1
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DiGiorno MC, Vithanage N, Victorio CG, Kreitler DF, Outlaw VK, Sawyer N. Structural Characterization of Disulfide-Linked p53-Derived Peptide Dimers. RESEARCH SQUARE 2024:rs.3.rs-4644285. [PMID: 39070635 PMCID: PMC11275974 DOI: 10.21203/rs.3.rs-4644285/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Disulfide bonds provide a convenient method for chemoselective alteration of peptide and protein structure and function. We previously reported that mild oxidation of a p53-derived bisthiol peptide (CTFANLWRLLAQNC) under dilute non-denaturing conditions led to unexpected disulfide-linked dimers as the exclusive product. The dimers were antiparallel, significantly α-helical, resistant to protease degradation, and easily reduced back to the original bisthiol peptide. Here we examine the intrinsic factors influencing peptide dimerization using a combination of amino acid substitution, circular dichroism (CD) spectroscopy, and X-ray crystallography. CD analysis of peptide variants suggests critical roles for Leu6 and Leu10 in the formation of stable disulfide-linked dimers. The 1.0 Å resolution crystal structure of the peptide dimer supports these data, revealing a leucine-rich LxxLL dimer interface with canonical knobs-into-holes packing. Two levels of higher-order oligomerization are also observed in the crystal: an antiparallel "dimer of dimers" mediated by Phe3 and Trp7 residues in the asymmetric unit and a tetramer of dimers mediated by Trp7 and Leu10. In CD spectra of Trp-containing peptide variants, minima at 227 nm provide evidence for the dimer of dimers in dilute aqueous solution. Importantly, and in contrast to the original dimer model, the canonical leucine-rich core and robust dimerization of most peptide variants suggests a tunable molecular architecture to target various proteins and evaluate how folding and oligomerization impact various properties, such as cell permeability.
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2
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Russo S, Bodo E. Solvation of Model Biomolecules in Choline-Aminoate Ionic Liquids: A Computational Simulation Using Polarizable Force Fields. Molecules 2024; 29:1524. [PMID: 38611804 PMCID: PMC11013605 DOI: 10.3390/molecules29071524] [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: 03/12/2024] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
One can foresee a very near future where ionic liquids will be used in applications such as biomolecular chemistry or medicine. The molecular details of their interaction with biological matter, however, are difficult to investigate due to the vast number of combinations of both the biological systems and the variety of possible liquids. Here, we provide a computational study aimed at understanding the interaction of a special class of biocompatible ionic liquids (choline-aminoate) with two model biological systems: an oligopeptide and an oligonucleotide. We employed molecular dynamics with a polarizable force field. Our results are in line with previous experimental and computational evidence on analogous systems and show how these biocompatible ionic liquids, in their pure form, act as gentle solvents for protein structures while simultaneously destabilizing DNA structure.
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Affiliation(s)
| | - Enrico Bodo
- Chemistry Department, University of Rome “La Sapienza”, P.le Aldo Moro 5, 00185 Rome, Italy;
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3
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Marshall LK, Fahrenbach AC, Thordarson P. RNA-Binding Peptides Inspired by the RNA Recognition Motif. ACS Chem Biol 2024; 19:243-248. [PMID: 38314708 DOI: 10.1021/acschembio.3c00694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
β-Hairpin peptides with RNA-binding sequences mimicking the central two β-strands of the RNA recognition motif (RRM) protein domain have been observed to bind in a 2:1 fashion to a series of RNA homooligonucleotides in aqueous solution (PBS buffer, pH 7.40) with binding energies (-27 to -35 kJ mol-1) similar to those of full-size protein RRMs. The peptides display mild selectivities with respect to the binding of the different homooligomers. Binding studies in 500 mM magnesium chloride suggest that the complex formation is not predominantly driven by Coulombic attraction. These peptides represent a starting point for further studies of non-Coulombic binding of RNA by peptides and proteins, which is important in the context of contemporary biology, potential therapeutic applications, and prebiotic peptide-RNA interactions.
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4
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Kreutzer AG, Parrocha CMT, Haerianardakani S, Guaglianone G, Nguyen JT, Diab MN, Yong W, Perez-Rosendahl M, Head E, Nowick JS. Antibodies Raised Against an Aβ Oligomer Mimic Recognize Pathological Features in Alzheimer's Disease and Associated Amyloid-Disease Brain Tissue. ACS CENTRAL SCIENCE 2024; 10:104-121. [PMID: 38292607 PMCID: PMC10823522 DOI: 10.1021/acscentsci.3c00592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 02/01/2024]
Abstract
Antibodies that target the β-amyloid peptide (Aβ) and its associated assemblies are important tools in Alzheimer's disease research and have emerged as promising Alzheimer's disease therapies. This paper reports the creation and characterization of a triangular Aβ trimer mimic composed of Aβ17-36 β-hairpins and the generation and study of polyclonal antibodies raised against the Aβ trimer mimic. The Aβ trimer mimic is covalently stabilized by three disulfide bonds at the corners of the triangular trimer to create a homogeneous oligomer. Structural, biophysical, and cell-based studies demonstrate that the Aβ trimer mimic shares characteristics with oligomers of full-length Aβ. X-ray crystallography elucidates the structure of the trimer and reveals that four copies of the trimer assemble to form a dodecamer. SDS-PAGE, size exclusion chromatography, and dynamic light scattering reveal that the trimer also forms higher-order assemblies in solution. Cell-based toxicity assays show that the trimer elicits LDH release, decreases ATP levels, and activates caspase-3/7 mediated apoptosis. Immunostaining studies on brain slices from people who lived with Alzheimer's disease and people who lived with Down syndrome reveal that the polyclonal antibodies raised against the Aβ trimer mimic recognize pathological features including different types of Aβ plaques and cerebral amyloid angiopathy.
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Affiliation(s)
- Adam G. Kreutzer
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Chelsea Marie T. Parrocha
- Department
of Pharmaceutical Sciences, University of
California Irvine, Irvine, California 92697, United States
| | - Sepehr Haerianardakani
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Gretchen Guaglianone
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - Jennifer T. Nguyen
- Department
of Pharmaceutical Sciences, University of
California Irvine, Irvine, California 92697, United States
| | - Michelle N. Diab
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
| | - William Yong
- Department
of Pathology and Laboratory Medicine, University
of California Irvine, Irvine, California 92697, United States
| | - Mari Perez-Rosendahl
- Department
of Pathology and Laboratory Medicine, University
of California Irvine, Irvine, California 92697, United States
| | - Elizabeth Head
- Department
of Pathology and Laboratory Medicine, University
of California Irvine, Irvine, California 92697, United States
| | - James S. Nowick
- Department
of Chemistry, University of California Irvine, Irvine, California 92697, United States
- Department
of Pharmaceutical Sciences, University of
California Irvine, Irvine, California 92697, United States
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5
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Richaud AD, Mandal S, Das A, Roche SP. Tunable CH/π Interactions within a Tryptophan Zipper Motif to Stabilize the Fold of Long β-Hairpin Peptides. ACS Chem Biol 2023; 18:2555-2563. [PMID: 37976523 DOI: 10.1021/acschembio.3c00553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The tryptophan zipper (Trpzip) is an iconic folding motif of β-hairpin peptides capitalizing on two pairs of cross-strand tryptophans, each stabilized by an aromatic-aromatic stacking in an edge-to-face (EtF) geometry. Yet, the origins and the contribution of this EtF packing to the unique Trpzip stability remain poorly understood. To address this question of structure-stability relationship, a library of Trpzip hairpins was developed by incorporating readily accessible nonproteinogenic tryptophans of varying electron densities. We found that each EtF geometry was, in fact, stabilized by an intricate combination of XH/π interactions. By tuning the π-electron density of Trpface rings, CH/π interactions are strengthened to gain additional stability. On the contrary, our DFT calculations support the notion that Trpedge modulations are challenging due to their simultaneous paradoxical engagement as H-bond donors in CH/π and acceptors in NH/π interactions.
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Affiliation(s)
- Alexis D Richaud
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431, United States
| | - Sourav Mandal
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Pashan, Pune 411008, India
| | - Aloke Das
- Department of Chemistry, Indian Institute of Science Education and Research Pune, Pashan, Pune 411008, India
| | - Stéphane P Roche
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431, United States
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6
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Nazzaro A, Lu B, Sawyer N, Watkins AM, Arora PS. Macrocyclic β-Sheets Stabilized by Hydrogen Bond Surrogates. Angew Chem Int Ed Engl 2023; 62:e202303943. [PMID: 37170337 PMCID: PMC10592574 DOI: 10.1002/anie.202303943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/09/2023] [Accepted: 05/10/2023] [Indexed: 05/13/2023]
Abstract
Mimics of protein secondary and tertiary structure offer rationally-designed inhibitors of biomolecular interactions. β-Sheet mimics have a storied history in bioorganic chemistry and are typically designed with synthetic or natural turn segments. We hypothesized that replacement of terminal inter-β-strand hydrogen bonds with hydrogen bond surrogates (HBS) may lead to conformationally-defined macrocyclic β-sheets without the requirement for natural or synthetic β-turns, thereby providing a minimal mimic of a protein β-sheet. To access turn-less antiparallel β-sheet mimics, we developed a facile solid phase synthesis protocol. We surveyed a dataset of protein β-sheets for naturally observed interstrand side chain interactions. This bioinformatics survey highlighted an over-abundance of aromatic-aromatic, cation-π and ionic interactions in β-sheets. In correspondence with natural β-sheets, we find that minimal HBS mimics show robust β-sheet formation when specific amino acid residue pairings are incorporated. In isolated β-sheets, aromatic interactions endow superior conformational stability over ionic or cation-π interactions. Circular dichroism and NMR spectroscopies, along with high-resolution X-ray crystallography, support our design principles.
