in alanine-based short peptides using circular dichroism (CD) with water and methanol as solvent. A1 (Ac-Pro-Pro-Ala-Lys-Ala-Lys-Ala-Lys-Ala-NH2 ) is designed to assess the effect of N-terminal homochiral diproline and lysine side chains to induce helical conformation. A2 (Ac-Pro-Pro-Glu-Glu-Ala-Ala-Lys-Lys-Ala-NH2 ) and A3 (Ac-dPro-Pro-Glu-Glu-Ala-Ala-Lys-Lys-Ala-NH2 ) with N-terminal homochiral and heterochiral diproline, respectively, are designed to assess the effect of Glu...Lys (i, i + 4) salt bridge interactions on the stabilization of helical conformation. The CD spectra of A1, A2 and A3 in water manifest different amplitudes of the observed polyproline II (PPII) signals, which indicate different conformational distributions of the polypeptide structure. The strong effect of solvent substitution from water to methanol is observed for the peptides, and CD spectra in methanol evidence A2 and A3 as helical folds. Temperature-dependent CD spectra of A1 and A2 in water depict an isodichroic point reflecting coexistence of two conformations, PPII and β-strand conformation, which is consistent with the previous studies. The results illuminate the effect of N-terminal diproline and charged side chains in dictating the preferences for extended-β, semi-extended PPII and helical conformation in alanine-based short peptides. The results of the present study will enhance our understanding on stabilization of helical conformation in short peptides and hence aid in the design of novel peptides with helical structures. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Department of Chemistry, School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib, 140406, Punjab, India
| | - Kinshuk Raj Srivastava
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48105, USA
| | - Susheel Durani
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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8
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Shuaib S, Goyal B. Scrutiny of the mechanism of small molecule inhibitor preventing conformational transition of amyloid-β 42 monomer: insights from molecular dynamics simulations. J Biomol Struct Dyn 2017; 36:663-678. [PMID: 28162045 DOI: 10.1080/07391102.2017.1291363] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is characterized by loss of intellectual functioning of brain and memory loss. According to amyloid cascade hypothesis, aggregation of amyloid-β42 (Aβ42) peptide can generate toxic oligomers and their accumulation in the brain is responsible for the onset of AD. In spite of carrying out a large number of experimental studies on inhibition of Aβ42 aggregation by small molecules, the detailed inhibitory mechanism remains elusive. In the present study, comparable molecular dynamics (MD) simulations were performed to elucidate the inhibitory mechanism of a sulfonamide inhibitor C1 (2,5-dichloro-N-(4-piperidinophenyl)-3-thiophenesulfonamide), reported for its in vitro and in vivo anti-aggregation activity against Aβ42. MD simulations reveal that C1 stabilizes native α-helix conformation of Aβ42 by interacting with key residues in the central helix region (13-26) with hydrogen bonds and π-π interactions. C1 lowers the solvent-accessible surface area of the central hydrophobic core (CHC), KLVFF (16-20), that confirms burial of hydrophobic residues leading to the dominance of helical conformation in the CHC region. The binding free energy analysis with MM-PBSA demonstrates that Ala2, Phe4, Tyr10, Gln15, Lys16, Leu17, Val18, Phe19, Phe20, Glu22, and Met35 contribute maximum to binding free energy (-43.1 kcal/mol) between C1 and Aβ42 monomer. Overall, MD simulations reveal that C1 inhibits Aβ42 aggregation by stabilizing native helical conformation and inhibiting the formation of aggregation-prone β-sheet conformation. The present results will shed light on the underlying inhibitory mechanism of small molecules that show potential in vitro anti-aggregation activity against Aβ42.
