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Kairys V, Baranauskiene L, Kazlauskiene M, Zubrienė A, Petrauskas V, Matulis D, Kazlauskas E. Recent advances in computational and experimental protein-ligand affinity determination techniques. Expert Opin Drug Discov 2024; 19:649-670. [PMID: 38715415 DOI: 10.1080/17460441.2024.2349169] [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] [Received: 03/18/2024] [Accepted: 04/25/2024] [Indexed: 05/22/2024]
Abstract
INTRODUCTION Modern drug discovery revolves around designing ligands that target the chosen biomolecule, typically proteins. For this, the evaluation of affinities of putative ligands is crucial. This has given rise to a multitude of dedicated computational and experimental methods that are constantly being developed and improved. AREAS COVERED In this review, the authors reassess both the industry mainstays and the newest trends among the methods for protein - small-molecule affinity determination. They discuss both computational affinity predictions and experimental techniques, describing their basic principles, main limitations, and advantages. Together, this serves as initial guide to the currently most popular and cutting-edge ligand-binding assays employed in rational drug design. EXPERT OPINION The affinity determination methods continue to develop toward miniaturization, high-throughput, and in-cell application. Moreover, the availability of data analysis tools has been constantly increasing. Nevertheless, cross-verification of data using at least two different techniques and careful result interpretation remain of utmost importance.
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Affiliation(s)
- Visvaldas Kairys
- Department of Bioinformatics, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Lina Baranauskiene
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | | | - Asta Zubrienė
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Vytautas Petrauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Daumantas Matulis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Egidijus Kazlauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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Wilhelm E, Poirier M, Da Rocha M, Bédard M, McDonald PP, Lavigne P, Hunter CL, Bell B. Mitotic deacetylase complex (MiDAC) recognizes the HIV-1 core promoter to control activated viral gene expression. PLoS Pathog 2024; 20:e1011821. [PMID: 38781120 PMCID: PMC11115230 DOI: 10.1371/journal.ppat.1011821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 04/05/2024] [Indexed: 05/25/2024] Open
Abstract
The human immunodeficiency virus (HIV) integrates into the host genome forming latent cellular reservoirs that are an obstacle for cure or remission strategies. Viral transcription is the first step in the control of latency and depends upon the hijacking of the host cell RNA polymerase II (Pol II) machinery by the 5' HIV LTR. Consequently, "block and lock" or "shock and kill" strategies for an HIV cure depend upon a full understanding of HIV transcriptional control. The HIV trans-activating protein, Tat, controls HIV latency as part of a positive feed-forward loop that strongly activates HIV transcription. The recognition of the TATA box and adjacent sequences of HIV essential for Tat trans-activation (TASHET) of the core promoter by host cell pre-initiation complexes of HIV (PICH) has been shown to be necessary for Tat trans-activation, yet the protein composition of PICH has remained obscure. Here, DNA-affinity chromatography was employed to identify the mitotic deacetylase complex (MiDAC) as selectively recognizing TASHET. Using biophysical techniques, we show that the MiDAC subunit DNTTIP1 binds directly to TASHET, in part via its CTGC DNA motifs. Using co-immunoprecipitation assays, we show that DNTTIP1 interacts with MiDAC subunits MIDEAS and HDAC1/2. The Tat-interacting protein, NAT10, is also present in HIV-bound MiDAC. Gene silencing revealed a functional role for DNTTIP1, MIDEAS, and NAT10 in HIV expression in cellulo. Furthermore, point mutations in TASHET that prevent DNTTIP1 binding block the reactivation of HIV by latency reversing agents (LRA) that act via the P-TEFb/7SK axis. Our data reveal a key role for MiDAC subunits DNTTIP1, MIDEAS, as well as NAT10, in Tat-activated HIV transcription and latency. DNTTIP1, MIDEAS and NAT10 emerge as cell cycle-regulated host cell transcription factors that can control activated HIV gene expression, and as new drug targets for HIV cure strategies.
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Affiliation(s)
| | | | - Morgane Da Rocha
- Département de microbiologie et d’infectiologie, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | - Mikaël Bédard
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | - Patrick P. McDonald
- Pulmonary Division, Medicine Faculty, Université de Sherbrooke; and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | - Pierre Lavigne
- Département de Biochimie et de Génomique Fonctionnelle, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
| | | | - Brendan Bell
- Département de microbiologie et d’infectiologie, Faculté de médecine et sciences de la santé, Université de Sherbrooke, and Centre de recherche du CHUS, Sherbrooke, Québec, Canada
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Sun NN, Xu QF, Yang MD, Li YN, Liu H, Tantai W, Shu GW, Li GL. A high-throughput differential scanning fluorimetry method for rapid detection of thermal stability and iron saturation in lactoferrin. Int J Biol Macromol 2024; 267:131285. [PMID: 38583841 DOI: 10.1016/j.ijbiomac.2024.131285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/09/2024]
Abstract
Thermal stability and iron saturation of lactoferrin (LF) are of great significance not only for the evaluation of the biological activities of LF but also for the optimization of the isolation and drying process parameters. Differential scanning calorimetry (DSC) is a well-established and efficient method for thermal stability and iron saturation detection in LF. However, multiple DSC measurements are typically performed sequentially, thus time-consuming and low throughput. Herein, we introduced the differential scanning fluorimetry (DSF) approach to overcome such limitations. The DSF can monitor LF thermal unfolding with a commonly available real-time PCR instrument and a fluorescent dye (SYPRO orange or Glomelt), and the measured melting temperature of LF is consistent with that determined by DSC. On the basis of that, a new quantification method was established for determination of iron saturation levels using the linear correlation of the degree of ion saturation of LF with DSF measurements. Such DSF method is simple, inexpensive, rapid (<15 min), and high throughput (>96 samples per experiment), and provides a valuable alternative tool for thermal stability detection of LF and other whey proteins.
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Affiliation(s)
- Na-Na Sun
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Qin-Feng Xu
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China.
| | - Meng-di Yang
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Yan-Ni Li
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Hao Liu
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Wei Tantai
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Guo-Wei Shu
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
| | - Guo-Liang Li
- School of Food Science and Engineering, National R&D Center for Goat Dairy Products Processing Technology, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, China
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Dávalos AL, Rivera Echeverri JD, Favaro DC, Junio de Oliveira R, Penteado Battesini Carretero G, Lacerda C, Midea Cuccovia I, Cangussu Cardoso MV, Farah CS, Kopke Salinas R. Uncovering the Association Mechanism between Two Intrinsically Flexible Proteins. ACS Chem Biol 2024; 19:669-686. [PMID: 38486495 DOI: 10.1021/acschembio.3c00649] [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: 03/19/2024]
Abstract
The understanding of protein-protein interaction mechanisms is key to the atomistic description of cell signaling pathways and for the development of new drugs. In this context, the mechanism of intrinsically disordered proteins folding upon binding has attracted attention. The VirB9 C-terminal domain (VirB9Ct) and the VirB7 N-terminal motif (VirB7Nt) associate with VirB10 to form the outer membrane core complex of the Type IV Secretion System injectisome. Despite forming a stable and rigid complex, VirB7Nt behaves as a random coil, while VirB9Ct is intrinsically dynamic in the free state. Here we combined NMR, stopped-flow fluorescence, and computer simulations using structure-based models to characterize the VirB9Ct-VirB7Nt coupled folding and binding mechanism. Qualitative data analysis suggested that VirB9Ct preferentially binds to VirB7Nt by way of a conformational selection mechanism at lower temperatures. However, at higher temperatures, energy barriers between different VirB9Ct conformations are more easily surpassed. Under these conditions the formation of non-native initial encounter complexes may provide alternative pathways toward the native complex conformation. These observations highlight the intimate relationship between folding and binding, calling attention to the fact that the two molecular partners must search for the most favored intramolecular and intermolecular interactions on a rugged and funnelled conformational energy landscape, along which multiple intermediates may lead to the final native state.
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Affiliation(s)
- Angy Liseth Dávalos
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
| | | | - Denize C Favaro
- Department of Organic Chemistry, State University of Campinas, Campinas, 13083-862, Brazil
- Structural Biology Initiative, CUNY Advanced Science Research Center, New York, New York 10031, United States
| | - Ronaldo Junio de Oliveira
- Department of Physics, Institute of Exact, Natural and Educational Sciences, Federal University of Triângulo Mineiro, Uberaba, 38064-200, Brazil
| | | | - Caroline Lacerda
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
| | - Iolanda Midea Cuccovia
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
| | | | - Chuck S Farah
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
| | - Roberto Kopke Salinas
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, 05508-000, Brazil
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Hait S, Kundu S. Revisiting structural organization of proteins at high temperature from a network perspective. Comput Biol Chem 2024; 108:107978. [PMID: 37956471 DOI: 10.1016/j.compbiolchem.2023.107978] [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] [Received: 08/01/2023] [Revised: 10/08/2023] [Accepted: 10/29/2023] [Indexed: 11/15/2023]
Abstract
Interactions between distantly placed amino acids in the primary chain (long-range) play a very crucial role in the formation and stabilization of the tertiary structure of a protein, while interactions between closely placed amino acids in the primary chain (short-range) mostly stabilize the secondary structures. Every protein needs to maintain marginal stability in order to perform its physiological functions in its native environment. The requirements for this stability in mesophilic and thermophilic proteins are different. Thermophilic proteins need to form more interactions as well as more stable interactions to survive in the extreme environment, they live in. Here, we aim to find out how the interacting amino acids in three-dimensional space are positioned in the primary chains in thermophilic and mesophilic. How does this arrangement help thermophiles to maintain their structural integrity at high temperatures? Working on a dataset of 1560 orthologous pairs we perceive that thermophiles are not only enriched with long-range interactions, they feature bigger connected clusters and higher network densities compared to their mesophilic orthologs, at higher interaction strengths between the amino acids. Moreover, we have observed the enrichment of different types of interactions at different secondary structural regions.
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Affiliation(s)
- Suman Hait
- Department of Biophysics, Molecular Biology and Bioinformatics, 92, Acharya Prafulla Chandra Road, Kolkata 700009, India.
| | - Sudip Kundu
- Department of Biophysics, Molecular Biology and Bioinformatics, 92, Acharya Prafulla Chandra Road, Kolkata 700009, India.