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Affiliation(s)
- Alex Nazzaro
- Department of Chemistry, New York University, 100 Washington Square East, NY 10013, New York, USA
| | - Brandon Lu
- Department of Chemistry, New York University, 100 Washington Square East, NY 10013, New York, USA
| | - Nicholas Sawyer
- Department of Chemistry, New York University, 100 Washington Square East, NY 10013, New York, USA
| | | | - Paramjit S Arora
- Department of Chemistry, New York University, 100 Washington Square East, NY 10013, New York, USA
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7
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Victorio CG, Sawyer N. Folding-Assisted Peptide Disulfide Formation and Dimerization. ACS Chem Biol 2023; 18:1480-1486. [PMID: 37390465 DOI: 10.1021/acschembio.3c00268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
Abstract
Disulfide bonds form covalent bonds between distal regions of peptides and proteins to dramatically impact their folding, stability, and oligomerization. Given the prevalence of disulfide bonds in many natural products, considerable effort has been invested in site-selective disulfide bond formation approaches to control the folding of chemically synthesized peptides and proteins. Here, we show that the careful choice of thiol oxidation conditions can lead to monomeric or dimeric species from fully deprotected linear bisthiol peptides. Starting from a p53-derived peptide, we found that oxidation under aqueous (nondenaturing) conditions produces antiparallel dimers with enhanced α-helical character, while oxidation under denaturing conditions promotes formation of a nonhelical intramolecular disulfide species. Examination across peptide variants suggests that intramolecular disulfide formation is robust across diverse peptide sequences, while dimerization is sensitive to both the α-helical folding of the linear peptide and aromatic residues at the dimerization interface. All disulfide species are more resistant to protease degradation than the linear peptide but are easily reduced to restore the initial bisthiol peptide. Both disulfide formation approaches are compatible with α-helix-stabilizing cross-linkers. These results provide an approach for using disulfide bonds to control peptide folding and oligomerization to better understand how folding influences interactions with diverse molecular targets.
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Affiliation(s)
- Clara G Victorio
- Department of Chemistry, Fordham University, 441 E. Fordham Rd., Bronx, New York 10458, United States
| | - Nicholas Sawyer
- Department of Chemistry, Fordham University, 441 E. Fordham Rd., Bronx, New York 10458, United States
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8
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Kreutzer AG, Guaglianone G, Yoo S, Parrocha CMT, Ruttenberg SM, Malonis RJ, Tong K, Lin YF, Nguyen JT, Howitz WJ, Diab MN, Hamza IL, Lai JR, Wysocki VH, Nowick JS. Probing differences among Aβ oligomers with two triangular trimers derived from Aβ. Proc Natl Acad Sci U S A 2023; 120:e2219216120. [PMID: 37216514 PMCID: PMC10235986 DOI: 10.1073/pnas.2219216120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 04/17/2023] [Indexed: 05/24/2023] Open
Abstract
The assembly of the β-amyloid peptide (Aβ) to form oligomers and fibrils is closely associated with the pathogenesis and progression of Alzheimer's disease. Aβ is a shape-shifting peptide capable of adopting many conformations and folds within the multitude of oligomers and fibrils the peptide forms. These properties have precluded detailed structural elucidation and biological characterization of homogeneous, well-defined Aβ oligomers. In this paper, we compare the structural, biophysical, and biological characteristics of two different covalently stabilized isomorphic trimers derived from the central and C-terminal regions Aβ. X-ray crystallography reveals the structures of the trimers and shows that each trimer forms a ball-shaped dodecamer. Solution-phase and cell-based studies demonstrate that the two trimers exhibit markedly different assembly and biological properties. One trimer forms small soluble oligomers that enter cells through endocytosis and activate capase-3/7-mediated apoptosis, while the other trimer forms large insoluble aggregates that accumulate on the outer plasma membrane and elicit cellular toxicity through an apoptosis-independent mechanism. The two trimers also exhibit different effects on the aggregation, toxicity, and cellular interaction of full-length Aβ, with one trimer showing a greater propensity to interact with Aβ than the other. The studies described in this paper indicate that the two trimers share structural, biophysical, and biological characteristics with oligomers of full-length Aβ. The varying structural, assembly, and biological characteristics of the two trimers provide a working model for how different Aβ trimers can assemble and lead to different biological effects, which may help shed light on the differences among Aβ oligomers.
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Affiliation(s)
- Adam G. Kreutzer
- Department of Chemistry, University of California Irvine, Irvine, CA92697
| | | | - Stan Yoo
- Department of Chemistry, University of California Irvine, Irvine, CA92697
| | | | | | - Ryan J. Malonis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY10461
| | - Karen Tong
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY10461
| | - Yu-Fu Lin
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, OH43210
| | - Jennifer T. Nguyen
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA92697
| | - William J. Howitz
- Department of Chemistry, University of California Irvine, Irvine, CA92697
| | - Michelle N. Diab
- Department of Chemistry, University of California Irvine, Irvine, CA92697
| | - Imane L. Hamza
- Department of Chemistry, University of California Irvine, Irvine, CA92697
| | - Jonathan R. Lai
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY10461
| | - Vicki H. Wysocki
- Resource for Native Mass Spectrometry Guided Structural Biology, The Ohio State University, Columbus, OH43210
| | - James S. Nowick
- Department of Chemistry, University of California Irvine, Irvine, CA92697
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA92697
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9
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Pal S. Impact of Hydrogen‐Bond Surrogate Model on Helix Stabilization and Development of Protein‐Protein Interaction Inhibitors. ChemistrySelect 2023. [DOI: 10.1002/slct.202204207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Affiliation(s)
- Sunit Pal
- Chemical Genomics Centre of the Max Planck Society Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
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10
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Schulig L, Geist N, Delcea M, Link A, Kulke M. Fundamental Redesign of the TIGER2hs Kernel to Address Severe Parameter Sensitivity. J Chem Inf Model 2022; 62:4200-4209. [PMID: 36004729 DOI: 10.1021/acs.jcim.2c00476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Replica exchange molecular dynamics simulations are one of the most popular approaches to enhance conformational sampling of molecular systems. Applications range from protein folding to protein-protein or other host-guest interactions, as well as binding free energy calculations. While these methods are computationally expensive, highly accurate results can be obtained. We recently developed TIGER2hs, an improved version of the temperature intervals with global exchange of replicas (TIGER2) algorithm. This method combines the replica-based enhanced sampling in an explicit solvent with a hybrid solvent energy evaluation. During the exchange attempts, bulk water is replaced by an implicit solvent model, allowing sampling with significantly less replicas than parallel tempering (REMD). This enables accurate enhanced sampling calculations with only a fraction of computational resources compared to REMD. Our latest results highlight several issues with sampling imbalance and parameter sensitivity within the original TIGER2 exchange algorithms that affect the overall state populations. A high sensitivity on replica number and maximum temperature is eliminated by changing to a pairwise exchange kernel (PE) without additional sorting. Simulations are controlled by adjusting the average temperature change per exchange ⟨ΔT/χ⟩ to below 30 K to mimic a controlled temperature mixing of replicas similar to REMD. Thus, this parameter provides an applicable property for selecting combinations of replica number and maximum temperature to adjust simulations for best accuracy, with flexible resource investment. This increases the robustness of the method and ensures results in excellent agreement with REMD, as demonstrated for three different peptides.
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Affiliation(s)
- Lukas Schulig
- Department of Medicinal and Pharmaceutical Chemistry, University of Greifswald, Friedrich-Ludwig-Jahn-Straße 17, 17489 Greifswald, Germany
| | - Norman Geist
- Department of Biophysical Chemistry, University of Greifswald, Felix-Hausdorff-Straße 4, 17489 Greifswald, Germany
| | - Mihaela Delcea
- Department of Biophysical Chemistry, University of Greifswald, Felix-Hausdorff-Straße 4, 17489 Greifswald, Germany
| | - Andreas Link
- Department of Medicinal and Pharmaceutical Chemistry, University of Greifswald, Friedrich-Ludwig-Jahn-Straße 17, 17489 Greifswald, Germany
| | - Martin Kulke
- MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Road, East Lansing, Michigan 48824, United States of America
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11
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Yadav HOS, Kuo AT, Urata S, Funahashi K, Imamura Y, Shinoda W. Adsorption characteristics of peptides on ω-functionalized self-assembled monolayers: a molecular dynamics study. Phys Chem Chem Phys 2022; 24:14805-14815. [PMID: 35695085 DOI: 10.1039/d2cp01348g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular dynamics simulations were employed to investigate the adsorption behavior of a variety of amino-acid side-chain analogs (SCAs) and a β-hairpin (HP7) peptide on a series of liquid-like self-assembled monolayers (SAMs) with terminal functional groups of -OH, -OCH3, -CH3, and -CF3. The relationships between the adsorption free energy of the SCAs and the interfacial properties of water on the SAMs were examined to determine the acute predictors of protein adsorption on the SAM surfaces. The structural changes of HP7 on the SAM surfaces were also investigated to understand the relationship between the surface nature and protein denaturation. It was found that the adsorption free energy of the SCAs was linearly related to the surface hydrophobicity, which was computed as the free energy of cavity formation near the SAM-water interfaces. In addition, the hydrophobic -CH3 and -CF3 SAMs produced substantial conformational changes in HP7 because of the strong hydrophobic attractions to the nonpolar side chains. The hydrophilic surface terminated by -OH also promoted structural changes in HP7 resulting from the formation of hydrogen bonds between the hydrophilic tail and HP7. Consequently, the moderate amphiphilic surface terminated by -OCH3 avoided the denaturation of HP7 most efficiently, thus improving the biocompatibility of the surface. In conclusion, these results provide a deep understanding of protein adsorption for a wide range of polymeric surfaces, and they can potentially aid the design of appropriate biocompatible coatings for medical applications.
