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Bakker MJ, Gaffour A, Juhás M, Zapletal V, Stošek J, Bratholm LA, Pavlíková Přecechtělová J. Streamlining NMR Chemical Shift Predictions for Intrinsically Disordered Proteins: Design of Ensembles with Dimensionality Reduction and Clustering. J Chem Inf Model 2024; 64:6542-6556. [PMID: 39099394 DOI: 10.1021/acs.jcim.4c00809] [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: 08/06/2024]
Abstract
By merging advanced dimensionality reduction (DR) and clustering algorithm (CA) techniques, our study advances the sampling procedure for predicting NMR chemical shifts (CS) in intrinsically disordered proteins (IDPs), making a significant leap forward in the field of protein analysis/modeling. We enhance NMR CS sampling by generating clustered ensembles that accurately reflect the different properties and phenomena encapsulated by the IDP trajectories. This investigation critically assessed different rapid CS predictors, both neural network (e.g., Sparta+ and ShiftX2) and database-driven (ProCS-15), and highlighted the need for more advanced quantum calculations and the subsequent need for more tractable-sized conformational ensembles. Although neural network CS predictors outperformed ProCS-15 for all atoms, all tools showed poor agreement with HN CSs, and the neural network CS predictors were unable to capture the influence of phosphorylated residues, highly relevant for IDPs. This study also addressed the limitations of using direct clustering with collective variables, such as the widespread implementation of the GROMOS algorithm. Clustered ensembles (CEs) produced by this algorithm showed poor performance with chemical shifts compared to sequential ensembles (SEs) of similar size. Instead, we implement a multiscale DR and CA approach and explore the challenges and limitations of applying these algorithms to obtain more robust and tractable CEs. The novel feature of this investigation is the use of solvent-accessible surface area (SASA) as one of the fingerprints for DR alongside previously investigated α carbon distance/angles or ϕ/ψ dihedral angles. The ensembles produced with SASA tSNE DR produced CEs better aligned with the experimental CS of between 0.17 and 0.36 r2 (0.18-0.26 ppm) depending on the system and replicate. Furthermore, this technique produced CEs with better agreement than traditional SEs in 85.7% of all ensemble sizes. This study investigates the quality of ensembles produced based on different input features, comparing latent spaces produced by linear vs nonlinear DR techniques and a novel integrated silhouette score scanning protocol for tSNE DR.
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Affiliation(s)
- Michael J Bakker
- Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203/8, 500 05 Hradec Králové, Czech Republic
| | - Amina Gaffour
- Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203/8, 500 05 Hradec Králové, Czech Republic
| | - Martin Juhás
- Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203/8, 500 05 Hradec Králové, Czech Republic
- Department of Chemistry, Faculty of Science, University of Hradec Králové, Rokitanského 62, 500 03 Hradec Králové, Czech Republic
| | - Vojtěch Zapletal
- Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203/8, 500 05 Hradec Králové, Czech Republic
| | - Jakub Stošek
- Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203/8, 500 05 Hradec Králové, Czech Republic
- Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Lars A Bratholm
- School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS Bristol, U.K
| | - Jana Pavlíková Přecechtělová
- Faculty of Pharmacy in Hradec Králové, Charles University, Akademika Heyrovského 1203/8, 500 05 Hradec Králové, Czech Republic
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2
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McIvor JAP, Larsen DS, Mercadante D. Charge Relaying within a Phospho-Motif Rescue Binding Competency of a Disordered Transcription Factor. J Chem Inf Model 2024; 64:6041-6052. [PMID: 39074869 DOI: 10.1021/acs.jcim.4c00286] [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: 07/31/2024]
Abstract
Structural disorder in proteins is central to cellular signaling, where conformational plasticity equips molecules to promiscuously interact with different partners. By engaging with multiple binding partners via the rearrangement of its three helices, the nuclear coactivator binding domain (NCBD) of the CBP/p300 transcription factor is a paradigmatic example of promiscuity. Recently, molecular simulations and experiments revealed that, through the establishment of long-range electrostatic interactions, intended as salt-bridges formed between the post-translationally inserted phosphate and positively charged residues in helix H3 of NCBD, phosphorylation triggers NCBD compaction, lowering its affinity for binding partners. By means of extensive molecular simulations, we here investigated the effect of short-range electrostatics on the conformational ensemble of NCBD, by monitoring the interactions between a phosphorylated serine and conserved positively charged residues within the NCBD phospho-motif. We found that empowering proximal electrostatic interactions, as opposed to long-range electrostatics, can reshape the NCBD ensemble rescuing the binding competency of phosphorylated NCBD. Given the conservation of positive charges in phospho-motifs, proximal electrostatic interactions might dampen the effects of phosphorylation and act as a relay to regulate phosphorylated intrinsically disordered proteins, ultimately tuning the binding affinity for different cellular partners.