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Hoare BL, Tippett DN, Kaur A, Cullum SA, Miljuš T, Koers EJ, Harwood CR, Dijon N, Holliday ND, Sykes DA, Veprintsev DB. ThermoBRET: A Ligand-Engagement Nanoscale Thermostability Assay Applied to GPCRs. Chembiochem 2024; 25:e202300459. [PMID: 37872746 DOI: 10.1002/cbic.202300459] [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: 06/22/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023]
Abstract
Measurements of membrane protein thermostability reflect ligand binding. Current thermostability assays often require protein purification or rely on pre-existing radiolabelled or fluorescent ligands, limiting their application to established targets. Alternative methods, such as fluorescence-detection size exclusion chromatography thermal shift, detect protein aggregation but are not amenable to high-throughput screening. Here, we present a ThermoBRET method to quantify the relative thermostability of G protein coupled receptors (GPCRs), using cannabinoid receptors (CB1 and CB2 ) and the β2 -adrenoceptor (β2 AR) as model systems. ThermoBRET reports receptor unfolding, does not need labelled ligands and can be used with non-purified proteins. It uses Bioluminescence Resonance Energy Transfer (BRET) between Nanoluciferase (Nluc) and a thiol-reactive fluorescent dye that binds cysteines exposed by unfolding. We demonstrate that the melting point (Tm ) of Nluc-fused GPCRs can be determined in non-purified detergent solubilised membrane preparations or solubilised whole cells, revealing differences in thermostability for different solubilising conditions and in the presence of stabilising ligands. We extended the range of the assay by developing the thermostable tsNLuc by incorporating mutations from the fragments of split-Nluc (Tm of 87 °C versus 59 °C). ThermoBRET allows the determination of GPCR thermostability, which is useful for protein purification optimisation and drug discovery screening.
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Affiliation(s)
- Bradley L Hoare
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Current address, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC 3052, Australia
| | - David N Tippett
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Current address, Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Amandeep Kaur
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Sean A Cullum
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Tamara Miljuš
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Eline J Koers
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Clare R Harwood
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Nicola Dijon
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Nicholas D Holliday
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - David A Sykes
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Dmitry B Veprintsev
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK
- Division of Physiology, Pharmacology & Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
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Hamre AG, Al-Sadawi R, Johannesen KM, Bisarro B, Kjendseth ÅR, Leiros HKS, Sørlie M. Initial characterization of an iron superoxide dismutase from Thermobifida fusca. J Biol Inorg Chem 2023; 28:689-698. [PMID: 37725277 PMCID: PMC10520107 DOI: 10.1007/s00775-023-02019-9] [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: 11/16/2022] [Accepted: 08/24/2023] [Indexed: 09/21/2023]
Abstract
Superoxide dismutases (SODs) are enzymes that catalyze the dismutation of the superoxide radical anion into O2 and H2O2 in a two-step reaction. They are ubiquitous to all forms of life and four different types of metal centers are detected, dividing this class of enzymes into Cu-/Zn-, Ni-, Mn-, and Fe-SODs. In this study, a superoxide dismutase from the thermophilic bacteria Thermobifida fusca (TfSOD) was cloned and expressed before the recombinant enzyme was characterized. The enzyme was found to be active for superoxide dismutation measured by inhibition of cytochrome c oxidation and the inhibition of the autoxidation of pyrogallol. Its pH-optimum was determined to be 7.5, while it has a broad temperature optimum ranging from 20 to 90 °C. Combined with the Tm that was found to be 78.5 ± 0.5 °C at pH 8.0, TfSOD can be defined as a thermostable enzyme. Moreover, the crystal structure of TfSOD was determined and refined to 1.25 Å resolution. With electron paramagnetic resonance spectroscopy, it was confirmed that iron is the metal co-factor of TfSOD. The cell potential (Em) for the TfSOD-Fe3+/TfSOD-Fe2+ redox couple was determined to be 287 mV.
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Affiliation(s)
- Anne Grethe Hamre
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, 1432, Ås, Norway
| | - Rim Al-Sadawi
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, 1432, Ås, Norway
| | - Kirsti Merete Johannesen
- Department of Chemistry, Faculty of Science and Technology, UiT The Arctic University of Norway, 9037, Tromsö, Norway
| | - Bastien Bisarro
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, 1432, Ås, Norway
| | - Åsmund Røhr Kjendseth
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, 1432, Ås, Norway
| | - Hanna-Kirsti S Leiros
- Department of Chemistry, Faculty of Science and Technology, UiT The Arctic University of Norway, 9037, Tromsö, Norway
| | - Morten Sørlie
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO 5003, 1432, Ås, Norway.
- Department for Physics and Technology, Faculty of Science and Technology, UiT The Arctic University of Norway, 9037, Tromsö, Norway.
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Kotov V, Killer M, Jungnickel KEJ, Lei J, Finocchio G, Steinke J, Bartels K, Strauss J, Dupeux F, Humm AS, Cornaciu I, Márquez JA, Pardon E, Steyaert J, Löw C. Plasticity of the binding pocket in peptide transporters underpins promiscuous substrate recognition. Cell Rep 2023; 42:112831. [PMID: 37467108 DOI: 10.1016/j.celrep.2023.112831] [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] [Received: 02/15/2023] [Revised: 06/09/2023] [Accepted: 07/03/2023] [Indexed: 07/21/2023] Open
Abstract
Proton-dependent oligopeptide transporters (POTs) are promiscuous transporters of the major facilitator superfamily that constitute the main route of entry for a wide range of dietary peptides and orally administrated peptidomimetic drugs. Given their clinical and pathophysiological relevance, several POT homologs have been studied extensively at the structural and molecular level. However, the molecular basis of recognition and transport of diverse peptide substrates has remained elusive. We present 14 X-ray structures of the bacterial POT DtpB in complex with chemically diverse di- and tripeptides, providing novel insights into the plasticity of the conserved central binding cavity. We analyzed binding affinities for more than 80 peptides and monitored uptake by a fluorescence-based transport assay. To probe whether all 8400 natural di- and tripeptides can bind to DtpB, we employed state-of-the-art molecular docking and machine learning and conclude that peptides with compact hydrophobic residues are the best DtpB binders.
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Affiliation(s)
- Vadim Kotov
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany
| | - Maxime Killer
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany; Faculty of Biosciences, Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Hamburg, Germany
| | - Katharina E J Jungnickel
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany
| | - Jian Lei
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany; State Key Laboratory of Biotherapy and Cancer Center, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, Sichuan 610041, People's Republic of China
| | - Giada Finocchio
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany
| | - Josi Steinke
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany
| | - Kim Bartels
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany
| | - Jan Strauss
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany
| | - Florine Dupeux
- European Molecular Biology Laboratory (EMBL) Grenoble, 71 Avenue des Martyrs CS 90181, 38042 Grenoble Cedex 9, France
| | - Anne-Sophie Humm
- European Molecular Biology Laboratory (EMBL) Grenoble, 71 Avenue des Martyrs CS 90181, 38042 Grenoble Cedex 9, France
| | - Irina Cornaciu
- European Molecular Biology Laboratory (EMBL) Grenoble, 71 Avenue des Martyrs CS 90181, 38042 Grenoble Cedex 9, France
| | - José A Márquez
- European Molecular Biology Laboratory (EMBL) Grenoble, 71 Avenue des Martyrs CS 90181, 38042 Grenoble Cedex 9, France
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium; VIB-VUB Center for Structural Biology, VIB, 1050 Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium; VIB-VUB Center for Structural Biology, VIB, 1050 Brussels, Belgium
| | - Christian Löw
- Center for Structural Systems Biology (CSSB), Notkestraße 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory (EMBL) Hamburg, Notkestraße 85, 22607 Hamburg, Germany.
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9
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Liu S, Sommese RF, Nedoma NL, Stevens LM, Dutra JK, Zhang L, Edmonds DJ, Wang Y, Garnsey M, Clasquin MF. Structural basis of lipid-droplet localization of 17-beta-hydroxysteroid dehydrogenase 13. Nat Commun 2023; 14:5158. [PMID: 37620305 PMCID: PMC10449848 DOI: 10.1038/s41467-023-40766-0] [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] [Received: 04/10/2023] [Accepted: 08/07/2023] [Indexed: 08/26/2023] Open
Abstract
Hydroxysteroid 17-beta-dehydrogenase 13 (HSD17B13) is a hepatic lipid droplet-associated enzyme that is upregulated in patients with non-alcoholic fatty liver disease. Recently, there have been several reports that predicted loss of function variants in HSD17B13 protect against the progression of steatosis to non-alcoholic steatohepatitis with fibrosis and hepatocellular carcinoma. Here we report crystal structures of full length HSD17B13 in complex with its NAD+ cofactor, and with lipid/detergent molecules and small molecule inhibitors from two distinct series in the ligand binding pocket. These structures provide insights into a mechanism for lipid droplet-associated proteins anchoring to membranes as well as a basis for HSD17B13 variants disrupting function. Two series of inhibitors interact with the active site residues and the bound cofactor similarly, yet they occupy different paths leading to the active site. These structures provide ideas for structure-based design of inhibitors that may be used in the treatment of liver disease.
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Affiliation(s)
- Shenping Liu
- Medicine Design, Pfizer Inc, Groton, CT, 06340, USA.
| | | | | | | | - Jason K Dutra
- Medicine Design, Pfizer Inc, Cambridge, MA, 02139, USA
| | - Liying Zhang
- Medicine Design, Pfizer Inc, Cambridge, MA, 02139, USA
- Discovery Chemistry, Merck Research Laboratories, Cambridge, MA, USA
| | - David J Edmonds
- Medicine Design, Pfizer Inc, Cambridge, MA, 02139, USA
- Medicinal Chemistry, Roche, Basel, Switzerland
| | - Yang Wang
- Medicine Design, Pfizer Inc, Cambridge, MA, 02139, USA
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Llowarch P, Usselmann L, Ivanov D, Holdgate GA. Thermal unfolding methods in drug discovery. BIOPHYSICS REVIEWS 2023; 4:021305. [PMID: 38510342 PMCID: PMC10903397 DOI: 10.1063/5.0144141] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 04/13/2023] [Indexed: 03/22/2024]
Abstract
Thermal unfolding methods, applied in both isolated protein and cell-based settings, are increasingly used to identify and characterize hits during early drug discovery. Technical developments over recent years have facilitated their application in high-throughput approaches, and they now are used more frequently for primary screening. Widespread access to instrumentation and automation, the ability to miniaturize, as well as the capability and capacity to generate the appropriate scale and quality of protein and cell reagents have all played a part in these advances. As the nature of drug targets and approaches to their modulation have evolved, these methods have broadened our ability to provide useful chemical start points. Target proteins without catalytic function, or those that may be difficult to express and purify, are amenable to these methods. Here, we provide a review of the applications of thermal unfolding methods applied in hit finding during early drug discovery.
