1
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Khavani M, Mehranfar A, Mofrad MRK. On the interactions of peptides with gold nanoparticles: effects of sequence and size. J Biomol Struct Dyn 2024; 42:4429-4441. [PMID: 37306472 DOI: 10.1080/07391102.2023.2220816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 05/28/2023] [Indexed: 06/13/2023]
Abstract
Peptide-based self-assembly and synthesis techniques have emerged as a viable approach to designing active and stable inorganic nanostructures in aqueous media. In the present study, we use all-atom molecular dynamic (MD) simulations to study the interactions of ten short peptides (namely A3, AgBP1, AgBP2, AuBP1, AuBP2, GBP1, Midas2, Pd4, Z1, and Z2) with different gold nanoparticles (of different diameters ranging from 2 to 8 nm). Our MD simulation results imply that the gold nanoparticles have a remarkable effect on the stability and conformational properties of peptides. Moreover, the size of the gold nanoparticles and the type of peptide amino acid sequences play important roles in the stability of the peptide-AuNP complexes. Our results reveal that some amino acids such as Tyr, Phe, Met, Lys, Arg, and Gln have direct contact with the metal surface in comparison with Gly, Ala, Pro, Thr, and Val residues. The peptide adsorption on the surface of the gold nanoparticles is favorable from the energetic viewpoint, in which the van der Waals (vdW) interactions between the peptides and metal surface can be considered as one of the driving forces for the complexation process. The calculated Gibbs binding energies indicate that AuNPs have more sensitivity against the GBP1 peptide in the presence of different peptides. Overall, the results of this study can provide new insight into the peptide interaction with the gold nanoparticles from the molecular viewpoint, which can be important for designing new biomaterials based on the peptides and gold nanoparticles.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Mohammad Khavani
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California Berkeley, Berkeley, California, USA
| | - Aliyeh Mehranfar
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California Berkeley, Berkeley, California, USA
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California Berkeley, Berkeley, California, USA
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2
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Sanyal T, Mittal J, Shell MS. A hybrid, bottom-up, structurally accurate, Go¯-like coarse-grained protein model. J Chem Phys 2019; 151:044111. [PMID: 31370551 PMCID: PMC6663515 DOI: 10.1063/1.5108761] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 06/24/2019] [Indexed: 12/21/2022] Open
Abstract
Coarse-grained (CG) protein models in the structural biology literature have improved over the years from being simple tools to understand general folding and aggregation driving forces to capturing detailed structures achieved by actual folding sequences. Here, we ask whether such models can be developed systematically from recent advances in bottom-up coarse-graining methods without relying on bioinformatic data (e.g., protein data bank statistics). We use relative entropy coarse-graining to develop a hybrid CG but Go¯-like CG peptide model, hypothesizing that the landscape of proteinlike folds is encoded by the backbone interactions, while the sidechain interactions define which of these structures globally minimizes the free energy in a unique native fold. To construct a model capable of capturing varied secondary structures, we use a new extended ensemble relative entropy method to coarse-grain based on multiple reference atomistic simulations of short polypeptides with varied α and β character. Subsequently, we assess the CG model as a putative protein backbone forcefield by combining it with sidechain interactions based on native contacts but not incorporating native distances explicitly, unlike standard Go¯ models. We test the model's ability to fold a range of proteins and find that it achieves high accuracy (∼2 Å root mean square deviation resolution for both short sequences and large globular proteins), suggesting the strong role that backbone conformational preferences play in defining the fold landscape. This model can be systematically extended to non-natural amino acids and nonprotein polymers and sets the stage for extensions to non-Go¯ models with sequence-specific sidechain interactions.
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Affiliation(s)
- Tanmoy Sanyal
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Jeetain Mittal
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - M. Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
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3
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A test of AMBER force fields in predicting the secondary structure of α-helical and β-hairpin peptides. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.074] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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4
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Smith DJ, Shell MS. Can Simple Interaction Models Explain Sequence-Dependent Effects in Peptide Homodimerization? J Phys Chem B 2017; 121:5928-5943. [PMID: 28537734 DOI: 10.1021/acs.jpcb.7b03186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The development of rapid methods to explain and predict peptide interactions, aggregation, and self-assembly has become important to understanding amyloid disease pathology, the shelf stability of peptide therapeutics, and the design of novel peptide materials. Although experimental aggregation databases have been used to develop correlative and statistical models, molecular simulations offer atomic-level details that potentially provide greater physical insight and allow one to single out the most explanatory simple models. Here, we outline one such approach using a case study that develops homodimerization models for serine-glycine peptides with various hydrophobic leucine mutations. Using detailed all-atom simulations, we calculate reference dimerization free energy profiles and binding constants for a small peptide library. We then use statistical methods to systematically assess whether simple interaction models, which do not require expensive simulations and free energy calculation, can capture them. Surprisingly, some combinations of a few simple scaling laws well recapitulate the detailed, all-atom results with high accuracy. Specifically, we find that a recently proposed phenomenological hydrophobic force law and coarse measures of entropic effects in binding offer particularly high explanatory power, underscoring the physical relevance to association that these driving forces can play.
