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Lyons NS, Johnson SB, Sobrado P. Methods for biochemical characterization of flavin-dependent N-monooxygenases involved in siderophore biosynthesis. Methods Enzymol 2024; 702:247-280. [PMID: 39155115 DOI: 10.1016/bs.mie.2024.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
Siderophores are essential molecules released by some bacteria and fungi in iron-limiting environments to sequester ferric iron, satisfying metabolic needs. Flavin-dependent N-hydroxylating monooxygenases (NMOs) catalyze the hydroxylation of nitrogen atoms to generate important siderophore functional groups such as hydroxamates. It has been demonstrated that the function of NMOs is essential for virulence, implicating these enzymes as potential drug targets. This chapter aims to serve as a resource for the characterization of NMO's enzymatic activities using several biochemical techniques. We describe assays that allow for the determination of steady-state kinetic parameters, detection of hydroxylated amine products, measurement of the rate-limiting step(s), and the application toward drug discovery efforts. While not exhaustive, this chapter will provide a foundation for the characterization of enzymes involved in siderophore biosynthesis, allowing for gaps in knowledge within the field to be addressed.
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Affiliation(s)
- Noah S Lyons
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States
| | - Sydney B Johnson
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States; Center for Drug Discovery, Virginia Tech, Blacksburg, VA, United States; Department of Chemistry, Missouri University of Science and Technology, Rolla, MO, United States.
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2
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Brandt F, Ullrich M, Laube M, Kopka K, Bachmann M, Löser R, Pietzsch J, Pietzsch HJ, van den Hoff J, Wodtke R. "Clickable" Albumin Binders for Modulating the Tumor Uptake of Targeted Radiopharmaceuticals. J Med Chem 2021; 65:710-733. [PMID: 34939412 DOI: 10.1021/acs.jmedchem.1c01791] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The intentional binding of radioligands to albumin gains increasing attention in the context of radiopharmaceutical cancer therapy as it can lead to an enhanced radioactivity uptake into the tumor lesions and, thus, to a potentially improved therapeutic outcome. However, the influence of the radioligand's albumin-binding affinity on the time profile of tumor uptake has been only partly addressed so far. Based on the previously identified Nε-4-(4-iodophenyl)butanoyl-lysine scaffold, we designed "clickable" lysine-derived albumin binders (cLABs) and determined their dissociation constants toward albumin by novel assay methods. Structure-activity relationships were derived, and selected cLABs were applied for the modification of the somatostatin receptor subtype 2 ligand (Tyr3)octreotate. These novel conjugates were radiolabeled with copper-64 and subjected to a detailed in vitro and in vivo radiopharmacological characterization. Overall, the results of this study provide an incentive for further investigations of albumin binders for applications in endoradionuclide therapies.
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Affiliation(s)
- Florian Brandt
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Martin Ullrich
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Markus Laube
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Klaus Kopka
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Michael Bachmann
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,National Center for Tumor Diseases (NCT) Dresden, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307 Dresden, Germany
| | - Reik Löser
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Jens Pietzsch
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Hans-Jürgen Pietzsch
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
| | - Jörg van den Hoff
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.,Technische Universität Dresden, Department of Nuclear Medicine, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307 Dresden, Germany
| | - Robert Wodtke
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany
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3
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BRET- and fluorescence anisotropy-based assays for real-time monitoring of ligand binding to M 2 muscarinic acetylcholine receptors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118930. [PMID: 33347921 DOI: 10.1016/j.bbamcr.2020.118930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/26/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022]
Abstract
BRET and fluorescence anisotropy (FA) are two fluorescence-based techniques used for the characterization of ligand binding to G protein-coupled receptors (GPCRs) and both allow monitoring of ligand binding in real time. In this study, we present the first direct comparison of BRET-based and FA-based binding assays using the human M2 muscarinic acetylcholine receptor (M2R) and two TAMRA (5-carboxytetramethylrhodamine)-labeled fluorescent ligands as a model system. The determined fluorescent ligand affinities from both assays were in good agreement with results obtained from radioligand competition binding experiments. The assays yielded real-time kinetic binding data revealing differences in the mechanism of binding for the investigated fluorescent probes. Furthermore, the investigation of various unlabeled M2R ligands yielded pharmacological profiles in accordance with earlier reported data. Taken together, this study showed that BRET- and FA-based binding assays represent valuable alternatives to radioactivity-based methods for screening purposes and for a precise characterization of binding kinetics supporting the exploration of binding mechanisms.