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Affiliation(s)
- Hari O S Yadav
- Department of Materials Chemistry, Nagoya University, Nagoya 464-8603, Japan
| | - An-Tsung Kuo
- Materials Integration Laboratories, AGC Inc., Yokohama, Kanagawa, 230-0045, Japan
| | - Shingo Urata
- Planning Division, AGC Inc., Yokohama, Kanagawa, 230-0045, Japan
| | - Kosuke Funahashi
- Innovative Technology Laboratories, AGC Inc., Yokohama, Kanagawa, 230-0045, Japan
| | - Yutaka Imamura
- Innovative Technology Laboratories, AGC Inc., Yokohama, Kanagawa, 230-0045, Japan
| | - Wataru Shinoda
- Department of Materials Chemistry, Nagoya University, Nagoya 464-8603, Japan.,Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan. .,Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan
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12
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Chekmarev SF. Extraction of kinetics from equilibrium distributions of states using the Metropolis Monte Carlo method. Phys Rev E 2022; 105:034407. [PMID: 35428044 DOI: 10.1103/physreve.105.034407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
The Metropolis Monte Carlo (MMC) method is used to extract reaction kinetics from a given equilibrium distribution of states of a complex system. The approach is illustrated by the folding/unfolding reaction for two proteins: a model β-hairpin and α-helical protein α_{3}D. For the β-hairpin, the free energy surfaces (FESs) and free energy profiles (FEPs) are employed as the equilibrium distributions of states, playing a role of the potentials of mean force to determine the acceptance probabilities of new states in the MMC simulations. Based on the FESs and PESs for a set of temperatures that were simulated with the molecular dynamics (MD) method, the MMC simulations are performed to extract folding/unfolding rates. It has been found that the rate constants and first-passage time (FPT) distributions obtained in the MMC simulations change with temperature in good agreement with those from the MD simulations. For α_{3}D protein, whose equilibrium folding/unfolding was studied with the single-molecule FRET method [Chung et al., J. Phys. Chem. A 115, 3642 (2011)1089-563910.1021/jp1009669], the FRET-efficiency histograms at different denaturant concentrations were used as the equilibrium distributions of protein states. It has been found that the rate constants for folding and unfolding obtained in the MMC simulations change with denaturant concentration in reasonable agreement with the constants that were extracted from the photon trajectories on the basis of theoretical models. The simulated FPT distributions are single-exponential, which is consistent with the assumption of two-state kinetics that was made in the theoretical models. The promising feature of the present approach is that it is based solely on the equilibrium distributions of states, without introducing any additional parameters to perform simulations, which suggests its applicability to other complex systems.
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Affiliation(s)
- Sergei F Chekmarev
- Institute of Thermophysics, SB RAS, 630090 Novosibirsk, Russia and Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
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13
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Richaud AD, Zhao G, Hobloss S, Roche SP. Folding in Place: Design of β-Strap Motifs to Stabilize the Folding of Hairpins with Long Loops. J Org Chem 2021; 86:13535-13547. [PMID: 34499510 PMCID: PMC8576641 DOI: 10.1021/acs.joc.1c01442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Despite their pivotal role in defining antibody affinity and protein function, β-hairpins harboring long noncanonical loops remain synthetically challenging because of the large entropic penalty associated with their conformational folding. Little is known about the contribution and impact of stabilizing motifs on the folding of β-hairpins with loops of variable length and plasticity. Here, we report a design of minimalist β-straps (strap = strand + cap) that offset the entropic cost of long-loop folding. The judicious positioning of noncovalent interactions (hydrophobic cluster and salt-bridge) within the novel 8-mer β-strap design RW(V/H)W···WVWE stabilizes hairpins with up to 10-residue loops of varying degrees of plasticity (Tm up to 52 °C; 88 ± 1% folded at 18 °C). This "hyper" thermostable β-strap outperforms the previous gold-standard technology of β-strand-β-cap (16-mer) and provides a foundation for producing new classes of long hairpins as a viable and practical alternative to macrocyclic peptides.
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Affiliation(s)
- Alexis D Richaud
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431, United States
| | - Guangkuan Zhao
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431, United States
| | - Samir Hobloss
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431, United States
| | - Stéphane P Roche
- Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, Florida 33431, United States
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14
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Pace JR, Lampkin BJ, Abakah C, Moyer A, Miao J, Deprey K, Cerulli RA, Lin YS, Baleja JD, Baker D, Kritzer JA. Stapled β-Hairpins Featuring 4-Mercaptoproline. J Am Chem Soc 2021; 143:15039-15044. [PMID: 34516087 DOI: 10.1021/jacs.1c04378] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptides constrained by intramolecular cross-links, especially stapled α-helices, have emerged as versatile scaffolds for drug development. However, there are fewer examples of similarly constrained scaffolds for other secondary structures. Here, we used a novel computational strategy to identify an optimal staple for antiparallel β-strands, and then we incorporated that staple within a β-hairpin peptide. The hairpin uses 4-mercaptoproline as a novel staple component, which contributes to a unique, kinked structure. The stapled hairpins show a high degree of structure in aqueous solution, excellent resistance to degradation in cell lysates, and cytosolic penetration at micromolar concentrations. They also overlay with a unique subset of kinked hairpin motifs at protein-protein interaction interfaces. Thus, these scaffolds represent promising starting points for developing inhibitors of cellular protein-protein interactions.
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Affiliation(s)
- Jennifer R Pace
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Bryan J Lampkin
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Charles Abakah
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Adam Moyer
- Molecular Engineering and Sciences Institute, University of Washington, Seattle Washington 98195, United States
| | - Jiayuan Miao
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Kirsten Deprey
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Robert A Cerulli
- Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts 02111, United States
| | - Yu-Shan Lin
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - James D Baleja
- Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts 02111, United States
| | - David Baker
- Molecular Engineering and Sciences Institute, University of Washington, Seattle Washington 98195, United States.,Department of Biochemistry, Institute for Protein Design, and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, United States
| | - Joshua A Kritzer
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
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15
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Chekmarev SF. First-passage times in protein folding: exploring the native-like states vs. overcoming the free energy barrier. Phys Chem Chem Phys 2021; 23:17856-17865. [PMID: 34378547 DOI: 10.1039/d0cp06560a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Using a model β-hairpin protein as a representative example of simple two-state folders whose kinetics are uncomplicated by the presence of on- and off-pathway intermediates, it is studied how the search for the protein's native state among native-like states affects the folding kinetics. It is revealed that the first-passage time (FPT) distributions are essentially single-exponential not only for the times to overcome the free energy barrier between the unfolded and native-like states but also for the times to find the native state among the native-like ones. The FPT distributions of this type are observed through all studied two-state-like regimes of protein folding, varying from a regime close to two-state folding to a regime close to downhill folding. If the protein explores native-like states for a time much longer than the time to overcome the free energy barrier, which is characteristic of high temperatures, the resulting FPT distribution to reach the native state remains close to exponential but the mean FPT (MFPT) is determined not by the height of the free energy barrier but by the time to explore native-like states. In particular, the mean time to overcome the free energy barrier is in reasonable agreement with the Kramers rate formula and generally far shorter than the overall MFPT to reach the native state. The observed increase of the overall MFPT, as a result of longer exploration of native-like states, may lead to an overestimate of the height of the free energy barrier between the unfolded and folded states when it is calculated from the overall MFPT.
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16
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Monti A, Sturlese M, Caporale A, Roger JDA, Mascanzoni F, Ruvo M, Doti N. Design, synthesis, structural analysis and biochemical studies of stapled AIF(370-394) analogues as ligand of CypA. Biochim Biophys Acta Gen Subj 2020; 1864:129717. [PMID: 32861757 DOI: 10.1016/j.bbagen.2020.129717] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/28/2020] [Accepted: 08/19/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND The neuronal apoptotic process requires the nuclear translocation of Apoptosis Inducing Factor (AIF) in complex with Cyclophilin A (CypA) with consequent chromatin condensation and DNA degradation events. Targeting CypA by delivering an AIF-blocking peptide (AIF(370-394)) provides a significant neuroprotection, demonstrating the biological relevance of the AIF/CypA complex. To date pharmaceutical compounds targeting this complex are missing. METHODS We designed and synthesized a set of mono and bicyclic AIF(370-394) analogs containing both disulfide and 1,2,3-triazole bridges, in the attempt to both stabilize the peptide conformation and improve its binding affinity to CypA. Peptide structures in solution and in complex with CypA have been studied by circular dichroism (CD), Nuclear Magnetic Resonance (NMR) and molecular modeling. The ability of stapled peptides to interact with CypA was evaluated by using Epic Corning label free technique and Isothermal Titration Calorimetry experiments. RESULTS We identified a stapled peptide analogue of AIF(370-394) with a ten-fold improved affinity for CypA. Molecular modeling studies reveal that the new peptide acquires β-turn/β-fold structures and shares with the parent molecule the same binding region on CypA. CONCLUSIONS Data obtained provide invaluable assistance in designing new ligand of CypA for therapeutic approaches in neurodegenerative diseases. GENERAL SIGNIFICANCE Due to the crucial role of AIF/CypA complex formation in neurodegeneration, identification of selective inhibitors is of high importance for targeted therapies. We describe new bicyclic peptide inhibitors with improved affinity for CypA, investigating the kinetic, thermodynamic and structural effects of conformational constraints on the protein-ligand interaction, and their utility for drug design.
