1
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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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2
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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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3
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Palazzesi F, Valsson O, Parrinello M. Conformational Entropy as Collective Variable for Proteins. J Phys Chem Lett 2017; 8:4752-4756. [PMID: 28906117 DOI: 10.1021/acs.jpclett.7b01770] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Many enhanced sampling methods rely on the identification of appropriate collective variables. For proteins, even small ones, finding appropriate descriptors has proven challenging. Here we suggest that the NMR S2 order parameter can be used to this effect. We trace the validity of this statement to the suggested relation between S2 and conformational entropy. Using the S2 order parameter and a surrogate for the protein enthalpy in conjunction with metadynamics or variationally enhanced sampling, we are able to reversibly fold and unfold a small protein and draw its free energy at a fraction of the time that is needed in unbiased simulations. We also use S2 in combination with the free energy flooding method to compute the unfolding rate of this peptide. We repeat this calculation at different temperatures to obtain the unfolding activation energy.
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Affiliation(s)
- Ferruccio Palazzesi
- Department of Chemistry and Applied Biosciences, ETH Zurich c/o USI Campus , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
- Facoltà di Informatica, Instituto di Scienze Computationali, Università della Svizzera italiana , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
| | - Omar Valsson
- Department of Chemistry and Applied Biosciences, ETH Zurich c/o USI Campus , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
- Facoltà di Informatica, Instituto di Scienze Computationali, Università della Svizzera italiana , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
- National Center for Computational Design and Discovery of Novel Materials MARVEL, Università della Svizzera italiana , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
| | - Michele Parrinello
- Department of Chemistry and Applied Biosciences, ETH Zurich c/o USI Campus , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
- Facoltà di Informatica, Instituto di Scienze Computationali, Università della Svizzera italiana , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
- National Center for Computational Design and Discovery of Novel Materials MARVEL, Università della Svizzera italiana , Via Giuseppe Buffi 13, CH-6900, Lugano, Switzerland
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4
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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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5
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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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6
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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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7
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Long range Trp-Trp interaction initiates the folding pathway of a pro-angiogenic β-hairpin peptide. Sci Rep 2015; 5:16651. [PMID: 26602442 PMCID: PMC4658480 DOI: 10.1038/srep16651] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/16/2015] [Indexed: 01/06/2023] Open
Abstract
HPLW, a designed VEGF (Vascular Endothelium Growth Factor) receptor-binding peptide, assumes a well folded β-hairpin conformation in water and is able to induce angiogenesis in vivo. In this study, we investigated at atomic resolution the thermal folding/unfolding pathway of HPLW by means of an original multi-technique approach combining DSC, NMR, MD and mutagenesis analyses. In particular, careful NMR investigation of the single proton melting temperatures together with DSC analysis accurately delineate the peptide folding mechanism, which is corroborated by computational folding/unfolding simulations. The HPLW folding process consists of two main events, which are successive but do not superimpose. The first folding step initiates at 320 K upon the hydrophobic collapse of the Trp5 and Trp13 side-chains which stabilizes the concurrent β-turn formation, whose COi-HNi + 3 hydrogen bond (Asp10 → Arg7) appears particularly stable. At 316 K, once the β-turn is completely formed, the two β-strands pair, very likely starting by Trp5 and Trp13, which thus play a key role also in the final step of the β-hairpin folding. Overall, here we describe a multi-state hierarchical folding pathway of a highly structured β-hairpin, which can be classified as a broken-zipper mechanism.
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8
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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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9
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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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10
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Byrne A, Williams DV, Barua B, Hagen SJ, Kier BL, Andersen NH. Folding dynamics and pathways of the trp-cage miniproteins. Biochemistry 2014; 53:6011-21. [PMID: 25184759 PMCID: PMC4179588 DOI: 10.1021/bi501021r] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Using alternate measures of fold stability for a wide variety of Trp-cage mutants has raised the possibility that prior dynamics T-jump measures may not be reporting on complete cage formation for some species. NMR relaxation studies using probes that only achieve large chemical shift difference from unfolded values on complete cage formation indicate slower folding in some but not all cases. Fourteen species have been examined, with cage formation time constants (1/kF) ranging from 0.9-7.5 μs at 300 K. The present study does not change the status of the Trp-cage as a fast folding, essentially two-state system, although it does alter the stage at which this description applies. A diversity of prestructuring events, depending on the specific analogue examined, may appear in the folding scenario, but in all cases, formation of the N-terminal helix is complete either at or before the cage-formation transition state. In contrast, the fold-stabilizing H-bonding interactions of the buried Ser14 side chain and the Arg/Asp salt bridge are post-transition state features on the folding pathway. The study has also found instances in which a [P12W] mutation is fold destabilizing but still serves to accelerate the folding process.
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Affiliation(s)
- Aimee Byrne
- Department of Chemistry, University of Washington , Seattle, Washington 98195, United States
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11
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González-Charro V, Rey A. Intermediates in the folding equilibrium of repeat proteins from the TPR family. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:433-43. [DOI: 10.1007/s00249-014-0975-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/20/2014] [Accepted: 07/03/2014] [Indexed: 11/29/2022]
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12
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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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13
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Kier BL, Anderson JM, Andersen NH. Circular permutation of a WW domain: folding still occurs after excising the turn of the folding-nucleating hairpin. J Am Chem Soc 2014; 136:741-9. [PMID: 24350581 PMCID: PMC4051316 DOI: 10.1021/ja410824x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A hyperstable Pin1 WW domain has been circularly permuted via excision of the fold-nucleating turn; it still folds to form the native three-strand sheet and hydrophobic core features. Multiprobe folding dynamics studies of the normal and circularly permuted sequences, as well as their constituent hairpin fragments and comparable-length β-strand-loop-β-strand models, indicate 2-state folding for all topologies. N-terminal hairpin formation is the fold nucleating event for the wild-type sequence; the slower folding circular permutant has a more distributed folding transition state.
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Affiliation(s)
- Brandon L. Kier
- 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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14
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Abstract
Since the first report in 1993 (JACS 115, 5887-5888) of a peptide able to form a monomeric β-hairpin structure in aqueous solution, the design of peptides forming either β-hairpins (two-stranded antiparallel β-sheets) or three-stranded antiparallel β-sheets has become a field of growing interest and activity. These studies have yielded great insights into the principles governing the stability and folding of β-hairpins and antiparallel β-sheets. This chapter provides an overview of the reported β-hairpin/β-sheet peptides focussed on the applied design criteria, reviews briefly the factors contributing to β-hairpin/β-sheet stability, and describes a protocol for the de novo design of β-sheet-forming peptides based on them. Guidelines to select appropriate turn and strand residues and to avoid self-association are provided. The methods employed to check the success of new designed peptides are also summarized. Since NMR is the best technique to that end, NOEs and chemical shifts characteristic of β-hairpins and three-stranded antiparallel β-sheets are given.
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Affiliation(s)
- M Angeles Jiménez
- Consejo Superior de Investigaciones Científicas (CSIC), Instituto de Química Física Rocasolano (IQFR), Serrano 119, 28006, Madrid, Spain,
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