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Alesio J, Bothun GD. Differential scanning fluorimetry to assess PFAS binding to bovine serum albumin protein. Sci Rep 2024; 14:6501. [PMID: 38499613 PMCID: PMC10948889 DOI: 10.1038/s41598-024-57140-9] [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: 01/10/2024] [Accepted: 03/14/2024] [Indexed: 03/20/2024] Open
Abstract
The rapid screening of protein binding affinity for poly- and perfluoroalkyl substances (PFAS) benefits risk assessment and fate and transport modelling. PFAS are known to bioaccumulate in livestock through contaminated food and water. One excretion pathway is through milk, which may be facilitated by binding to milk proteins such as bovine serum albumin (BSA). We report a label-free differential scanning fluorimetry approach to determine PFAS-BSA binding over a broad temperature range. This method utilizes the tryptophan residue within the protein binding pocket as an intrinsic fluorophore, eliminating the need for fluorophore labels that may influence binding. BSA association constants were determined by (a) an equilibrium-based model at the melting temperature of BSA and (b) the Hill adsorption model to account for temperature dependent binding and binding cooperativity. Differences in binding between PFAS and fatty acid analogs revealed that a combination of size and hydrophobicity drives PFAS binding.
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Affiliation(s)
- Jessica Alesio
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, 02881, USA
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, 02881, USA.
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2
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Ford A, Breitgoff F, Pasquini M, MacKenzie A, McElroy S, Baker S, Abrusci P, Varzandeh S, Bird L, Gavard A, Damerell D, Redhead M. Application of particle swarm optimization to understand the mechanism of action of allosteric inhibitors of the enzyme HSD17β13. PATTERNS (NEW YORK, N.Y.) 2023; 4:100733. [PMID: 37223265 PMCID: PMC10201303 DOI: 10.1016/j.patter.2023.100733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 09/06/2022] [Accepted: 03/24/2023] [Indexed: 05/25/2023]
Abstract
Understanding a drug candidate's mechanism of action is crucial for its further development. However, kinetic schemes are often complex and multi-parametric, especially for proteins in oligomerization equilibria. Here, we demonstrate the use of particle swarm optimization (PSO) as a method to select between different sets of parameters that are too far apart in the parameter space to be found by conventional approaches. PSO is based upon the swarming of birds: each bird in the flock assesses multiple landing spots while at the same time sharing that information with its neighbors. We applied this approach to the kinetics of HSD17β13 enzyme inhibitors, which displayed unusually large thermal shifts. Thermal shift data for HSD17β13 indicated that the inhibitor shifted the oligomerization equilibrium toward the dimeric state. Validation of the PSO approach was provided by experimental mass photometry data. These results encourage further exploration of multi-parameter optimization algorithms as tools in drug discovery.
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Affiliation(s)
- Amy Ford
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Frauke Breitgoff
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Miriam Pasquini
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | | | - Stuart McElroy
- Bioascent, Bo'Ness Road, Chapelhall, Motherwell ML1 5SH, UK
| | - Steve Baker
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Patrizia Abrusci
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Simon Varzandeh
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Louise Bird
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Angeline Gavard
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - David Damerell
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
| | - Martin Redhead
- Exscientia, The Schrödinger Building, Oxford Science Park, Oxford OX4 4GE, UK
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3
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de Araujo ED, Orlova A, Ashraf QF, Moriggl R, Gunning PT. Inhibitor Library Screening of SH2 Domains Through Denaturation-Based Assays. Methods Mol Biol 2023; 2705:213-223. [PMID: 37668976 DOI: 10.1007/978-1-0716-3393-9_11] [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: 09/06/2023]
Abstract
Screening of inhibitor libraries for candidate ligands is an important step in the drug discovery process. Thermal denaturation-based screening strategies are built on the premise that a protein-ligand complex has an altered stability profile compared to the protein alone. As such, these assays provide an accessible and rapid methodology for stratifying ligands that directly engage with the protein target of interest. Here, we describe three denaturation-based strategies for examining protein-inhibitor binding, in the context of SH2 domains. This includes conventional dye-based Thermal Shift Assays (TSA), nonconventional labeled ligand-based TSA, and Cellular Thermal Shift Assays (CETSA). Conventional dye-based TSA reports on the fluorescence of an external hydrophobic dye as it interacts with heat-exposed nonpolar protein surfaces as the temperature is incrementally increased. By contrast, nonconventional-labeled ligand TSA involves a fluorescence-tagged probe (phosphopeptide for SH2 domains) that is quenched as it dissociates from the protein during the denaturation process. CETSA involves monitoring the presence of the protein via Western blotting as the temperature is increased. In all three approaches, performing the assay in the presence of a candidate ligand can alter the melting profile of the protein. These assays offer primary screening tools to examine SH2 domain inhibitors libraries with varying chemical motifs, and a subset of the advantages and limitations of each approach is also discussed.