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Affiliation(s)
- Jordan A P McIvor
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
| | - Danaé S Larsen
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
| | - Davide Mercadante
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand
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3
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Fersht AR. From covalent transition states in chemistry to noncovalent in biology: from β- to Φ-value analysis of protein folding. Q Rev Biophys 2024; 57:e4. [PMID: 38597675 DOI: 10.1017/s0033583523000045] [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] [Indexed: 04/11/2024]
Abstract
Solving the mechanism of a chemical reaction requires determining the structures of all the ground states on the pathway and the elusive transition states linking them. 2024 is the centenary of Brønsted's landmark paper that introduced the β-value and structure-activity studies as the only experimental means to infer the structures of transition states. It involves making systematic small changes in the covalent structure of the reactants and analysing changes in activation and equilibrium-free energies. Protein engineering was introduced for an analogous procedure, Φ-value analysis, to analyse the noncovalent interactions in proteins central to biological chemistry. The methodology was developed first by analysing noncovalent interactions in transition states in enzyme catalysis. The mature procedure was then applied to study transition states in the pathway of protein folding - 'part (b) of the protein folding problem'. This review describes the development of Φ-value analysis of transition states and compares and contrasts the interpretation of β- and Φ-values and their limitations. Φ-analysis afforded the first description of transition states in protein folding at the level of individual residues. It revealed the nucleation-condensation folding mechanism of protein domains with the transition state as an expanded, distorted native structure, containing little fully formed secondary structure but many weak tertiary interactions. A spectrum of transition states with various degrees of structural polarisation was then uncovered that spanned from nucleation-condensation to the framework mechanism of fully formed secondary structure. Φ-analysis revealed how movement of the expanded transition state on an energy landscape accommodates the transition from framework to nucleation-condensation mechanisms with a malleability of structure as a unifying feature of folding mechanisms. Such movement follows the rubric of analysis of classical covalent chemical mechanisms that began with Brønsted. Φ-values are used to benchmark computer simulation, and Φ and simulation combine to describe folding pathways at atomic resolution.
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Affiliation(s)
- Alan R Fersht
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK
- Gonville and Caius College, University of Cambridge, Cambridge, UK
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4
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Evolutionary fine-tuning of residual helix structure in disordered proteins manifests in complex structure and lifetime. Commun Biol 2023; 6:63. [PMID: 36653471 PMCID: PMC9849366 DOI: 10.1038/s42003-023-04445-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023] Open
Abstract
Transcription depends on complex networks, where folded hub proteins interact with intrinsically disordered transcription factors undergoing coupled folding and binding. For this, local residual structure, a prototypical feature of intrinsic disorder, is key. Here, we dissect the unexplored functional potential of residual structure by comparing structure, kinetics, and thermodynamics within the model system constituted of the DREB2A transcription factor interacting with the αα-hub RCD1-RST. To maintain biological relevance, we developed an orthogonal evolutionary approach for the design of variants with varying amounts of structure. Biophysical analysis revealed a correlation between the amount of residual helical structure and binding affinity, manifested in altered complex lifetime due to changed dissociation rate constants. It also showed a correlation between helical structure in free and bound DREB2A variants. Overall, this study demonstrated how evolution can balance and fine-tune residual structure to regulate complexes in coupled folding and binding, potentially affecting transcription factor competition.