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4
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LeBlanc EV, Polvi EJ, Veri AO, Privé GG, Cowen LE. Structure-guided approaches to targeting stress responses in human fungal pathogens. J Biol Chem 2020; 295:14458-14472. [PMID: 32796038 DOI: 10.1074/jbc.rev120.013731] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/11/2020] [Indexed: 11/06/2022] Open
Abstract
Fungi inhabit extraordinarily diverse ecological niches, including the human body. Invasive fungal infections have a devastating impact on human health worldwide, killing ∼1.5 million individuals annually. The majority of these deaths are attributable to species of Candida, Cryptococcus, and Aspergillus Treating fungal infections is challenging, in part due to the emergence of resistance to our limited arsenal of antifungal agents, necessitating the development of novel therapeutic options. Whereas conventional antifungal strategies target proteins or cellular components essential for fungal growth, an attractive alternative strategy involves targeting proteins that regulate fungal virulence or antifungal drug resistance, such as regulators of fungal stress responses. Stress response networks enable fungi to adapt, grow, and cause disease in humans and include regulators that are highly conserved across eukaryotes as well as those that are fungal-specific. This review highlights recent developments in elucidating crystal structures of fungal stress response regulators and emphasizes how this knowledge can guide the design of fungal-selective inhibitors. We focus on the progress that has been made with highly conserved regulators, including the molecular chaperone Hsp90, the protein phosphatase calcineurin, and the small GTPase Ras1, as well as with divergent stress response regulators, including the cell wall kinase Yck2 and trehalose synthases. Exploring structures of these important fungal stress regulators will accelerate the design of selective antifungals that can be deployed to combat life-threatening fungal diseases.
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Affiliation(s)
- Emmanuelle V LeBlanc
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Elizabeth J Polvi
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Amanda O Veri
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Gilbert G Privé
- Departments of Medical Biophysics and Biochemistry, University of Toronto, Toronto, Ontario, Canada.,Princess Margaret Cancer Centre, Toronto, Ontario, Canada
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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5
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Robinson RM, Klancher CA, Rodriguez PJ, Sobrado P. Flavin oxidation in flavin-dependent N-monooxygenases. Protein Sci 2018; 28:90-99. [PMID: 30098072 DOI: 10.1002/pro.3487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/14/2018] [Accepted: 07/23/2018] [Indexed: 01/08/2023]
Abstract
Siderophore A (SidA) from Aspergillus fumigatus is a flavin-containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H2 O2 is the main product. The effect of pH on steady-state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pKa value >9 was determined and assigned to the FAD-N5 atom. In the presence of Orn, the pH dependence displayed a pKa value of 6.7 ±0.1 and of 7.70 ±0.10 in the presence of Lys. Q102 interacts with NADPH and, upon mutation to alanine, leads to destabilization of the C4a-hydroperoxyflavin (FADOOH ). Flavin oxidation with Q102A showed a pKa value of ~8.0. The data are consistent with the pKa of the FAD N5-atom being modulated to a value >9 in the absence of Orn, which aids in the stabilization of FADOOH . Changes in the FAD-N5 environment lead to a decrease in the pKa value, which facilitates elimination of H2 O2 or H2 O. These findings are supported by solvent kinetic isotope effect experiments, which show that proton transfer from the FAD N5-atom is rate limiting in the absence of a substrate, however, is significantly less rate limiting in the presence of Orn and or Lys.
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Affiliation(s)
- Reeder M Robinson
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
| | - Catherine A Klancher
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
| | - Pedro J Rodriguez
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
| | - Pablo Sobrado
- Department of Biochemistry and Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia, 24061
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6
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Abstract
The devastating infections that fungal pathogens cause in humans are underappreciated relative to viral, bacterial and parasitic diseases. In recent years, the contributions to virulence of reductive iron uptake, siderophore-mediated uptake and heme acquisition have been identified in the best studied and most life-threatening fungal pathogens: Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus. In particular, exciting new work illustrates the importance of iron acquisition from heme and hemoglobin in the virulence of pathogenic yeasts. However, the challenge of establishing how these fungi gain access to hemoglobin in blood and to other sources of heme remains to be fully addressed. Recent studies are also expanding our knowledge of iron uptake in less-well studied fungal pathogens, including dimorphic fungi where new information reveals an integration of iron acquisition with morphogenesis and cell-surface properties for adhesion to host cells. Overall, the accumulating information provides opportunities to exploit iron acquisition for antifungal therapy, and new work highlights the development of specific inhibitors of siderophore biosynthesis and metal chelators for therapeutic use alone or in conjunction with existing antifungal drugs. It is clear that iron-related therapies will need to be customized for specific diseases because the emerging view is that fungal pathogens use different combinations of strategies for iron acquisition in the varied niches of vertebrate hosts.