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Affiliation(s)
- Elvin D de Araujo
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Anna Orlova
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria
| | - Qirat F Ashraf
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
- Department of Chemistry, University of Toronto, Toronto, ON, Canada
| | - Richard Moriggl
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria
| | - Patrick T Gunning
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada.
- Department of Chemistry, University of Toronto, Toronto, ON, Canada.
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Scott L, Chalikian TV. Stabilization of G-Quadruplex-Duplex Hybrid Structures Induced by Minor Groove-Binding Drugs. Life (Basel) 2022; 12:life12040597. [PMID: 35455088 PMCID: PMC9030760 DOI: 10.3390/life12040597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/09/2022] [Accepted: 04/13/2022] [Indexed: 11/16/2022] Open
Abstract
Once it had been realized that G-quadruplexes exist in the cell and are involved in regulation of genomic processes, the quest for ligands recognizing these noncanonical structures was underway. Many organic compounds that tightly associate with G-quadruplexes have been identified. However, the specificity of G-quadruplex-binding ligands towards individual structures remains problematic, as the common recognition element of these ligands is the G-tetrad. In this paper, we focus on G-quadruplex-duplex hybrids (QDH) containing a hairpin duplex incorporated as a stem-loop into the G-quadruplex core. The presence of a stem-loop renders QDH amenable to sequence-specific recognition by duplex-binding drugs. Should the thermodynamic crosstalk between the stem-loop and the tetraplex core be sufficiently strong, the drug binding to the loop would lead to the stabilization of the entire structure. We studied the stabilizing influence of the minor groove-binders netropsin and Hoechst 33258 on a family of QDH structures, as well as a G-quadruplex and a hairpin modeling the G-quadruplex core and the stem-loop of the QDH’s. We found that the binding of either drug results in an enhancement of the thermal stability of all DNA structures, as expressed by increases in the melting temperature, TM. Analysis of the hierarchical order of increases in TM revealed that the drug-induced stabilization arises from drug binding to the G-quadruplex domain of a QDH and the stem-loop, if the latter contains an all-AT binding site. This result attests to the thermodynamic crosstalk between the stem-loop and the tetraplex core of a QDH. Given the existing library of minor groove-binding drugs recognizing mixed A·T and G·C DNA sequences, our results point to an untapped avenue for sequence-specific recognition of QDH structures in vitro and, possibly, in vivo; thereby, opening the way for selective stabilization of four-stranded DNA structures at predetermined genomic loci, with implications for the control of genomic events.