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Affiliation(s)
- Suniba Shuaib
- a Department of Chemistry , School of Basic and Applied Sciences, Sri Guru Granth Sahib World University , Fatehgarh Sahib 140406 , Punjab , India
| | - Bhupesh Goyal
- a Department of Chemistry , School of Basic and Applied Sciences, Sri Guru Granth Sahib World University , Fatehgarh Sahib 140406 , Punjab , India
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9
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Goyal D, Shuaib S, Mann S, Goyal B. Rationally Designed Peptides and Peptidomimetics as Inhibitors of Amyloid-β (Aβ) Aggregation: Potential Therapeutics of Alzheimer's Disease. ACS COMBINATORIAL SCIENCE 2017; 19:55-80. [PMID: 28045249 DOI: 10.1021/acscombsci.6b00116] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease with no clinically accepted treatment to cure or halt its progression. The worldwide effort to develop peptide-based inhibitors of amyloid-β (Aβ) aggregation can be considered an unplanned combinatorial experiment. An understanding of what has been done and achieved may advance our understanding of AD pathology and the discovery of effective therapeutic agents. We review here the history of such peptide-based inhibitors, including those based on the Aβ sequence and those not derived from that sequence, containing both natural and unnatural amino acid building blocks. Peptide-based aggregation inhibitors hold significant promise for future AD therapy owing to their high selectivity, effectiveness, low toxicity, good tolerance, low accumulation in tissues, high chemical and biological diversity, possibility of rational design, and highly developed methods for analyzing their mode of action, proteolytic stability (modified peptides), and blood-brain barrier (BBB) permeability.
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Affiliation(s)
- Deepti Goyal
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
| | - Suniba Shuaib
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
| | - Sukhmani Mann
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
| | - Bhupesh Goyal
- Department of Chemistry,
School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib-140406, Punjab, India
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10
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Shuaib S, Saini RK, Goyal D, Goyal B. Insights into the Inhibitory Mechanism of Dicyanovinyl-Substituted J147 Derivative against Aβ42
Aggregation and Protofibril Destabilization: A Molecular Dynamics Simulation Study. ChemistrySelect 2017. [DOI: 10.1002/slct.201601970] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Suniba Shuaib
- Department of Chemistry; School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib- 140406, Punjab India
| | - Rajneet Kaur Saini
- Department of Chemistry; School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib- 140406, Punjab India
| | - Deepti Goyal
- Department of Chemistry; School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib- 140406, Punjab India
| | - Bhupesh Goyal
- Department of Chemistry; School of Basic and Applied Sciences; Sri Guru Granth Sahib World University; Fatehgarh Sahib- 140406, Punjab India
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11
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Sequence-, structure-, and dynamics-based comparisons of structurally homologous CheY-like proteins. Proc Natl Acad Sci U S A 2017; 114:1578-1583. [PMID: 28143938 DOI: 10.1073/pnas.1621344114] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We recently introduced a physically based approach to sequence comparison, the property factor method (PFM). In the present work, we apply the PFM approach to the study of a challenging set of sequences-the bacterial chemotaxis protein CheY, the N-terminal receiver domain of the nitrogen regulation protein NT-NtrC, and the sporulation response regulator Spo0F. These are all response regulators involved in signal transduction. Despite functional similarity and structural homology, they exhibit low sequence identity. PFM sequence comparison demonstrates a statistically significant qualitative difference between the sequence of CheY and those of the other two proteins that is not found using conventional alignment methods. This difference is shown to be consonant with structural characteristics, using distance matrix comparisons. We also demonstrate that residues participating strongly in native contacts during unfolding are distributed differently in CheY than in the other two proteins. The PFM result is also in accord with dynamic simulation results of several types. Molecular dynamics simulations of all three proteins were carried out at several temperatures, and it is shown that the dynamics of CheY are predicted to differ from those of NT-NtrC and Spo0F. The predicted dynamic properties of the three proteins are in good agreement with experimentally determined B factors and with fluctuations predicted by the Gaussian network model. We pinpoint the differences between the PFM and traditional sequence comparisons and discuss the informatic basis for the ability of the PFM approach to detect physical differences between these sequences that are not apparent from traditional alignment-based comparison.
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12
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Srivastava KR, Goyal B, Kumar A, Durani S. Scrutiny of electrostatic-driven conformational ordering of polypeptide chains in DMSO: a study with a model oligopeptide. RSC Adv 2017. [DOI: 10.1039/c7ra02137b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The molecular mechanism of DMSO-induced stabilisation of β-sheets is attributed to the combination of polar electrostatic interactions among side chains, and backbone desolvation through bulky side chains which promotes backbone hydrogen bonding.