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Affiliation(s)
- Poppy Llowarch
- High Throughput Screening, Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Alderley Park, United Kingdom
| | - Laura Usselmann
- High Throughput Screening, Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Alderley Park, United Kingdom
| | - Delyan Ivanov
- High Throughput Screening, Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Alderley Park, United Kingdom
| | - Geoffrey A. Holdgate
- High Throughput Screening, Hit Discovery, Discovery Sciences, R&D, AstraZeneca, Alderley Park, United Kingdom
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11
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Bai N, Adeshina Y, Bychkov I, Xia Y, Gowthaman R, Miller SA, Gupta AK, Johnson DK, Lan L, Golemis EA, Makhov PB, Xu L, Pillai MM, Boumber Y, Karanicolas J. Rationally designed inhibitors of the Musashi protein-RNA interaction by hotspot mimicry. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523326. [PMID: 36711508 PMCID: PMC9882015 DOI: 10.1101/2023.01.09.523326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
RNA-binding proteins (RBPs) are key post-transcriptional regulators of gene expression, and thus underlie many important biological processes. Here, we developed a strategy that entails extracting a "hotspot pharmacophore" from the structure of a protein-RNA complex, to create a template for designing small-molecule inhibitors and for exploring the selectivity of the resulting inhibitors. We demonstrate this approach by designing inhibitors of Musashi proteins MSI1 and MSI2, key regulators of mRNA stability and translation that are upregulated in many cancers. We report this novel series of MSI1/MSI2 inhibitors is specific and active in biochemical, biophysical, and cellular assays. This study extends the paradigm of "hotspots" from protein-protein complexes to protein-RNA complexes, supports the "druggability" of RNA-binding protein surfaces, and represents one of the first rationally-designed inhibitors of non-enzymatic RNA-binding proteins. Owing to its simplicity and generality, we anticipate that this approach may also be used to develop inhibitors of many other RNA-binding proteins; we also consider the prospects of identifying potential off-target interactions by searching for other RBPs that recognize their cognate RNAs using similar interaction geometries. Beyond inhibitors, we also expect that compounds designed using this approach can serve as warheads for new PROTACs that selectively degrade RNA-binding proteins.
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Affiliation(s)
- Nan Bai
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia PA 19111
- Department of Molecular Biosciences, University of Kansas, Lawrence KS 66045
| | - Yusuf Adeshina
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia PA 19111
- Center for Computational Biology, University of Kansas, Lawrence KS 66045
| | - Igor Bychkov
- Division of Hematology/Oncology, Department of Medicine, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Yan Xia
- Department of Molecular Biosciences, University of Kansas, Lawrence KS 66045
| | - Ragul Gowthaman
- Center for Computational Biology, University of Kansas, Lawrence KS 66045
| | - Sven A. Miller
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia PA 19111
| | | | - David K. Johnson
- Center for Computational Biology, University of Kansas, Lawrence KS 66045
| | - Lan Lan
- Department of Molecular Biosciences, University of Kansas, Lawrence KS 66045
| | - Erica A. Golemis
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia PA 19111
- Department of Cancer and Cellular Biology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140
| | - Petr B. Makhov
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia PA 19111
| | - Liang Xu
- Department of Molecular Biosciences, University of Kansas, Lawrence KS 66045
- Department of Radiation Oncology, University of Kansas Medical Center, Kansas City KS 66160
| | - Manoj M. Pillai
- Section of Hematology, Yale Cancer Center, New Haven CT 06520
- Department of Pathology, Yale University School of Medicine, New Haven CT 06520
| | - Yanis Boumber
- Division of Hematology/Oncology, Department of Medicine, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - John Karanicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia PA 19111
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, PA 19140
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12
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Esperante S, Alvarez-Paggi D, Salgueiro M, Desimone M, de Oliveira G, Arán M, García-Pardo J, Aptekmann A, Ventura S, Alonso L, de Prat-Gay G. A finely tuned interplay between calcium binding, ionic strength and pH modulates conformational and oligomerization equilibria in the Respiratory Syncytial Virus Matrix (M) protein. Arch Biochem Biophys 2022; 731:109424. [DOI: 10.1016/j.abb.2022.109424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/14/2022] [Accepted: 09/29/2022] [Indexed: 11/30/2022]
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13
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Sanchez TW, Ronzetti MH, Owens AE, Antony M, Voss T, Wallgren E, Talley D, Balakrishnan K, Leyes Porello SE, Rai G, Marugan JJ, Michael SG, Baljinnyam B, Southall N, Simeonov A, Henderson MJ. Real-Time Cellular Thermal Shift Assay to Monitor Target Engagement. ACS Chem Biol 2022; 17:2471-2482. [PMID: 36049119 PMCID: PMC9486815 DOI: 10.1021/acschembio.2c00334] [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] [Indexed: 01/19/2023]
Abstract
Determining a molecule's mechanism of action is paramount during chemical probe development and drug discovery. The cellular thermal shift assay (CETSA) is a valuable tool to confirm target engagement in cells for a small molecule that demonstrates a pharmacological effect. CETSA directly detects biophysical interactions between ligands and protein targets, which can alter a protein's unfolding and aggregation properties in response to thermal challenge. In traditional CETSA experiments, each temperature requires an individual sample, which restricts throughput and requires substantial optimization. To capture the full aggregation profile of a protein from a single sample, we developed a prototype real-time CETSA (RT-CETSA) platform by coupling a real-time PCR instrument with a CCD camera to detect luminescence. A thermally stable Nanoluciferase variant (ThermLuc) was bioengineered to withstand unfolding at temperatures greater than 90 °C and was compatible with monitoring target engagement events when fused to diverse targets. Utilizing well-characterized inhibitors of lactate dehydrogenase alpha, RT-CETSA showed significant correlation with enzymatic, biophysical, and other cell-based assays. A data analysis pipeline was developed to enhance the sensitivity of RT-CETSA to detect on-target binding. RT-CETSA technology advances capabilities of the CETSA method and facilitates the identification of ligand-target engagement in cells, a critical step in assessing the mechanism of action of a small molecule.
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14
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Allert MJ, Hellinga HW. Discovery of Thermostable, Fluorescently Responsive Glucose Biosensors by Structure-Assisted Function Extrapolation. Biochemistry 2022; 61:276-293. [PMID: 35084821 DOI: 10.1021/acs.biochem.1c00738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Accurate assignment of protein function from sequence remains a fascinating and difficult challenge. The periplasmic-binding protein (PBP) superfamily present an interesting case of function prediction because they are both ubiquitous in prokaryotes and tend to diversify through gene duplication "explosions" that can lead to large numbers of paralogs in a genome. An engineered version of the moderately thermostable glucose-binding PBP from Escherichia coli has been used successfully as a reagentless fluorescent biosensor both in vitro and in vivo. To develop more robust sensors that meet the challenges of real-world applications, we report the discovery of thermostable homologues that retain a glucose-mediated conformationally coupled fluorescence response. Accurately identifying a glucose-binding PBP homologue among closely related paralogs is challenging. We demonstrate that a structure-based method that filters sequences by residues that bind glucose in an archetype structure is highly effective. Using fully sequenced bacterial genomes, we found that this filter reduced high paralog numbers to single hits in a genome, consistent with the accurate separation of glucose binding from other functions. We expressed engineered proteins for eight homologues, chosen to represent different degrees of sequence identity, and tested their glucose-mediated fluorescence responses. We accurately predicted the presence of glucose binding down to 31% sequence identity. We have also successfully identified suitable candidates for next-generation robust, fluorescent glucose sensors.
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Affiliation(s)
- Malin J Allert
- Department of Biochemistry, Duke University Medical Center, Box 3711, Durham, North Carolina 27710, United States
| | - Homme W Hellinga
- Department of Biochemistry, Duke University Medical Center, Box 3711, Durham, North Carolina 27710, United States
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15
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Cundy NJ, Hare RK, Tang T, Leach AG, Jowitt TA, Qureshi O, Gordon J, Barnes NM, Brady CA, Raven EL, Grainger RS, Butterworth S. Design, synthesis and evaluation of tryptophan analogues as tool compounds to study IDO1 activity. RSC Chem Biol 2021; 2:1651-1660. [PMID: 34977580 PMCID: PMC8637876 DOI: 10.1039/d0cb00209g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 08/20/2021] [Indexed: 11/22/2022] Open
Abstract
The metabolism of l-tryptophan to N-formyl-l-kynurenine by indoleamine-2,3-dioxygenase 1 (IDO1) is thought to play a critical role in tumour-mediated immune suppression. Whilst there has been significant progress in elucidating the overall enzymatic mechanism of IDO1 and related enzymes, key aspects of the catalytic cycle remain poorly understood. Here we report the design, synthesis and biological evaluation of a series of tryptophan analogues which have the potential to intercept putative intermediates in the metabolism of 1 by IDO1. Functionally-relevant binding to IDO1 was demonstrated through enzymatic inhibition, however no IDO1-mediated metabolism of these compounds was observed. Subsequent T m-shift analysis shows the most active compound, 17, exhibits a distinct profile from known competitive IDO1 inhibitors, with docking studies supporting the hypothesis that 17 may bind at the recently-discovered Si site. These findings provide a start-point for development of further mechanistic probes and more potent tryptophan-based IDO1 inhibitors.
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Affiliation(s)
- Nicholas J Cundy
- School of Chemistry, University of Birmingham Edgbaston Birmingham B15 2TT UK
| | - Roseanna K Hare
- Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester Manchester M13 9PL UK
| | - Tina Tang
- Celentyx Ltd, Birmingham Research Park 97 Vincent Drive Birmingham B15 2SQ UK
| | - Andrew G Leach
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester Manchester M13 9PL UK
| | - Thomas A Jowitt
- Wellcome Trust Centre for Cell Matrix Research, Faculty of Biology, Medicine and Health, University of Manchester Manchester M13 9PL UK
| | - Omar Qureshi
- Celentyx Ltd, Birmingham Research Park 97 Vincent Drive Birmingham B15 2SQ UK
| | - John Gordon
- Celentyx Ltd, Birmingham Research Park 97 Vincent Drive Birmingham B15 2SQ UK
| | - Nicholas M Barnes
- Celentyx Ltd, Birmingham Research Park 97 Vincent Drive Birmingham B15 2SQ UK
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham Edgbaston Birmingham B15 2TT UK
| | - Catherine A Brady
- Celentyx Ltd, Birmingham Research Park 97 Vincent Drive Birmingham B15 2SQ UK
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham Edgbaston Birmingham B15 2TT UK
| | - Emma L Raven
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Richard S Grainger
- School of Chemistry, University of Birmingham Edgbaston Birmingham B15 2TT UK
| | - Sam Butterworth
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester Manchester M13 9PL UK
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16
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Cocaine binding to the Fab fragment of a humanized anti-cocaine mAb quantitated by dye absorption and fluorescence spectroscopy. J Immunol Methods 2021; 496:113103. [PMID: 34298065 DOI: 10.1016/j.jim.2021.113103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/13/2021] [Accepted: 07/16/2021] [Indexed: 11/21/2022]
Abstract
In this work, we establish that cocaine binding to the Fab fragment of a recombinant humanized anti-cocaine mAb (h2E2) can be directly and easily quantitated using simple and inexpensive absorption and fluorescence measurements, employing dyes typically used for differential scanning fluorimetry, DASPMI and SYPRO Orange. For concentrated samples of the Fab fragment, absorbance spectroscopy employing these dyes reveals the number of cocaine sites present, using either DASPMI (by measuring the increase in dye absorbance) or SYPRO Orange (by measuring the change in dye maximal absorbance wavelength). Interestingly, we observed that cocaine binding to the Fab fragment had a much different effect on the SYPRO Orange dye absorbance than previously reported for the intact h2E2 mAb, resulting in a large decrease in the total dye absorbance for the Fab fragment, in contrast to previous results with the intact h2E2 mAb. For dilute samples of Fab fragment, a dye fluorescence emission spectroscopy assay was developed to quantitate the number of cocaine (and other high affinity cocaine metabolites) binding sites via the ligand-induced decrease in fluorescence emission of both of these extrinsic dyes. The difference in the cocaine titrations for the high affinity (Kd < 30 nM) ligands, cocaine, cocaethylene and benzoylecgonine and the low affinity (Kd > 30 μM) ligands, norcocaine, ecgonine methyl ester, and ecgonine were obvious using this assay. These simple, direct, and inexpensive techniques should prove useful for evaluation of other small molecule antigen binding Fab fragments, enabling quantitation and rapid biochemical assessments necessary for determining Fab fragment suitability for in vivo uses and other assays and experiments.