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Affiliation(s)
- Alessandra Monti
- Istituto di Biostrutture e Bioimmagini-CNR; Via Mezzocannone, 16, 80134 Napoli, Italy; DISTABIF, Università degli Studi della Campania Luigi Vanvitelli, Via Vivaldi 43, 81100 Caserta, CE, Italy
| | - Mattia Sturlese
- Molecular Modeling Section, Dipartimento di Scienze del Farmaco, Università di Padova, via F. Marzolo 5, 35131 Padova, Italy
| | - Andrea Caporale
- Istituto di Biostrutture e Bioimmagini-CNR; Via Mezzocannone, 16, 80134 Napoli, Italy
| | - Jessica De Almeida Roger
- Molecular Modeling Section, Dipartimento di Scienze del Farmaco, Università di Padova, via F. Marzolo 5, 35131 Padova, Italy
| | - Fabiola Mascanzoni
- Istituto di Biostrutture e Bioimmagini-CNR; Via Mezzocannone, 16, 80134 Napoli, Italy
| | - Menotti Ruvo
- Istituto di Biostrutture e Bioimmagini-CNR; Via Mezzocannone, 16, 80134 Napoli, Italy
| | - Nunzianna Doti
- Istituto di Biostrutture e Bioimmagini-CNR; Via Mezzocannone, 16, 80134 Napoli, Italy.
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17
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Lin FY, Huang J, Pandey P, Rupakheti C, Li J, Roux B, MacKerell AD. Further Optimization and Validation of the Classical Drude Polarizable Protein Force Field. J Chem Theory Comput 2020; 16:3221-3239. [PMID: 32282198 PMCID: PMC7306265 DOI: 10.1021/acs.jctc.0c00057] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The CHARMM Drude-2013 polarizable force field (FF) was developed to include the explicit treatment of induced electronic polarizability, resulting in a more accurate description of the electrostatic interactions in molecular dynamics (MD) simulations. While the Drude-2013 protein FF has shown success in improving the folding properties of α-helical peptides and to reproduce experimental observables in simulations up to 1 μs, some limitations were noted regarding the stability of β-sheet structures in simulations longer than 100 ns as well as larger deviations from crystal structures in simulations of a number of proteins compared to the additive CHARMM36 protein FF. The origin of the instability has been identified and appears to be primarily due to overestimated atomic polarizabilities and induced dipole-dipole interactions on the Cβ, Cγ, and Cδ side chain atoms. To resolve this and other issues, a number of aspects of the model were revisited, resulting in Drude-2019 protein FF. Backbone parameters were optimized targeting the conformational properties of the (Ala)5 peptide in solution along with gas phase properties of the alanine dipeptide. Dipeptides that contain N-acetylated and N'-methylamidated termini, excluding Gly, Pro, and Ala, were used as models to optimize the atomic polarizabilities and Thole screening factors on selected Cβ, Cγ, and Cδ carbons by targeting quantum mechanical (QM) dipole moments and molecular polarizabilities. In addition, to obtain better conformational properties, side chain χ1 and χ2 dihedral parameters were optimized targeting QM data for the respective side chain dipeptide conformations as well as Protein Data Bank survey data based on the χ1, χ2 sampling from Hamiltonian replica-exchange MD simulations of (Ala)4-X-(Ala)4 in solution, where X is the amino acid of interest. Further improvements include optimizing nonbonded interactions between charged residues to reproduce QM interaction energies of the charged-protein model compounds and experimental osmotic pressures. Validation of the optimized Drude protein FF includes MD simulations of a collection of peptides and proteins including β-sheet structures, as well as transmembrane ion channels. Results showed that the updated Drude-2019 protein FF yields smaller overall root-mean-square differences of proteins as compared to the additive CHARMM36m and Drude-2013 FFs as well as similar or improved agreement with experimental NMR properties, allowing for long time scale simulation studies of proteins and more complex biomolecular systems in conjunction with the remainder of the Drude polarizable FF.
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Affiliation(s)
- Fang-Yu Lin
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
| | - Jing Huang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
- Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang, China
| | - Poonam Pandey
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
| | - Chetan Rupakheti
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Jing Li
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Alexander D. MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, MD 21201, USA
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18
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Lin FY, MacKerell AD. Improved Modeling of Cation-π and Anion-Ring Interactions Using the Drude Polarizable Empirical Force Field for Proteins. J Comput Chem 2020; 41:439-448. [PMID: 31518010 PMCID: PMC7322827 DOI: 10.1002/jcc.26067] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/15/2019] [Accepted: 08/25/2019] [Indexed: 12/22/2022]
Abstract
Cation-π interactions are noncovalent interactions between a π-electron system and a positively charged ion that are regarded as a strong noncovalent interaction and are ubiquitous in biological systems. Similarly, though less studied, anion-ring interactions are present in proteins along with in-plane interactions of anions with aromatic rings. As these interactions are between a polarizing ion and a polarizable π system, the accuracy of the treatment of these interactions in molecular dynamics (MD) simulations using additive force fields (FFs) may be limited. In the present work, to allow for a better description of ion-π interactions in proteins in the Drude-2013 protein polarizable FF, we systematically optimized the parameters for these interactions targeting model compound quantum mechanical (QM) interaction energies with atom pair-specific Lennard-Jones parameters along with virtual particles as selected ring centroids introduced to target the QM interaction energies and geometries. Subsequently, MD simulations were performed on a series of protein structures where ion-π pairs occur to evaluate the optimized parameters in the context of the Drude-2013 FF. The resulting FF leads to a significant improvement in reproducing the ion-π pair distances observed in experimental protein structures, as well as a smaller root-mean-square differences and fluctuations of the overall protein structures from experimental structures. Accordingly, the optimized Drude-2013 protein polarizable FF is suggested for use in MD simulations of proteins where cation-π and anion-ring interactions are critical. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Fang-Yu Lin
- Computer-Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Alexander D. MacKerell
- Computer-Aided Drug Design Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
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19
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Merritt HI, Sawyer N, Arora PS. Bent Into Shape: Folded Peptides to Mimic Protein Structure and Modulate Protein Function. Pept Sci (Hoboken) 2020; 112:e24145. [PMID: 33575525 PMCID: PMC7875438 DOI: 10.1002/pep2.24145] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 12/11/2019] [Indexed: 12/16/2022]
Abstract
Protein secondary and tertiary structure mimics have served as model systems to probe biophysical parameters that guide protein folding and as attractive reagents to modulate protein interactions. Here we review contemporary methods to reproduce loop, helix, sheet and coiled-coil conformations in short peptides.
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Affiliation(s)
| | | | - Paramjit S. Arora
- Department of Chemistry New York University, New York, New York 10003, United States
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20
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Zhang Z, Sun T, Li L, Zhang D. Effects of PHB and SFC charge models on the side chain-side chain interactions in the simulation of β-hairpins. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.136801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Deplazes E, Chin YKY, King GF, Mancera RL. The unusual conformation of cross-strand disulfide bonds is critical to the stability of β-hairpin peptides. Proteins 2019; 88:485-502. [PMID: 31589791 DOI: 10.1002/prot.25828] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/27/2019] [Accepted: 09/17/2019] [Indexed: 01/04/2023]
Abstract
The cross-strand disulfides (CSDs) found in β-hairpin antimicrobial peptides (β-AMPs) show a unique disulfide geometry that is characterized by unusual torsion angles and a short Cα-Cα distance. While the sequence and disulfide bond connectivity of disulfide-rich peptides is well studied, much less is known about the disulfide geometry found in CSDs and their role in the stability of β-AMPs. To address this, we solved the nuclear magnetic resonance (NMR) structure of the β-AMP gomesin (Gm) at 278, 298, and 310 K, examined the disulfide bond geometry of over 800 disulfide-rich peptides, and carried out extensive molecular dynamics (MD) simulation of the peptides Gm and protegrin. The NMR data suggests Cα-Cα distances characteristic for CSDs are independent of temperature. Analysis of disulfide-rich peptides from the Protein Data Bank revealed that right-handed and left-handed rotamers are equally likely in CSDs. The previously reported preference for right-handed rotamers was likely biased by restricting the analysis to peptides and proteins solved using X-ray crystallography. Furthermore, data from MD simulations showed that the short Cα-Cα distance is critical for the stability of these peptides. The unique disulfide geometry of CSDs poses a challenge to biomolecular force fields and to retain the stability of β-hairpin fold over long simulation times, restraints on the torsion angles might be required.
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Affiliation(s)
- Evelyne Deplazes
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and Curtin Institute for Computation, Curtin University, Perth, Western Australia, Australia
| | - Yanni K-Y Chin
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Ricardo L Mancera
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and Curtin Institute for Computation, Curtin University, Perth, Western Australia, Australia
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22
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Geist N, Kulke M, Schulig L, Link A, Langel W. Replica-Based Protein Structure Sampling Methods II: Advanced Hybrid Solvent TIGER2hs. J Phys Chem B 2019; 123:5995-6006. [PMID: 31265293 DOI: 10.1021/acs.jpcb.9b03134] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In many cases, native states of proteins may be predicted with sufficient accuracy by molecular dynamics simulations (MDSs) with modern force fields. Enhanced sampling methods based on MDS are applied for exploring the phase space of a protein sequence and to overcome barriers on rough conformational energy landscapes. The minimum free energy state is obtained with sampling algorithms providing sufficient convergence and accuracy. A reliable but computationally very expensive method is replica exchange molecular dynamics, with many modifications to this approach presented in the past. Recently, we demonstrated how our temperature intervals with global exchange of replicas hybrid (TIGER2h) solvent sampling algorithm made a good compromise between efficiency and accuracy. There, all states are sampled under full explicit solvent conditions with a freely chosen number of replicas, whereas an implicit solvent is used during the swap decisions. This hybrid method yielded a much better approximation to the agreement with calculations in an explicit solvent than fully implicit solvent simulations. Here, we present an extension of TIGER2h and add a few layers of explicit water molecules around the peptide for the energy calculations, whereas the dynamics in fully explicit water is maintained. We claim that these water layers better reproduce steric effects, the polarization of the solvent, and the resulting reaction field energy than typical implicit solvent models. By investigating the protein-solvent interactions across comprehensive thermodynamic state ensembles, we found a strong conformational dependence of this reaction field energy. All simulations were performed with nanoscale molecular dynamics on two peptides, the α-helical peptide (AAQAA)3 and the β-hairpin peptide HP7. A production-ready TIGER2hs implementation is supplied, approaching the accuracy of full explicit solvent sampling at a fraction of computational resources.