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Nam K, Wolf-Watz M. Protein dynamics: The future is bright and complicated! STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:014301. [PMID: 36865927 PMCID: PMC9974214 DOI: 10.1063/4.0000179] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Biological life depends on motion, and this manifests itself in proteins that display motion over a formidable range of time scales spanning from femtoseconds vibrations of atoms at enzymatic transition states, all the way to slow domain motions occurring on micro to milliseconds. An outstanding challenge in contemporary biophysics and structural biology is a quantitative understanding of the linkages among protein structure, dynamics, and function. These linkages are becoming increasingly explorable due to conceptual and methodological advances. In this Perspective article, we will point toward future directions of the field of protein dynamics with an emphasis on enzymes. Research questions in the field are becoming increasingly complex such as the mechanistic understanding of high-order interaction networks in allosteric signal propagation through a protein matrix, or the connection between local and collective motions. In analogy to the solution to the "protein folding problem," we argue that the way forward to understanding these and other important questions lies in the successful integration of experiment and computation, while utilizing the present rapid expansion of sequence and structure space. Looking forward, the future is bright, and we are in a period where we are on the doorstep to, at least in part, comprehend the importance of dynamics for biological function.
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Affiliation(s)
- Kwangho Nam
- Department of Chemistry and Biochemistry, University of Texas at Arlington, Arlington, Texas 76019, USA
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6
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Rowling PJE, Murton BL, Du Z, Itzhaki LS. Multivalent Interaction of Beta-Catenin With its Intrinsically Disordered Binding Partner Adenomatous Polyposis Coli. Front Mol Biosci 2022; 9:896493. [PMID: 35755812 PMCID: PMC9214244 DOI: 10.3389/fmolb.2022.896493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
The Wnt signalling pathway plays key roles in cell proliferation, differentiation and fate decisions in embryonic development and maintenance of adult tissues, and the twelve Armadillo (ARM) repeat-containing protein β-catenin acts as the signal transducer in this pathway. Here we investigate the interaction between β-catenin's ARM repeat domain and the intrinsically disordered protein adenomatous polyposis coli (APC). APC is a giant multivalent scaffold that brings together the different components of the so-called "β-catenin destruction complex", which drives β-catenin degradation via the ubiquitin-proteasome pathway. Mutations and truncations in APC, resulting in loss of APC function and hence elevated β-catenin levels and upregulation of Wnt signalling, are associated with numerous cancers including colorectal carcinomas. APC has a long intrinsically disordered region (IDR) that contains a series of 15-residue and 20-residue binding regions for β-catenin. Here we explore the multivalent nature of the interaction of β-catenin with the highest affinity APC repeat, both at equilibrium and under kinetic conditions. We use a combination of single-site substitutions, deletions and insertions to dissect the mechanism of molecular recognition and the roles of the three β-catenin-binding subdomains of APC.
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Affiliation(s)
| | | | | | - Laura S. Itzhaki
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
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7
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Disordered regions flanking the binding interface modulate affinity between CBP and NCOA. J Mol Biol 2022; 434:167643. [DOI: 10.1016/j.jmb.2022.167643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 01/01/2023]
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8
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Karlsson E, Sorgenfrei FA, Andersson E, Dogan J, Jemth P, Chi CN. The dynamic properties of a nuclear coactivator binding domain are evolutionarily conserved. Commun Biol 2022; 5:286. [PMID: 35354917 PMCID: PMC8967867 DOI: 10.1038/s42003-022-03217-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 03/02/2022] [Indexed: 12/21/2022] Open
Abstract
Evolution of proteins is constrained by their structure and function. While there is a consensus that the plasticity of intrinsically disordered proteins relaxes the structural constraints on evolution there is a paucity of data on the molecular details of these processes. The Nuclear Coactivator Binding Domain (NCBD) from CREB-binding protein is a protein interaction domain, which contains a hydrophobic core but is not behaving as a typical globular domain, and has been described as 'molten-globule like'. The highly dynamic properties of NCBD makes it an interesting model system for evolutionary structure-function investigation of intrinsically disordered proteins. We have here compared the structure and biophysical properties of an ancient version of NCBD present in a bilaterian animal ancestor living around 600 million years ago with extant human NCBD. Using a combination of NMR spectroscopy, circular dichroism and kinetics we show that although NCBD has increased its thermodynamic stability, it has retained its dynamic biophysical properties in the ligand-free state in the evolutionary lineage leading from the last common bilaterian ancestor to humans. Our findings suggest that the dynamic properties of NCBD have been maintained by purifying selection and thus are important for its function, which includes mediating several distinct protein-protein interactions.
