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Lindner C, Friemel A, Schwegler N, Timmermann L, Pham TL, Reusche V, Kovermann M, Thomas F. Thermostable WW-Domain Scaffold to Design Functional β-Sheet Miniproteins. J Am Chem Soc 2024. [PMID: 38853610 DOI: 10.1021/jacs.4c03498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
There has been a recent surge in the design of miniproteins for medicinal chemistry, biomaterial design, or synthetic biology. In particular, there is an interest in peptide scaffolds that fold reliably, predictably, and with solid stability. In this article, we present the design of a highly thermostable WW domain, a three-stranded β-sheet motif, with a superior melting temperature of about 90 °C to serve as a core scaffold onto which receptor-like properties can be grafted. We have performed specific rounds of sequence iteration on a WW-domain consensus sequence to decipher sequence positions that affect structural and, thus, thermal stability. We identified a sequence-structure relationship that yields a highly thermostable WW-domain scaffold. High-resolution NMR spectroscopy was applied, which enabled the identification of structural features at the atomic scale that contribute to this high thermostability. Finally, we grafted the binding motifs of the three WW-domain groups─Group I, Group II/III, and Group IV─and organophosphate and metal binding onto the highly thermostable WW-domain scaffold and obtained thermostable de novo WW domains that indeed display the different binding modes that were intended. The organophosphate-binding WW domains exhibit melting temperatures that are up to 34 K higher than previously reported top-down designs. These results impressively demonstrate that the highly thermostable WW-domain core scaffold is a solid platform for the design of discrete and reliably folding functional β-sheet peptide miniproteins, providing an essential addition to the toolbox of peptide scaffolds previously used in synthetic biology and material design.
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Affiliation(s)
- Christina Lindner
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Anke Friemel
- Physical Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Niklas Schwegler
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
- Institute for Molecular Systems Engineering and Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
| | - Lisa Timmermann
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Truc Lam Pham
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Vanessa Reusche
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Michael Kovermann
- Physical Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Franziska Thomas
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
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2
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Pham TL, Thomas F. Design of Functional Globular β-Sheet Miniproteins. Chembiochem 2024; 25:e202300745. [PMID: 38275210 DOI: 10.1002/cbic.202300745] [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: 10/31/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 01/27/2024]
Abstract
The design of discrete β-sheet peptides is far less advanced than e. g. the design of α-helical peptides. The reputation of β-sheet peptides as being poorly soluble and aggregation-prone often hinders active design efforts. Here, we show that this reputation is unfounded. We demonstrate this by looking at the β-hairpin and WW domain. Their structure and folding have been extensively studied and they have long served as model systems to investigate protein folding and folding kinetics. The resulting fundamental understanding has led to the development of hyperstable β-sheet scaffolds that fold at temperatures of 100 °C or high concentrations of denaturants. These have been used to design functional miniproteins with protein or nucleic acid binding properties, in some cases with such success that medical applications are conceivable. The β-sheet scaffolds are not always completely rigid, but can be specifically designed to respond to changes in pH, redox potential or presence of metal ions. Some engineered β-sheet peptides also exhibit catalytic properties, although not comparable to those of natural proteins. Previous reviews have focused on the design of stably folded and non-aggregating β-sheet sequences. In our review, we now also address design strategies to obtain functional miniproteins from β-sheet folding motifs.
