1
|
Hanson GSM, Coxon CR. Fluorinated Tags to Study Protein Conformation and Interactions Using 19F NMR. Chembiochem 2024; 25:e202400195. [PMID: 38744671 DOI: 10.1002/cbic.202400195] [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: 03/01/2024] [Revised: 04/19/2024] [Accepted: 05/14/2024] [Indexed: 05/16/2024]
Abstract
The incorporation of fluorine atoms into a biomacromolecule provides a background-free and environmentally sensitive reporter of structure, conformation and interactions using 19F NMR. There are several methods to introduce the 19F reporter - either by synthetic incorporation via solid phase peptide synthesis; by suppressing the incorporation or biosynthesis of a natural amino acid and supplementing the growth media with a fluorinated counterpart during protein expression; and by genetic code expansion to add new amino acids to the amino acid alphabet. This review aims to discuss progress in the field of introducing fluorinated handles into biomolecules for NMR studies by post-translational bioconjugation or 'fluorine-tagging'. We will discuss the range of chemical tagging 'warheads' that have been used, explore the applications of fluorine tags, discuss ways to enhance reporter sensitivity and how the signal to noise ratios can be boosted. Finally, we consider some key challenges of the field and offer some ideas for future directions.
Collapse
Affiliation(s)
- George S M Hanson
- EaStChem School of Chemistry, University of Edinburgh, Joseph Black Building, Kings Buildings, West Mains Road, EH9 3FJ, Edinburgh, UK
| | - Christopher R Coxon
- EaStChem School of Chemistry, University of Edinburgh, Joseph Black Building, Kings Buildings, West Mains Road, EH9 3FJ, Edinburgh, UK
| |
Collapse
|
2
|
Qianzhu H, Abdelkader EH, Otting G, Huber T. Genetic Encoding of Fluoro-l-tryptophans for Site-Specific Detection of Conformational Heterogeneity in Proteins by NMR Spectroscopy. J Am Chem Soc 2024; 146:13641-13650. [PMID: 38687675 DOI: 10.1021/jacs.4c03743] [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: 05/02/2024]
Abstract
The substitution of a single hydrogen atom in a protein by fluorine yields a site-specific probe for sensitive detection by 19F nuclear magnetic resonance (NMR) spectroscopy, where the absence of background signal from the protein facilitates the detection of minor conformational species. We developed genetic encoding systems for the site-selective incorporation of 4-fluorotryptophan, 5-fluorotryptophan, 6-fluorotryptophan, and 7-fluorotryptophan in response to an amber stop codon and used them to investigate conformational heterogeneity in a designed amino acid binding protein and in flaviviral NS2B-NS3 proteases. These proteases have been shown to present variable conformations in X-ray crystal structures, including flips of the indole side chains of tryptophan residues. The 19F NMR spectra of different fluorotryptophan isomers installed at the conserved site of Trp83 indicate that the indole ring flip is common in flaviviral NS2B-NS3 proteases in the apo state and suppressed by an active-site inhibitor.
Collapse
Affiliation(s)
- Haocheng Qianzhu
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Elwy H Abdelkader
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Gottfried Otting
- ARC Centre of Excellence for Innovations in Peptide & Protein Science, Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Thomas Huber
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| |
Collapse
|
3
|
Buchholz CR, Pomerantz WCK. 19F NMR viewed through two different lenses: ligand-observed and protein-observed 19F NMR applications for fragment-based drug discovery. RSC Chem Biol 2021; 2:1312-1330. [PMID: 34704040 PMCID: PMC8496043 DOI: 10.1039/d1cb00085c] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 07/07/2021] [Indexed: 12/28/2022] Open
Abstract
19F NMR has emerged as a powerful tool in drug discovery, particularly in fragment-based screens. The favorable magnetic resonance properties of the fluorine-19 nucleus, the general absence of fluorine in biological settings, and its ready incorporation into both small molecules and biopolymers, has enabled multiple applications of 19F NMR using labeled small molecules and proteins in biophysical, biochemical, and cellular experiments. This review will cover developments in ligand-observed and protein-observed 19F NMR experiments tailored towards drug discovery with a focus on fragment screening. We also cover the key advances that have furthered the field in recent years, including quantitative, structural, and in-cell methodologies. Several case studies are described for each application to highlight areas for innovation and to further catalyze new NMR developments for using this versatile nucleus.