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Affiliation(s)
- Elin Karlsson
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden
| | - Frieda A Sorgenfrei
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden.,acib GmbH, Krenngasse 37, 8010 Graz c/o University of Graz, Institute of Chemistry, NAWI Graz, BioTechMed Graz, Heinrichstrasse 28, 8010, Graz, Austria
| | - Eva Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden
| | - Jakob Dogan
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden
| | - Per Jemth
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden.
| | - Celestine N Chi
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden. .,Department of Pharmaceutical Biosciences, Uppsala University, BMC Box 582, SE-75123, Uppsala, Sweden.
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9
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Malagrinò F, Diop A, Pagano L, Nardella C, Toto A, Gianni S. Unveiling induced folding of intrinsically disordered proteins - Protein engineering, frustration and emerging themes. Curr Opin Struct Biol 2021; 72:153-160. [PMID: 34902817 DOI: 10.1016/j.sbi.2021.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 10/26/2021] [Accepted: 11/01/2021] [Indexed: 01/01/2023]
Abstract
Intrinsically disordered proteins (IDPs) can be generally described as a class of proteins that lack a well-defined ordered structure in isolation at physiological conditions. Upon binding to their physiological ligands, IDPs typically undergo a disorder-to-order transition, which may or may not lead to the complete folding of the IDP. In this short review, we focus on some of the key findings pertaining to the mechanisms of such induced folding. In particular, first we describe the general features of the reaction; then, we discuss some of the most remarkable findings obtained from applying protein engineering in synergy with kinetic studies to induced folding; and finally, we offer a critical view on some of the emerging themes when considering the structural heterogeneity of IDPs vis-à-vis to their inherent frustration.
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Affiliation(s)
- Francesca Malagrinò
- Istituto Pasteur, Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari Del CNR, Sapienza Università, di Roma, 00185, Rome, Italy
| | - Awa Diop
- Istituto Pasteur, Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari Del CNR, Sapienza Università, di Roma, 00185, Rome, Italy
| | - Livia Pagano
- Istituto Pasteur, Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari Del CNR, Sapienza Università, di Roma, 00185, Rome, Italy
| | - Caterina Nardella
- Istituto Pasteur, Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari Del CNR, Sapienza Università, di Roma, 00185, Rome, Italy
| | - Angelo Toto
- Istituto Pasteur, Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari Del CNR, Sapienza Università, di Roma, 00185, Rome, Italy.
| | - Stefano Gianni
- Istituto Pasteur, Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli" and Istituto di Biologia e Patologia Molecolari Del CNR, Sapienza Università, di Roma, 00185, Rome, Italy.