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17
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Fröhlich C, Sørum V, Huber S, Samuelsen Ø, Berglund F, Kristiansson E, Kotsakis SD, Marathe NP, Larsson DGJ, Leiros HKS. Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1. J Antimicrob Chemother 2021; 75:2554-2563. [PMID: 32464640 PMCID: PMC7443720 DOI: 10.1093/jac/dkaa175] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/27/2020] [Accepted: 04/06/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND MBLs form a large and heterogeneous group of bacterial enzymes conferring resistance to β-lactam antibiotics, including carbapenems. A large environmental reservoir of MBLs has been identified, which can act as a source for transfer into human pathogens. Therefore, structural investigation of environmental and clinically rare MBLs can give new insights into structure-activity relationships to explore the role of catalytic and second shell residues, which are under selective pressure. OBJECTIVES To investigate the structure and activity of the environmental subclass B1 MBLs MYO-1, SHD-1 and ECV-1. METHODS The respective genes of these MBLs were cloned into vectors and expressed in Escherichia coli. Purified enzymes were characterized with respect to their catalytic efficiency (kcat/Km). The enzymatic activities and MICs were determined for a panel of different β-lactams, including penicillins, cephalosporins and carbapenems. Thermostability was measured and structures were solved using X-ray crystallography (MYO-1 and ECV-1) or generated by homology modelling (SHD-1). RESULTS Expression of the environmental MBLs in E. coli resulted in the characteristic MBL profile, not affecting aztreonam susceptibility and decreasing susceptibility to carbapenems, cephalosporins and penicillins. The purified enzymes showed variable catalytic activity in the order of <5% to ∼70% compared with the clinically widespread NDM-1. The thermostability of ECV-1 and SHD-1 was up to 8°C higher than that of MYO-1 and NDM-1. Using solved structures and molecular modelling, we identified differences in their second shell composition, possibly responsible for their relatively low hydrolytic activity. CONCLUSIONS These results show the importance of environmental species acting as reservoirs for MBL-encoding genes.
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Affiliation(s)
- Christopher Fröhlich
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT The Arctic University of Norway, Tromsø, Norway
| | - Vidar Sørum
- Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway
| | - Sandra Huber
- Department of Laboratory Medicine, University Hospital of North Norway, Tromsø, Norway
| | - Ørjan Samuelsen
- Department of Pharmacy, UiT The Arctic University of Norway, Tromsø, Norway.,Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
| | - Fanny Berglund
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - Erik Kristiansson
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - Stathis D Kotsakis
- Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - Nachiket P Marathe
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden.,Institute of Marine Research, Bergen, Norway
| | - D G Joakim Larsson
- Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - Hanna-Kirsti S Leiros
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, UiT The Arctic University of Norway, Tromsø, Norway
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18
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Atsavapranee B, Stark CD, Sunden F, Thompson S, Fordyce PM. Fundamentals to function: Quantitative and scalable approaches for measuring protein stability. Cell Syst 2021; 12:547-560. [PMID: 34139165 DOI: 10.1016/j.cels.2021.05.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/16/2021] [Accepted: 05/07/2021] [Indexed: 12/11/2022]
Abstract
Folding a linear chain of amino acids into a three-dimensional protein is a complex physical process that ultimately confers an impressive range of diverse functions. Although recent advances have driven significant progress in predicting three-dimensional protein structures from sequence, proteins are not static molecules. Rather, they exist as complex conformational ensembles defined by energy landscapes spanning the space of sequence and conditions. Quantitatively mapping the physical parameters that dictate these landscapes and protein stability is therefore critical to develop models that are capable of predicting how mutations alter function of proteins in disease and informing the design of proteins with desired functions. Here, we review the approaches that are used to quantify protein stability at a variety of scales, from returning multiple thermodynamic and kinetic measurements for a single protein sequence to yielding indirect insights into folding across a vast sequence space. The physical parameters derived from these approaches will provide a foundation for models that extend beyond the structural prediction to capture the complexity of conformational ensembles and, ultimately, their function.
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Affiliation(s)
| | - Catherine D Stark
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA; ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Fanny Sunden
- Department of Biochemistry, Stanford University, Stanford, CA 94305, USA
| | - Samuel Thompson
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
| | - Polly M Fordyce
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; ChEM-H, Stanford University, Stanford, CA 94305, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94110, USA.
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19
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Kazlauskas E, Petrauskas V, Paketurytė V, Matulis D. Standard operating procedure for fluorescent thermal shift assay (FTSA) for determination of protein-ligand binding and protein stability. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:373-379. [PMID: 33914114 DOI: 10.1007/s00249-021-01537-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/31/2021] [Accepted: 04/09/2021] [Indexed: 01/29/2023]
Abstract
A standard operating procedure for a fluorescence-based thermal shift assay (FTSA) is provided describing its typical applications, advantages and limitations. FTSA is a simple, robust, universal and quick assay to determine protein-ligand binding affinities and protein stabilities in the presence of various excipients and solution conditions. Therefore, the assay is very useful for the straightforward characterization of new recombinantly produced proteins. The assay has a wide dynamic range enabling simultaneous determination of affinities in the milimolar to picomolar range. The assay could be used for essentially any protein that is sufficiently soluble and stable in the studied aqueous solution. Here we provide examples and typical experimental protocols for both affinity and stability determinations.
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Affiliation(s)
- Egidijus Kazlauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, 10257, Vilnius, Lithuania
| | - Vytautas Petrauskas
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, 10257, Vilnius, Lithuania
| | - Vaida Paketurytė
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, 10257, Vilnius, Lithuania
| | - Daumantas Matulis
- Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio 7, 10257, Vilnius, Lithuania.
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20
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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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21
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Crossen J, Diamond SL. Thermal shift assay to probe melting of thrombin, fibrinogen, fibrin monomer, and fibrin: Gly-Pro-Arg-Pro induces a fibrin monomer-like state in fibrinogen. Biochim Biophys Acta Gen Subj 2021; 1865:129805. [PMID: 33276061 PMCID: PMC7752828 DOI: 10.1016/j.bbagen.2020.129805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/30/2020] [Accepted: 11/24/2020] [Indexed: 11/24/2022]
Abstract
BACKGROUND Thrombin activates fibrinogen and binds the fibrin E-domain (Kd ~ 2.8 μM) and the splice variant γ'-domain (Kd ~ 0.1 μM). We investigated if the loading of D-Phe-Pro-Arg-chloromethylketone inhibited thrombin (PPACK-thrombin) onto fibrin could enhance fibrin stability. METHODS A 384-well plate thermal shift assay (TSA) with SYPRO-orange provided melting temperatures (Tm) of thrombin, PPACK-thrombin, fibrinogen, fibrin monomer, and fibrin. RESULTS Large increases in Tm indicated that calcium led to protein stabilization (0 vs. 2 mM Ca2+) for fibrinogen (54.0 vs. 62.3 °C) and fibrin (62.3 vs. 72.2 °C). Additionally, active site inhibition with PPACK dramatically increased the Tm of thrombin (58.3 vs. 78.3 °C). Treatment of fibrinogen with fibrin polymerization inhibitor GPRP increased fibrinogen stability by ΔTm = 9.3 °C, similar to the ΔTm when fibrinogen was converted to fibrin monomer (ΔTm = 8.8 °C) or to fibrin (ΔTm = 10.4 °C). Addition of PPACK-thrombin at high 5:1 M ratio to fibrin(ogen) had little effect on fibrin(ogen) Tm values, indicating that thrombin binding does not detectably stabilize fibrin via a putative bivalent E-domain to γ'-domain interaction. CONCLUSIONS TSA was a sensitive assay of protein stability and detected: (1) the effects of calcium-stabilization, (2) thrombin active site labeling, (3) fibrinogen conversion to fibrin, and (4) GPRP induced changes in fibrinogen stability being essentially equivalent to that of fibrin monomer or polymerized fibrin. SIGNIFICANCE The low volume, high throughput assay has potential for use in understanding interactions with rare or mutant fibrin(ogen) variants.
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Affiliation(s)
- J Crossen
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States..
| | - S L Diamond
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, United States..
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22
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Kirley TL, Norman AB. Ligand binding to a humanized anti-cocaine mAb measured by dye absorption spectroscopy. Biochem Biophys Res Commun 2020; 535:93-98. [PMID: 33348081 DOI: 10.1016/j.bbrc.2020.12.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 12/09/2020] [Indexed: 12/21/2022]
Abstract
Here we demonstrate that the antigen binding function of a humanized anti-cocaine mAb (h2E2) can be directly and easily determined using simple and inexpensive absorption spectroscopy and dyes commonly used for differential scanning fluorimetry, such as DASPMI and SYPRO Orange. Therapeutic monoclonal antibodies are commonly formulated in buffers which can interfere with necessary functional assays, containing additives and excipients such as mild detergents. Using the undiluted therapeutic product h2E2 mAb in its formulation buffer containing 0.01% polysorbate 80, the number of antigen/cocaine binding sites can be determined by the increase in absorbance (for DASPMI dye) or by the decrease in absorbance maximum wavelength (for SYPRO Orange dye), confirming proper function of the therapeutic mAb product. This ligand-induced visible dye absorption change can also be used to qualitatively evaluate the relative affinities of various metabolites of cocaine. These results are confirmed and extended by binding data obtained in the same formulation buffer using intrinsic tyrosine and tryptophan fluorescence quenching by cocaine, as well as by differential scanning fluorimetry. Interestingly, the binding of the cocaine metabolite norcocaine was demonstrated to be differentially affected by the pH 6 formulation buffer used for this mAb, presumably due to the differential ionizability of the demethylated norcocaine tropane ring nitrogen. This simple, direct, and inexpensive technique should prove useful for evaluation of other small molecule binding mAbs directly in their formulation buffers containing detergent, allowing rapid functional assessment of the produced therapeutic proteins.