Collapse
Affiliation(s)
- Caroline R Buchholz
- Department of Medicinal Chemistry, University of Minnesota 308 Harvard Street SE Minneapolis Minnesota 55455 USA
| | - William C K Pomerantz
- Department of Medicinal Chemistry, University of Minnesota 308 Harvard Street SE Minneapolis Minnesota 55455 USA
- Department of Chemistry, University of Minnesota 207 Pleasant St. SE Minneapolis Minnesota 55455 USA
| |
Collapse
|
4
|
Schiedel M, Moroglu M, Ascough DMH, Chamberlain AER, Kamps JJAG, Sekirnik AR, Conway SJ. Chemical Epigenetics: The Impact of Chemical and Chemical Biology Techniques on Bromodomain Target Validation. Angew Chem Int Ed Engl 2019; 58:17930-17952. [DOI: 10.1002/anie.201812164] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/08/2019] [Indexed: 12/22/2022]
Affiliation(s)
- Matthias Schiedel
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Mustafa Moroglu
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| | - David M. H. Ascough
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Anna E. R. Chamberlain
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Jos J. A. G. Kamps
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Angelina R. Sekirnik
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Stuart J. Conway
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA UK
| |
Collapse
|
5
|
Schiedel M, Moroglu M, Ascough DMH, Chamberlain AER, Kamps JJAG, Sekirnik AR, Conway SJ. Chemische Epigenetik: der Einfluss chemischer und chemo‐biologischer Techniken auf die Zielstruktur‐Validierung von Bromodomänen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201812164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Matthias Schiedel
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| | - Mustafa Moroglu
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| | - David M. H. Ascough
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| | - Anna E. R. Chamberlain
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| | - Jos J. A. G. Kamps
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| | - Angelina R. Sekirnik
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| | - Stuart J. Conway
- Department of ChemistryChemistry Research LaboratoryUniversity of Oxford Mansfield Road Oxford OX1 3TA Großbritannien
| |
Collapse
|
6
|
Akter M, Drinkwater N, Devine SM, Drew SC, Krishnarjuna B, Debono CO, Wang G, Scanlon MJ, Scammells PJ, McGowan S, MacRaild CA, Norton RS. Identification of the Binding Site of Apical Membrane Antigen 1 (AMA1) Inhibitors Using a Paramagnetic Probe. ChemMedChem 2019; 14:603-612. [PMID: 30653832 DOI: 10.1002/cmdc.201800802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Indexed: 11/08/2022]
Abstract
Apical membrane antigen 1 (AMA1) is essential for the invasion of host cells by malaria parasites. Several small-molecule ligands have been shown to bind to a conserved hydrophobic cleft in Plasmodium falciparum AMA1. However, a lack of detailed structural information on the binding pose of these molecules has hindered their further optimisation as inhibitors. We have developed a spin-labelled peptide based on RON2, the native binding partner of AMA1, to probe the binding sites of compounds on PfAMA1. The crystal structure of this peptide bound to PfAMA1 shows that it binds at one end of the hydrophobic groove, leaving much of the binding site unoccupied and allowing fragment hits to bind without interference. In paramagnetic relaxation enhancement (PRE)-based NMR screening, the 1 H relaxation rates of compounds binding close to the probe were enhanced. Compounds experienced different degrees of PRE as a result of their different orientations relative to the spin label while bound to AMA1. Thus, PRE-derived distance constraints can be used to identify binding sites and guide further hit optimisation.
Collapse
Affiliation(s)
- Mansura Akter
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Nyssa Drinkwater
- Biomedicine Discovery Institute, Department of Microbiology, Monash University, Wellington Road, Clayton, Victoria, 3800, Australia
| | - Shane M Devine
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Simon C Drew
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Bankala Krishnarjuna
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Cael O Debono
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Geqing Wang
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Peter J Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Sheena McGowan
- Biomedicine Discovery Institute, Department of Microbiology, Monash University, Wellington Road, Clayton, Victoria, 3800, Australia
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| |
Collapse
|
7
|
Polshakov VI, Batuev EA, Mantsyzov AB. NMR screening and studies of target–ligand interactions. RUSSIAN CHEMICAL REVIEWS 2019. [DOI: 10.1070/rcr4836] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
8
|
Abdelkarim H, Hitchinson B, Banerjee A, Gaponenko V. Advances in NMR Methods to Identify Allosteric Sites and Allosteric Ligands. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1163:171-186. [PMID: 31707704 DOI: 10.1007/978-981-13-8719-7_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
NMR allows assessment of protein structure in solution. Unlike conventional X-ray crystallography that provides snapshots of protein conformations, all conformational states are simultaneously accessible to analysis by NMR. This is a significant advantage for discovery and characterization of allosteric effects. These effects are observed when binding at one site of the protein affects another distinct site through conformational transitions. Allosteric regulation of proteins has been observed in multiple physiological processes in health and disease, providing an opportunity for the development of allosteric inhibitors. These compounds do not directly interact with the orthosteric site of the protein but influence its structure and function. In this book chapter, we provide an overview on how NMR methods are utilized to identify allosteric sites and to discover novel inhibitors, highlighting examples from the field. We also describe how NMR has contributed to understanding of allosteric mechanisms and propose that it is likely to play an important role in clarification and further development of key concepts of allostery.
Collapse
Affiliation(s)
- Hazem Abdelkarim
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Ben Hitchinson
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Avik Banerjee
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
| | - Vadim Gaponenko
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
| |
Collapse
|
9
|
|
10
|
Dalvit C, Knapp S. 19 F NMR isotropic chemical shift for efficient screening of fluorinated fragments which are racemates and/or display multiple conformers. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:1091-1095. [PMID: 28762528 DOI: 10.1002/mrc.4640] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/12/2017] [Accepted: 07/29/2017] [Indexed: 06/07/2023]
Abstract
Fluorine ligand-based NMR spectroscopy is now an established method for performing binding screening against a macromolecular target. Typically, the transverse relaxation rate of the fluorine signals is monitored in the absence and presence of the target. However, useful structural information can sometimes be obtained from the analysis of the fluorine isotropic chemical shift. This is particularly relevant for molecules that are racemates and/or display multiple conformers. The large difference in fluorine isotropic chemical shift between free and bound state deriving mainly from the breaking and/or making of intramolecular and/or intermolecular hydrogen bonds allows the detection of very weak affinity ligands. According to our experimental results, racemates should always be included in the generation of the fluorinated fragment libraries. The selection or the availability of only one of the enantiomers for the fluorinated screening library could result in missing relevant chemical scaffold motifs.