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Affiliation(s)
- Norman Geist
- Institut für Biochemie , Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
| | - Martin Kulke
- Institut für Biochemie , Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
| | - Lukas Schulig
- Institut für Pharmazie , Universität Greifswald , Friedrich-Ludwig-Jahn-Straße 17 , 17487 Greifswald , Germany
| | - Andreas Link
- Institut für Pharmazie , Universität Greifswald , Friedrich-Ludwig-Jahn-Straße 17 , 17487 Greifswald , Germany
| | - Walter Langel
- Institut für Biochemie , Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
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23
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Chekmarev SF. Alternation of phases of regular and irregular dynamics in protein folding. Phys Rev E 2019; 99:022412. [PMID: 30934237 DOI: 10.1103/physreve.99.022412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Indexed: 06/09/2023]
Abstract
The regularity of the dynamics in different phases of protein folding is investigated for a set of proteins which undergo a cooperative, two-state folding transition. To determine the degree of regularity of the dynamics, the fractal dimension of probability fluxes is calculated on the basis of simulated folding trajectories. It has been found that the phases of regular and irregular dynamics alternate as follows. In the initial (collapse) phase of folding, the dynamics are essentially regular. Then, as the protein comes to the basin of semicompact states that precedes the transition state, the dynamics become irregular. At the transition state, the dynamics are regularized again but become less regular when the nativelike states are explored. Depending on the specific conditions at which the protein folding was considered, some phases of the dynamics could not be well resolved, but no significant deviation from this general picture has been observed. The regularization of the dynamics at the transition state is discussed in relation to the recent studies of the Hamiltonian dynamics of small clusters, where both regular and chaotic dynamics were observed depending on the flatness of the energy surface at the transition state.
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Affiliation(s)
- Sergei F Chekmarev
- Institute of Thermophysics, SB RAS, 630090 Novosibirsk, Russia and Physics Department, Novosibirsk State University, 630090 Novosibirsk, Russia
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24
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Abstract
Peptide secondary and tertiary structure motifs frequently serve as inspiration for the development of protein-protein interaction (PPI) inhibitors. While a wide variety of strategies have been used to stabilize or imitate α-helices, similar strategies for β-sheet stabilization are more limited. Synthetic scaffolds that stabilize reverse turns and cross-strand interactions have provided important insights into β-sheet stability and folding. However, these templates occupy regions of the β-sheet that might impact the β-sheet's ability to bind at a PPI interface. Here, we present the hydrogen bond surrogate (HBS) approach for stabilization of β-hairpin peptides. The HBS linkage replaces a cross-strand hydrogen bond with a covalent linkage, conferring significant conformational and proteolytic resistance. Importantly, this approach introduces the stabilizing linkage in the buried β-sheet interior, retains all side chains for further functionalization, and allows efficient solid-phase macrocyclization. We anticipate that HBS stabilization of PPI β-sheets will enhance the development of β-sheet PPI inhibitors and expand the repertoire of druggable PPIs.
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Affiliation(s)
- Nicholas Sawyer
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
| | - Paramjit S. Arora
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
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25
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Kulke M, Geist N, Möller D, Langel W. Replica-Based Protein Structure Sampling Methods: Compromising between Explicit and Implicit Solvents. J Phys Chem B 2018; 122:7295-7307. [PMID: 29966412 DOI: 10.1021/acs.jpcb.8b05178] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The structure of a protein is often not completely accessible by experiments. In silico, replica exchange molecular dynamics (REMD) is the standard sampling method for predicting the secondary and tertiary structures from the amino acid sequence, but it is computationally very expensive. Two recent adaptations from REMD, temperature intervals with global exchange of replicas (TIGER2) and TIGER2A, have been tested here in implicit and explicit solvents. Additionally, explicit, implicit, and hybrid solvent REMD are compared. On the basis of the hybrid REMD (REMDh) method, we present a new hybrid TIGER2h algorithm for faster structural sampling, while retaining good accuracy. The implementations of REMDh, TIGER2, TIGER2A, and TIGER2h are provided for nanoscale molecular dynamics (NAMD). All the methods were tested with two model peptides of known structure, (AAQAA)3 and HP7, with helix and sheet motifs, respectively. The TIGER2 methods and REMDh were also applied to the unknown structure of the collagen type I telopeptides, which represent bigger proteins with some degree of disorder. We present simulations covering more than 180 μs and analyze the performance and convergence of the distributions of states between the particular methods by dihedral principal component and secondary structure analysis.
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Affiliation(s)
- Martin Kulke
- Institut für Biochemie , Ernst-Moritz-Arndt-Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
| | - Norman Geist
- Institut für Biochemie , Ernst-Moritz-Arndt-Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
| | - Daniel Möller
- Institut für Biochemie , Ernst-Moritz-Arndt-Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
| | - Walter Langel
- Institut für Biochemie , Ernst-Moritz-Arndt-Universität Greifswald , Felix-Hausdorff-Straße 4 , 17487 Greifswald , Germany
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26
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Zamora-Carreras H, Maestro B, Strandberg E, Ulrich AS, Sanz JM, Jiménez MÁ. Roles of Amphipathicity and Hydrophobicity in the Micelle-Driven Structural Switch of a 14-mer Peptide Core from a Choline-Binding Repeat. Chemistry 2018; 24:5825-5839. [PMID: 29369425 DOI: 10.1002/chem.201704802] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Indexed: 01/16/2023]
Abstract
Choline-binding repeats (CBRs) are ubiquitous sequences with a β-hairpin core that are found in the surface proteins of several microorganisms such as S. pneumoniae (pneumococcus). Previous studies on a 14-mer CBR sequence derived from the pneumoccal LytA autolysin (LytA239-252 peptide) have demonstrated a switch behaviour for this peptide, so that it acquires a stable, native-like β-hairpin conformation in aqueous solution but is reversibly transformed into an amphipathic α-helix in the presence of detergent micelles. With the aim of understanding the factors responsible for this unusual β-hairpin to α-helix transition, and to specifically assess the role of peptide hydrophobicity and helical amphipathicity in the process, we designed a series of LytA239-252 variants affecting these two parameters and studied their interaction with dodecylphosphocholine (DPC) micelles by solution NMR, circular dichroism and fluorescence spectroscopies. Our results indicate that stabilising cross-strand interactions become essential for β-hairpin stability in the absence of optimal turn sequences. Moreover, both amphipathicity and hydrophobicity display comparable importance for helix stabilisation of CBR-derived peptides in micelles, indicating that these sequences represent a novel class of micelle/membrane-interacting peptides.
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Affiliation(s)
- Héctor Zamora-Carreras
- Instituto de Química Física Rocasolano (IQFR), Consejo Superior de Investigaciones Científicas (CSIC), Serrano 119, 28006, Madrid, Spain
| | - Beatriz Maestro
- Instituto de Biología MolecularyCelular, Universidad Miguel Hernández, Elche, 03202, Alicante, Spain
| | - Erik Strandberg
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021, Karlsruhe, Germany
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021, Karlsruhe, Germany.,Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Jesús M Sanz
- Instituto de Biología MolecularyCelular, Universidad Miguel Hernández, Elche, 03202, Alicante, Spain.,Biological Research Centre (CIB), Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain
| | - M Ángeles Jiménez
- Instituto de Química Física Rocasolano (IQFR), Consejo Superior de Investigaciones Científicas (CSIC), Serrano 119, 28006, Madrid, Spain
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27
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Williams TM, Sable R, Singh S, Vicente MGH, Jois S. Peptide ligands for targeting the extracellular domain of EGFR: Comparison between linear and cyclic peptides. Chem Biol Drug Des 2018; 91:605-619. [PMID: 29052959 PMCID: PMC5775921 DOI: 10.1111/cbdd.13125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/27/2017] [Accepted: 10/04/2017] [Indexed: 01/08/2023]
Abstract
Colorectal cancer (CRC) is the third most common solid internal malignancy among cancers. Early detection of cancer is key to increasing the survival rate of colorectal cancer patients. Overexpression of the EGFR protein is associated with CRC. We have designed a series of peptides that are highly specific for the extracellular domain of EGFR, based on our earlier studies on linear peptides. The previously reported linear peptide LARLLT, known to bind to EGFR, was modified with the goals of increasing its stability and its specificity toward EGFR. Peptide modifications, including D-amino acid substitution, cyclization, and chain reversal, were investigated. In addition, to facilitate labeling of the peptide with a fluorescent dye, an additional lysine residue was introduced onto the linear (KLARLLT) and cyclic peptides cyclo(KLARLLT) (Cyclo.L1). The lysine residue was also converted into an azide group in both a linear and reversed cyclic peptide sequences cyclo(K(N3)larllt) (Cyclo.L1.1) to allow for subsequent "click" conjugation. The cyclic peptides showed enhanced binding to EGFR by SPR. NMR and molecular modeling studies suggest that the peptides acquire a β-turn structure in solution. In vitro stability studies in human serum show that the cyclic peptide is more stable than the linear peptide.