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Affiliation(s)
- Terence L Kirley
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA.
| | - Andrew B Norman
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267-0575, USA
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23
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Virdi RS, Bavisotto RV, Hopper NC, Vuksanovic N, Melkonian TR, Silvaggi NR, Frick DN. Discovery of Drug-Like Ligands for the Mac1 Domain of SARS-CoV-2 Nsp3. SLAS DISCOVERY 2020; 25:1162-1170. [PMID: 32981460 PMCID: PMC7684785 DOI: 10.1177/2472555220960428] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Small molecules that bind the SARS-CoV-2 nonstructural protein 3 Mac1 domain in place of ADP-ribose could be useful as molecular probes or scaffolds for COVID-19 antiviral drug discovery because Mac1 has been linked to the ability of coronaviruses to evade cellular detection. A high-throughput assay based on differential scanning fluorimetry (DSF) was therefore optimized and used to identify possible Mac1 ligands in small libraries of drugs and drug-like compounds. Numerous promising compounds included nucleotides, steroids, β-lactams, and benzimidazoles. The main drawback to this approach was that a high percentage of compounds in some libraries were found to influence the observed Mac1 melting temperature. To prioritize DSF screening hits, the shapes of the observed melting curves and initial assay fluorescence were examined, and the results were compared with virtual screens performed using AutoDock Vina. The molecular basis for alternate ligand binding was also examined by determining a structure of one of the hits, cyclic adenosine monophosphate, with atomic resolution.
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Affiliation(s)
- Rajdeep S Virdi
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Robert V Bavisotto
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Nicholas C Hopper
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Nemanja Vuksanovic
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Trevor R Melkonian
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Nicholas R Silvaggi
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - David N Frick
- Department of Chemistry and Biochemistry, The University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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24
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Virdi RS, Bavisotto RV, Hopper NC, Vuksanovic N, Melkonian TR, Silvaggi NR, Frick DN. Discovery of Drug-like Ligands for the Mac1 Domain of SARS-CoV-2 Nsp3. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 32676591 DOI: 10.1101/2020.07.06.190413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Small molecules that bind the SARS-CoV-2 non-structural protein 3 Mac1 domain in place of ADP-ribose could be useful as molecular probes or scaffolds for COVID-19 antiviral drug discovery because Mac1 has been linked to coronavirus' ability to evade cellular detection. A high-throughput assay based on differential scanning fluorimetry (DSF) was therefore optimized and used to identify possible Mac1 ligands in small libraries of drugs and drug-like compounds. Numerous promising compounds included nucleotides, steroids, beta-lactams, and benzimidazoles. The main drawback to this approach was that a high percentage of compounds in some libraries were found to influence the observed Mac1 melting temperature. To prioritize DSF screening hits, the shapes of the observed melting curves and initial assay fluorescence were examined, and the results were compared with virtual screens performed using Autodock VINA. The molecular basis for alternate ligand binding was also examined by determining a structure of one of the hits, cyclic adenosine monophosphate, with atomic resolution.
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25
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Khowsathit J, Bazzoli A, Cheng H, Karanicolas J. Computational Design of an Allosteric Antibody Switch by Deletion and Rescue of a Complex Structural Constellation. ACS CENTRAL SCIENCE 2020; 6:390-403. [PMID: 32232139 PMCID: PMC7099597 DOI: 10.1021/acscentsci.9b01065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Indexed: 05/08/2023]
Abstract
Therapeutic monoclonal antibodies have transformed medicine, especially with regards to treating cancers and disorders of the immune system. More than 50 antibody-derived drugs have already reached the clinic, the majority of which target cytokines or cell-surface receptors. Unfortunately, many of these targets have pleiotropic functions: they serve multiple different roles, and often not all of these roles are disease-related. This can be problematic because antibodies act throughout the body, and systemic neutralization of such targets can lead to safety concerns. To address this, we have developed a strategy whereby an antibody's ability to recognize its antigen is modulated by a second layer of control, relying on addition of an exogenous small molecule. In previous studies, we began to explore this idea by introducing a deactivating tryptophan-to-glycine mutation in the domain-domain interface of a single-chain variable fragment (scFv), and then restoring activity by adding back indole to fit the designed cavity. Here, we now describe a novel computational strategy for enumerating larger cavities that can be formed by simultaneously introducing multiple adjacent large-to-small mutations; we then carry out a complementary virtual screen to identify druglike compounds to match each candidate cavity. We first demonstrate the utility of this strategy in a fluorescein-binding single-chain variable fragment (scFv) and experimentally characterize a triple mutant with reduced antigen-binding (Rip-3) that can be rescued using a complementary ligand (Stitch-3). Because our design is built upon conserved residues in the antibody framework, we then show that the same mutation/ligand pair can also be used to modulate antigen-binding in an scFv build from a completely unrelated framework. This set of residues is present in many therapeutic antibodies as well, suggesting that this mutation/ligand pair may serve as a general starting point for introducing ligand-dependence into many clinically relevant antibodies.
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Affiliation(s)
- Jittasak Khowsathit
- Program
in Molecular Therapeutics, Fox Chase Cancer
Center, Philadelphia, Pennsylvania 19111, United States
- Department of Molecular
Biosciences and Center for Computational Biology, University
of Kansas, Lawrence, Kansas 66045, United
States
| | - Andrea Bazzoli
- Department of Molecular
Biosciences and Center for Computational Biology, University
of Kansas, Lawrence, Kansas 66045, United
States
| | - Hong Cheng
- Program
in Molecular Therapeutics, Fox Chase Cancer
Center, Philadelphia, Pennsylvania 19111, United States
| | - John Karanicolas
- Program
in Molecular Therapeutics, Fox Chase Cancer
Center, Philadelphia, Pennsylvania 19111, United States
- Department of Molecular
Biosciences and Center for Computational Biology, University
of Kansas, Lawrence, Kansas 66045, United
States
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26
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Wu KJ, Ho SH, Dong JY, Fu L, Wang SP, Liu H, Wu C, Leung CH, Wang HMD, Ma DL. Aliphatic Group-Tethered Iridium Complex as a Theranostic Agent against Malignant Melanoma Metastasis. ACS APPLIED BIO MATERIALS 2020; 3:2017-2027. [DOI: 10.1021/acsabm.9b01156] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ke-Jia Wu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa 999078, Macao SAR, China
| | - Shih-Hsin Ho
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Jia-Yi Dong
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa 999078, Macao SAR, China
| | - Ling Fu
- Graduate Institute of Biomedical Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Shuang-Peng Wang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa 999078, Macao SAR, China
| | - Hao Liu
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong 999077, Hong Kong, China
| | - Chun Wu
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong 999077, Hong Kong, China
| | - Chung-Hang Leung
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa 999078, Macao SAR, China
| | - Hui-Min David Wang
- Graduate Institute of Biomedical Engineering, National Chung Hsing University, Taichung 402, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung City 404, Taiwan
| | - Dik-Lung Ma
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong 999077, Hong Kong, China
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27
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Roslan AA, Kandandapani S, Ridzwan NFW, Mohamad SB, Tayyab S. Biophysical and computational approaches to unravel the molecular interaction mechanism of bromodeoxyuridine, a proliferative marker with human serum albumin. MONATSHEFTE FUR CHEMIE 2019. [DOI: 10.1007/s00706-019-02518-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Kirley TL, Norman AB, Wetzel HN. A novel differential scanning fluorimetry analysis of a humanized anti-cocaine mAb and its ligand binding characteristics. J Immunol Methods 2019; 476:112676. [PMID: 31634480 DOI: 10.1016/j.jim.2019.112676] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/24/2019] [Accepted: 09/25/2019] [Indexed: 02/02/2023]
Abstract
An anti-cocaine monoclonal antibody (mAb) designated h2E2 will soon enter clinical trials for the treatment of cocaine abuse disorders. Importantly, this antibody selectively binds cocaine and its active metabolite, cocaethylene, with high affinity, while binding inactive metabolites with substantially lower affinities. Here, we used differential scanning fluorimetry (DSF) to characterize the stability and ligand binding properties of this antibody and its cocaine-binding Fab fragment. The Sypro orange dye commonly used for DSF revealed multiple overlapping thermal protein denaturation transitions for both the mAb and the Fab fragment, making quantitative analysis of ligand binding by thermal stabilization problematic. However, by using the "rotor" dye, DASPMI (4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide), which measures the rotational restriction of the fluorescent dye (as opposed to the Sypro orange dye which measures the hydrophobicity of the dye microenvironment), a simple two state thermal denaturation transition that is stabilized by ligand binding was observed for the h2E2 mAb, enabling Boltzmann fitting and quantitative thermodynamic analysis of the DASPMI DSF mAb cocaine and metabolite binding data. The computed affinities were consistent with ligand binding affinities determined using other techniques. Thus, this novel DASPMI DSF method can simply, inexpensively, and very rapidly generate ligand binding constants for the h2E2 mAb, despite the presence of multiple, overlapping, thermally unfolding protein domains characteristic of all mAbs. This approach is likely applicable to other mAbs currently in use for many research and therapeutic applications.
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Affiliation(s)
- Terence L Kirley
- From the Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267-0575, United States of America.
| | - Andrew B Norman
- From the Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267-0575, United States of America
| | - Hanna N Wetzel
- From the Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267-0575, United States of America
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29
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Hall J. A simple model for determining affinity from irreversible thermal shifts. Protein Sci 2019; 28:1880-1887. [PMID: 31361943 PMCID: PMC6739816 DOI: 10.1002/pro.3701] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/25/2019] [Accepted: 07/25/2019] [Indexed: 11/23/2022]
Abstract
Thermal denaturation (Tm) data are easy to obtain; it is a technique that is used by both small labs and large‐scale industrial organizations. The link between ligand affinity (KD) and ΔTm is understood for reversible denaturation; however, there is a gap in our understanding of how to quantitatively interpret ΔTm for the many proteins that irreversibly denature. To better understand the origin, and extent of applicability, of a KD to ΔTm correlate, we define equations relating KD and ΔTm for irreversible protein unfolding, which we test with computational models and experimental data. These results suggest a general relationship exists between KD and ΔTm for irreversible denaturation.