Collapse
Affiliation(s)
- Claudio Dalvit
- Faculty of Science, University of Neuchatel, 2000, Neuchatel, Switzerland
| | - Stefan Knapp
- Institute of Pharmaceutical Chemistry, Goethe University Frankfurt, Riedberg Campus, 60438, Frankfurt, Germany
- Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford University, Oxford, OX3 7DQ, UK
| |
Collapse
|
11
|
Ayoub AM, Hawk LML, Herzig RJ, Jiang J, Wisniewski AJ, Gee CT, Zhao P, Zhu JY, Berndt N, Offei-Addo NK, Scott TG, Qi J, Bradner JE, Ward TR, Schönbrunn E, Georg GI, Pomerantz WC. BET Bromodomain Inhibitors with One-Step Synthesis Discovered from Virtual Screen. J Med Chem 2017; 60:4805-4817. [PMID: 28535045 PMCID: PMC5558211 DOI: 10.1021/acs.jmedchem.6b01336] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chemical inhibition of epigenetic regulatory proteins BrdT and Brd4 is emerging as a promising therapeutic strategy in contraception, cancer, and heart disease. We report an easily synthesized dihydropyridopyrimidine pan-BET inhibitor scaffold, which was uncovered via a virtual screen followed by testing in a fluorescence anisotropy assay. Dihydropyridopyimidine 3 was subjected to further characterization and is highly selective for the BET family of bromodomains. Structure-activity relationship data and ligand deconstruction highlight the importance of the substitution of the uracil moiety for potency and selectivity. Compound 3 was also cocrystallized with Brd4 for determining the ligand binding pose and rationalizing subsequent structure-activity data. An additional series of dihydropyridopyrimidines was synthesized to exploit the proximity of a channel near the ZA loop of Brd4, leading to compounds with submicromolar affinity and cellular target engagement. Given these findings, novel and easily synthesized inhibitors are being introduced to the growing field of bromodomain inhibitor development.
Collapse
Affiliation(s)
- Alex M. Ayoub
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| | - Laura M. L. Hawk
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| | - Ryan J. Herzig
- Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55455, United States
| | - Jiewei Jiang
- Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55455, United States
| | - Andrea J. Wisniewski
- Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55455, United States
| | - Clifford T. Gee
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| | - Peiliang Zhao
- Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55455, United States
| | - Jin-Yi Zhu
- Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, United States
| | - Norbert Berndt
- Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, United States
| | - Nana K. Offei-Addo
- Department of Medical Oncology, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 360 Longwood Avenue, Boston, MA, 02215, United States
| | - Thomas G. Scott
- Department of Medical Oncology, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 360 Longwood Avenue, Boston, MA, 02215, United States
| | - Jun Qi
- Department of Medical Oncology, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 360 Longwood Avenue, Boston, MA, 02215, United States
| | - James E. Bradner
- Department of Medical Oncology, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 360 Longwood Avenue, Boston, MA, 02215, United States
| | - Timothy R. Ward
- Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55455, United States
| | - Ernst Schönbrunn
- Drug Discovery Department, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, United States
| | - Gunda I. Georg
- Department of Medicinal Chemistry and Institute for Therapeutics Discovery and Development, University of Minnesota, 717 Delaware St. SE, Minneapolis, MN 55455, United States
| | - William C.K. Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| |
Collapse
|
12
|
Devine SM, MacRaild CA, Norton RS, Scammells PJ. Antimalarial drug discovery targeting apical membrane antigen 1. MEDCHEMCOMM 2017; 8:13-20. [PMID: 30108688 PMCID: PMC6072474 DOI: 10.1039/c6md00495d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/27/2016] [Indexed: 01/06/2023]
Abstract
Malaria continues to frustrate humanity's attempts to eradicate this deadly disease. Although gains have been made over the last 15 years, drug resistance to malaria continues to be a major concern. The lack of new antimalarials with novel mechanisms of action continues to challenge the scientific community to find innovative targets to combat this persistent disease. One such target, apical membrane antigen 1 (AMA1), is an essential protein that helps the parasite invade host erythrocytes. Recently, a number of efforts have focused on the druggability of this target, aiming to block the interactions of AMA1 that mediate invasion of host cells. This review covers recent progress in drug discovery targeting this crucial protein-protein interaction in malaria.