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10
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Jensen TMT, Bartling CRO, Karlsson OA, Åberg E, Haugaard-Kedström LM, Strømgaard K, Jemth P. Molecular Details of a Coupled Binding and Folding Reaction between the Amyloid Precursor Protein and a Folded Domain. ACS Chem Biol 2021; 16:1191-1200. [PMID: 34161732 PMCID: PMC8291497 DOI: 10.1021/acschembio.1c00176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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Intrinsically disordered
regions in proteins often function as
binding motifs in protein–protein interactions. The mechanistic
aspects and molecular details of such coupled binding and folding
reactions, which involve formation of multiple noncovalent bonds,
have been broadly studied theoretically, but experimental data are
scarce. Here, using a combination of protein semisynthesis to incorporate
phosphorylated amino acids, backbone amide-to-ester modifications,
side chain substitutions, and binding kinetics, we examined the interaction
between the intrinsically disordered motif of amyloid precursor protein
(APP) and the phosphotyrosine binding (PTB) domain of Mint2. We show
that the interaction is regulated by a self-inhibitory segment of
the PTB domain previously termed ARM. The helical ARM linker decreases
the association rate constant 30-fold through a fast pre-equilibrium
between an open and a closed state. Extensive side chain substitutions
combined with kinetic experiments demonstrate that the rate-limiting
transition state for the binding reaction is governed by native and
non-native hydrophobic interactions and hydrogen bonds. Hydrophobic
interactions were found to be particularly important during crossing
of the transition state barrier. Furthermore, linear free energy relationships
show that the overall coupled binding and folding reaction involves
cooperative formation of interactions with roughly 30% native contacts
formed at the transition state. Our data support an emerging picture
of coupled binding and folding reactions following overall chemical
principles similar to those of folding of globular protein domains
but with greater malleability of ground and transition states.
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Affiliation(s)
- Thomas M. T. Jensen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-75123 Uppsala, Sweden
| | - Christian R. O. Bartling
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark
| | - O. Andreas Karlsson
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-75123 Uppsala, Sweden
| | - Emma Åberg
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-75123 Uppsala, Sweden
| | - Linda M. Haugaard-Kedström
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark
| | - Per Jemth
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, SE-75123 Uppsala, Sweden
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11
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Smith BM, Rowling PJE, Dobson CM, Itzhaki LS. Parallel and Sequential Pathways of Molecular Recognition of a Tandem-Repeat Protein and Its Intrinsically Disordered Binding Partner. Biomolecules 2021; 11:827. [PMID: 34206070 PMCID: PMC8228192 DOI: 10.3390/biom11060827] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 02/07/2023] Open
Abstract
The Wnt signalling pathway plays an important role in cell proliferation, differentiation, and fate decisions in embryonic development and the maintenance of adult tissues. The twelve armadillo (ARM) repeat-containing protein β-catenin acts as the signal transducer in this pathway. Here, we investigated the interaction between β-catenin and the intrinsically disordered transcription factor TCF7L2, comprising a very long nanomolar-affinity interface of approximately 4800 Å2 that spans ten of the twelve ARM repeats of β-catenin. First, a fluorescence reporter system for the interaction was engineered and used to determine the kinetic rate constants for the association and dissociation. The association kinetics of TCF7L2 and β-catenin were monophasic and rapid (7.3 ± 0.1 × 107 M-1·s-1), whereas dissociation was biphasic and slow (5.7 ± 0.4 × 10-4 s-1, 15.2 ± 2.8 × 10-4 s-1). This reporter system was then combined with site-directed mutagenesis to investigate the striking variability in the conformation adopted by TCF7L2 in the three different crystal structures of the TCF7L2-β-catenin complex. We found that the mutation had very little effect on the association kinetics, indicating that most interactions form after the rate-limiting barrier for association. Mutations of the N- and C-terminal subdomains of TCF7L2 that adopt relatively fixed conformations in the crystal structures had large effects on the dissociation kinetics, whereas the mutation of the labile sub-domain connecting them had negligible effect. These results point to a two-site avidity mechanism of binding with the linker region forming a "fuzzy" complex involving transient contacts that are not site-specific. Strikingly, the two mutations in the N-terminal subdomain that had the largest effects on the dissociation kinetics showed two additional phases, indicating partial flux through an alternative dissociation pathway that is inaccessible to the wild type. The results presented here provide insights into the kinetics of the molecular recognition of a long intrinsically disordered region with an elongated repeat-protein surface, a process found to involve parallel routes with sequential steps in each.