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Affiliation(s)
- Justin Hall
- Worldwide Medicinal Chemistry, Pfizer, Groton, Connecticut
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30
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Determination of Ligand Binding Affinity and Specificity of Purified START Domains by Thermal Shift Assays Using Circular Dichroism. Methods Mol Biol 2019. [PMID: 30790263 DOI: 10.1007/978-1-4939-9136-5_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2023]
Abstract
The use of direct calorimetric methods such as isothermal titration calorimetry for measuring the affinity and specificity of protein-ligand interactions requires large amounts of proteins and ligands. When material is scarce and/or in the absence of calorimeters, thermal Shift Assays (TSA) using Circular Dichroism (CD) or other spectroscopic methods offers an alternative and quantitative method for the determination of apparent or indirect thermodynamical parameters describing the affinity of ligands for proteins. Indeed, the binding constants of ligands (Kb) and other parameters such as the enthalpy and Gibbs free energy of binding may be estimated from the changes in the stability curves ΔGu(T) of a protein in the presence of a ligand. Here we describe the application of two different procedures proposed by Layton and Hellinga et al. (Biochemistry 49:10831-10841, 2010) to evaluate the apparent Kb of testosterone to the START (StAR-related lipid transfer domain) domains.
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31
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Biswas A, Ghosh S, Sinha D, Dutta A, Seal S, Bagchi A, Sau S. Dimerization ability, denaturation mechanism, and the stability of a staphylococcal phage repressor and its two domains. Int J Biol Macromol 2019; 124:903-914. [DOI: 10.1016/j.ijbiomac.2018.11.263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 11/29/2022]
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32
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Bai N, Roder H, Dickson A, Karanicolas J. Isothermal Analysis of ThermoFluor Data can readily provide Quantitative Binding Affinities. Sci Rep 2019; 9:2650. [PMID: 30804351 PMCID: PMC6389909 DOI: 10.1038/s41598-018-37072-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/30/2018] [Indexed: 01/20/2023] Open
Abstract
Differential scanning fluorimetry (DSF), also known as ThermoFluor or Thermal Shift Assay, has become a commonly-used approach for detecting protein-ligand interactions, particularly in the context of fragment screening. Upon binding to a folded protein, most ligands stabilize the protein; thus, observing an increase in the temperature at which the protein unfolds as a function of ligand concentration can serve as evidence of a direct interaction. While experimental protocols for this assay are well-developed, it is not straightforward to extract binding constants from the resulting data. Because of this, DSF is often used to probe for an interaction, but not to quantify the corresponding binding constant (Kd). Here, we propose a new approach for analyzing DSF data. Using unfolding curves at varying ligand concentrations, our "isothermal" approach collects from these the fraction of protein that is folded at a single temperature (chosen to be temperature near the unfolding transition). This greatly simplifies the subsequent analysis, because it circumvents the complicating temperature dependence of the binding constant; the resulting constant-temperature system can then be described as a pair of coupled equilibria (protein folding/unfolding and ligand binding/unbinding). The temperature at which the binding constants are determined can also be tuned, by adding chemical denaturants that shift the protein unfolding temperature. We demonstrate the application of this isothermal analysis using experimental data for maltose binding protein binding to maltose, and for two carbonic anhydrase isoforms binding to each of four inhibitors. To facilitate adoption of this new approach, we provide a free and easy-to-use Python program that analyzes thermal unfolding data and implements the isothermal approach described herein ( https://sourceforge.net/projects/dsf-fitting ).
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Affiliation(s)
- Nan Bai
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA
| | - Heinrich Roder
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Alex Dickson
- Department of Biochemistry & Molecular Biology and Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - John Karanicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
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33
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Deore PS, Manderville RA. Aptamer-induced thermofluorimetric protein stabilization and G-quadruplex nucleic acid staining by SYPRO orange dye. NEW J CHEM 2019. [DOI: 10.1039/c9nj00188c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Serendipitously discovered nucleic acid staining by SYPRO Orange dye utilized to demonstrate proteins thermal stabilization (increase in melting temperature,Tm) as a function of increased DNA aptamer binding affinity (decrease in dissociation constant,Kd).
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Affiliation(s)
- Prashant S. Deore
- Departments of Chemistry & Toxicology
- University of Guelph
- Guelph
- Canada
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34
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Sperandio D, Aktoudianakis V, Babaoglu K, Chen X, Elbel K, Chin G, Corkey B, Du J, Jiang B, Kobayashi T, Mackman R, Martinez R, Yang H, Zablocki J, Kusam S, Jordan K, Webb H, Bates JG, Lad L, Mish M, Niedziela-Majka A, Metobo S, Sapre A, Hung M, Jin D, Fung W, Kan E, Eisenberg G, Larson N, Newby ZER, Lansdon E, Tay C, Neve RM, Shevick SL, Breckenridge DG. Structure-guided discovery of a novel, potent, and orally bioavailable 3,5-dimethylisoxazole aryl-benzimidazole BET bromodomain inhibitor. Bioorg Med Chem 2018; 27:457-469. [PMID: 30606676 DOI: 10.1016/j.bmc.2018.11.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 12/12/2022]
Abstract
The bromodomain and extra-terminal (BET) family of proteins, consisting of the bromodomains containing protein 2 (BRD2), BRD3, BRD4, and the testis-specific BRDT, are key epigenetic regulators of gene transcription and has emerged as an attractive target for anticancer therapy. Herein, we describe the discovery of a novel potent BET bromodomain inhibitor, using a systematic structure-based approach focused on improving potency, metabolic stability, and permeability. The optimized dimethylisoxazole aryl-benzimidazole inhibitor exhibited high potency towards BRD4 and related BET proteins in biochemical and cell-based assays and inhibited tumor growth in two proof-of-concept preclinical animal models.
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Affiliation(s)
- David Sperandio
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA.
| | - Vangelis Aktoudianakis
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Kerim Babaoglu
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Xiaowu Chen
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Kristyna Elbel
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Gregory Chin
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Britton Corkey
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Jinfa Du
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Bob Jiang
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Tetsuya Kobayashi
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Richard Mackman
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Ruben Martinez
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Hai Yang
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Jeff Zablocki
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Saritha Kusam
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Kim Jordan
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Heather Webb
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Jamie G Bates
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Latesh Lad
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Michael Mish
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Anita Niedziela-Majka
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Sammy Metobo
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Annapurna Sapre
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Magdeleine Hung
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Debi Jin
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Wanchi Fung
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Elaine Kan
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Gene Eisenberg
- Department of Drug Metabolism, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Nate Larson
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Zachary E R Newby
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Eric Lansdon
- Department of Structural Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Chin Tay
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Richard M Neve
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Sophia L Shevick
- Department of Medicinal Chemistry, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
| | - David G Breckenridge
- Department of Biology, Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA 94404, USA
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35
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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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36
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Campe R, Hollenbach E, Kämmerer L, Hendriks J, Höffken HW, Kraus H, Lerchl J, Mietzner T, Tresch S, Witschel M, Hutzler J. A new herbicidal site of action: Cinmethylin binds to acyl-ACP thioesterase and inhibits plant fatty acid biosynthesis. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2018; 148:116-125. [PMID: 29891362 DOI: 10.1016/j.pestbp.2018.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 05/16/2023]
Abstract
The prevalent occurrence of herbicide resistant weeds increases the necessity for new site of action herbicides for effective control as well as to relax selection pressure on the known sites of action. As a consequence, interest increased in the unexploited molecule cinmethylin as a new solution for the control of weedy grasses in cereals. Therefore, the mechanism of action of cinmethylin was reevaluated. We applied the chemoproteomic approach cellular Target Profiling™ from Evotec to identify the cinmethylin target in Lemna paucicostata protein extracts. We found three potential targets belonging to the same protein family of fatty acid thioesterases (FAT) to bind to cinmethylin with high affinity. Binding of cinmethylin to FAT proteins from Lemna and Arabidopsis was confirmed by fluorescence-based thermal shift assay. The plastid localized enzyme FAT plays a crucial role in plant lipid biosynthesis, by mediating the release of fatty acids (FA) from its acyl carrier protein (ACP) which is necessary for FA export to the endoplasmic reticulum. GC-MS analysis of free FA composition in Lemna extracts revealed strong reduction of unsaturated C18 as well as saturated C14, and C16 FAs upon treatment with cinmethylin, indicating that FA release for subsequent lipid biosynthesis is the primary target of cinmethylin. Lipid biosynthesis is a prominent target of different herbicide classes. To assess whether FAT inhibition constitutes a new mechanism of action within this complex pathway, we compared physiological effects of cinmethylin to different ACCase and VLCFA synthesis inhibitors and identified characteristic differences in plant symptomology and free FA composition upon treatment with the three herbicide classes. Also, principal component analysis of total metabolic profiling of treated Lemna plants showed strong differences in overall metabolic changes after cinmethylin, ACCase or VLCFA inhibitor treatments. Our results identified and confirmed FAT as the cinmethylin target and validate FAT inhibition as a new site of action different from other lipid biosynthesis inhibitor classes.
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Affiliation(s)
- Ruth Campe
- BASF SE, Speyerer Straße 2, D-67117 Limburgerhof, Germany.
| | - Eva Hollenbach
- BASF SE, Speyerer Straße 2, D-67117 Limburgerhof, Germany
| | - Lara Kämmerer
- BASF SE, Speyerer Straße 2, D-67117 Limburgerhof, Germany
| | | | | | - Helmut Kraus
- BASF Corporation, 26 Davis Drive, Research Triangle Park, 27709-3528 NC, United States
| | - Jens Lerchl
- BASF SE, Speyerer Straße 2, D-67117 Limburgerhof, Germany
| | - Thomas Mietzner
- BASF SE, Carl Bosch Straße 38, D-67056 Ludwigshafen, Germany
| | - Stefan Tresch
- BASF SE, Carl Bosch Straße 38, D-67056 Ludwigshafen, Germany
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Mazal H, Aviram H, Riven I, Haran G. Effect of ligand binding on a protein with a complex folding landscape. Phys Chem Chem Phys 2018; 20:3054-3062. [PMID: 28721412 DOI: 10.1039/c7cp03327c] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ligand binding to a protein can stabilize it significantly against unfolding. The variation of the folding free energy, ΔΔG0, due to ligand binding can be derived from a simple reaction scheme involving exclusive binding to the native state. One obtains the following expression: , where Kd is the ligand dissociation constant and L is its concentration, R is the universal gas constant and T is the temperature. This expression has been shown to correctly describe experimental results on multiple proteins. In the current work we studied the effect of ligand binding on the stability of the multi-domain protein adenylate kinase from E. coli (AKE). Unfolding experiments were conducted using single-molecule FRET spectroscopy, which allowed us to directly obtain the fraction of unfolded protein in a model-free way from FRET efficiency histograms. Surprisingly, it was found that the effect of two inhibitors (Ap5A and AMPPNP) and a substrate (AMP) on the stability of AKE was much smaller than expected based on Kd values obtained independently using microscale thermophoresis. To shed light on this issue, we measured the Kd for Ap5A over a range of chemical denaturant concentrations where the protein is still folded. It was found that Kd increases dramatically over this range, likely due to the population of folding intermediates, whose binding to the ligand is much weaker than that of the native state. We propose that binding to folding intermediates may dominate the effect of ligands on the stability of multi-domain proteins, and could therefore have a strong impact on protein homeostasis in vivo.