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Affiliation(s)
- David J Smith
- Department of Chemical Engineering, University of California, Santa Barbara , Santa Barbara, California 93106, United States
| | - M Scott Shell
- Department of Chemical Engineering, University of California, Santa Barbara , Santa Barbara, California 93106, United States
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5
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Tomsett M, Maffucci I, Le Bailly BAF, Byrne L, Bijvoets SM, Lizio MG, Raftery J, Butts CP, Webb SJ, Contini A, Clayden J. A tendril perversion in a helical oligomer: trapping and characterizing a mobile screw-sense reversal. Chem Sci 2017; 8:3007-3018. [PMID: 28451368 PMCID: PMC5380885 DOI: 10.1039/c6sc05474a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 01/24/2017] [Indexed: 11/21/2022] Open
Abstract
Helical oligomers of achiral monomers adopt domains of uniform screw sense, which are occasionally interrupted by screw-sense reversals. These rare, elusive, and fast-moving features have eluded detailed characterization. We now describe the structure and habits of a screw-sense reversal trapped within a fragment of a helical oligoamide foldamer of the achiral quaternary amino acid 2-aminoisobutyric acid (Aib). The reversal was enforced by compelling the amide oligomer to adopt a right-handed screw sense at one end and a left-handed screw sense at the other. The trapped reversal was characterized by X-ray crystallography, and its dynamic properties were monitored by NMR and circular dichroism, and modelled computationally. Raman spectroscopy indicated that a predominantly helical architecture was maintained despite the reversal. NMR and computational results indicated a stepwise shift from one screw sense to another on moving along the helical chain, indicating that in solution the reversal is not localised at a specific location, but is free to migrate across a number of residues. Analogous unconstrained screw-sense reversals that are free to move within a helical structure are likely to provide the mechanism by which comparable helical polymers and foldamers undergo screw-sense inversion.
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Affiliation(s)
- Michael Tomsett
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Irene Maffucci
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini" , Università degli Studi di Milano , Via Venezian , 21 20133 Milano , Italy
| | - Bryden A F Le Bailly
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Liam Byrne
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Stefan M Bijvoets
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - M Giovanna Lizio
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess St , Manchester M1 7DN , UK
| | - James Raftery
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
| | - Craig P Butts
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
| | - Simon J Webb
- School of Chemistry , University of Manchester , Oxford Road , Manchester M13 9PL , UK
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess St , Manchester M1 7DN , UK
| | - Alessandro Contini
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini" , Università degli Studi di Milano , Via Venezian , 21 20133 Milano , Italy
| | - Jonathan Clayden
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , UK .
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6
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Robinson MK, Monroe JI, Shell MS. Are AMBER Force Fields and Implicit Solvation Models Additive? A Folding Study with a Balanced Peptide Test Set. J Chem Theory Comput 2016; 12:5631-5642. [DOI: 10.1021/acs.jctc.6b00788] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Melina K. Robinson
- Department
of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Jacob I. Monroe
- Department
of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - M. Scott Shell
- Department
of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
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7
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Pellegrino S, Tonali N, Erba E, Kaffy J, Taverna M, Contini A, Taylor M, Allsop D, Gelmi ML, Ongeri S. β-Hairpin mimics containing a piperidine-pyrrolidine scaffold modulate the β-amyloid aggregation process preserving the monomer species. Chem Sci 2016; 8:1295-1302. [PMID: 28451272 PMCID: PMC5359901 DOI: 10.1039/c6sc03176e] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/05/2016] [Indexed: 12/22/2022] Open
Abstract
Alzheimer's disease is a neurodegenerative disorder linked to oligomerization and fibrillization of amyloid β peptides, with Aβ1-42 being the most aggregative and neurotoxic one. We report herein the synthesis and conformational analysis of Aβ1-42-amyloid related β-hairpin peptidomimetics, built on a piperidine-pyrrolidine semi rigid β-turn inducer and bearing two small recognition peptide sequences, designed on oligomeric and fibril structures of Aβ1-42. According to these peptide sequences, a stable β-hairpin or a dynamic equilibrium between two possible architectures was observed. These original constructs are able to greatly delay the kinetics of Aβ1-42 aggregation process as demonstrated by thioflavin-T fluorescence, and transmission electron microscopy. Capillary electrophoresis indicates their ability to preserve the monomer species, inhibiting the formation of toxic oligomers. Furthermore, compounds protect against toxic effects of Aβ on neuroblastoma cells even at substoichiometric concentrations. This study is the first example of acyclic small β-hairpin mimics possessing such a highly efficient anti-aggregation activity. The protective effect is more pronounced than that observed with molecules which have undergone clinical trials. The structural elements made in this study provide valuable insights in the understanding of the aggregation process and insights to explore the design of novel acyclic β-hairpin targeting other types of amyloid-forming proteins.
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Affiliation(s)
- S Pellegrino
- DISFARM-Sez. Chimica Generale e Organica "A. Marchesini" , Universitá degli Studi di Milano , via Venezian 21 , 20133 Milano , Italy .
| | - N Tonali
- Molécules Fluorées et Chimie Médicinale , BioCIS , Univ. Paris-Sud , CNRS , Université Paris Saclay , 5 rue Jean-Baptiste Clément , 92296 Châtenay-Malabry Cedex , France .
| | - E Erba
- DISFARM-Sez. Chimica Generale e Organica "A. Marchesini" , Universitá degli Studi di Milano , via Venezian 21 , 20133 Milano , Italy .
| | - J Kaffy
- Molécules Fluorées et Chimie Médicinale , BioCIS , Univ. Paris-Sud , CNRS , Université Paris Saclay , 5 rue Jean-Baptiste Clément , 92296 Châtenay-Malabry Cedex , France .
| | - M Taverna
- Protéines et Nanotechnologies en Sciences Séparatives , Institut Galien Paris-Sud , Univ. Paris-Sud , CNRS , Université Paris Saclay , 5 rue Jean-Baptiste Clément , 92296 Châtenay-Malabry Cedex , France
| | - A Contini
- DISFARM-Sez. Chimica Generale e Organica "A. Marchesini" , Universitá degli Studi di Milano , via Venezian 21 , 20133 Milano , Italy .
| | - M Taylor
- Lancaster University , Division of Biomedical and Life Sciences , Faculty of Health and Medicine , Lancaster LA1 4YQ , UK
| | - D Allsop
- Lancaster University , Division of Biomedical and Life Sciences , Faculty of Health and Medicine , Lancaster LA1 4YQ , UK
| | - M L Gelmi
- DISFARM-Sez. Chimica Generale e Organica "A. Marchesini" , Universitá degli Studi di Milano , via Venezian 21 , 20133 Milano , Italy .
| | - S Ongeri
- Molécules Fluorées et Chimie Médicinale , BioCIS , Univ. Paris-Sud , CNRS , Université Paris Saclay , 5 rue Jean-Baptiste Clément , 92296 Châtenay-Malabry Cedex , France .