Collapse
Affiliation(s)
- Shane M Devine
- Medicinal Chemistry , Monash Institute of Pharmaceutical Sciences , Monash University , Parkville , VIC 3052 , Australia . ;
| | - Christopher A MacRaild
- Medicinal Chemistry , Monash Institute of Pharmaceutical Sciences , Monash University , Parkville , VIC 3052 , Australia . ;
| | - Raymond S Norton
- Medicinal Chemistry , Monash Institute of Pharmaceutical Sciences , Monash University , Parkville , VIC 3052 , Australia . ;
| | - Peter J Scammells
- Medicinal Chemistry , Monash Institute of Pharmaceutical Sciences , Monash University , Parkville , VIC 3052 , Australia . ;
| |
Collapse
|
13
|
Urick AK, Calle LP, Espinosa JF, Hu H, Pomerantz WCK. Protein-Observed Fluorine NMR Is a Complementary Ligand Discovery Method to 1H CPMG Ligand-Observed NMR. ACS Chem Biol 2016; 11:3154-3164. [PMID: 27627661 PMCID: PMC8325173 DOI: 10.1021/acschembio.6b00730] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
To evaluate its potential as a ligand discovery tool, we compare a newly developed 1D protein-observed fluorine NMR (PrOF NMR) screening method with the well-characterized ligand-observed 1H CPMG NMR screen. We selected the first bromodomain of Brd4 as a model system to benchmark PrOF NMR because of the high ligandability of Brd4 and the need for small molecule inhibitors of related epigenetic regulatory proteins. We compare the two methods' hit sensitivity, triaging ability, experiment speed, material consumption, and the potential for false positives and negatives. To this end, we screened 930 fragment molecules against Brd4 in mixtures of five and followed up these studies with mixture deconvolution and affinity characterization of the top hits. In selected examples, we also compare the environmental responsiveness of the 19F chemical shift to 1H in 1D-protein observed 1H NMR experiments. To address concerns of perturbations from fluorine incorporation, ligand binding trends and affinities were verified via thermal shift assays and isothermal titration calorimetry. We conclude that for the protein understudy here, PrOF NMR and 1H CPMG have similar sensitivity, with both being effective tools for ligand discovery. In cases where an unlabeled protein can be used, 1D protein-observed 1H NMR may also be effective; however, the 19F chemical shift remains significantly more responsive.
Collapse
Affiliation(s)
- Andrew K. Urick
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Discovery Chemistry Research & Technologies, Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, United States
| | - Luis Pablo Calle
- Discovery Chemistry Research & Technologies, Lilly Research Laboratories, Eli Lilly and Company, Centro de Investigación Lilly, 28108 Alcobendas, Madrid, Spain
| | - Juan F. Espinosa
- Discovery Chemistry Research & Technologies, Lilly Research Laboratories, Eli Lilly and Company, Centro de Investigación Lilly, 28108 Alcobendas, Madrid, Spain
| | - Haitao Hu
- Discovery Chemistry Research & Technologies, Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, United States
| | - William C. K. Pomerantz
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
14
|
Hawk LML, Gee CT, Urick AK, Hu H, Pomerantz WCK. Paramagnetic relaxation enhancement for protein-observed 19F NMR as an enabling approach for efficient fragment screening. RSC Adv 2016; 6:95715-95721. [PMID: 28496971 PMCID: PMC5421645 DOI: 10.1039/c6ra21226c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Protein-observed 19F (PrOF) NMR is an emerging tool for ligand discovery. To optimize the efficiency of PrOF NMR experiments, paramagnetic relaxation enhancement through the addition of chelated Ni(II) was used to shorten longitudinal relaxation time without causing significant line broadening. Thus enhancing relaxation time leads to shorter experiments without perturbing the binding of low- or high-affinity ligands. This method allows for time-efficient screening of potential ligands for a wide variety of proteins in the growing field of fragment-based ligand discovery.
Collapse
Affiliation(s)
- Laura M L Hawk
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| | - Clifford T Gee
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| | - Andrew K Urick
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, United States
| | - Haitao Hu
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, United States
| | - William C K Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455, United States
| |
Collapse
|
15
|
Norton RS, Leung EWW, Chandrashekaran IR, MacRaild CA. Applications of (19)F-NMR in Fragment-Based Drug Discovery. Molecules 2016; 21:molecules21070860. [PMID: 27438818 PMCID: PMC6273323 DOI: 10.3390/molecules21070860] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 06/21/2016] [Accepted: 06/21/2016] [Indexed: 11/16/2022] Open
Abstract
(19)F-NMR has proved to be a valuable tool in fragment-based drug discovery. Its applications include screening libraries of fluorinated fragments, assessing competition among elaborated fragments and identifying the binding poses of promising hits. By observing fluorine in both the ligand and the target protein, useful information can be obtained on not only the binding pose but also the dynamics of ligand-protein interactions. These applications of (19)F-NMR will be illustrated in this review with studies from our fragment-based drug discovery campaigns against protein targets in parasitic and infectious diseases.
Collapse
Affiliation(s)
- Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
| | - Eleanor W W Leung
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
| | - Indu R Chandrashekaran
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
| |
Collapse
|
16
|
Gee CT, Arntson KE, Urick AK, Mishra NK, Hawk LML, Wisniewski AJ, Pomerantz WCK. Protein-observed (19)F-NMR for fragment screening, affinity quantification and druggability assessment. Nat Protoc 2016; 11:1414-27. [PMID: 27414758 DOI: 10.1038/nprot.2016.079] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
NMR spectroscopy can be used to quantify the binding affinity between proteins and low-complexity molecules, termed 'fragments'; this versatile screening approach allows researchers to assess the druggability of new protein targets. Protein-observed (19)F-NMR (PrOF NMR) using (19)F-labeled amino acids generates relatively simple spectra that are able to provide dynamic structural information toward understanding protein folding and function. Changes in these spectra upon the addition of fragment molecules can be observed and quantified. This protocol describes the sequence-selective labeling of three proteins (the first bromodomains of Brd4 and BrdT, and the KIX domain of the CREB-binding protein) using commercially available fluorinated aromatic amino acids and fluorinated precursors as example applications of the method developed by our research group. Fragment-screening approaches are discussed, as well as Kd determination, ligand-efficiency calculations and druggability assessment, i.e., the ability to target these proteins using small-molecule ligands. Experiment times on the order of a few minutes and the simplicity of the NMR spectra obtained make this approach well-suited to the investigation of small- to medium-sized proteins, as well as the screening of multiple proteins in the same experiment.