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Affiliation(s)
- Hisham Mazal
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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Choudhary D, Kumar A, Magliery TJ, Sotomayor M. Using thermal scanning assays to test protein-protein interactions of inner-ear cadherins. PLoS One 2017; 12:e0189546. [PMID: 29261728 PMCID: PMC5736220 DOI: 10.1371/journal.pone.0189546] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/27/2017] [Indexed: 12/15/2022] Open
Abstract
Protein-protein interactions play a crucial role in biological processes such as cell-cell adhesion, immune system-pathogen interactions, and sensory perception. Understanding the structural determinants of protein-protein complex formation and obtaining quantitative estimates of their dissociation constant (KD) are essential for the study of these interactions and for the discovery of new therapeutics. At the same time, it is equally important to characterize protein-protein interactions in a high-throughput fashion. Here, we use a modified thermal scanning assay to test interactions of wild type (WT) and mutant variants of N-terminal fragments (EC1+2) of cadherin-23 and protocadherin-15, two proteins essential for inner-ear mechanotransduction. An environmentally sensitive fluorescent dye (SYPRO orange) is used to monitor melting temperature (Tm) shifts of protocadherin-15 EC1+2 (pcdh15) in the presence of increasing concentrations of cadherin-23 EC1+2 (cdh23). These Tm shifts are absent when we use proteins containing deafness-related missense mutations known to disrupt cdh23 binding to pcdh15, and are increased for some rationally designed mutants expected to enhance binding. In addition, surface plasmon resonance binding experiments were used to test if the Tm shifts correlated with changes in binding affinity. We used this approach to find a double mutation (cdh23(T15E)- pcdh15(G16D)) that enhances binding affinity of the cadherin complex by 1.98 kJ/mol, roughly two-fold that of the WT complex. We suggest that the thermal scanning methodology can be used in high-throughput format to quickly compare binding affinities (KD from nM up to 100 μM) for some heterodimeric protein complexes and to screen small molecule libraries to find protein-protein interaction inhibitors and enhancers.
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Affiliation(s)
- Deepanshu Choudhary
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Anusha Kumar
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Thomas J. Magliery
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
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Ernits K, Viigand K, Visnapuu T, Põšnograjeva K, Alamäe T. Thermostability Measurement of an α-Glucosidase Using a Classical Activity-based Assay and a Novel Thermofluor Method. Bio Protoc 2017; 7:e2349. [PMID: 34541099 DOI: 10.21769/bioprotoc.2349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 05/02/2017] [Accepted: 05/21/2017] [Indexed: 11/02/2022] Open
Abstract
α-glucosidases (including maltases and isomaltases) are enzymes which release glucose from a set of α-glucosidic substrates. Their catalytic activity, substrate specificity and thermostability can be assayed using this trait. Thermostability of proteins can also be determined using a high-throughput differential scanning fluorometry method, also named Thermofluor. We have shown that Thermofluor can also be applied to predict binding of substrates and inhibitors to a yeast α-glucosidase. The methods described here in detail were used in Viigand et al., 2016 .
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Affiliation(s)
- Karin Ernits
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Katrin Viigand
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Triinu Visnapuu
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | | | - Tiina Alamäe
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
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Chilton M, Clennell B, Edfeldt F, Geschwindner S. Hot-Spotting with Thermal Scanning: A Ligand- and Structure-Independent Assessment of Target Ligandability. J Med Chem 2017; 60:4923-4931. [PMID: 28537726 DOI: 10.1021/acs.jmedchem.7b00208] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Evaluating the ligandability of a protein target is a key component when defining hit-finding strategies or when prioritize among drug targets. Computational as well as biophysical approaches based on nuclear magnetic resonance (NMR) fragment screening are powerful approaches but suffer from specific constraints that limit their usage. Here, we demonstrate the applicability of high-throughput thermal scanning (HTTS) as a simple and generic biophysical fragment screening method to reproduce assessments from NMR-based screening. By applying this method to a large set of proteins we can furthermore show that the assessment is predictive of the success of high-throughput screening (HTS). The few divergences for targets of low ligandability originate from the sensitivity differences of the orthogonal biophysical methods. We thus applied a new strategy making use of modulations in the solvent structure to improve assay sensitivity. This novel approach enables improved ligandability assessments in accordance with NMR-based assessments and more importantly positions the methodology as a valuable option for biophysical fragment screening.
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Affiliation(s)
- Molly Chilton
- Innovative Medicines and Early Development Biotech Unit, Discovery Sciences, AstraZeneca R&D Gothenburg , 43183 Mölndal, Sweden
| | - Ben Clennell
- Innovative Medicines and Early Development Biotech Unit, Discovery Sciences, AstraZeneca R&D Gothenburg , 43183 Mölndal, Sweden
| | - Fredrik Edfeldt
- Innovative Medicines and Early Development Biotech Unit, Discovery Sciences, AstraZeneca R&D Gothenburg , 43183 Mölndal, Sweden
| | - Stefan Geschwindner
- Innovative Medicines and Early Development Biotech Unit, Discovery Sciences, AstraZeneca R&D Gothenburg , 43183 Mölndal, Sweden
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41
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Pacouret S, Bouzelha M, Shelke R, Andres-Mateos E, Xiao R, Maurer A, Mevel M, Turunen H, Barungi T, Penaud-Budloo M, Broucque F, Blouin V, Moullier P, Ayuso E, Vandenberghe LH. AAV-ID: A Rapid and Robust Assay for Batch-to-Batch Consistency Evaluation of AAV Preparations. Mol Ther 2017; 25:1375-1386. [PMID: 28427840 DOI: 10.1016/j.ymthe.2017.04.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/29/2017] [Accepted: 04/01/2017] [Indexed: 12/12/2022] Open
Abstract
Adeno-associated virus (AAV) vectors are promising clinical candidates for therapeutic gene transfer, and a number of AAV-based drugs may emerge on the market over the coming years. To insure the consistency in efficacy and safety of any drug vial that reaches the patient, regulatory agencies require extensive characterization of the final product. Identity is a key characteristic of a therapeutic product, as it ensures its proper labeling and batch-to-batch consistency. Currently, there is no facile, fast, and robust characterization assay enabling to probe the identity of AAV products at the protein level. Here, we investigated whether the thermostability of AAV particles could inform us on the composition of vector preparations. AAV-ID, an assay based on differential scanning fluorimetry (DSF), was evaluated in two AAV research laboratories for specificity, sensitivity, and reproducibility, for six different serotypes (AAV1, 2, 5, 6.2, 8, and 9), using 67 randomly selected AAV preparations. In addition to enabling discrimination of AAV serotypes based on their melting temperatures, the obtained fluorescent fingerprints also provided information on sample homogeneity, particle concentration, and buffer composition. Our data support the use of AAV-ID as a reproducible, fast, and low-cost method to ensure batch-to-batch consistency in manufacturing facilities and academic laboratories.
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Affiliation(s)
- Simon Pacouret
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA; Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Mohammed Bouzelha
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Rajani Shelke
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA
| | - Eva Andres-Mateos
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA
| | - Ru Xiao
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA
| | - Anna Maurer
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA; Biological and Biomedical Sciences Program, Division of Medical Sciences, Harvard Medical School, Boston, MA 02115, USA
| | - Mathieu Mevel
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Heikki Turunen
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA
| | - Trisha Barungi
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA
| | - Magalie Penaud-Budloo
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Frédéric Broucque
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Véronique Blouin
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Philippe Moullier
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Eduard Ayuso
- Atlantic Gene Therapies, INSERM UMR 1089, University of Nantes, Nantes University Hospital, 22 Boulevard Benoni Goullin, 44200 Nantes, France
| | - Luk H Vandenberghe
- Grousbeck Gene Therapy Center, 20 Staniford Street, Boston, MA 02114, USA; Department of Ophthalmology, Ocular Genomics Institute, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA; Schepens Eye Research Institute, 20 Staniford Street, Boston MA 02114, USA; Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
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42
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Kübler D, Bergmann A, Weger L, Ingenbosch KN, Hoffmann-Jacobsen K. Kinetics of Detergent-Induced Activation and Inhibition of a Minimal Lipase. J Phys Chem B 2017; 121:1248-1257. [DOI: 10.1021/acs.jpcb.6b11037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel Kübler
- Department of Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798 Krefeld, Germany
| | - Anna Bergmann
- Department of Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798 Krefeld, Germany
| | - Lukas Weger
- Department of Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798 Krefeld, Germany
| | - Kim N. Ingenbosch
- Department of Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798 Krefeld, Germany
| | - Kerstin Hoffmann-Jacobsen
- Department of Chemistry, Niederrhein University of Applied Sciences, Adlerstr. 32, 47798 Krefeld, Germany
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43
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Milani M, Byrne DP, Greaves G, Butterworth M, Cohen GM, Eyers PA, Varadarajan S. DRP-1 is required for BH3 mimetic-mediated mitochondrial fragmentation and apoptosis. Cell Death Dis 2017; 8:e2552. [PMID: 28079887 PMCID: PMC5386385 DOI: 10.1038/cddis.2016.485] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 12/16/2016] [Indexed: 01/01/2023]
Abstract
The concept of using BH3 mimetics as anticancer agents has been substantiated by the efficacy of selective drugs, such as Navitoclax and Venetoclax, in treating BCL-2-dependent haematological malignancies. However, most solid tumours depend on MCL-1 for survival, which is highly amplified in multiple cancers and a major factor determining chemoresistance. Most MCL-1 inhibitors that have been generated so far, while demonstrating early promise in vitro, fail to exhibit specificity and potency in a cellular context. To address the lack of standardised assays for benchmarking the in vitro binding of putative inhibitors before analysis of their cellular effects, we developed a rapid differential scanning fluorimetry (DSF)-based assay, and used it to screen a panel of BH3 mimetics. We next contrasted their binding signatures with their ability to induce apoptosis in a MCL-1 dependent cell line. Of all the MCL-1 inhibitors tested, only A-1210477 induced rapid, concentration-dependent apoptosis, which strongly correlated with a thermal protective effect on MCL-1 in the DSF assay. In cells that depend on both MCL-1 and BCL-XL, A-1210477 exhibited marked synergy with A-1331852, a BCL-XL specific inhibitor, to induce cell death. Despite this selectivity and potency, A-1210477 induced profound structural changes in the mitochondrial network in several cell lines that were not phenocopied following MCL-1 RNA interference or transcriptional repression, suggesting that A-1210477 induces mitochondrial fragmentation in an MCL-1-independent manner. However, A-1210477-induced mitochondrial fragmentation was dependent upon DRP-1, and silencing expression levels of DRP-1 diminished not just mitochondrial fragmentation but also BH3 mimetic-mediated apoptosis. These findings provide new insights into MCL-1 ligands, and the interplay between DRP-1 and the anti-apoptotic BCL-2 family members in the regulation of apoptosis.