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8
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Maffucci I, Contini A. An Updated Test of AMBER Force Fields and Implicit Solvent Models in Predicting the Secondary Structure of Helical, β-Hairpin, and Intrinsically Disordered Peptides. J Chem Theory Comput 2016; 12:714-27. [DOI: 10.1021/acs.jctc.5b01211] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Irene Maffucci
- Dipartimento di Scienze Farmaceutiche
− Sezione di Chimica Generale e Organica “Alessandro
Marchesini”, Università degli Studi di Milano, Via
Venezian, 21 20133 Milano, Italy
| | - Alessandro Contini
- Dipartimento di Scienze Farmaceutiche
− Sezione di Chimica Generale e Organica “Alessandro
Marchesini”, Università degli Studi di Milano, Via
Venezian, 21 20133 Milano, Italy
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9
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Sawle L, Ghosh K. Convergence of Molecular Dynamics Simulation of Protein Native States: Feasibility vs Self-Consistency Dilemma. J Chem Theory Comput 2016; 12:861-9. [DOI: 10.1021/acs.jctc.5b00999] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lucas Sawle
- Department of Physics and
Astronomy, University of Denver, Denver, Colorado 80209, United States
| | - Kingshuk Ghosh
- Department of Physics and
Astronomy, University of Denver, Denver, Colorado 80209, United States
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10
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Carmichael SP, Shell MS. Entropic (de)stabilization of surface-bound peptides conjugated with polymers. J Chem Phys 2015; 143:243103. [DOI: 10.1063/1.4929592] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Scott P. Carmichael
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - M. Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
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11
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Kumar A, Campitelli P, Thorpe MF, Ozkan SB. Partial unfolding and refolding for structure refinement: A unified approach of geometric simulations and molecular dynamics. Proteins 2015; 83:2279-92. [PMID: 26476100 DOI: 10.1002/prot.24947] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/11/2015] [Accepted: 09/29/2015] [Indexed: 12/26/2022]
Abstract
The most successful protein structure prediction methods to date have been template-based modeling (TBM) or homology modeling, which predicts protein structure based on experimental structures. These high accuracy predictions sometimes retain structural errors due to incorrect templates or a lack of accurate templates in the case of low sequence similarity, making these structures inadequate in drug-design studies or molecular dynamics simulations. We have developed a new physics based approach to the protein refinement problem by mimicking the mechanism of chaperons that rehabilitate misfolded proteins. The template structure is unfolded by selectively (targeted) pulling on different portions of the protein using the geometric based technique FRODA, and then refolded using hierarchically restrained replica exchange molecular dynamics simulations (hr-REMD). FRODA unfolding is used to create a diverse set of topologies for surveying near native-like structures from a template and to provide a set of persistent contacts to be employed during re-folding. We have tested our approach on 13 previous CASP targets and observed that this method of folding an ensemble of partially unfolded structures, through the hierarchical addition of contact restraints (that is, first local and then nonlocal interactions), leads to a refolding of the structure along with refinement in most cases (12/13). Although this approach yields refined models through advancement in sampling, the task of blind selection of the best refined models still needs to be solved. Overall, the method can be useful for improved sampling for low resolution models where certain of the portions of the structure are incorrectly modeled.
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Affiliation(s)
- Avishek Kumar
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe, Arizona
| | - Paul Campitelli
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe, Arizona
| | - M F Thorpe
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe, Arizona.,Rudolf Peierls Center for Theoretical Physics, University of Oxford, Oxford, OX1 3NP, United Kingdom
| | - S Banu Ozkan
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe, Arizona
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12
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Maffucci I, Clayden J, Contini A. Origin of Helical Screw Sense Selectivity Induced by Chiral Constrained Cα-Tetrasubstituted α-Amino Acids in Aib-based Peptides. J Phys Chem B 2015; 119:14003-13. [PMID: 26457452 DOI: 10.1021/acs.jpcb.5b07050] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mechanisms behind the propensity of chiral constrained Cα-tetrasubstituted amino acids (cCTAAs) to induce one particular helical screw sense, when included in the Ac-Aib2-cCTAA-Aib2-NHMe peptide model, were studied through replica exchange molecular dynamics, potential of mean force, and quantum theory of atoms in molecules calculations. We observed that cCTAAs exert their effect on helical screw sense selectivity through the positioning of the side chain to generate steric hindrance in either the (-x, +y, +z) or (+x, +y, -z) sectors of a right-handed 3D Cartesian space, where the z axis corresponds to the axis of the helix and the Cα lies on the +y semiaxis (0, +y, 0). The different strengthening of the noncovalent interactions, also comprising C-H···O interactions, exerted by the cCTAA in the right-handed or left-handed helix was also found important to define the preference of a cCTAA for a particular helix screw sense.