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Gautom T, Dheeman D, Levy C, Butterfield T, Alvarez Gonzalez G, Le Roy P, Caiger L, Fisher K, Johannissen L, Dixon N. Structural basis of terephthalate recognition by solute binding protein TphC. Nat Commun 2021; 12:6244. [PMID: 34716322 PMCID: PMC8556258 DOI: 10.1038/s41467-021-26508-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 10/06/2021] [Indexed: 11/08/2022] Open
Abstract
Biological degradation of Polyethylene terephthalate (PET) plastic and assimilation of the corresponding monomers ethylene glycol and terephthalate (TPA) into central metabolism offers an attractive route for bio-based molecular recycling and bioremediation applications. A key step is the cellular uptake of the non-permeable TPA into bacterial cells which has been shown to be dependent upon the presence of the key tphC gene. However, little is known from a biochemical and structural perspective about the encoded solute binding protein, TphC. Here, we report the biochemical and structural characterisation of TphC in both open and TPA-bound closed conformations. This analysis demonstrates the narrow ligand specificity of TphC towards aromatic para-substituted dicarboxylates, such as TPA and closely related analogues. Further phylogenetic and genomic context analysis of the tph genes reveals homologous operons as a genetic resource for future biotechnological and metabolic engineering efforts towards circular plastic bio-economy solutions.
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Affiliation(s)
- Trishnamoni Gautom
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
- Department of Biotechnology, Gauhati University, Guwahati, Assam, India
- Royal School of Bio-Sciences, Royal Global University, Guwahati, Assam, India
| | - Dharmendra Dheeman
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Colin Levy
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Thomas Butterfield
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Guadalupe Alvarez Gonzalez
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Philip Le Roy
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Lewis Caiger
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Karl Fisher
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Linus Johannissen
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK
| | - Neil Dixon
- Manchester Institute of Biotechnology (MIB) and Department of Chemistry, The University of Manchester, Manchester, UK.
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POT1 stability and binding measured by fluorescence thermal shift assays. PLoS One 2021; 16:e0245675. [PMID: 33784306 PMCID: PMC8009405 DOI: 10.1371/journal.pone.0245675] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/03/2021] [Indexed: 11/19/2022] Open
Abstract
The protein POT1 (Protection of Telomeres 1) is an integral part of the shelterin complex that protects the ends of human chromosomes from degradation or end fusions. It is the only component of shelterin that binds single-stranded DNA. We describe here the application of two separate fluorescent thermal shift assays (FTSA) that provide quantitative biophysical characterization of POT1 stability and its interactions. The first assay uses Sypro Orange™ and monitors the thermal stability of POT1 and its binding under a variety of conditions. This assay is useful for the quality control of POT1 preparations, for biophysical characterization of its DNA binding and, potentially, as an efficient screening tool for binding of small molecule drug candidates. The second assay uses a FRET-labeled human telomeric G-quadruplex structure that reveals the effects of POT1 binding on thermal stability from the DNA frame of reference. These complementary assays provide efficient biophysical approaches for the quantitative characterization of multiple aspects of POT1 structure and function. The results from these assays provide thermodynamics details of POT1 folding, the sequence selectivity of its DNA binding and the thermodynamic profile for its binding to its preferred DNA binding sequence. Most significantly, results from these assays elucidate two mechanisms for the inhibition of POT1 -DNA interactions. The first is by competitive inhibition at the POT1 DNA binding site. The second is indirect and is by stabilization of G-quadruplex formation within the normal POT1 single-stranded DNA sequence to prevent POT1 binding.
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Ha J, Park H, Park J, Park SB. Recent advances in identifying protein targets in drug discovery. Cell Chem Biol 2020; 28:394-423. [PMID: 33357463 DOI: 10.1016/j.chembiol.2020.12.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 11/11/2020] [Accepted: 11/30/2020] [Indexed: 02/06/2023]
Abstract
Phenotype-based screening has emerged as an alternative route for discovering new chemical entities toward first-in-class therapeutics. However, clarifying their mode of action has been a significant bottleneck for drug discovery. For target protein identification, conventionally bioactive small molecules are conjugated onto solid supports and then applied to isolate target proteins from whole proteome. This approach requires a high binding affinity between bioactive small molecules and their target proteins. Besides, the binding affinity can be significantly hampered after structural modifications of bioactive molecules with linkers. To overcome these limitations, two major strategies have recently been pursued: (1) the covalent conjugation between small molecules and target proteins using photoactivatable moieties or electrophiles, and (2) label-free target identification through monitoring target engagement by tracking the thermal, proteolytic, or chemical stability of target proteins. This review focuses on recent advancements in target identification from covalent capturing to label-free strategies.
