1
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Synakewicz M, Eapen RS, Perez-Riba A, Rowling PJE, Bauer D, Weißl A, Fischer G, Hyvönen M, Rief M, Itzhaki LS, Stigler J. Unraveling the Mechanics of a Repeat-Protein Nanospring: From Folding of Individual Repeats to Fluctuations of the Superhelix. ACS NANO 2022. [PMID: 35258937 DOI: 10.1101/2021.03.27.437344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Tandem-repeat proteins comprise small secondary structure motifs that stack to form one-dimensional arrays with distinctive mechanical properties that are proposed to direct their cellular functions. Here, we use single-molecule optical tweezers to study the folding of consensus-designed tetratricopeptide repeats (CTPRs), superhelical arrays of short helix-turn-helix motifs. We find that CTPRs display a spring-like mechanical response in which individual repeats undergo rapid equilibrium fluctuations between partially folded and unfolded conformations. We rationalize the force response using Ising models and dissect the folding pathway of CTPRs under mechanical load, revealing how the repeat arrays form from the center toward both termini simultaneously. Most strikingly, we also directly observe the protein's superhelical tertiary structure in the force signal. Using protein engineering, crystallography, and single-molecule experiments, we show that the superhelical geometry can be altered by carefully placed amino acid substitutions, and we examine how these sequence changes affect intrinsic repeat stability and inter-repeat coupling. Our findings provide the means to dissect and modulate repeat-protein stability and dynamics, which will be essential for researchers to understand the function of natural repeat proteins and to exploit artificial repeats proteins in nanotechnology and biomedical applications.
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Affiliation(s)
- Marie Synakewicz
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Rohan S Eapen
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Albert Perez-Riba
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Pamela J E Rowling
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Daniela Bauer
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Andreas Weißl
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Gerhard Fischer
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Marko Hyvönen
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Matthias Rief
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Laura S Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom†
| | - Johannes Stigler
- Gene Center Munich, Ludwig-Maximilians-Universität München, Feodor-Lynen-Straße 25, 81377 München, Germany
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2
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Synakewicz M, Eapen RS, Perez-Riba A, Rowling PJE, Bauer D, Weißl A, Fischer G, Hyvönen M, Rief M, Itzhaki LS, Stigler J. Unraveling the Mechanics of a Repeat-Protein Nanospring: From Folding of Individual Repeats to Fluctuations of the Superhelix. ACS NANO 2022; 16:3895-3905. [PMID: 35258937 PMCID: PMC8944806 DOI: 10.1021/acsnano.1c09162] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Tandem-repeat proteins comprise small secondary structure motifs that stack to form one-dimensional arrays with distinctive mechanical properties that are proposed to direct their cellular functions. Here, we use single-molecule optical tweezers to study the folding of consensus-designed tetratricopeptide repeats (CTPRs), superhelical arrays of short helix-turn-helix motifs. We find that CTPRs display a spring-like mechanical response in which individual repeats undergo rapid equilibrium fluctuations between partially folded and unfolded conformations. We rationalize the force response using Ising models and dissect the folding pathway of CTPRs under mechanical load, revealing how the repeat arrays form from the center toward both termini simultaneously. Most strikingly, we also directly observe the protein's superhelical tertiary structure in the force signal. Using protein engineering, crystallography, and single-molecule experiments, we show that the superhelical geometry can be altered by carefully placed amino acid substitutions, and we examine how these sequence changes affect intrinsic repeat stability and inter-repeat coupling. Our findings provide the means to dissect and modulate repeat-protein stability and dynamics, which will be essential for researchers to understand the function of natural repeat proteins and to exploit artificial repeats proteins in nanotechnology and biomedical applications.