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Affiliation(s)
- Irene Maffucci
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini", Università degli Studi di Milano , Via Venezian, 21, 20133 Milano, Italy
| | - Jonathan Clayden
- School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, U.K
| | - Alessandro Contini
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini", Università degli Studi di Milano , Via Venezian, 21, 20133 Milano, Italy
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13
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Zamudio-Vázquez R, Ivanova S, Moreno M, Hernandez-Alvarez MI, Giralt E, Bidon-Chanal A, Zorzano A, Albericio F, Tulla-Puche J. A new quinoxaline-containing peptide induces apoptosis in cancer cells by autophagy modulation. Chem Sci 2015; 6:4537-4549. [PMID: 29142702 PMCID: PMC5666514 DOI: 10.1039/c5sc00125k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/18/2015] [Indexed: 12/14/2022] Open
Abstract
The most cytotoxic compound from a library of quinoxaline-containing peptides is endocyted into HeLa cells, accumulates in acidic compartments, and blocks autophagy by altering lysosomal function, leading to apoptosis activation.
The synthesis of a new small library of quinoxaline-containing peptides is described. After cytotoxic evaluation in four human cancer cell lines, as well as detailed biological studies, it was found that the most active compound, RZ2, promotes the formation of acidic compartments, where it accumulates, blocking the progression of autophagy. Further disruption of the mitochondrial membrane potential and an increase in mitochondrial ROS was observed, causing cells to undergo apoptosis. Given its cytotoxic activity and protease-resistant features, RZ2 could be a potential drug candidate for cancer treatment and provide a basis for future research into the crosstalk between autophagy and apoptosis and its relevance in cancer therapy.
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Affiliation(s)
- Rubí Zamudio-Vázquez
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,CIBER-BBN , Networking Centre on Bioengineering , Biomaterials and Nanomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain
| | - Saška Ivanova
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,Department of Biochemistry and Molecular Biology , Faculty of Biology , University of Barcelona , Barcelona , Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) , Instituto de Salud Carlos III , Barcelona , Spain
| | - Miguel Moreno
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127
| | - Maria Isabel Hernandez-Alvarez
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,Department of Biochemistry and Molecular Biology , Faculty of Biology , University of Barcelona , Barcelona , Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) , Instituto de Salud Carlos III , Barcelona , Spain
| | - Ernest Giralt
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,Department of Organic Chemistry , Faculty of Chemistry , University of Barcelona , Barcelona , Spain
| | - Axel Bidon-Chanal
- Department of Physical Chemistry and Institute of Biomedicine (IBUB) , Faculty of Pharmacy , University of Barcelona , Santa Coloma de Gramenet , Spain
| | - Antonio Zorzano
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,Department of Biochemistry and Molecular Biology , Faculty of Biology , University of Barcelona , Barcelona , Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) , Instituto de Salud Carlos III , Barcelona , Spain
| | - Fernando Albericio
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,CIBER-BBN , Networking Centre on Bioengineering , Biomaterials and Nanomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain.,Department of Organic Chemistry , Faculty of Chemistry , University of Barcelona , Barcelona , Spain.,School of Chemistry , Yachay Tech , Yachay City of Knowledge , Urcuquí 100119 , Ecuador
| | - Judit Tulla-Puche
- Institute for Research in Biomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain . ; ; ; ; Tel: +34 934037127.,CIBER-BBN , Networking Centre on Bioengineering , Biomaterials and Nanomedicine , Baldiri Reixac 10 , 08028 Barcelona , Spain
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14
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Maffucci I, Pellegrino S, Clayden J, Contini A. Mechanism of stabilization of helix secondary structure by constrained Cα-tetrasubstituted α-amino acids. J Phys Chem B 2015; 119:1350-61. [PMID: 25528885 DOI: 10.1021/jp510775e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The theoretical basis behind the ability of constrained Cα-tetrasubstituted amino acids (CTAAs) to induce stable helical conformations has been studied through Replica Exchange Molecular Dynamics Potential of Mean Force Quantum Theory of Atoms In Molecules calculations on Ac-l-Ala-CTAA-l-Ala-Aib-l-Ala-NHMe peptide models. We found that the origin of helix stabilization by CTAAs can be ascribed to at least two complementary mechanisms limiting the backbone conformational freedom: steric hindrance predominantly in the (+x,+y,-z) sector of a right-handed 3D Cartesian space, where the z axis coincides with the helical axis and the Cα of the CTAA lies on the +y axis (0,+y,0), and the establishment of additional and relatively strong C-H···O interactions involving the CTAA.
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Affiliation(s)
- Irene Maffucci
- Dipartimento di Scienze Farmaceutiche - Sezione di Chimica Generale e Organica "Alessandro Marchesini", Università degli Studi di Milano , Via Venezian, 21 20133 Milano, Italy
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15
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Voelz VA, Elman B, Razavi AM, Zhou G. Surprisal Metrics for Quantifying Perturbed Conformational Dynamics in Markov State Models. J Chem Theory Comput 2014; 10:5716-28. [DOI: 10.1021/ct500827g] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Vincent A. Voelz
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Brandon Elman
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Asghar M. Razavi
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Guangfeng Zhou
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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16
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Liao C, Zhou J. Replica-Exchange Molecular Dynamics Simulation of Basic Fibroblast Growth Factor Adsorption on Hydroxyapatite. J Phys Chem B 2014; 118:5843-52. [DOI: 10.1021/jp501463r] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chenyi Liao
- School
of Chemistry and Chemical
Engineering, Guangdong Provincial Key Lab for Green Chemical Product
Technology, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Jian Zhou
- School
of Chemistry and Chemical
Engineering, Guangdong Provincial Key Lab for Green Chemical Product
Technology, South China University of Technology, Guangzhou, 510640, P. R. China
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17
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Jia X, Wang X, Liu J, Zhang JZH, Mei Y, He X. An improved fragment-based quantum mechanical method for calculation of electrostatic solvation energy of proteins. J Chem Phys 2013; 139:214104. [DOI: 10.1063/1.4833678] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Best RB, Mittal J, Feig M, MacKerell AD. Inclusion of many-body effects in the additive CHARMM protein CMAP potential results in enhanced cooperativity of α-helix and β-hairpin formation. Biophys J 2013; 103:1045-51. [PMID: 23009854 DOI: 10.1016/j.bpj.2012.07.042] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 07/21/2012] [Accepted: 07/24/2012] [Indexed: 12/01/2022] Open
Abstract
Folding simulations on peptides and proteins using empirical force fields have demonstrated the sensitivity of the results to details of the backbone potential. A recently revised version of the additive CHARMM protein force field, which includes optimization of the backbone CMAP potential to achieve good balance between different types of secondary structure, correcting the α-helical bias present in the former CHARMM22/CMAP energy function, is shown to result in improved cooperativity for the helix-coil transition. This is due to retention of the empirical corrections introduced in the original CMAP to reproduce folded protein structures-corrections that capture many-body effects missing from an energy surface fitted to gas phase calculations on dipeptides. The experimental temperature dependence of helix formation in (AAQAA)(3) and parameters for helix nucleation and elongation are in much better agreement with experiment than those obtained with other recent force fields. In contrast, CMAP parameters derived by fitting to a vacuum quantum mechanical surface for the alanine dipeptide do not reproduce the enhanced cooperativity, showing that the empirical backbone corrections, and not some other feature of the force field, are responsible. We also find that the cooperativity of β-hairpin formation is much improved relative to other force fields we have studied. Comparison with (ϕ,ψ) distributions from the Protein Data Bank further justifies the inclusion of many-body effects in the CMAP. These results suggest that the revised energy function will be suitable for both simulations of unfolded or intrinsically disordered proteins and for investigating protein-folding mechanisms.