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Affiliation(s)
- Truc Lam Pham
- Truc Lam Pham, Prof. Dr. Franziska Thomas, Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Franziska Thomas
- Truc Lam Pham, Prof. Dr. Franziska Thomas, Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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3
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Pham TL, Fazliev S, Baur P, Comba P, Thomas F. An Engineered β-Hairpin Peptide Forming Thermostable Complexes with Zn II , Ni II , and Cu II through a His 3 Site. Chembiochem 2023; 24:e202200588. [PMID: 36445805 PMCID: PMC10107957 DOI: 10.1002/cbic.202200588] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 11/30/2022]
Abstract
The three-dimensional structure of a peptide, which determines its function, can denature at elevated temperatures, in the presence of chaotropic reagents, or in organic solvents. These factors limit the applicability of peptides. Herein, we present an engineered β-hairpin peptide containing a His3 site that forms complexes with ZnII , NiII , and CuII . Circular dichroism spectroscopy shows that the peptide-metal complexes exhibit melting temperatures up to 80 °C and remain folded in 6 M guanidine hydrochloride as well as in organic solvents. Intrinsic fluorescence titration experiments were used to determine the dissociation constants of metal binding in the nano- to sub-nanomolar range. The coordination geometry of the peptide-CuII complex was studied by EPR spectroscopy, and a distorted square planar coordination geometry with weak interactions to axial ligands was revealed. Due to their impressive stability, the presented peptide-metal complexes open up interesting fields of application, such as the development of a new class of peptide-metal catalysts for stereoselective organic synthesis or the directed design of extremophilic β-sheet peptides.
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Affiliation(s)
- Truc Lam Pham
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Sunnatullo Fazliev
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.,Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Philipp Baur
- Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Peter Comba
- Institute of Inorganic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Franziska Thomas
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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Abstract
The natural function of many proteins depends on their ability to switch their conformation driven by environmental changes. In this work, we present a small, monomeric β-sheet peptide that switches between a molten globule and a folded state through Zn(II) binding. The solvent-exposed hydrophobic core on the β-sheet surface was substituted by a His3-site, whereas the internal hydrophobic core was left intact. Zn(II) is specifically recognized by the peptide relative to other divalent metal ions, binds in the lower micromolar range, and can be removed and re-added without denaturation of the peptide. In addition, the peptide is fully pH-switchable, has a pKa of about 6, and survives several cycles of acidification and neutralization. In-depth structural characterization of the switch was achieved by concerted application of circular dichroism (CD) and multinuclear NMR spectroscopy. Thus, this study represents a viable approach toward a globular β-sheet Zn(II) mini-receptor prototype.
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Affiliation(s)
- Truc Lam Pham
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
- Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
| | - Michael Kovermann
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Franziska Thomas
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
- Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
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5
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Neitz H, Paul NB, Häge FR, Lindner C, Graebner R, Kovermann M, Thomas F. Identification of novel functional mini-receptors by combinatorial screening of split-WW domains. Chem Sci 2022; 13:9079-9090. [PMID: 36091217 PMCID: PMC9365081 DOI: 10.1039/d2sc01078j] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 07/14/2022] [Indexed: 11/21/2022] Open
Abstract
A combinatorial approach toward novel functional WW domains based on coiled-coil-mediated reconstitution of split WW domains is presented. As such, an ATP-binding WW domain was found from a 4-by-6 library of N- and C-terminal WW domain fragments.
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Affiliation(s)
- Hermann Neitz
- Institute of Organic Chemistry, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Niels Benjamin Paul
- Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstr. 2, Göttingen 37077, Germany
| | - Florian R. Häge
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, Heidelberg 69120, Germany
- Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
| | - Christina Lindner
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, Heidelberg 69120, Germany
- Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
| | - Roman Graebner
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, Heidelberg 69120, Germany
- Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
| | - Michael Kovermann
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, Konstanz 78457, Germany
| | - Franziska Thomas
- Institute of Organic Chemistry, Heidelberg University, Im Neuenheimer Feld 270, Heidelberg 69120, Germany
- Centre for Advanced Materials, Heidelberg University, Im Neuenheimer Feld 225, Heidelberg 69120, Germany
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Graham KA, Byrne A, Mason M, Andersen NH. Optimizing the fold stability of the circularly permuted Trp-cage motif. Biopolymers 2019; 110:e23327. [PMID: 31479150 DOI: 10.1002/bip.23327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/11/2019] [Accepted: 08/13/2019] [Indexed: 11/09/2022]
Abstract
Through optimization of the linker region and key stabilizing mutations, it has been possible to improve the stability of the circularly permuted (cp) Trp-cage miniprotein. However, even the most stable Trp-cage circular permutants are still less stable than the analogous standard topology (std) Trp-cages. Extending mutational studies of Trp-cage fold stability to cp-species, including analogs lacking chain terminal charges, has uncovered and quantitated some additional stabilizing and destabilizing interactions. Upon protonation, the circular permutants are destabilized to a much greater extent than the standard topology series. End effects, particularly Coulombic interactions, appear to be more important for the cp-series while the Y10/P4 interaction in the cp-series is not as significant a stabilizing feature as the corresponding Y3/P19 in the standard topology series.