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Affiliation(s)
| | - Bhupesh Goyal
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | - Anil Kumar
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | - Susheel Durani
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
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13
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Goyal B, Srivastava KR, Durani S. Examination of the Effect of N-terminal Diproline and Charged Side Chains on the Stabilization of Helical Conformation in Alanine-based Short Peptides: A Molecular Dynamics Study. ChemistrySelect 2016. [DOI: 10.1002/slct.201601381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry; Indian Institute of Technology Bombay, Powai; Mumbai-400076 India
- Department of Chemistry; School of Basic and Applied Sciences; Sri Guru Granth Sahib World University, Fatehgarh; Sahib-140406, Punjab India
| | - Kinshuk Raj Srivastava
- Department of Chemistry; Indian Institute of Technology Bombay, Powai; Mumbai-400076 India
- Life Sciences Institute; University of Michigan; Ann Arbor, MI USA 48105
| | - Susheel Durani
- Department of Chemistry; Indian Institute of Technology Bombay, Powai; Mumbai-400076 India
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14
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Abstract
Over the last few years, there has been significant progress in the knowledge on protein folding. However, some aspects of protein folding still need further attention. One of these is the exact relationship between the folded and unfolded states and the differences between them. Whereas the folded state is well known, at least from a structural point of view (just think of the thousands of structures in online databases), the unfolded state is more elusive. Also, these are dynamic states of matter, and this aspect cannot be overlooked. Molecular dynamics-derived correlation matrices are an invaluable source of information on the protein dynamics. Here, bulk eigenvalue spectra of the correlation matrices obtained from the Trp-cage dynamics in the folded and unfolded states have been analyzed. The associated modes represent localized vibrations and are significantly affected by the fine details of the structure and interactions. Therefore, these bulk modes can be used as probes of the protein local dynamics in different states. The results of these analyses show that the correlation matrices describing the folded and unfolded dynamics belong to different symmetry classes. This finding provides new support to the phase-transition models of protein folding.
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Affiliation(s)
- Luigi L Palese
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (SMBNOS), University of Bari "Aldo Moro" , Piazza G.Cesare - Policlinico, 70124 Bari, Italy
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15
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Goyal B, Kumar A, Srivastava KR, Durani S. Scrutiny of chain-length and N-terminal effects in α-helix folding: a molecular dynamics study on polyalanine peptides. J Biomol Struct Dyn 2016; 35:1923-1935. [DOI: 10.1080/07391102.2016.1199972] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
- Department of Chemistry, School of Basic and Applied Sciences, Sri Guru Granth Sahib World University, Fatehgarh Sahib 140406, Punjab, India
| | - Anil Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
| | - Kinshuk Raj Srivastava
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
| | - Susheel Durani
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
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16
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Goyal B, Kumar A, Srivastava KR, Durani S. Computational scrutiny of the effect of N-terminal proline and residue stereochemistry in the nucleation of α-helix fold. RSC Adv 2016. [DOI: 10.1039/c6ra10934a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
N-Terminal l- to d-residue mutation nucleate helical fold in Ac–DAla–LAla3–NHMe (Ib, m2), Ac–DPro–LAla3–NHMe (IIb, m1), and Ac–DPro–LPro–LAla2–NHMe (IIIb, m2) peptides.
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Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | - Anil Kumar
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | | | - Susheel Durani
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
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17
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Goyal B, Srivastava KR, Kumar A, Patwari GN, Durani S. Probing the role of electrostatics of polypeptide main-chain in protein folding by perturbing N-terminal residue stereochemistry: DFT study with oligoalanine models. RSC Adv 2016. [DOI: 10.1039/c6ra22870d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Energetics of folding (ΔHE→F, in kcal mol−1) from the extended (E) structure to the folded (F) structure for Ia and Ib critically depend on the geometrical relationship between the backbone peptide units of the polypeptide structure.