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Affiliation(s)
- Robert B Best
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom.
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19
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Mittal J, Yoo TH, Georgiou G, Truskett TM. Structural ensemble of an intrinsically disordered polypeptide. J Phys Chem B 2012. [PMID: 23205890 DOI: 10.1021/jp308984e] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Intrinsically disordered proteins (IDPs), which play key roles in cell signaling and regulation, do not display specific tertiary structure when isolated in solution. Instead, they dynamically explore an ensemble of unfolded configurations, adopting more stable, ordered structures only after binding to their ligands. Whether ligands induce IDP structural changes upon binding or simply bind to pre-existing conformers that are populated within the IDP's structural ensemble is not well understood. Molecular simulations can provide information with the spatiotemporal resolution necessary to resolve these issues. Here, we report on the conformational ensemble of a 15-residue wild-type p53 fragment from the TAD domain and its mutant (TAD-P27L) obtained by replica exchange molecular dynamics simulation using an optimized (fully atomistic, explicit solvent) protein model and the experimental validation of the simulation results. We use a clustering method based on structural similarity to identify conformer states populated by the peptides in solution from the simulated ensemble. We show that p53 populates solution structures that strongly resemble the ligand (MDM2)-bound structure, but at the same time, the conformational free-energy landscape is relatively flat in the absence of the ligand.
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Affiliation(s)
- Jeetain Mittal
- Department of Chemical Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States.
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20
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Sammond DW, Payne CM, Brunecky R, Himmel ME, Crowley MF, Beckham GT. Cellulase linkers are optimized based on domain type and function: insights from sequence analysis, biophysical measurements, and molecular simulation. PLoS One 2012; 7:e48615. [PMID: 23139804 PMCID: PMC3490864 DOI: 10.1371/journal.pone.0048615] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 09/27/2012] [Indexed: 01/02/2023] Open
Abstract
Cellulase enzymes deconstruct cellulose to glucose, and are often comprised of glycosylated linkers connecting glycoside hydrolases (GHs) to carbohydrate-binding modules (CBMs). Although linker modifications can alter cellulase activity, the functional role of linkers beyond domain connectivity remains unknown. Here we investigate cellulase linkers connecting GH Family 6 or 7 catalytic domains to Family 1 or 2 CBMs, from both bacterial and eukaryotic cellulases to identify conserved characteristics potentially related to function. Sequence analysis suggests that the linker lengths between structured domains are optimized based on the GH domain and CBM type, such that linker length may be important for activity. Longer linkers are observed in eukaryotic GH Family 6 cellulases compared to GH Family 7 cellulases. Bacterial GH Family 6 cellulases are found with structured domains in either N to C terminal order, and similar linker lengths suggest there is no effect of domain order on length. O-glycosylation is uniformly distributed across linkers, suggesting that glycans are required along entire linker lengths for proteolysis protection and, as suggested by simulation, for extension. Sequence comparisons show that proline content for bacterial linkers is more than double that observed in eukaryotic linkers, but with fewer putative O-glycan sites, suggesting alternative methods for extension. Conversely, near linker termini where linkers connect to structured domains, O-glycosylation sites are observed less frequently, whereas glycines are more prevalent, suggesting the need for flexibility to achieve proper domain orientations. Putative N-glycosylation sites are quite rare in cellulase linkers, while an N-P motif, which strongly disfavors the attachment of N-glycans, is commonly observed. These results suggest that linkers exhibit features that are likely tailored for optimal function, despite possessing low sequence identity. This study suggests that cellulase linkers may exhibit function in enzyme action, and highlights the need for additional studies to elucidate cellulase linker functions.