Collapse
Affiliation(s)
- Clifford T Gee
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Keith E Arntson
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Andrew K Urick
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Neeraj K Mishra
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Laura M L Hawk
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Andrea J Wisniewski
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | | |
Collapse
|
17
|
Sarker M, Orrell KE, Xu L, Tremblay ML, Bak JJ, Liu XQ, Rainey JK. Tracking Transitions in Spider Wrapping Silk Conformation and Dynamics by (19)F Nuclear Magnetic Resonance Spectroscopy. Biochemistry 2016; 55:3048-59. [PMID: 27153372 PMCID: PMC5770200 DOI: 10.1021/acs.biochem.6b00429] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aciniform silk protein (AcSp1) is the primary component of wrapping silk, the toughest of the spider silks because of a combination of high tensile strength and extensibility. Argiope trifasciata AcSp1 contains a core repetitive domain with at least 14 homogeneous 200-amino acid units ("W" units). Upon fibrillogenesis, AcSp1 converts from an α-helix-rich soluble state to a mixed α-helical/β-sheet conformation. Solution-state nuclear magnetic resonance (NMR) spectroscopy allowed demonstration of variable local stability within the W unit, but comprehensive characterization was confounded by spectral overlap, which was exacerbated by decreased chemical shift dispersion upon denaturation. Here, (19)F NMR spectroscopy, in the context of a single W unit (W1), is applied to track changes in structure and dynamics. Four strategic positions in the W unit were mutated to tryptophan and biosynthetically labeled with 5-fluorotryptophan (5F-Trp). Simulated annealing-based structure calculations implied that these substitutions should be tolerated, while circular dichroism (CD) spectroscopy and (1)H-(15)N chemical shift displacements indicated minimal structural perturbation in W1 mutants. Fiber formation by W2 concatemers containing 5F-Trp substitutions in both W units demonstrated retention of functionality, a somewhat surprising finding in light of sequence conservation between species. Each 5F-Trp-labeled W1 exhibited a unique (19)F chemical shift, line width, longitudinal relaxation time constant (T1), and solvent isotope shift. Perturbation to (19)F chemical shift and nuclear spin relaxation parameters reflected changes in the conformation and dynamics at each 5F-Trp site upon addition of urea and dodecylphosphocholine (DPC). (19)F NMR spectroscopy allowed unambiguous localized tracking throughout titration with each perturbant, demonstrating distinct behavior for each perturbant not previously revealed by heteronuclear NMR experiments.
Collapse
Affiliation(s)
- Muzaddid Sarker
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Kathleen E. Orrell
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Lingling Xu
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Marie-Laurence Tremblay
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Jessi J. Bak
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Xiang-Qin Liu
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Jan K. Rainey
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| |
Collapse
|
18
|
Dalvit C, Vulpetti A. Weak Intermolecular Hydrogen Bonds with Fluorine: Detection and Implications for Enzymatic/Chemical Reactions, Chemical Properties, and Ligand/Protein Fluorine NMR Screening. Chemistry 2016; 22:7592-601. [DOI: 10.1002/chem.201600446] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Indexed: 01/05/2023]
Affiliation(s)
- Claudio Dalvit
- Faculty of Science University of Neuchâtel 2000 Neuchâtel Switzerland
- Sanofi, LG-CR/SDI/SBB 94403 Vitry-sur-Seine France
| | - Anna Vulpetti
- Novartis Institutes for Biomedical Research, Global Discovery Chemistry, CADD 4002 Basel Switzerland
| |
Collapse
|
19
|
Boulton S, Melacini G. Advances in NMR Methods To Map Allosteric Sites: From Models to Translation. Chem Rev 2016; 116:6267-304. [PMID: 27111288 DOI: 10.1021/acs.chemrev.5b00718] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The last five years have witnessed major developments in the understanding of the allosteric phenomenon, broadly defined as coupling between remote molecular sites. Such advances have been driven not only by new theoretical models and pharmacological applications of allostery, but also by progress in the experimental approaches designed to map allosteric sites and transitions. Among these techniques, NMR spectroscopy has played a major role given its unique near-atomic resolution and sensitivity to the dynamics that underlie allosteric couplings. Here, we highlight recent progress in the NMR methods tailored to investigate allostery with the goal of offering an overview of which NMR approaches are best suited for which allosterically relevant questions. The picture of the allosteric "NMR toolbox" is provided starting from one of the simplest models of allostery (i.e., the four-state thermodynamic cycle) and continuing to more complex multistate mechanisms. We also review how such an "NMR toolbox" has assisted the elucidation of the allosteric molecular basis for disease-related mutations and the discovery of novel leads for allosteric drugs. From this overview, it is clear that NMR plays a central role not only in experimentally validating transformative theories of allostery, but also in tapping the full translational potential of allosteric systems.