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Affiliation(s)
- Marie Synakewicz
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Rohan S. Eapen
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Albert Perez-Riba
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Pamela J. E. Rowling
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Daniela Bauer
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Andreas Weißl
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Gerhard Fischer
- Department
of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Marko Hyvönen
- Department
of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom
| | - Matthias Rief
- Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
| | - Laura S. Itzhaki
- Department
of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Johannes Stigler
- Gene
Center Munich, Ludwig-Maximilians-Universität
München, Feodor-Lynen-Straße 25, 81377 München, Germany
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3
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Chang MP, Huang W, Mai DJ. Monomer‐scale design of functional protein polymers using consensus repeat sequences. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Marina P. Chang
- Department of Materials Science and Engineering Stanford University Stanford California USA
| | - Winnie Huang
- Department of Chemical Engineering Stanford University Stanford California USA
| | - Danielle J. Mai
- Department of Chemical Engineering Stanford University Stanford California USA
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4
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Madden SK, Itzhaki LS. Exploring the binding of rationally engineered tandem-repeat proteins to E3 ubiquitin ligase Keap1. Protein Eng Des Sel 2021; 34:gzab027. [PMID: 34882773 PMCID: PMC8660007 DOI: 10.1093/protein/gzab027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 09/06/2021] [Accepted: 10/04/2021] [Indexed: 11/12/2022] Open
Abstract
The process of displaying functional peptides by 'grafting' them onto loops of a stable protein scaffold can be used to impart binding affinity for a target, but it can be difficult to predict the affinity of the grafted peptide and the effect of grafting on scaffold stability. In this study, we show that a series of peptides that bind to the E3 ubiquitin ligase Keap1 can be grafted into the inter-repeat loop of a consensus-designed tetratricopeptide repeat (CTPR) protein resulting in proteins with high stability. We found that these CTPR-grafted peptides had similar affinities to their free peptide counterparts and achieved a low nanomolar range. This result is likely due to a good structural match between the inter-repeat loop of the CTPR and the Keap1-binding peptide. The grafting process led to the discovery of a new Keap1-binding peptide, Ac-LDPETGELL-NH2, with low nanomolar affinity for Keap1, highlighting the potential of the repeat-protein class for application in peptide display.
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Affiliation(s)
- Sarah K Madden
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Laura S Itzhaki
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
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5
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Diamante A, Chaturbedy PK, Rowling PJE, Kumita JR, Eapen RS, McLaughlin SH, de la Roche M, Perez-Riba A, Itzhaki LS. Engineering mono- and multi-valent inhibitors on a modular scaffold. Chem Sci 2021; 12:880-895. [PMID: 33623657 PMCID: PMC7885266 DOI: 10.1039/d0sc03175e] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022] Open
Abstract
Here we exploit the simple, ultra-stable, modular architecture of consensus-designed tetratricopeptide repeat proteins (CTPRs) to create a platform capable of displaying both single as well as multiple functions and with diverse programmable geometrical arrangements by grafting non-helical short linear binding motifs (SLiMs) onto the loops between adjacent repeats. As proof of concept, we built synthetic CTPRs to bind and inhibit the human tankyrase proteins (hTNKS), which play a key role in Wnt signaling and are upregulated in cancer. A series of mono-valent and multi-valent hTNKS binders was assembled. To fully exploit the modular scaffold and to further diversify the multi-valent geometry, we engineered the binding modules with two different formats, one monomeric and the other trimeric. We show that the designed proteins are stable, correctly folded and capable of binding to and inhibiting the cellular activity of hTNKS leading to downregulation of the Wnt pathway. Multivalency in both the CTPR protein arrays and the hTNKS target results in the formation of large macromolecular assemblies, which can be visualized both in vitro and in the cell. When delivered into the cell by nanoparticle encapsulation, the multivalent CTPR proteins displayed exceptional activity. They are able to inhibit Wnt signaling where small molecule inhibitors have failed to date. Our results point to the tremendous potential of the CTPR platform to exploit a range of SLiMs and assemble synthetic binding molecules with built-in multivalent capabilities and precise, pre-programmed geometries.