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Affiliation(s)
- Deanne W. Sammond
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Christina M. Payne
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Roman Brunecky
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Michael E. Himmel
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Michael F. Crowley
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
| | - Gregg T. Beckham
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado, United States of America
- Department of Chemical Engineering, Colorado School of Mines, Golden, Colorado, United States of America
- * E-mail:
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21
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Charge effects on the fibril-forming peptide KTVIIE: a two-dimensional replica exchange simulation study. Biophys J 2012; 102:1952-60. [PMID: 22768952 DOI: 10.1016/j.bpj.2012.03.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 02/28/2012] [Accepted: 03/02/2012] [Indexed: 12/12/2022] Open
Abstract
The assembly of peptides into ordered nanostructures is increasingly recognized as both a bioengineering tool for generating new materials and a critical aspect of aggregation processes that underlie neurological diseases such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. There is a major problem in understanding how extremely subtle sequence changes can lead to profound and often unexpected differences in self-assembly behavior. To better delineate the complex interplay of different microscopic driving forces in such cases, we develop a methodology to quantify and compare the propensity of different peptide sequences to form small oligomers during early self-assembly stages. This umbrella-sampling replica exchange molecular dynamics method performs a replica exchange molecular dynamics simulation along peptide association reaction coordinates using umbrella restraints. With this method, we study a set of sequence-similar peptides that differ in net charge: K(+)TVIIE(-), K(+)TVIIE, and (+)K(+)TVIIE. Interestingly, experiments show that only the monovalent peptide, K(+)TVIIE, forms fibrils, whereas the others do not. We examine dimer, trimer, and tetramer formation processes of these peptides, and compute high-accuracy potential of mean force association curves. The potential of mean forces recapitulate a higher stability and equilibrium constant of the fibril-forming peptide, similar to experiment, but reveal that entropic contributions to association free energies can play a surprisingly significant role. The simulations also show behavior reminiscent of experimental aggregate polymorphism, revealed in multiple stable conformational states and association pathways. Our results suggest that sequence changes can have significant effects on self-assembly through not only direct peptide-peptide interactions but conformational entropies and degeneracies as well.
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22
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Xu Z, Lazim R, Sun T, Mei Y, Zhang D. Solvent effect on the folding dynamics and structure of E6-associated protein characterized from ab initio protein folding simulations. J Chem Phys 2012; 136:135102. [PMID: 22482589 DOI: 10.1063/1.3698164] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Solvent effect on protein conformation and folding mechanism of E6-associated protein (E6ap) peptide are investigated using a recently developed charge update scheme termed as adaptive hydrogen bond-specific charge (AHBC). On the basis of the close agreement between the calculated helix contents from AHBC simulations and experimental results, we observed based on the presented simulations that the two ends of the peptide may simultaneously take part in the formation of the helical structure at the early stage of folding and finally merge to form a helix with lowest backbone RMSD of about 0.9 Å in 40% 2,2,2-trifluoroethanol solution. However, in pure water, the folding may start at the center of the peptide sequence instead of at the two opposite ends. The analysis of the free energy landscape indicates that the solvent may determine the folding clusters of E6ap, which subsequently leads to the different final folded structure. The current study demonstrates new insight to the role of solvent in the determination of protein structure and folding dynamics.
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Affiliation(s)
- Zhijun Xu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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23
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Hayre NR, Singh RRP, Cox DL. Sequence-dependent stability test of a left-handed β-helix motif. Biophys J 2012; 102:1443-52. [PMID: 22455928 PMCID: PMC3309403 DOI: 10.1016/j.bpj.2012.02.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 01/25/2012] [Accepted: 02/07/2012] [Indexed: 11/18/2022] Open
Abstract
The left-handed β-helix (LHBH) is an intriguing, rare structural pattern in polypeptides that has been implicated in the formation of amyloid aggregates. We used accurate all-atom replica-exchange molecular dynamics (REMD) simulations to study the relative stability of diverse sequences in the LHBH conformation. Ensemble-average coordinates from REMD served as a scoring criterion to identify sequences and threadings optimally suited to the LHBH, as in a fold recognition paradigm. We examined the repeatability of our REMD simulations, finding that single simulations can be reliable to a quantifiable extent. We find expected behavior for the positive and negative control cases of a native LHBH and intrinsically disordered sequences, respectively. Polyglutamine and a designed hexapeptide repeat show remarkable affinity for the LHBH motif. A structural model for misfolded murine prion protein was also considered, and showed intermediate stability under the given conditions. Our technique is found to be an effective probe of LHBH stability, and promises to be scalable to broader studies of this and potentially other novel or rare motifs. The superstable character of the designed hexapeptide repeat suggests theoretical and experimental follow-ups.
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Affiliation(s)
- Natha R Hayre
- Department of Physics, University of California, Davis, California, USA.
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24
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Duan LL, Gao Y, Mei Y, Zhang QG, Tang B, Zhang JZH. Folding of a helix is critically stabilized by polarization of backbone hydrogen bonds: study in explicit water. J Phys Chem B 2012; 116:3430-5. [PMID: 22369598 DOI: 10.1021/jp212516g] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Multiple single-trajectory molecular dynamics (MD) simulation at room temperature (300 K) in explicit water was carried out to study the folding dynamics of an α-helix (PDB 2I9M ) using a polarized charge scheme that includes electronic polarization of backbone hydrogen bonds. Starting from an extended conformation, the 17-residue peptide was successfully folded into the native structure (α-helix) between 80 and 130 ns with a root-mean-square deviation of ~1.0 Å. Analysis of the time-dependent trajectories revealed that helix formation of the peptide started at the terminals and progressed toward the center of the peptide. For comparison, MD trajectories generated under various versions of standard AMBER force fields failed to show any significant or stable helix formation in our simulation. Our result shows clear evidence that the electronic polarization of backbone hydrogen bonds energetically stabilizes the helix formation and is critical to the stable folding of the short helix structure.