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Affiliation(s)
- Gaurav Bairwa
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, 456-756, Republic of Korea
| | - James W Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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7
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Martin Del Campo JS, Eckshtain-Levi M, Vogelaar NJ, Sobrado P. Identification of Aspergillus fumigatus UDP-Galactopyranose Mutase Inhibitors. Sci Rep 2017; 7:10836. [PMID: 28883473 PMCID: PMC5589893 DOI: 10.1038/s41598-017-11022-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/17/2017] [Indexed: 01/08/2023] Open
Abstract
Aspergillus fumigatus is an opportunistic human pathogen responsible for deadly, invasive infections in immunocompromised patients. The A. fumigatus cell wall is a complex network of polysaccharides among them galactofuran, which is absent in humans. UDP-galactopyranose mutase (UGM) catalyzes the conversion of UDP-galactofuranose (UDP-Galf) to UDP-galactopyranose (UDP-Galp) and is an important virulence factor. UGM is a flavin-dependent enzyme that requires the reduced flavin for activity; flavin reduction is achieved by reaction with NADPH. The aim of this work was to discover inhibitors of UGM by targeting the NADPH binding site using an ADP-TAMRA probe in a high-throughput screening assay. The flavonoids (2S)-hesperetin and (2S)-naringenin were validated as competitive inhibitors of UGM against NADPH with Ki values of 6 µM and 74 µM, respectively. To gain insight into the active chemical substituents involved in the inhibition of UGM, several derivatives of these inhibitors were studied. The results show that the hydroxyl groups of (2S)-hesperetin are important for inhibition, in particular the phenyl-chroman moiety. Congo red susceptibility assay and growth temperature effects showed that these compounds affected cell wall biosynthesis in A. fumigatus. This work is the first report of inhibition studies on UGM from eukaryotic human pathogens.
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Affiliation(s)
| | | | - Nancy J Vogelaar
- Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24061, USA. .,Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA.
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8
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Martín del Campo JS, Vogelaar N, Tolani K, Kizjakina K, Harich K, Sobrado P. Inhibition of the Flavin-Dependent Monooxygenase Siderophore A (SidA) Blocks Siderophore Biosynthesis and Aspergillus fumigatus Growth. ACS Chem Biol 2016; 11:3035-3042. [PMID: 27588426 DOI: 10.1021/acschembio.6b00666] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen and the most common causative agent of fatal invasive mycoses. The flavin-dependent monooxygenase siderophore A (SidA) catalyzes the oxygen and NADPH dependent hydroxylation of l-ornithine (l-Orn) to N5-l-hydroxyornithine in the biosynthetic pathway of hydroxamate-containing siderophores in A. fumigatus. Deletion of the gene that codes for SidA has shown that it is essential in establishing infection in mice models. Here, a fluorescence polarization high-throughput assay was used to screen a 2320 compound library for inhibitors of SidA. Celastrol, a natural quinone methide, was identified as a noncompetitive inhibitor of SidA with a MIC value of 2 μM. Docking experiments suggest that celastrol binds across the NADPH and l-Orn pocket. Celastrol prevents A. fumigatus growth in blood agar. The addition of purified ferric-siderophore abolished the inhibitory effect of celastrol. Thus, celastrol inhibits A. fumigatus growth by blocking siderophore biosynthesis through SidA inhibiton.
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Affiliation(s)
| | - Nancy Vogelaar
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Karishma Tolani
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Karina Kizjakina
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Kim Harich
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Pablo Sobrado
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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9
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Balhara M, Chaudhary R, Ruhil S, Singh B, Dahiya N, Parmar VS, Jaiwal PK, Chhillar AK. Siderophores; iron scavengers: the novel & promising targets for pathogen specific antifungal therapy. Expert Opin Ther Targets 2016; 20:1477-1489. [PMID: 27797604 DOI: 10.1080/14728222.2016.1254196] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The recent emergence of resistance, toxicity paradigm and limited efficacy of conventional antifungal drugs necessitate the identification of de novo targets in fungal metabolism. One of the most critical physiological processes during in vivo pathogenesis is maintenance of iron homeostasis. The most life threatening opportunistic human fungal pathogens like Aspergillus, Candida and Cryptococcus exploit the siderophore mediated iron uptake mechanism either for survival, virulence, propagation or resistance to oxidative stress envisaged in vivo during infection. Areas covered: In this review, we will highlight the metabolic pathways; specifically siderophore biosynthesis, uptake and utilisation, triggered in the fungal pathogens in iron starving conditions and the various putative targets viable in these pathways to be recruited as novel therapeutic antidotes either via biosynthetic enzymes catalytic site inhibitors or as drug conjugates through trojan horse approach and further role in the development of fungal specific reliable diagnostic markers. Expert opinion: Siderophores are the weapons released by a pathogen to conquer the battle for iron acquisition. Hence, the fungal siderophore biosynthetic pathways along with their uptake and utilisation mechanisms represent an ideal target for pathogen specific, host friendly therapeutic strategy which would block the proliferation of parasite without causing any harm to the mammalian host.