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Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | | | - Anil Kumar
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | - G. Naresh Patwari
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
| | - Susheel Durani
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
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18
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Palese LL. Correlation Analysis of Trp-Cage Dynamics in Folded and Unfolded States. J Phys Chem B 2015; 119:15568-73. [PMID: 26619349 DOI: 10.1021/acs.jpcb.5b09678] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fundamental and still debated problem is how folded structures of proteins are related to their unfolded state. Besides the classical view, in which a large number of conformations characterize the unfolded state while the folded one is dominated by a single structure, recently a reassessment of the denatured state has been suggested. A growing amount of evidence indicates that not only the folded but also the unfolded state is at least partially organized. Here, we try to answer the question of how different protein dynamics is in folded and unfolded states by performing all-atom molecular dynamics simulations on the model protein Trp-cage. Random matrix theory inspired analysis of the correlation matrices has been carried out. The spectra of these correlation matrices show that the low rank modes of Trp-cage dynamics are outside of the limit expected for a random system both in folded and in unfolded conditions. These findings shed light on the nature of the unfolded state of the proteins, suggesting that it is much less random than previously thought.
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Affiliation(s)
- Luigi L Palese
- Department of Basic Medical Sciences, Neurosciences and Sense Organs (SMBNOS), University of Bari "Aldo Moro" , Piazza G. Cesare - Policlinico, 70124 Bari, Italy
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19
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Abstract
Protein dynamics is essential for proteins to function. Here we predicted the existence of rare, large nonlinear excitations, termed intrinsic localized modes (ILMs), of the main chain of proteins based on all-atom molecular dynamics simulations of two fast-folder proteins and of a rigid α/β protein at 300 K and at 380 K in solution. These nonlinear excitations arise from the anharmonicity of the protein dynamics. The ILMs were detected by computing the Shannon entropy of the protein main-chain fluctuations. In the non-native state (significantly explored at 380 K), the probability of their excitation was increased by a factor between 9 and 28 for the fast-folder proteins and by a factor 2 for the rigid protein. This enhancement in the non-native state was due to glycine, as demonstrated by simulations in which glycine was mutated to alanine. These ILMs might play a functional role in the flexible regions of proteins and in proteins in a non-native state (i.e. misfolded or unfolded states).
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20
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Caballero D, Smith WW, O'Hern CS, Regan L. Equilibrium transitions between side-chain conformations in leucine and isoleucine. Proteins 2015; 83:1488-99. [PMID: 26018846 DOI: 10.1002/prot.24837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 04/30/2015] [Accepted: 05/20/2015] [Indexed: 12/12/2022]
Abstract
Despite recent improvements in computational methods for protein design, we still lack a quantitative, predictive understanding of the intrinsic probabilities for amino acids to adopt particular side-chain conformations. Surprisingly, this question has remained unsettled for many years, in part because of inconsistent results from different experimental approaches. To explicitly determine the relative populations of different side-chain dihedral angles, we performed all-atom hard-sphere Langevin Dynamics simulations of leucine (Leu) and isoleucine (Ile) dipeptide mimetics with stereo-chemical constraints and repulsive-only steric interactions between non-bonded atoms. We determine the relative populations of the different χ(1) and χ(2) dihedral angle combinations as a function of the backbone dihedral angles ϕ and ψ. We also propose, and test, a mechanism for inter-conversion between the different side-chain conformations. Specifically, we discover that some of the transitions between side-chain dihedral angle combinations are very frequent, whereas others are orders of magnitude less frequent, because they require rare coordinated motions to avoid steric clashes. For example, to transition between different values of χ(2), the Leu side-chain bond angles κ(1) and κ(2) must increase, whereas to transition in χ(1), the Ile bond angles λ(1) and λ(2) must increase. These results emphasize the importance of computational approaches in stimulating further experimental studies of the conformations of side-chains in proteins. Moreover, our studies emphasize the power of simple steric models to inform our understanding of protein structure, dynamics, and design.
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Affiliation(s)
- Diego Caballero
- Department of Physics, Yale University, New Haven, Connecticut.,Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut
| | - W Wendell Smith
- Department of Physics, Yale University, New Haven, Connecticut
| | - Corey S O'Hern
- Department of Physics, Yale University, New Haven, Connecticut.,Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut.,Department of Mechanical Engineering & Materials Science, Yale University, New Haven, Connecticut.,Department of Applied Physics, Yale University, New Haven, Connecticut
| | - Lynne Regan
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut.,Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, Connecticut.,Department of Chemistry, Yale University, New Haven, Connecticut
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