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Affiliation(s)
- Aurora Diamante
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
| | - Piyush K Chaturbedy
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
| | - Pamela J E Rowling
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
| | - Janet R Kumita
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
| | - Rohan S Eapen
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
| | - Stephen H McLaughlin
- MRC Laboratory of Molecular Biology , Francis Crick Avenue , Cambridge Biomedical Campus , Cambridge , CB2 0QH , UK
| | - Marc de la Roche
- Department of Biochemistry , University of Cambridge , Tennis Court Road , Cambridge CB2 1GA , UK
| | - Albert Perez-Riba
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
| | - Laura S Itzhaki
- Department of Pharmacology , University of Cambridge , Tennis Court Road , Cambridge CB2 1PD , UK . ;
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6
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Ripka JF, Perez-Riba A, Chaturbedy PK, Itzhaki LS. Testing the length limit of loop grafting in a helical repeat protein. Curr Res Struct Biol 2020; 3:30-40. [PMID: 34235484 PMCID: PMC8244534 DOI: 10.1016/j.crstbi.2020.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/13/2020] [Accepted: 12/02/2020] [Indexed: 11/19/2022] Open
Abstract
Alpha-helical repeat proteins such as consensus-designed tetratricopeptide repeats (CTPRs) are exceptionally stable molecules that are able to tolerate destabilizing sequence alterations and are therefore becoming increasingly valued as a modular platform for biotechnology and biotherapeutic applications. A simple approach to functionalize the CTPR scaffold that we are pioneering is the insertion of short linear motifs (SLiMs) into the loops between adjacent repeats. Here, we test the limits of the scaffold by inserting 17 highly diverse amino acid sequences of up to 58 amino acids in length into a two-repeat protein and examine the impact on protein folding, stability and solubility. The sequences include three SLiMs that bind oncoproteins and eleven naturally occurring linker sequences all predicted to be intrinsically disordered but with conformational preferences ranging from compact globules to expanded coils. We show that the loop-grafted proteins retain the native CTPR structure and are thermally stable with melting temperatures above 60 °C, despite the longest loop sequence being almost the same size as the CTPR scaffold itself (68 amino acids). Although the main determinant of the effect of stability was found to be loop length and was relatively insensitive to amino acid composition, the relationship between protein solubility and the loop sequences was more complex, with the presence of negatively charged amino acids enhancing the solubility. Our findings will help us to fully realize the potential of the repeat-protein scaffold, allowing a rational design approach to create artificial modular proteins with customized functional capabilities.
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Key Words
- CD, circular dichroism
- CTPRs, consensus-designed tetratricopeptide repeats
- FCR, fraction of charged residues
- IDPs, intrinsically disordered proteins
- IDRs, intrinsically disordered regions
- Intrinsically disordered protein
- Intrinsically disordered region
- NCPR, net charge per residue
- PBIP1, polo-box interacting protein 1
- Peptide grafting
- SLiMs, short linear motifs
- TBP, tankyrase-binding peptides
- Tandem-repeat protein
- Tetratricopeptide repeat
- ves, effective solvation volume
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Affiliation(s)
- Juliane F. Ripka
- Department of Pharmacology University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | | | - Piyush K. Chaturbedy
- Department of Pharmacology University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Laura S. Itzhaki
- Department of Pharmacology University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
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7
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Perez-Riba A, Komives E, Main ERG, Itzhaki LS. Decoupling a tandem-repeat protein: Impact of multiple loop insertions on a modular scaffold. Sci Rep 2019; 9:15439. [PMID: 31659184 PMCID: PMC6817815 DOI: 10.1038/s41598-019-49905-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 08/29/2019] [Indexed: 11/25/2022] Open
Abstract
The simple topology and modular architecture of tandem-repeat proteins such as tetratricopeptide repeats (TPRs) and ankyrin repeats makes them straightforward to dissect and redesign. Repeat-protein stability can be manipulated in a predictable way using site-specific mutations. Here we explore a different type of modification - loop insertion - that will enable a simple route to functionalisation of this versatile scaffold. We previously showed that a single loop insertion has a dramatically different effect on stability depending on its location in the repeat array. Here we dissect this effect by a combination of multiple and alternated loop insertions to understand the origins of the context-dependent loss in stability. We find that the scaffold is remarkably robust in that its overall structure is maintained. However, adjacent repeats are now only weakly coupled, and consequently the increase in solvent protection, and thus stability, with increasing repeat number that defines the tandem-repeat protein class is lost. Our results also provide us with a rulebook with which we can apply these principles to the design of artificial repeat proteins with precisely tuned folding landscapes and functional capabilities, thereby paving the way for their exploitation as a versatile and truly modular platform in synthetic biology.