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Affiliation(s)
- Li L Duan
- State Key Laboratory of Precision Spectroscopy, Department of Physics, and Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, China
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25
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Carmichael SP, Shell MS. A New Multiscale Algorithm and Its Application to Coarse-Grained Peptide Models for Self-Assembly. J Phys Chem B 2012; 116:8383-93. [DOI: 10.1021/jp2114994] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Scott P. Carmichael
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California
| | - M. Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California
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26
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Dirks RM, Xu H, Shaw DE. Improving Sampling by Exchanging Hamiltonians with Efficiently Configured Nonequilibrium Simulations. J Chem Theory Comput 2011; 8:162-71. [DOI: 10.1021/ct200464v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert M. Dirks
- D. E. Shaw Research, 120 W. 45th St., 39th Floor, New York, New York 10036, United States
| | - Huafeng Xu
- D. E. Shaw Research, 120 W. 45th St., 39th Floor, New York, New York 10036, United States
| | - David E. Shaw
- D. E. Shaw Research, 120 W. 45th St., 39th Floor, New York, New York 10036, United States
- Center for Computational Biology and Bioinformatics, Columbia University, New York, New York 10032, United States
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27
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Pritchard-Bell A, Shell MS. Smoothing protein energy landscapes by integrating folding models with structure prediction. Biophys J 2011; 101:2251-9. [PMID: 22067165 DOI: 10.1016/j.bpj.2011.09.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 09/13/2011] [Accepted: 09/19/2011] [Indexed: 10/15/2022] Open
Abstract
Decades of work has investigated the energy landscapes of simple protein models, but what do the landscapes of real, large, atomically detailed proteins look like? We explore an approach to this problem that systematically extracts simple funnel models of actual proteins using ensembles of structure predictions and physics-based atomic force fields and sampling. Central to our effort are calculations of a quantity called the relative entropy, which quantifies the extent to which a given set of structure decoys and a putative native structure can be projected onto a theoretical funnel description. We examine 86 structure prediction targets and one coupled folding-binding system, and find that in a majority of cases the relative entropy robustly signals which structures are nearest to native (i.e., which appear to lie closest to a funnel bottom). Importantly, the landscape model improves substantially upon purely energetic measures in scoring decoys. Our results suggest that physics-based models-including both folding theories and all-atom force fields-may be successfully integrated with structure prediction efforts. Conversely, detailed predictions of structures and the relative entropy approach enable one to extract coarse topographic features of protein landscapes that may enhance the development and application of simpler folding models.
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Affiliation(s)
- Ari Pritchard-Bell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California, USA
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28
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Revilla-López G, Torras J, Nussinov R, Alemán C, Zanuy D. Exploring the energy landscape of a molecular engineered analog of a tumor-homing peptide. Phys Chem Chem Phys 2011; 13:9986-94. [PMID: 21258721 PMCID: PMC7385989 DOI: 10.1039/c0cp02572k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently a new non-coded amino acid was designed as a replacement for Arg, to protect the tumor-homing pentapeptide CREKA (Cys-Arg-Glu-Lys-Ala) from proteases. This constrained Arg analog, denoted c(5)Arg, was engineered to also promote the stability of the CREKA bioactive conformation. The conformational profile of the CREKA analog obtained by replacing Arg by c(5)Arg has been extensively investigated in this work. Two molecular dynamics simulations-based strategies have been employed: a modified simulated annealing and replica exchange. Results obtained using both techniques show that the conformational features of the new analog fulfill the purpose of its design. The new CREKA analog not only preserves the main structural attributes found for the bioactive conformation of the parent peptide but also shows lower flexibility. Moreover, the conformational profile of the mutated peptide narrows towards the most stable structures previously observed for the parent CREKA peptide.
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Affiliation(s)
- Guillem Revilla-López
- Departament d'Enginyeria Química, E. T. S. d'Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
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29
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Beckham GT, Bomble YJ, Matthews JF, Taylor CB, Resch MG, Yarbrough JM, Decker SR, Bu L, Zhao X, McCabe C, Wohlert J, Bergenstråhle M, Brady JW, Adney WS, Himmel ME, Crowley MF. The O-glycosylated linker from the Trichoderma reesei Family 7 cellulase is a flexible, disordered protein. Biophys J 2011; 99:3773-81. [PMID: 21112302 DOI: 10.1016/j.bpj.2010.10.032] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 10/19/2010] [Accepted: 10/20/2010] [Indexed: 10/18/2022] Open
Abstract
Fungi and bacteria secrete glycoprotein cocktails to deconstruct cellulose. Cellulose-degrading enzymes (cellulases) are often modular, with catalytic domains for cellulose hydrolysis and carbohydrate-binding modules connected by linkers rich in serine and threonine with O-glycosylation. Few studies have probed the role that the linker and O-glycans play in catalysis. Since different expression and growth conditions produce different glycosylation patterns that affect enzyme activity, the structure-function relationships that glycosylation imparts to linkers are relevant for understanding cellulase mechanisms. Here, the linker of the Trichoderma reesei Family 7 cellobiohydrolase (Cel7A) is examined by simulation. Our results suggest that the Cel7A linker is an intrinsically disordered protein with and without glycosylation. Contrary to the predominant view, the O-glycosylation does not change the stiffness of the linker, as measured by the relative fluctuations in the end-to-end distance; rather, it provides a 16 Å extension, thus expanding the operating range of Cel7A. We explain observations from previous biochemical experiments in the light of results obtained here, and compare the Cel7A linker with linkers from other cellulases with sequence-based tools to predict disorder. This preliminary screen indicates that linkers from Family 7 enzymes from other genera and other cellulases within T. reesei may not be as disordered, warranting further study.