Collapse
Affiliation(s)
- Stephen Boulton
- Department of Chemistry and Chemical Biology Department of Biochemistry and Biomedical Sciences, McMaster University , 1280 Main St. W., Hamilton L8S 4M1, Canada
| | - Giuseppe Melacini
- Department of Chemistry and Chemical Biology Department of Biochemistry and Biomedical Sciences, McMaster University , 1280 Main St. W., Hamilton L8S 4M1, Canada
| |
Collapse
|
20
|
Krishnarjuna B, Lim SS, Devine SM, Debono CO, Lam R, Chandrashekaran IR, Jaipuria G, Yagi H, Atreya HS, Scanlon MJ, MacRaild CA, Scammells PJ, Norton RS. Solution NMR characterization of apical membrane antigen 1 and small molecule interactions as a basis for designing new antimalarials. J Mol Recognit 2016; 29:281-91. [DOI: 10.1002/jmr.2529] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/28/2015] [Indexed: 01/12/2023]
Affiliation(s)
- Bankala Krishnarjuna
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - San Sui Lim
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Shane M. Devine
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Cael O. Debono
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Raymond Lam
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Indu R. Chandrashekaran
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Garima Jaipuria
- NMR Research Centre; Indian Institute of Science; Bangalore 560012 India
| | - Hiromasa Yagi
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | | | - Martin J. Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Christopher A. MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Peter J. Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences; Monash University; 381 Royal Parade Parkville Victoria 3052 Australia
| |
Collapse
|
21
|
Delgadillo RF, Parker ML, Lebrun M, Boulanger MJ, Douguet D. Stability of the Plasmodium falciparum AMA1-RON2 Complex Is Governed by the Domain II (DII) Loop. PLoS One 2016; 11:e0144764. [PMID: 26731670 PMCID: PMC4701444 DOI: 10.1371/journal.pone.0144764] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/22/2015] [Indexed: 12/20/2022] Open
Abstract
Plasmodium falciparum is an obligate intracellular protozoan parasite that employs a highly sophisticated mechanism to access the protective environment of the host cells. Key to this mechanism is the formation of an electron dense ring at the parasite-host cell interface called the Moving Junction (MJ) through which the parasite invades. The MJ incorporates two key parasite components: the surface protein Apical Membrane Antigen 1 (AMA1) and its receptor, the Rhoptry Neck Protein (RON) complex, the latter one being targeted to the host cell membrane during invasion. Crystal structures of AMA1 have shown that a partially mobile loop, termed the DII loop, forms part of a deep groove in domain I and overlaps with the RON2 binding site. To investigate the mechanism by which the DII loop influences RON2 binding, we measured the kinetics of association and dissociation and binding equilibria of a PfRON2sp1 peptide with both PfAMA1 and an engineered form of PfAMA1 where the flexible region of the DII loop was replaced by a short Gly-Ser linker (ΔDII-PfAMA1). The reactions were tracked by fluorescence anisotropy as a function of temperature and concentration and globally fitted to acquire the rate constants and corresponding thermodynamic profiles. Our results indicate that both PfAMA1 constructs bound to the PfRON2sp1 peptide with the formation of one intermediate in a sequential reversible reaction: A↔B↔C. Consistent with Isothermal Titration Calorimetry measurements, final complex formation was enthalpically driven and slightly entropically unfavorable. Importantly, our experimental data shows that the DII loop lengthened the complex half-life time by 18-fold (900 s and 48 s at 25°C for Pf and ΔDII-Pf complex, respectively). The longer half-life of the Pf complex appeared to be driven by a slower dissociation process. These data highlight a new influential role for the DII loop in kinetically locking the functional binary complex to enable host cell invasion.
Collapse
Affiliation(s)
- Roberto F. Delgadillo
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, CNRS, UMR 7275, 660, route des Lucioles, Sophia Antipolis, 06560, Valbonne, France
| | - Michelle L. Parker
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Maryse Lebrun
- UMR 5235 CNRS, Université de Montpellier, 34095, Montpellier, France
| | - Martin J. Boulanger
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Dominique Douguet
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, CNRS, UMR 7275, 660, route des Lucioles, Sophia Antipolis, 06560, Valbonne, France
- * E-mail:
| |
Collapse
|
22
|
Vaughan MD, Su Z, Daub E, Honek JF. Intriguing cellular processing of a fluorinated amino acid during protein biosynthesis in Escherichia coli. Org Biomol Chem 2016; 14:8942-8946. [DOI: 10.1039/c6ob01690a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unusual in vivo processing of a fluorinated amino acid provides unexpected dual protein labeling in E. coli.
Collapse
Affiliation(s)
- Mark D. Vaughan
- Department of Chemistry
- University of Waterloo
- Waterloo
- ON N2L 3G1 Canada
| | - Zhengding Su
- Department of Chemistry
- University of Waterloo
- Waterloo
- ON N2L 3G1 Canada
| | - Elisabeth Daub
- Department of Chemistry
- University of Waterloo
- Waterloo
- ON N2L 3G1 Canada
| | - J. F. Honek
- Department of Chemistry
- University of Waterloo
- Waterloo
- ON N2L 3G1 Canada
| |
Collapse
|
23
|
Arntson KE, Pomerantz WCK. Protein-Observed Fluorine NMR: A Bioorthogonal Approach for Small Molecule Discovery. J Med Chem 2015; 59:5158-71. [PMID: 26599421 DOI: 10.1021/acs.jmedchem.5b01447] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The (19)F isotope is 100% naturally abundant and is the second most sensitive and stable NMR-active nucleus. Unlike the ubiquitous hydrogen atom, fluorine is nearly absent in biological systems, making it a unique bioorthogonal atom for probing molecular interactions in biology. Over 73 fluorinated proteins have been studied by (19)F NMR since the seminal studies of Hull and Sykes in 1974. With advances in cryoprobe production and fluorinated amino acid incorporation strategies, protein-based (19)F NMR offers opportunities to the medicinal chemist for characterizing and ultimately discovering new small molecule protein ligands. This review will highlight new advances using (19)F NMR for characterizing small molecule interactions with both small and large proteins as well as detailing NMR resonance assignment challenges and amino acid incorporation approaches.