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Affiliation(s)
- Tyrslai M. Williams
- Department of Chemistry, Louisiana State University, Baton Rouge LA 70803, USA
| | - Rushikesh Sable
- Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe LA 71201, USA
| | - Sitanshu Singh
- Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe LA 71201, USA
| | - M. Graça H. Vicente
- Department of Chemistry, Louisiana State University, Baton Rouge LA 70803, USA
| | - Seetharama Jois
- Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe, Monroe LA 71201, USA
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28
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Amitay M, Goldstein M. Evaluating the peptide structure prediction capabilities of a purely ab-initio method. Protein Eng Des Sel 2017; 30:723-727. [PMID: 29040794 DOI: 10.1093/protein/gzx052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 09/08/2017] [Indexed: 01/25/2023] Open
Abstract
DEEPSAM is a relatively new global optimization algorithm aimed to predict the structure of bio-molecules from sequence, without any additional preliminary assumption. It is an evolutionary algorithm whose mutation operators are built by hybridizing the diffusion equation method, molecular dynamics simulated annealing, and a quasi-Newton local minimization method. The goal of this study was to evaluate the structure prediction capabilities of DEEPSAM by running it upon NMR structures of linear peptides (10-20 residues). The results indicate that DEEPSAM successfully predicted the conformations of these peptides, using modest computing resources.
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Affiliation(s)
- M Amitay
- Department of Bioinformatics, Jerusalem College of Technology, Havaad Haleumi 21, Jerusalem 9372115, Israel
| | - M Goldstein
- Department of Computer Science, Jerusalem College of Technology, Havaad Haleumi 21, Jerusalem 9372115, Israel
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29
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Anderson JM, Shcherbakov AA, Kier BL, Kellock J, Shu I, Byrne AL, Eidenschink LA, Andersen NH. Optimization of a β-sheet-cap for long loop closure. Biopolymers 2017; 107. [PMID: 27701729 DOI: 10.1002/bip.22995] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 12/25/2022]
Abstract
Protein loops make up a large portion of the secondary structure in nature. But very little is known concerning loop closure dynamics and the effects of loop composition on fold stability. We have designed a small system with stable β-sheet structures, including features that allow us to probe these questions. Using paired Trp residues that form aromatic clusters on folding, we are able to stabilize two β-strands connected by varying loop lengths and composition (an example sequence: RWITVTI - loop - KKIRVWE). Using NMR and CD, both fold stability and folding dynamics can be investigated for these systems. With the 16 residue loop peptide (sequence: RWITVTI-(GGGGKK)2 GGGG-KKIRVWE) remaining folded (ΔGU = 1.6 kJ/mol at 295K). To increase stability and extend the series to longer loops, we added an additional Trp/Trp pair in the loop flanking position. With this addition to the strands, the 16 residue loop (sequence: RWITVRIW-(GGGGKK)2 GGGG-WKTIRVWE) supports a remarkably stable β-sheet (ΔGU = 6.3 kJ/mol at 295 K, Tm = ∼55°C). Given the abundance of loops in binding motifs and between secondary structures, these constructs can be powerful tools for peptide chemists to study loop effects; with the Trp/Trp pair providing spectroscopic probes for assessing both stability and dynamics by NMR.
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Affiliation(s)
- Jordan M Anderson
- Department of Chemistry, University of Washington, Seattle, Washington
| | | | - Brandon L Kier
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Jackson Kellock
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Irene Shu
- Department of Chemistry, University of Washington, Seattle, Washington
| | - Aimee L Byrne
- Department of Chemistry, University of Washington, Seattle, Washington
| | | | - Niels H Andersen
- Department of Chemistry, University of Washington, Seattle, Washington
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30
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Gupta M, Khatua P, Chakravarty C, Bandyopadhyay S. The sensitivity of folding free energy landscapes of trpzips to mutations in the hydrophobic core. Phys Chem Chem Phys 2017; 19:22813-22825. [DOI: 10.1039/c7cp03825a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The sensitivity of the stability of folded states and free energy landscapes to the differences in the hydrophobic content of the core residues has been studied for the set of 16-residue trpzips, namely, Trpzip4, Trpzip5 and Trpzip6.
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Affiliation(s)
- Madhulika Gupta
- Department of Chemistry
- Indian Institute of Technology-Delhi
- New Delhi 110016
- India
| | - Prabir Khatua
- Molecular Modeling Laboratory
- Department of Chemistry
- Indian Institute of Technology
- Kharagpur 721302
- India
| | | | - Sanjoy Bandyopadhyay
- Molecular Modeling Laboratory
- Department of Chemistry
- Indian Institute of Technology
- Kharagpur 721302
- India
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31
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Sivanesam K, Kier BL, Whedon SD, Chatterjee C, Andersen NH. Hairpin structure stability plays a role in the activity of two antimicrobial peptides. FEBS Lett 2016; 590:4480-4488. [PMID: 27859052 DOI: 10.1002/1873-3468.12477] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 10/24/2016] [Accepted: 10/24/2016] [Indexed: 11/06/2022]
Abstract
Many naturally occurring antimicrobial peptides (AMPs) are amphipathic with a β-hairpin conformation stabilized by cross-strand disulfides across the associated β-strands. Here, we show that the disulfides are not essential. Other structuring means such as better β-turns and noncovalent cross-strand interactions can, with proper design, replace the disulfides with no loss in antimicrobial activity. Our results also demonstrate that the hairpin turn region may play a role in membrane recognition for at least one member of this class, since a homodimeric turnless β-sheet analog showed no antimicrobial activity. We also examined the effects of N-terminal fatty acid adducts on AMPs. Surprisingly, the large hydrophobic carboxylic moieties examined completely eliminated the antimicrobial activity of previously active β-hairpin peptides.
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Affiliation(s)
| | - Brandon L Kier
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Samuel D Whedon
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | | | - Niels H Andersen
- Department of Chemistry, University of Washington, Seattle, WA, USA
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32
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Jannone JM, Grigg JI, Aguirre LM, Jones EM. Electrostatic Interactions at N- and C-Termini Determine Fibril Polymorphism in Serum Amyloid A Fragments. J Phys Chem B 2016; 120:10258-10268. [PMID: 27632709 DOI: 10.1021/acs.jpcb.6b07672] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Amyloid polymorphism presents a challenge to physical theories of amyloid formation and stability. The amyloidogenic protein serum amyloid A (SAA) exhibits complex and unexplained structural polymorphism in its N-terminal fragments: the N-terminal 11-residue peptide (SAA1-11) forms left-handed helical fibrils, while extension by one residue (SAA1-12) produces a rare right-handed amyloid. In this study, we use a combination of vibrational spectroscopy and ultramicroscopy to examine fibrils of these peptides and their terminally acetylated and amidated variants, in an effort to uncover the physical basis for this effect. Raman spectroscopy and atomic force microscopy provide evidence that SAA1-12 forms a β-helical fibril architecture, while SAA1-11 forms more typical stacked β-sheets. Importantly, N-terminal acetylation blocks fibril formation by SAA1-12 with no effect on SAA1-11, while C-terminal amidation has nearly the opposite effect. Together, these data suggest distinct electrostatic interactions at the N- and C-termini stabilize the two fibril structures; we propose model fibril structures in which C-terminal extension changes the favored intermolecular interaction between peptide monomers from an Arg1-C-terminus charge pair to an N-terminus-C-terminus charge pair. This model suggests a general mechanism for charge-mediated amyloid polymorphism and may inform strategies for design of peptide-based nanomaterials stabilized by engineered intermolecular contacts.
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Affiliation(s)
- Justine M Jannone
- Department of Chemistry and Biochemistry, California Polytechnic State University San Luis Obispo, California 93407 United States
| | - James I Grigg
- Department of Chemistry and Biochemistry, California Polytechnic State University San Luis Obispo, California 93407 United States
| | - Lauren M Aguirre
- Department of Chemistry and Biochemistry, California Polytechnic State University San Luis Obispo, California 93407 United States
| | - Eric M Jones
- Department of Chemistry and Biochemistry, California Polytechnic State University San Luis Obispo, California 93407 United States
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33
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Anderson JM, Jurban B, Huggins KNL, Shcherbakov AA, Shu I, Kier B, Andersen NH. Nascent Hairpins in Proteins: Identifying Turn Loci and Quantitating Turn Contributions to Hairpin Stability. Biochemistry 2016; 55:5537-5553. [DOI: 10.1021/acs.biochem.6b00732] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jordan M. Anderson
- Department of Chemistry, University of Washington, Seattle, Washington 98105, United States
| | - Brice Jurban
- Department of Chemistry, University of Washington, Seattle, Washington 98105, United States
| | - Kelly N. L. Huggins
- Department of Chemistry, University of Washington, Seattle, Washington 98105, United States
| | | | - Irene Shu
- Department of Chemistry, University of Washington, Seattle, Washington 98105, United States
| | - Brandon Kier
- Department of Chemistry, University of Washington, Seattle, Washington 98105, United States
| | - Niels H. Andersen
- Department of Chemistry, University of Washington, Seattle, Washington 98105, United States
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34
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Goyal B, Srivastava KR, Patel K, Durani S. Modulation of β-Hairpin Peptide Self-Assembly: A Twenty-Residue Poly-lβ-Hairpin Modified Rationally as a Mixed-l,dHydrolase. ChemistrySelect 2016. [DOI: 10.1002/slct.201600078] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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
- Department of Physics and Astronomy; Michigan State University; East Lansing USA
| | - Kirti Patel
- Department of Chemistry; Indian Institute of Technology Bombay; Powai Mumbai- 400076 India
- Department of Chemistry; N. B. Mehta Science College, Bordi, Dahanu; Dist. Thane Maharashtra India
| | - Susheel Durani
- Department of Chemistry; Indian Institute of Technology Bombay; Powai Mumbai- 400076 India
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35
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Anderson JM, Kier BL, Jurban B, Byrne A, Shu I, Eidenschink LA, Shcherbakov AA, Hudson M, Fesinmeyer RM, Andersen NH. Aryl-aryl interactions in designed peptide folds: Spectroscopic characteristics and optimal placement for structure stabilization. Biopolymers 2016; 105:337-356. [PMID: 26850220 PMCID: PMC5638712 DOI: 10.1002/bip.22821] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/01/2016] [Accepted: 02/03/2016] [Indexed: 01/27/2023]
Abstract
We have extended our studies of Trp/Trp to other Aryl/Aryl through-space interactions that stabilize hairpins and other small polypeptide folds. Herein we detail the NMR and CD spectroscopic features of these types of interactions. NMR data remains the best diagnostic for characterizing the common T-shape orientation. Designated as an edge-to-face (EtF or FtE) interaction, large ring current shifts are produced at the edge aryl ring hydrogens and, in most cases, large exciton couplets appear in the far UV circular dichroic (CD) spectrum. The preference for the face aryl in FtE clusters is W ≫ Y ≥ F (there are some exceptions in the Y/F order); this sequence corresponds to the order of fold stability enhancement and always predicts the amplitude of the lower energy feature of the exciton couplet in the CD spectrum. The CD spectra for FtE W/W, W/Y, Y/W, and Y/Y pairs all include an intense feature at 225-232 nm. An additional couplet feature seen for W/Y, W/F, Y/Y, and F/Y clusters, is a negative feature at 197-200 nm. Tyr/Tyr (as well as F/Y and F/F) interactions produce much smaller exciton couplet amplitudes. The Trp-cage fold was employed to search for the CD effects of other Trp/Trp and Trp/Tyr cluster geometries: several were identified. In this account, we provide additional examples of the application of cross-strand aryl/aryl clusters for the design of stable β-sheet models and a scale of fold stability increments associated with all possible FtE Ar/Ar clusters in several structural contexts. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 337-356, 2016.