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Affiliation(s)
- Meenakshi Balhara
- a Centre for Biotechnology , Maharshi Dayanand University , Rohtak , Haryana , India
| | - Renu Chaudhary
- a Centre for Biotechnology , Maharshi Dayanand University , Rohtak , Haryana , India
| | - Sonam Ruhil
- a Centre for Biotechnology , Maharshi Dayanand University , Rohtak , Haryana , India
| | - Bharat Singh
- a Centre for Biotechnology , Maharshi Dayanand University , Rohtak , Haryana , India
| | - Nisha Dahiya
- b Division of Epidemiology and Communicable Diseases , Indian Council of Medical Research , Delhi , India
| | - Virinder S Parmar
- c Bioorganic Laboratory, Department of Chemistry , University of Delhi , Delhi , India
| | - Pawan K Jaiwal
- a Centre for Biotechnology , Maharshi Dayanand University , Rohtak , Haryana , India
| | - Anil K Chhillar
- a Centre for Biotechnology , Maharshi Dayanand University , Rohtak , Haryana , India
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10
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Lamb AL. Breaking a pathogen's iron will: Inhibiting siderophore production as an antimicrobial strategy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1054-70. [PMID: 25970810 DOI: 10.1016/j.bbapap.2015.05.001] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 04/29/2015] [Accepted: 05/06/2015] [Indexed: 12/24/2022]
Abstract
The rise of antibiotic resistance is a growing public health crisis. Novel antimicrobials are sought, preferably developing nontraditional chemical scaffolds that do not inhibit standard targets such as cell wall synthesis or the ribosome. Iron scavenging has been proposed as a viable target, because bacterial and fungal pathogens must overcome the nutritional immunity of the host to be virulent. This review highlights the recent work toward exploiting the biosynthetic enzymes of siderophore production for the design of next generation antimicrobials.
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Affiliation(s)
- Audrey L Lamb
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
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11
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Development of a high-throughput screening-compatible assay to identify inhibitors of the CK2α/CK2β interaction. Anal Biochem 2015; 468:4-14. [DOI: 10.1016/j.ab.2014.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/22/2014] [Accepted: 09/05/2014] [Indexed: 01/10/2023]
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12
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Wilson K, Mole DJ, Homer NZM, Iredale JP, Auer M, Webster SP. A magnetic bead-based ligand binding assay to facilitate human kynurenine 3-monooxygenase drug discovery. ACTA ACUST UNITED AC 2014; 20:292-8. [PMID: 25296660 DOI: 10.1177/1087057114554171] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Human kynurenine 3-monooxygenase (KMO) is emerging as an important drug target enzyme in a number of inflammatory and neurodegenerative disease states. Recombinant protein production of KMO, and therefore discovery of KMO ligands, is challenging due to a large membrane targeting domain at the C-terminus of the enzyme that causes stability, solubility, and purification difficulties. The purpose of our investigation was to develop a suitable screening method for targeting human KMO and other similarly challenging drug targets. Here, we report the development of a magnetic bead-based binding assay using mass spectrometry detection for human KMO protein. The assay incorporates isolation of FLAG-tagged KMO enzyme on protein A magnetic beads. The protein-bound beads are incubated with potential binding compounds before specific cleavage of the protein-compound complexes from the beads. Mass spectrometry analysis is used to identify the compounds that demonstrate specific binding affinity for the target protein. The technique was validated using known inhibitors of KMO. This assay is a robust alternative to traditional ligand-binding assays for challenging protein targets, and it overcomes specific difficulties associated with isolating human KMO.
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Affiliation(s)
- Kris Wilson
- Drug Discovery Core, University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Damian J Mole
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Natalie Z M Homer
- Mass Spectrometry Core, Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - John P Iredale
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
| | - Manfred Auer
- School of Biological Sciences and School of Biomedical Sciences, University of Edinburgh, C H Waddington Building, The University of Edinburgh, Edinburgh, UK
| | - Scott P Webster
- Drug Discovery Core, University/BHF Centre for Cardiovascular Science, Queen's Medical Research Institute, The University of Edinburgh, Edinburgh, UK
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