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Affiliation(s)
- Mateus Milani
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
| | - Dominic P Byrne
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Georgia Greaves
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
| | - Michael Butterworth
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
| | - Gerald M Cohen
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, Ashton Street, Liverpool L69 3GE, UK
| | - Patrick A Eyers
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Shankar Varadarajan
- Department of Molecular and Clinical Cancer Medicine, Institute of Translational Medicine, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, Ashton Street, Liverpool L69 3GE, UK
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44
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Physical and molecular bases of protein thermal stability and cold adaptation. Curr Opin Struct Biol 2016; 42:117-128. [PMID: 28040640 DOI: 10.1016/j.sbi.2016.12.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 11/15/2016] [Accepted: 12/11/2016] [Indexed: 11/20/2022]
Abstract
The molecular bases of thermal and cold stability and adaptation, which allow proteins to remain folded and functional in the temperature ranges in which their host organisms live and grow, are still only partially elucidated. Indeed, both experimental and computational studies fail to yield a fully precise and global physical picture, essentially because all effects are context-dependent and thus quite intricate to unravel. We present a snapshot of the current state of knowledge of this highly complex and challenging issue, whose resolution would enable large-scale rational protein design.
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45
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Thermodynamic properties of leukotriene A 4 hydrolase inhibitors. Bioorg Med Chem 2016; 24:5243-5248. [DOI: 10.1016/j.bmc.2016.08.047] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/20/2016] [Accepted: 08/25/2016] [Indexed: 02/03/2023]
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46
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Motamedi-Shad N, Jagger AM, Liedtke M, Faull SV, Nanda AS, Salvadori E, Wort JL, Kay CW, Heyer-Chauhan N, Miranda E, Perez J, Ordóñez A, Haq I, Irving JA, Lomas DA. An antibody that prevents serpin polymerisation acts by inducing a novel allosteric behaviour. Biochem J 2016; 473:3269-90. [PMID: 27407165 PMCID: PMC5264506 DOI: 10.1042/bcj20160159] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 07/08/2016] [Accepted: 07/12/2016] [Indexed: 11/30/2022]
Abstract
Serpins are important regulators of proteolytic pathways with an antiprotease activity that involves a conformational transition from a metastable to a hyperstable state. Certain mutations permit the transition to occur in the absence of a protease; when associated with an intermolecular interaction, this yields linear polymers of hyperstable serpin molecules, which accumulate at the site of synthesis. This is the basis of many pathologies termed the serpinopathies. We have previously identified a monoclonal antibody (mAb4B12) that, in single-chain form, blocks α1-antitrypsin (α1-AT) polymerisation in cells. Here, we describe the structural basis for this activity. The mAb4B12 epitope was found to encompass residues Glu32, Glu39 and His43 on helix A and Leu306 on helix I. This is not a region typically associated with the serpin mechanism of conformational change, and correspondingly the epitope was present in all tested structural forms of the protein. Antibody binding rendered β-sheet A - on the opposite face of the molecule - more liable to adopt an 'open' state, mediated by changes distal to the breach region and proximal to helix F. The allosteric propagation of induced changes through the molecule was evidenced by an increased rate of peptide incorporation and destabilisation of a preformed serpin-enzyme complex following mAb4B12 binding. These data suggest that prematurely shifting the β-sheet A equilibrium towards the 'open' state out of sequence with other changes suppresses polymer formation. This work identifies a region potentially exploitable for a rational design of ligands that is able to dynamically influence α1-AT polymerisation.
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Affiliation(s)
- Neda Motamedi-Shad
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - Alistair M. Jagger
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - Maximilian Liedtke
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
| | - Sarah V. Faull
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge CB2 0XY, U.K
| | - Arjun Scott Nanda
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - Enrico Salvadori
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
- London Centre for Nanotechnology, 17-19 Gordon Street, London WC1H 0AH, U.K
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, U.K
| | - Joshua L. Wort
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - Christopher W.M. Kay
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
- London Centre for Nanotechnology, 17-19 Gordon Street, London WC1H 0AH, U.K
| | - Narinder Heyer-Chauhan
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - Elena Miranda
- Department of Biology and Biotechnologies ‘Charles Darwin’, Sapienza University of Rome, Rome 00185, Italy
| | - Juan Perez
- Departamento de Biologia Celular, Genetica y Fisiologia, Facultad de Ciencias, Campus Teatinos, Universidad de Malaga, Malaga 29071, Spain
| | - Adriana Ordóñez
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge CB2 0XY, U.K
| | - Imran Haq
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - James A. Irving
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
| | - David A. Lomas
- Centre for Respiratory Biology, UCL Respiratory, University College London, London WC1E 6JF, U.K
- Institute of Structural and Molecular Biology/Birkbeck, University of London, London WC1E 7HX, U.K
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47
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Ca-asp bound X-ray structure and inhibition of Bacillus anthracis dihydroorotase (DHOase). Bioorg Med Chem 2016; 24:4536-4543. [PMID: 27499369 DOI: 10.1016/j.bmc.2016.07.055] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 01/01/2023]
Abstract
Dihydroorotase (DHOase) is the third enzyme in the de novo pyrimidine synthesis pathway and is responsible for the reversible cyclization of carbamyl-aspartate (Ca-asp) to dihydroorotate (DHO). DHOase is further divided into two classes based on several structural characteristics, one of which is the length of the flexible catalytic loop that interacts with the substrate, Ca-asp, regulating the enzyme activity. Here, we present the crystal structure of Class I Bacillus anthracis DHOase with Ca-asp in the active site, which shows the peptide backbone of glycine in the shorter loop forming the necessary hydrogen bonds with the substrate, in place of the two threonines found in Class II DHOases. Despite the differences in the catalytic loop, the structure confirms that the key interactions between the substrate and active site residues are similar between Class I and Class II DHOase enzymes, which we further validated by mutagenesis studies. B. anthracis DHOase is also a potential antibacterial drug target. In order to identify prospective inhibitors, we performed high-throughput screening against several libraries using a colorimetric enzymatic assay and an orthogonal fluorescence thermal binding assay. Surface plasmon resonance was used for determining binding affinity (KD) and competition analysis with Ca-asp. Our results highlight that the primary difference between Class I and Class II DHOase is the catalytic loop. We also identify several compounds that can potentially be further optimized as potential B. anthracis inhibitors.
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STARD6 on steroids: solution structure, multiple timescale backbone dynamics and ligand binding mechanism. Sci Rep 2016; 6:28486. [PMID: 27340016 PMCID: PMC4919784 DOI: 10.1038/srep28486] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 06/03/2016] [Indexed: 12/17/2022] Open
Abstract
START domain proteins are conserved α/β helix-grip fold that play a role in the non-vesicular and intracellular transport of lipids and sterols. The mechanism and conformational changes permitting the entry of the ligand into their buried binding sites is not well understood. Moreover, their functions and the identification of cognate ligands is still an active area of research. Here, we report the solution structure of STARD6 and the characterization of its backbone dynamics on multiple time-scales through 15N spin-relaxation and amide exchange studies. We reveal for the first time the presence of concerted fluctuations in the Ω1 loop and the C-terminal helix on the microsecond-millisecond time-scale that allows for the opening of the binding site and ligand entry. We also report that STARD6 binds specifically testosterone. Our work represents a milestone for the study of ligand binding mechanism by other START domains and the elucidation of the biological function of STARD6.
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An effective thiol-reactive probe for differential scanning fluorimetry with a standard real-time polymerase chain reaction device. Anal Biochem 2016; 499:63-65. [PMID: 26851339 DOI: 10.1016/j.ab.2016.01.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 01/25/2016] [Indexed: 11/20/2022]
Abstract
Differential scanning fluorimetry (DSF) is used to assess protein stability, transition states, or the Kd values of various ligands, drug molecules, and antibodies. All fluorescent probes published to date either are incompatible with hydrophobic proteins/ligands, precluding analyses of transmembrane or membrane-associated proteins, or have excitation and detection wavelengths outside the range of real-time polymerase chain reaction (RT-PCR) machines, necessitating the use of dedicated devices. Here, we describe a thiol-reactive probe, BODIPY FL L-cystine (BFC), to overcome both of these shortcomings. The probe supports an inexpensive application of DSF measurements suitable for detection with standard RT-PCR machines in a hydrophilic or hydrophobic environment.
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Role of Residues W228 and Y233 in the Structure and Activity of Metallo-β-Lactamase GIM-1. Antimicrob Agents Chemother 2015; 60:990-1002. [PMID: 26643332 DOI: 10.1128/aac.02017-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/21/2015] [Indexed: 11/20/2022] Open
Abstract
Metallo-β-lactamases (MBLs) hydrolyze virtually all β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems. The worldwide emergence of antibiotic-resistant bacteria harboring MBLs poses an increasing clinical threat. The MBL German imipenemase-1 (GIM-1) possesses an active site that is narrower and more hydrophobic than the active sites of other MBLs. The GIM-1 active-site groove is shaped by the presence of the aromatic side chains of tryptophan at residue 228 and tyrosine at residue 233, positions where other MBLs harbor hydrophilic residues. To investigate the importance of these two residues, eight site-directed mutants of GIM-1, W228R/A/Y/S and Y233N/A/I/S, were generated and characterized using enzyme kinetics, thermostability assays, and determination of the MICs of representative β-lactams. The structures of selected mutants were obtained by X-ray crystallography, and their interactions with β-lactam substrates were modeled in silico. Steady-state kinetics revealed that both positions are important to GIM-1 activity but that the effects of individual mutations vary depending on the β-lactam substrate. Activity against type 1 substrates bearing electron-donating C-3/C-4 substituents (cefoxitin, meropenem) could be enhanced by mutations at position 228, whereas hydrolysis of type 2 substrates (benzylpenicillin, ampicillin, ceftazidime, imipenem) with methyl or positively charged substituents was favored by mutations at position 233. The crystal structures showed that mutations at position 228 or the Y233A variant alters the conformation of GIM-1 loop L1 rather than that of loop L3, on which the mutations are located. Taken together, these data show that point mutations at both positions 228 and 233 can influence the catalytic properties and the structure of GIM-1.
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