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Affiliation(s)
- Jordan M Anderson
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | - Brandon L Kier
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | - Brice Jurban
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | - Aimee Byrne
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | - Irene Shu
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | | | | | - Mike Hudson
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | - R M Fesinmeyer
- Department of Chemistry, University of Washington, Seattle, WA, 98195
| | - Niels H Andersen
- Department of Chemistry, University of Washington, Seattle, WA, 98195
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36
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Salveson PJ, Spencer RK, Nowick JS. X-ray Crystallographic Structure of Oligomers Formed by a Toxic β-Hairpin Derived from α-Synuclein: Trimers and Higher-Order Oligomers. J Am Chem Soc 2016; 138:4458-67. [PMID: 26926877 PMCID: PMC4825732 DOI: 10.1021/jacs.5b13261] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
![]()
Oligomeric
assemblies of the protein α-synuclein are thought
to cause neurodegeneration in Parkinson’s disease and related
synucleinopathies. Characterization of α-synuclein oligomers
at high resolution is an outstanding challenge in the field of structural
biology. The absence of high-resolution structures of oligomers formed
by α-synuclein impedes understanding the synucleinopathies at
the molecular level. This paper reports the X-ray crystallographic
structure of oligomers formed by a peptide derived from residues 36–55
of α-synuclein. The peptide 1a adopts a β-hairpin
structure, which assembles in a hierarchical fashion. Three β-hairpins
assemble to form a triangular trimer. Three copies of the triangular
trimer assemble to form a basket-shaped nonamer. Two nonamers pack
to form an octadecamer. Molecular modeling suggests that full-length
α-synuclein may also be able to assemble in this fashion. Circular
dichroism spectroscopy demonstrates that peptide 1a interacts
with anionic lipid bilayer membranes, like oligomers of full-length
α-synuclein. LDH and MTT assays demonstrate that peptide 1a is toxic toward SH-SY5Y cells. Comparison of peptide 1a to homologues suggests that this toxicity results from
nonspecific interactions with the cell membrane. The oligomers formed
by peptide 1a are fundamentally different than the proposed
models of the fibrils formed by α-synuclein and suggest that
α-Syn36–55, rather than the NAC, may nucleate
oligomer formation.
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Affiliation(s)
- Patrick J Salveson
- Department of Chemistry, University of California Irvine , Irvine, California 92697-2025, United States
| | - Ryan K Spencer
- Department of Chemistry, University of California Irvine , Irvine, California 92697-2025, United States
| | - James S Nowick
- Department of Chemistry, University of California Irvine , Irvine, California 92697-2025, United States
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37
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Makwana KM, Mahalakshmi R. Stereopositional Outcome in the Packing of Dissimilar Aromatics in Designed β-Hairpins. Chemistry 2016; 22:4147-56. [DOI: 10.1002/chem.201504428] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 12/15/2015] [Indexed: 01/06/2023]
Affiliation(s)
- Kamlesh Madhusudan Makwana
- Molecular Biophysics Laboratory; Department of Biological Sciences; Indian Institute of Science Education and Research, Bhopal; 462023 Madhya Pradesh India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory; Department of Biological Sciences; Indian Institute of Science Education and Research, Bhopal; 462023 Madhya Pradesh India
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38
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Kier BL, Newbloom GM, Pozzo LD, Andersen NH. A Structuring Repeat for Peptide Design: Long Beta Ribbons. Chembiochem 2016; 17:224-7. [PMID: 26603832 DOI: 10.1002/cbic.201500618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Indexed: 12/20/2022]
Abstract
Beta sheets are inherently length-limited; adding residues to the ends of model β-sheets does not necessarily grow the β-sheet. Here, we present a method for extending β-sheets to any length with a stabilizing repeat unit containing cross-strand Trp residues. Beta ribbons as long as 35 residues (approaching 100 Å in length) are reported and characterized.
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Affiliation(s)
- Brandon L Kier
- Department of Chemistry, University of Washington, Box 351700, Bagley Hall, Seattle, WA, 98195-1700, USA.
| | - Gregory M Newbloom
- Department of Chemical Engineering, University of Washington, Box 351750, Benson Hall, Seattle, WA, 98195-1750, USA
| | - Lilo D Pozzo
- Department of Chemical Engineering, University of Washington, Box 351750, Benson Hall, Seattle, WA, 98195-1750, USA
| | - Niels H Andersen
- Department of Chemistry, University of Washington, Box 351700, Bagley Hall, Seattle, WA, 98195-1700, USA.
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39
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Madhusudan Makwana K, Mahalakshmi R. Implications of aromatic-aromatic interactions: From protein structures to peptide models. Protein Sci 2015; 24:1920-33. [PMID: 26402741 DOI: 10.1002/pro.2814] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 09/17/2015] [Accepted: 09/18/2015] [Indexed: 12/11/2022]
Abstract
With increasing structural information on proteins, the opportunity to understand physical forces governing protein folding is also expanding. One of the significant non-covalent forces between the protein side chains is aromatic-aromatic interactions. Aromatic interactions have been widely exploited and thoroughly investigated in the context of folding, stability, molecular recognition, and self-assembly processes. Through this review, we discuss the contribution of aromatic interactions to the activity and stability of thermophilic, mesophilic, and psychrophilic proteins. Being hydrophobic, aromatic amino acids tend to reside in the protein hydrophobic interior or transmembrane segments of proteins. In such positions, it can play a diverse role in soluble and membrane proteins, and in α-helix and β-sheet stabilization. We also highlight here some excellent investigations made using peptide models and several approaches involving aryl-aryl interactions, as an increasingly popular strategy in protein and peptide engineering. A recent survey described the existence of aromatic clusters (trimer, tetramer, pentamer, and higher order assemblies), revealing the self-associating property of aryl groups, even in folded protein structures. The application of this self-assembly of aromatics in the generation of modern bionanomaterials is also discussed.
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Affiliation(s)
- Kamlesh Madhusudan Makwana
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, 462023, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, 462023, India
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40
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Bachmann SJ, van Gunsteren WF. Structural and energetic effects of the use of polarisable water to solvate proteins. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1042085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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41
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Matsumoto M, Lee SJ, Gagné MR, Waters ML. Cross-strand histidine-aromatic interactions enhance acyl-transfer rates in beta-hairpin peptide catalysts. Org Biomol Chem 2015; 12:8711-8. [PMID: 25254932 DOI: 10.1039/c4ob01754d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A reactive tagging methodology was used to select the species most reactive to an acylation reagent from a solid phase library of beta hairpin peptides. Hits bearing an electron-rich aromatic residue across strand from a reactive histidine were found to competitively become N-acylated. In addition to displaying rapid N-acylation rates the hit peptide was additionally deacylated in the presence of a nucleophile, thus closing a putative catalytic cycle. Variants of the hit peptide were studied to elucidate both the magnitude (up to 18,000-fold over background, kcat/kuncat = 94,000,000, or 45-fold over Boc-histidine methyl ester) and mechanism of acyl transfer catalysis. A combination of CH-π, cation-π and HisH(+)-O interactions in the cationic imidazole transition state is implicated in the rate acceleration, in addition to the fidelity of the beta hairpin fold. Moreover, NMR structural data on key intermediates or models thereof suggest that a key feature of this catalyst is the ability to access several different stabilizing conformations along the catalysis reaction coordinate.
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Affiliation(s)
- M Matsumoto
- Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina 27599-3290, USA.
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42
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Razavi AM, Voelz VA. Kinetic Network Models of Tryptophan Mutations in β-Hairpins Reveal the Importance of Non-Native Interactions. J Chem Theory Comput 2015; 11:2801-12. [DOI: 10.1021/acs.jctc.5b00088] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Asghar M. Razavi
- Department
of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Vincent A. Voelz
- Department
of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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43
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Kier BL, Anderson JM, Andersen NH. Disulfide-Mediated β-Strand Dimers: Hyperstable β-Sheets Lacking Tertiary Interactions and Turns. J Am Chem Soc 2015; 137:5363-71. [PMID: 25835058 PMCID: PMC7450586 DOI: 10.1021/ja5117809] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Disulfide bonds between cysteine residues are essential to the structure and folding of many proteins. Yet their role in the design of structured peptides and proteins has frequently been limited to use as intrachain covalent staples that reinforce existing structure or induce knot-like conformations. In β-hairpins, their placement at non-H-bonding positions across antiparallel strands has proven useful for achieving fully folded positive controls. Here we report a new class of designed β-sheet peptide dimers with strand-central disulfides as a key element. We have found that the mere presence of a disulfide bond near the middle of a short peptide chain is sufficient to nucleate some antiparallel β-sheet structure; addition of β-capping units and other favorable cross-strand interactions yield hyperstable sheets. Strand-central cystines were found to be superior to the best designed reversing turns in terms of nucleating β-sheet structure formation. We have explored the limitations and possibilities of this technique (the use of disulfides as sheet nucleators), and we provide a set of rules and rationales for the application and further design of disulfide-tethered "turnless" β-sheets.