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Affiliation(s)
- Katherine A Graham
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Aimee Byrne
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Micheal Mason
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Niels H Andersen
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
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7
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Investigating the Effect of Chain Connectivity on the Folding of a Beta-Sheet Protein On and Off the Ribosome. J Mol Biol 2018; 430:5207-5216. [PMID: 30365950 PMCID: PMC6288478 DOI: 10.1016/j.jmb.2018.10.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 09/11/2018] [Accepted: 10/16/2018] [Indexed: 11/21/2022]
Abstract
Determining the relationship between protein folding pathways on and off the ribosome remains an important area of investigation in biology. Studies on isolated domains have shown that alteration of the separation of residues in a polypeptide chain, while maintaining their spatial contacts, may affect protein stability and folding pathway. Due to the vectorial emergence of the polypeptide chain from the ribosome, chain connectivity may have an important influence upon cotranslational folding. Using MATH, an all β-sandwich domain, we investigate whether the connectivity of residues and secondary structure elements is a key determinant of when cotranslational folding can occur on the ribosome. From Φ-value analysis, we show that the most structured region of the transition state for folding in MATH includes the N and C terminal strands, which are located adjacent to each other in the structure. However, arrest peptide force-profile assays show that wild-type MATH is able to fold cotranslationally, while some C-terminal residues remain sequestered in the ribosome, even when destabilized by 2–3 kcal mol−1. We show that, while this pattern of Φ-values is retained in two circular permutants in our studies of the isolated domains, one of these permutants can fold only when fully emerged from the ribosome. We propose that in the case of MATH, onset of cotranslational folding is determined by the ability to form a sufficiently stable folding nucleus involving both β-sheets, rather than by the location of the terminal strands in the ribosome tunnel. Adjacent N and C terminal strands are most structured region in the transition state. Two circular permutants retain the same folding pathway as wild-type MATH. On the ribosome, early emergence of terminal strands does not promote earlier folding. Formation of both β-sheets is energetically critical for folding on the ribosome. Folding pathway minimizes formation of partly structured states prone to mis-folding.
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8
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Anderson JM, Andersen NH. A pH Switch for β-Sheet Protein Folding. Angew Chem Int Ed Engl 2017; 56:7074-7077. [PMID: 28523654 PMCID: PMC5607017 DOI: 10.1002/anie.201700860] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/26/2017] [Indexed: 01/24/2023]
Abstract
Protein design advancements have led to biotechnological strategies based on more stable and more specific structures. Herein we present a 6-residue sequence (HPATGK) that acts as a stable structure-nucleating turn at physiological and higher pH but is notably unfavorable for chain direction reversal at low pH. When placed into the turn of a β-sheet, this leads to a pH switch of folding. Using a standard 3-stranded β-sheet model, the WW domain, it was found that the pH switch sequence insertion caused minimal change at pH 8 but a ca. 50 °C drop in the melting temperature (Tm ) was observed at pH 2.5: ΔΔGF ≥11.3 kJ mol-1 . Using the strategies demonstrated in this article, the redesign of β-sheets to contain a global, or local, pH-dependent conformational switch should be possible.
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9
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A pH Switch for β-Sheet Protein Folding. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201700860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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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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11
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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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12
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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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13
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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: 19] [Impact Index Per Article: 2.1] [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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14
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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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15
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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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