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Affiliation(s)
- Ben M. Smith
- 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;
| | - Christopher M. Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK;
| | - Laura S. Itzhaki
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK;
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12
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Gianni S, Freiberger MI, Jemth P, Ferreiro DU, Wolynes PG, Fuxreiter M. Fuzziness and Frustration in the Energy Landscape of Protein Folding, Function, and Assembly. Acc Chem Res 2021; 54:1251-1259. [PMID: 33550810 PMCID: PMC8023570 DOI: 10.1021/acs.accounts.0c00813] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Indexed: 12/20/2022]
Abstract
Are all protein interactions fully optimized? Do suboptimal interactions compromise specificity? What is the functional impact of frustration? Why does evolution not optimize some contacts? Proteins and their complexes are best described as ensembles of states populating an energy landscape. These ensembles vary in breadth from narrow ensembles clustered around a single average X-ray structure to broader ensembles encompassing a few different functional "taxonomic" states on to near continua of rapidly interconverting conformations, which are called "fuzzy" or even "intrinsically disordered". Here we aim to provide a comprehensive framework for confronting the structural and dynamical continuum of protein assemblies by combining the concepts of energetic frustration and interaction fuzziness. The diversity of the protein structural ensemble arises from the frustrated conflicts between the interactions that create the energy landscape. When frustration is minimal after folding, it results in a narrow ensemble, but residual frustrated interactions result in fuzzy ensembles, and this fuzziness allows a versatile repertoire of biological interactions. Here we discuss how fuzziness and frustration play off each other as proteins fold and assemble, viewing their significance from energetic, functional, and evolutionary perspectives.We demonstrate, in particular, that the common physical origin of both concepts is related to the ruggedness of the energy landscapes, intramolecular in the case of frustration and intermolecular in the case of fuzziness. Within this framework, we show that alternative sets of suboptimal contacts may encode specificity without achieving a single structural optimum. Thus, we demonstrate that structured complexes may not be optimized, and energetic frustration is realized via different sets of contacts leading to multiplicity of specific complexes. Furthermore, we propose that these suboptimal, frustrated, or fuzzy interactions are under evolutionary selection and expand the biological repertoire by providing a multiplicity of biological activities. In accord, we show that non-native interactions in folding or interaction landscapes can cooperate to generate diverse functional states, which are essential to facilitate adaptation to different cellular conditions. Thus, we propose that not fully optimized structures may actually be beneficial for biological activities of proteins via an alternative set of suboptimal interactions. The importance of such variability has not been recognized across different areas of biology.This account provides a modern view on folding, function, and assembly across the protein universe. The physical framework presented here is applicable to the structure and dynamics continuum of proteins and opens up new perspectives for drug design involving not fully structured, highly dynamic protein assemblies.
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Affiliation(s)
- Stefano Gianni
- Istituto
Pasteur - Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche
“A. Rossi Fanelli” and Istituto di Biologia e Patologia
Molecolari del CNR, Sapienza Università
di Roma, 00185 Rome, Italy
| | - María Inés Freiberger
- Protein
Physiology Lab, Departamento de Química Biológica, Facultad
de Ciencias Exactas y Naturales, Universidad
de Buenos Aires-CONICET-IQUIBICEN, 1428 Buenos Aires, Argentina
| | - Per Jemth
- Department
of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, SE-75123 Uppsala, Sweden
| | - Diego U. Ferreiro
- Protein
Physiology Lab, Departamento de Química Biológica, Facultad
de Ciencias Exactas y Naturales, Universidad
de Buenos Aires-CONICET-IQUIBICEN, 1428 Buenos Aires, Argentina
| | - Peter G. Wolynes
- Center
for Theoretical Biological Physics, Rice
University, 6500 Main Street, Houston, Texas 77251-1892, United States
| | - Monika Fuxreiter
- MTA-DE
Laboratory of Protein Dynamics, Department of Biochemistry and Molecular
Biology, University of Debrecen, Nagyerdei krt 98, H-4032 Debrecen, Hungary
- Department
of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy
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