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Affiliation(s)
- Brandon L Kier
- Chemistry Department, University of Washington, Seattle, Washington 98195, United States
| | - Jordan M Anderson
- Chemistry Department, University of Washington, Seattle, Washington 98195, United States
| | - Niels H Andersen
- Chemistry Department, University of Washington, Seattle, Washington 98195, United States
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44
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Makwana KM, Mahalakshmi R. NMR Analysis of Tuning Cross-Strand Phe/Tyr/Trp-Trp Interactions in Designed β-Hairpin Peptides: Terminal Switch from L to D Amino Acid as a Strategy for β-Hairpin Capping. J Phys Chem B 2015; 119:5376-85. [PMID: 25849307 DOI: 10.1021/acs.jpcb.5b00554] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Interaction among the side chains of aromatic amino acids is a well-known mechanism of protein and peptide structure stabilization, particularly in β sheets. Using short β-hairpin models bearing the sequence Ac-Leu-Xxx-Val-DPro-Gly-Leu-Trp-Val-NH2, we report the surprising observation of significant destabilization in aryl–tryptophan interactions, which results in poorly folded peptide populations accompanied by lowering of stability. We find that such destabilization arises from forced occupancy of the indole ring in the shielded Edge position, in T-shaped aryl geometries. We demonstrate that this destabilizing effect can be efficiently salvaged by replacing the N-terminal LLeu with DLeu, which causes an increase in the folded hairpin population, while retaining Trp in the Edge position. Our observation of unique cross strand NOEs and data from temperature-dependent NMR and CD measurements reveals the formation of a locally stabilized aliphatic–aromatic network, leading to an overall increase in ΔGF° by ∼ −0.6 to −1.2 kcal/mol. Our results suggest that a contextual evaluation of stabilization by tryptophan is necessary in β hairpins. Furthermore, we report for the first time that the use of D isomers of aliphatic amino acids at the terminus is stabilizing, which can serve as a new strategy for increasing β-hairpin stability.
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Affiliation(s)
- Kamlesh M Makwana
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462023, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462023, India
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45
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Chekmarev SF. Protein folding as a complex reaction: a two-component potential for the driving force of folding and its variation with folding scenario. PLoS One 2015; 10:e0121640. [PMID: 25848943 PMCID: PMC4388825 DOI: 10.1371/journal.pone.0121640] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/11/2015] [Indexed: 11/19/2022] Open
Abstract
The Helmholtz decomposition of the vector field of probability fluxes in a two-dimensional space of collective variables makes it possible to introduce a potential for the driving force of protein folding [Chekmarev, J. Chem. Phys. 139 (2013) 145103]. The potential has two components: one component (Φ) is responsible for the source and sink of the folding flow, which represent, respectively, the unfolded and native state of the protein, and the other (Ψ) accounts for the flow vorticity inherently generated at the periphery of the flow field and provides the canalization of the flow between the source and sink. Both components obey Poisson’s equations with the corresponding source/sink terms. In the present paper, we consider how the shape of the potential changes depending on the scenario of protein folding. To mimic protein folding dynamics projected onto a two-dimensional space of collective variables, the two-dimensional Müller and Brown potential is employed. Three characteristic scenarios are considered: a single pathway from the unfolded to the native state without intermediates, two parallel pathways without intermediates, and a single pathway with an off-pathway intermediate. To determine the probability fluxes, the hydrodynamic description of the folding reaction is used, in which the first-passage folding is viewed as a steady flow of the representative points of the protein from the unfolded to the native state. We show that despite the possible complexity of the folding process, the Φ-component is simple and universal in shape. The Ψ-component is more complex and reveals characteristic features of the process of folding. The present approach is potentially applicable to other complex reactions, for which the transition from the reactant to the product can be described in a space of two (collective) variables.
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Affiliation(s)
- Sergei F. Chekmarev
- Institute of Thermophysics, 630090 Novosibirsk, Russia and Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russia
- * E-mail:
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Goyal B, Patel K, Srivastava KR, Durani S. De novo design of stereochemically-bent sixteen-residue β-hairpin as a hydrolase mimic. RSC Adv 2015. [DOI: 10.1039/c5ra19015k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Stepwise design of sixteen-residue β-hairpin as a hydrolase mimic involving fold design by stereochemical mutation followed by inverse-design of sequence.
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Affiliation(s)
- Bhupesh Goyal
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai–400076
- India
| | - Kirti Patel
- 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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47
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Sivanesam K, Byrne A, Bisaglia M, Bubacco L, Andersen N. Binding Interactions of Agents That Alter α-Synuclein Aggregation. RSC Adv 2015; 5:11577-11590. [PMID: 25705374 DOI: 10.1039/c5ra00325c] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Further examination of peptides with well-folded antiparallel β strands as inhibitors of amyloid formation from α-synuclein has resulted in more potent inhibitors. Several of these had multiple Tyr residues and represent a new lead for inhibitor design by small peptides that do not divert α-synuclein to non-amyloid aggregate formation. The most potent inhibitor obtained in this study is a backbone cyclized version of a previously studied β hairpin, designated as WW2, with a cross-strand Trp/Trp cluster. The cyclization was accomplished by adding a d-Pro-l-Pro turn locus across strand termini. At a 2:1 peptide to α-synuclein ratio, cyclo-WW2 displays complete inhibition of β-structure formation. Trp-bearing antiparallel β-sheets held together by a disulphide bond are also potent inhibitors. 15N HSQC spectra of α-synuclein provided new mechanistic details. The time course of 15N HSQC spectral changes observed during β-oligomer formation has revealed which segments of the structure become part of the rigid core of an oligomer at early stages of amyloidogenesis and that the C-terminus remains fully flexible throughout the process. All of the effective peptide inhibitors display binding-associated titration shifts in 15N HSQC spectra of α-synuclein in the C-terminal Q109-E137 segment. Cyclo-WW2, the most potent inhibitor, also displays titration shifts in the G41-T54 span of α-synuclein, an additional binding site. The earliest aggregation event appears to be centered about H50 which is also a binding site for our most potent inhibitor.
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Affiliation(s)
- K Sivanesam
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - A Byrne
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - M Bisaglia
- Department of Biology, University of Padua, 35121 Padova, Italy
| | - L Bubacco
- Department of Biology, University of Padua, 35121 Padova, Italy
| | - N Andersen
- Department of Chemistry, University of Washington, Seattle, WA 98195
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48
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An improved capping unit for stabilizing the ends of associated β-strands. FEBS Lett 2014; 588:4749-53. [PMID: 25451230 DOI: 10.1016/j.febslet.2014.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 10/14/2014] [Accepted: 11/06/2014] [Indexed: 12/25/2022]
Abstract
Understanding protein beta structures has been hindered by the challenge of designing small, well-folded β-sheet systems. A β-capping motif was previously designed to help solve this problem, but not without limitations, as the termini of this β-cap were not fully available for chain extension. Combining Coulombic side chain attractions with a Trp/Trp edge-to-face interaction we produced a new capping motif that provided greater β-sheet stability. This stability was maintained even in systems lacking a turn locus with a high propensity for chain direction reversal. The Coulombic cap was shown to improve β-sheet stability in a number of difficult systems, hence providing an additional tool for protein structure and folding studies.
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49
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Yu Z, Selvam S, Mao H. Intermediates Stabilized by Tryptophan Pairs Exist in Trpzip Beta-Hairpins. Biochemistry 2014; 53:5978-86. [DOI: 10.1021/bi500194g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Zhongbo Yu
- Department
of Chemistry and
Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Sangeetha Selvam
- Department
of Chemistry and
Biochemistry, Kent State University, Kent, Ohio 44242, United States
| | - Hanbin Mao
- Department
of Chemistry and
Biochemistry, Kent State University, Kent, Ohio 44242, United States
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50
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Kier BL, Andersen NH. Captides: rigid junctions between beta sheets and small molecules. J Pept Sci 2014; 20:704-15. [PMID: 24909552 DOI: 10.1002/psc.2657] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/29/2014] [Accepted: 04/30/2014] [Indexed: 12/15/2022]
Abstract
An extensive series of covalently linked small molecule-peptide adducts based on a terminally capped-beta hairpin motif is reported. The constructs can be prepared by standard solid-phase Fmoc chemistry with one to four peptide chains linked to small molecule hubs bearing carboxylic acid moieties. The key feature of interest is the precise, buried environment of the small molecule, and its rigid orientation relative to one or more short but fully structured peptide chain(s). Most of this study employs a minimalist nine residue 'captide', a capped β-turn, but we illustrate general applicability to peptides which can terminate in a beta strand. The non-peptide portion of these adducts can include nearly any molecule bearing one or more carboxylic acid groups. Fold-dependent rigidity sets this strategy apart from the currently available bioconjugation methods, which typically engender significant flexibility between peptide and tag. Applications to catalyst enhancement, drug design, higher-order assembly, and FRET calibration rulers are discussed.
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Affiliation(s)
- Brandon L Kier
- University of Washington - Chemistry, Bagley Hall Room 205 Box 351700, Seattle, WA, 98195-1700, USA
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