Collapse
Affiliation(s)
- Keith E Arntson
- Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - William C K Pomerantz
- Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
24
|
Urick AK, Hawk LML, Cassel MK, Mishra NK, Liu S, Adhikari N, Zhang W, dos Santos CO, Hall JL, Pomerantz WCK. Dual Screening of BPTF and Brd4 Using Protein-Observed Fluorine NMR Uncovers New Bromodomain Probe Molecules. ACS Chem Biol 2015; 10:2246-56. [PMID: 26158404 PMCID: PMC4858447 DOI: 10.1021/acschembio.5b00483] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Bromodomain-containing protein dysregulation is linked to cancer, diabetes, and inflammation. Selective inhibition of bromodomain function is a newly proposed therapeutic strategy. We describe a (19)F NMR dual screening method for small molecule discovery using fluorinated tryptophan resonances on two bromodomain-containing proteins. The chemical shift dispersion of (19)F resonances within fluorine-labeled proteins enables the simultaneous analysis of two fluorinated bromodomains by NMR. A library of 229 small molecules was screened against the first bromodomain of Brd4 and the BPTF bromodomain. We report the first small molecule selective for BPTF over Brd4, termed AU1. The Kd = 2.8 μM for AU1, which is active in a cell-based reporter assay. No binding is detected with Brd4. Three new Brd4 inhibitors with submicromolar affinity were also discovered. Brd4 hits were validated in a thermal stability assay and potency determined via fluorescence anisotropy. The speed, ease of interpretation, and low protein concentration needed for protein-observed (19)F NMR experiments in a multiprotein format offers a new method to discover and characterize selective ligands for bromodomain-containing proteins.
Collapse
Affiliation(s)
- Andrew K. Urick
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis, MN 55455
| | - Laura M. L. Hawk
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis, MN 55455
| | - Melissa K. Cassel
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis, MN 55455
| | - Neeraj K. Mishra
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE Minneapolis, MN 55455
| | - Shuai Liu
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125
| | - Neeta Adhikari
- Lillehei Heart Institute, Department of Medicine, 2231 6thStreet SE, Minneapolis, MN 55455
| | - Wei Zhang
- Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125
| | | | - Jennifer L. Hall
- Lillehei Heart Institute, Department of Medicine, 2231 6thStreet SE, Minneapolis, MN 55455
| | | |
Collapse
|
25
|
Parker ML, Boulanger MJ. An Extended Surface Loop on Toxoplasma gondii Apical Membrane Antigen 1 (AMA1) Governs Ligand Binding Selectivity. PLoS One 2015; 10:e0126206. [PMID: 25955165 PMCID: PMC4425356 DOI: 10.1371/journal.pone.0126206] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 03/31/2015] [Indexed: 11/18/2022] Open
Abstract
Apicomplexan parasites are the causative agents of globally prevalent diseases including malaria and toxoplasmosis. These obligate intracellular pathogens have evolved a sophisticated host cell invasion strategy that relies on a parasite-host cell junction anchored by interactions between apical membrane antigens (AMAs) on the parasite surface and rhoptry neck 2 (RON2) proteins discharged from the parasite and embedded in the host cell membrane. Key to formation of the AMA1-RON2 complex is displacement of an extended surface loop on AMA1 called the DII loop. While conformational flexibility of the DII loop is required to expose the mature RON2 binding groove, a definitive role of this substructure has not been elucidated. To establish a role of the DII loop in Toxoplasma gondii AMA1, we engineered a form of the protein where the mobile portion of the loop was replaced with a short Gly-Ser linker (TgAMA1ΔDIIloop). Isothermal titration calorimetry measurements with a panel of RON2 peptides revealed an influential role for the DII loop in governing selectivity. Most notably, an Eimeria tenella RON2 (EtRON2) peptide that showed only weak binding to TgAMA1 bound with high affinity to TgAMA1ΔDIIloop. To define the molecular basis for the differential binding, we determined the crystal structure of TgAMA1ΔDIIloop in complex with the EtRON2 peptide. When analyzed in the context of existing AMA1-RON2 structures, spatially distinct anchor points in the AMA1 groove were identified that, when engaged, appear to provide the necessary traction to outcompete the DII loop. Collectively, these data support a model where the AMA1 DII loop serves as a structural gatekeeper to selectively filter out ligands otherwise capable of binding with high affinity in the AMA1 apical groove. These data also highlight the importance of considering the functional implications of the DII loop in the ongoing development of therapeutic intervention strategies targeting the AMA1-RON2 invasion complex.