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Affiliation(s)
- Gregg T Beckham
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, Colorado, USA
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30
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Gee J, Shell MS. Two-dimensional replica exchange approach for peptide–peptide interactions. J Chem Phys 2011; 134:064112. [DOI: 10.1063/1.3551576] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Gong Z, Xiao Y, Xiao Y. RNA stability under different combinations of amber force fields and solvation models. J Biomol Struct Dyn 2011; 28:431-41. [PMID: 20919758 DOI: 10.1080/07391102.2010.10507372] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The proper matching of force field and solvent is critical to obtain correct result in molecular dynamics simulation of bio-molecules. This problem has been intensively investigated for protein but not for RNA yet. In this paper, we use standard molecular dynamics and replica exchange molecular dynamics to take a series of tests on the RNA stability under different combinations of Amber force field parameters (ff98, ff99 and ff99bsc0) and the general Born implicit solvent models (igb1, igb2 and igb5). It is found that only ff98 and ff99bsc0 with igb1 can keep the native conformations of RNA hairpin and duplex. Our results suggest that ff98 plus igb1 may be reasonable choice for molecular dynamics simulation of RNA dynamics.
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Affiliation(s)
- Zhou Gong
- Biomolecular Physics and Modeling Group, Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China
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32
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Hayre NR, Singh RRP, Cox DL. Evaluating force field accuracy with long-time simulations of a β-hairpin tryptophan zipper peptide. J Chem Phys 2011; 134:035103. [DOI: 10.1063/1.3532931] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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33
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Yang D, Arya G. Structure and binding of the H4 histone tail and the effects of lysine 16 acetylation. Phys Chem Chem Phys 2010; 13:2911-21. [PMID: 21157623 DOI: 10.1039/c0cp01487g] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The H4 histone tail plays a critical role in chromatin folding and regulation--it mediates strong interactions with the acidic patch of proximal nucleosomes and its acetylation at lysine 16 (K16) leads to partial unfolding of chromatin. The molecular mechanism associated with the H4 tail/acidic patch interactions and its modulation via K16 acetylation remains unknown. Here we employ a combination of molecular dynamics simulations, molecular docking calculations, and free energy computations to investigate the structure of the H4 tail in solution, the binding of the H4 tail with the acidic patch, and the effects of K16 acetylation. The H4 tail exhibits a disordered configuration except in the region Ala15-Lys20, where it exhibits a strong propensity for an α-helical structure. This α-helical region is found to dock very favorably into the acidic patch groove of a nucleosome with a binding free energy of approximately -7 kcal mol(-1). We have identified the specific interactions that stabilize this binding as well as the associated energetics. The acetylation of K16 is found to reduce the α-helix forming propensity of the H4 tail and K16's accessibility for mediating external interactions. More importantly, K16 acetylation destabilizes the binding of the H4 tail at the acidic patch by mitigating specific salt bridges and longer-ranged electrostatic interactions mediated by K16. Our study thus provides new microscopic insights into the compaction of chromatin and its regulation via posttranslational modifications of histone tails, which could be of interest to chromatin biology, cancer, epigenetics, and drug design.
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Affiliation(s)
- Darren Yang
- Department of NanoEngineering, University of California at San Diego, 9500 Gilman Drive, MC 0448, La Jolla, CA 92093, USA
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34
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Duan LL, Mei Y, Zhang D, Zhang QG, Zhang JZH. Folding of a helix at room temperature is critically aided by electrostatic polarization of intraprotein hydrogen bonds. J Am Chem Soc 2010; 132:11159-64. [PMID: 20698682 DOI: 10.1021/ja102735g] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report direct folding of a 17-residue helix protein (pdb:2I9M) by standard molecular dynamics simulation (single trajectory) at room temperature with implicit solvent. Starting from a fully extended structure, 2I9M successfully folds into the native conformation within 16 ns using adaptive hydrogen bond-specific charges to take into account the electrostatic polarization effect. Cluster analysis shows that conformations in the native state cluster have the highest population (78.4%) among all sampled conformations. Folding snapshots and the secondary structure analysis demonstrate that the folding of 2I9M begins at terminals and progresses toward the center. A plot of the free energy landscape indicates that there is no significant free energy barrier during folding, which explains the observed fast folding speed. For comparison, exactly the same molecular dynamics simulation but carried out under existing AMBER charges failed to fold 2I9M into native-like structures. The current study demonstrates that electrostatic polarization of intraprotein hydrogen bonding, which stabilizes the helix, is critical to the successful folding of 2I9m.
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Affiliation(s)
- Li L Duan
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
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35
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Lin EI, Shell MS. Can Peptide Folding Simulations Provide Predictive Information for Aggregation Propensity? J Phys Chem B 2010; 114:11899-908. [DOI: 10.1021/jp104114n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Edmund I. Lin
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106-5080
| | - M. Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106-5080
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36
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Xiang Y, Duan L, Zhang JZH. Folding dynamics of a small protein at room temperature via simulated coherent two-dimensional infrared spectroscopy. Phys Chem Chem Phys 2010; 12:15681-8. [PMID: 20676442 DOI: 10.1039/c0cp00375a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding protein folding is of fundamental and practical importance in chemistry and biology. Despite the great success that has been made in tackling this problem, a detailed knowledge of how the elementary processes such as hydrogen-bond formation occur during protein folding has remained largely elusive. Using the combined power of molecular dynamics simulation with electrostatic polarization and coherent two-dimensional infrared spectroscopy, we are able to delineate the order of the hydrogen-bond formation event of a 17-residue peptide during its folding from an extended state to the native α-helix state. The folding is carried out by a single trajectory room-temperature molecular dynamics simulation that includes the polarization effect of hydrogen bonding, which is critical to the successful folding of the peptide. The onset and evolution of the isotope-labeled amide I vibration diagonal and cross peaks on the simulated 2DIR spectra allow us to build a structure-spectrum connection, and thus provide a microscopic picture of the helix folding process.
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Affiliation(s)
- Yun Xiang
- State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Sciences, East China Normal University, Shanghai 200062, China.
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37
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Shell MS. A replica-exchange approach to computing peptide conformational free energies. MOLECULAR SIMULATION 2010. [DOI: 10.1080/08927021003720546] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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