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Affiliation(s)
- Albert Perez-Riba
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
- Donnelly Centre for Cellular & Biomolecular Research, University of Toronto, Toronto, Canada
| | - Elizabeth Komives
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0378, USA
| | - Ewan R G Main
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Laura S Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.
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8
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Bioorthogonal protein-DNA conjugation methods for force spectroscopy. Sci Rep 2019; 9:13820. [PMID: 31554828 PMCID: PMC6761116 DOI: 10.1038/s41598-019-49843-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/24/2019] [Indexed: 12/17/2022] Open
Abstract
Accurate and stable site-specific attachment of DNA molecules to proteins is a requirement for many single-molecule force spectroscopy techniques. The most commonly used method still relies on maleimide chemistry involving cysteine residues in the protein of interest. Studies have consequently often focused on model proteins that either have no cysteines or with a small number of cysteines that can be deleted so that cysteines can then be introduced at specific sites. However, many proteins, especially in eukaryotes, contain too many cysteine residues to be amenable to this strategy, and therefore there is tremendous need for new and broadly applicable approaches to site-specific conjugation. Here we present bioorthogonal approaches for making DNA-protein conjugates required in force spectroscopy experiments. Unnatural amino acids are introduced site-specifically and conjugated to DNA oligos bearing the respective modifications to undergo either strain-promoted azidealkyne cycloaddition (SPAAC) or inverse-electron-demand Diels-Alder (IE-DA) reactions. We furthermore show that SPAAC is compatible with a previously published peptide-based attachment approach. By expanding the available toolkit to tag-free methods based on bioorthogonal reactions, we hope to enable researchers to interrogate the mechanics of a much broader range of proteins than is currently possible.
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9
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Madden SK, Perez‐Riba A, Itzhaki LS. Exploring new strategies for grafting binding peptides onto protein loops using a consensus-designed tetratricopeptide repeat scaffold. Protein Sci 2019; 28:738-745. [PMID: 30746804 PMCID: PMC6423998 DOI: 10.1002/pro.3586] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 12/27/2022]
Abstract
Peptide display approaches, in which peptide epitopes of known binding activities are grafted onto stable protein scaffolds, have been developed to constrain the peptide in its bioactive conformation and to enhance its stability. However, peptide grafting can be a lengthy process requiring extensive computational modeling and/or optimisation by directed evolution techniques. In this study, we show that ultra-stable consensus-designed tetratricopeptide repeat (CTPR) proteins are amenable to the grafting of peptides that bind the Kelch-like ECH-associated protein 1 (Keap1) onto the loop between adjacent repeats. We explore simple strategies to optimize the grafting process and show that modest improvements in Keap1-binding affinity can be obtained by changing the composition of the linker sequence flanking either side of the binding peptide.
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Affiliation(s)
- Sarah K. Madden
- Department of PharmacologyUniversity of CambridgeCambridgeUnited Kingdom
| | - Albert Perez‐Riba
- Department of PharmacologyUniversity of CambridgeCambridgeUnited Kingdom
- Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Laura S. Itzhaki
- Department of PharmacologyUniversity of CambridgeCambridgeUnited Kingdom
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