Collapse
Affiliation(s)
- Michelle L. Parker
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Martin J. Boulanger
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
- * E-mail:
| |
Collapse
|
26
|
Pihan E, Delgadillo RF, Tonkin ML, Pugnière M, Lebrun M, Boulanger MJ, Douguet D. Computational and biophysical approaches to protein-protein interaction inhibition of Plasmodium falciparum AMA1/RON2 complex. J Comput Aided Mol Des 2015; 29:525-39. [PMID: 25822046 DOI: 10.1007/s10822-015-9842-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 03/25/2015] [Indexed: 11/30/2022]
Abstract
Invasion of the red blood cell by Plasmodium falciparum parasites requires formation of an electron dense circumferential ring called the Moving Junction (MJ). The MJ is anchored by a high affinity complex of two parasite proteins: Apical Membrane Antigen 1 (PfAMA1) displayed on the surface of the parasite and Rhoptry Neck Protein 2 that is discharged from the parasite and imbedded in the membrane of the host cell. Structural studies of PfAMA1 revealed a conserved hydrophobic groove localized to the apical surface that coordinates RON2 and invasion inhibitory peptides. In the present work, we employed computational and biophysical methods to identify competitive P. falciparum AMA1-RON2 inhibitors with the goal of exploring the 'druggability' of this attractive antimalarial target. A virtual screen followed by molecular docking with the PfAMA1 crystal structure was performed using an eight million compound collection that included commercial molecules, the ChEMBL malaria library and approved drugs. The consensus approach resulted in the selection of inhibitor candidates. We also developed a fluorescence anisotropy assay using a modified inhibitory peptide to experimentally validate the ability of the selected compounds to inhibit the AMA1-RON2 interaction. Among those, we identified one compound that displayed significant inhibition. This study offers interesting clues to improve the throughput and reliability of screening for new drug leads.
Collapse
Affiliation(s)
- Emilie Pihan
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, CNRS, UMR 7275, 660, Route des Lucioles, Sophia Antipolis, 06560, Valbonne, France
| | | | | | | | | | | | | |
Collapse
|
27
|
Gee CT, Koleski EJ, Pomerantz WCK. Fragment screening and druggability assessment for the CBP/p300 KIX domain through protein-observed 19F NMR spectroscopy. Angew Chem Int Ed Engl 2015; 54:3735-9. [PMID: 25651535 DOI: 10.1002/anie.201411658] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Indexed: 11/08/2022]
Abstract
(19)F NMR spectroscopy of labeled proteins is a sensitive method for characterizing structure, conformational dynamics, higher-order assembly, and ligand binding. Fluorination of aromatic side chains has been suggested as a labeling strategy for small-molecule ligand discovery for protein-protein interaction interfaces. Using a model transcription factor binding domain of the CREB binding protein (CBP)/p300, KIX, we report the first full small-molecule screen using protein-observed (19)F NMR spectroscopy. Screening of 508 compounds and validation by (1)H-(15)N HSQC NMR spectroscopy led to the identification of a minimal pharmacaphore for the MLL-KIX interaction site. Hit rate analysis for the CREB-KIX and MLL-KIX sites provided a metric to assess the ligandability or "druggability" of each interface informing future medicinal chemistry efforts. The structural information from the simplified spectra and data collection speed, affords a new screening tool for analysis of protein interfaces and discovery of small molecules.
Collapse
Affiliation(s)
- Clifford T Gee
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Twin Cities (USA)
| | | | | |
Collapse
|
28
|
Gee CT, Koleski EJ, Pomerantz WCK. Fragment Screening and Druggability Assessment for the CBP/p300 KIX Domain through Protein-Observed19F NMR Spectroscopy. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201411658] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
29
|
Tonkin ML, Boulanger MJ. The shear stress of host cell invasion: exploring the role of biomolecular complexes. PLoS Pathog 2015; 11:e1004539. [PMID: 25629317 PMCID: PMC4309608 DOI: 10.1371/journal.ppat.1004539] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Michelle L. Tonkin
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Martin J. Boulanger
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
- * E-mail:
| |
Collapse
|
30
|
Lim SS, Yang W, Krishnarjuna B, Kannan Sivaraman K, Chandrashekaran IR, Kass I, MacRaild CA, Devine SM, Debono CO, Anders RF, Scanlon MJ, Scammells PJ, Norton RS, McGowan S. Structure and dynamics of apical membrane antigen 1 from Plasmodium falciparum FVO. Biochemistry 2014; 53:7310-20. [PMID: 25360546 DOI: 10.1021/bi5012089] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Apical membrane antigen 1 (AMA1) interacts with RON2 to form a protein complex that plays a key role in the invasion of host cells by malaria parasites. Blocking this protein-protein interaction represents a potential route to controlling malaria and related parasitic diseases, but the polymorphic nature of AMA1 has proven to be a major challenge to vaccine-induced antibodies and peptide inhibitors exerting strain-transcending inhibitory effects. Here we present the X-ray crystal structure of AMA1 domains I and II from Plasmodium falciparum strain FVO. We compare our new structure to those of AMA1 from P. falciparum 3D7 and Plasmodium vivax. A combination of normalized B factor analysis and computational methods has been used to investigate the flexibility of the domain I loops and how this correlates with their roles in determining the strain specificity of human antibody responses and inhibitory peptides. We also investigated the domain II loop, a key region involved in inhibitor binding, by comparison of multiple AMA1 crystal structures. Collectively, these results provide valuable insights that should contribute to the design of strain-transcending agents targeting P. falciparum AMA1.
Collapse
Affiliation(s)
- San Sui Lim
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|