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Affiliation(s)
- Jaeyoung Ha
- Department of Biophysics and Chemical Biology, Seoul National University, Seoul 08826, Korea
| | - Hankum Park
- CRI Center for Chemical Proteomics, Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Jongmin Park
- Department of Chemistry, Kangwon National University, Chuncheon 24341, Korea.
| | - Seung Bum Park
- Department of Biophysics and Chemical Biology, Seoul National University, Seoul 08826, Korea; CRI Center for Chemical Proteomics, Department of Chemistry, Seoul National University, Seoul 08826, Korea.
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Park H, Ha J, Park SB. Label-free target identification in drug discovery via phenotypic screening. Curr Opin Chem Biol 2019; 50:66-72. [DOI: 10.1016/j.cbpa.2019.02.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/28/2019] [Accepted: 02/06/2019] [Indexed: 11/25/2022]
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9
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Mac Sweeney A, Chambovey A, Wicki M, Müller M, Artico N, Lange R, Bijelic A, Breibeck J, Rompel A. The crystallization additive hexatungstotellurate promotes the crystallization of the HSP70 nucleotide binding domain into two different crystal forms. PLoS One 2018; 13:e0199639. [PMID: 29949628 PMCID: PMC6021075 DOI: 10.1371/journal.pone.0199639] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 06/11/2018] [Indexed: 11/18/2022] Open
Abstract
The use of the tellurium-centered Anderson-Evans polyoxotungstate [TeW6O24]6- (TEW) as a crystallization additive has been described. Here, we present the use of TEW as an additive in the crystallization screening of the nucleotide binding domain (NBD) of HSP70. Crystallization screening of the HSP70 NBD in the absence of TEW using a standard commercial screen resulted in a single crystal form. An identical crystallization screen of the HSP70 NBD in the presence of TEW resulted in both the "TEW free" crystal form and an additional crystal form with a different crystal packing. TEW binding was observed in both crystal forms, either as a well-defined molecule or in overlapping alternate positions suggesting translational disorder. The structures were solved by both molecular replacement and single wavelength anomalous diffraction (SAD) using the anomalous signal of a single bound molecule of TEW. This study adds one more example of TEW binding to a protein and influencing its crystallization behavior.
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Affiliation(s)
- Aengus Mac Sweeney
- Drug Discovery Biology, Idorsia Pharmaceuticals Ltd., Allschwil, Switzerland
| | - Alain Chambovey
- Drug Discovery Biology, Idorsia Pharmaceuticals Ltd., Allschwil, Switzerland
| | - Micha Wicki
- Drug Discovery Biology, Idorsia Pharmaceuticals Ltd., Allschwil, Switzerland
| | - Manon Müller
- Drug Discovery Biology, Idorsia Pharmaceuticals Ltd., Allschwil, Switzerland
| | - Nadia Artico
- Drug Discovery Biology, Idorsia Pharmaceuticals Ltd., Allschwil, Switzerland
| | - Roland Lange
- Drug Discovery Biology, Idorsia Pharmaceuticals Ltd., Allschwil, Switzerland
| | - Aleksandar Bijelic
- University of Vienna, Faculty of Chemistry, Department of Biophysical Chemistry, Vienna, Austria
| | - Joscha Breibeck
- University of Vienna, Faculty of Chemistry, Department of Biophysical Chemistry, Vienna, Austria
| | - Annette Rompel
- University of Vienna, Faculty of Chemistry, Department of Biophysical Chemistry, Vienna, Austria
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