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Khanppnavar B, Choo JPS, Hagedoorn PL, Smolentsev G, Štefanić S, Kumaran S, Tischler D, Winkler FK, Korkhov VM, Li Z, Kammerer RA, Li X. Structural basis of the Meinwald rearrangement catalysed by styrene oxide isomerase. Nat Chem 2024:10.1038/s41557-024-01523-y. [PMID: 38744914 DOI: 10.1038/s41557-024-01523-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 03/27/2024] [Indexed: 05/16/2024]
Abstract
Membrane-bound styrene oxide isomerase (SOI) catalyses the Meinwald rearrangement-a Lewis-acid-catalysed isomerization of an epoxide to a carbonyl compound-and has been used in single and cascade reactions. However, the structural information that explains its reaction mechanism has remained elusive. Here we determine cryo-electron microscopy (cryo-EM) structures of SOI bound to a single-domain antibody with and without the competitive inhibitor benzylamine, and elucidate the catalytic mechanism using electron paramagnetic resonance spectroscopy, functional assays, biophysical methods and docking experiments. We find ferric haem b bound at the subunit interface of the trimeric enzyme through H58, where Fe(III) acts as the Lewis acid by binding to the epoxide oxygen. Y103 and N64 and a hydrophobic pocket binding the oxygen of the epoxide and the aryl group, respectively, position substrates in a manner that explains the high regio-selectivity and stereo-specificity of SOI. Our findings can support extending the range of epoxide substrates and be used to potentially repurpose SOI for the catalysis of new-to-nature Fe-based chemical reactions.
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Affiliation(s)
- Basavraj Khanppnavar
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Joel P S Choo
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
| | - Peter-Leon Hagedoorn
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | | | - Saša Štefanić
- Nanobody Service Facility. AgroVet-Strickhof, University of Zurich, Lindau, Switzerland
| | | | - Dirk Tischler
- Microbial Biotechnology, Ruhr University Bochum, Bochum, Germany
| | | | - Volodymyr M Korkhov
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland.
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
| | - Zhi Li
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore.
| | - Richard A Kammerer
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland.
| | - Xiaodan Li
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland.
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Khanppnavar B, Schuster D, Lavriha P, Uliana F, Özel M, Mehta V, Leitner A, Picotti P, Korkhov VM. Regulatory sites of CaM-sensitive adenylyl cyclase AC8 revealed by cryo-EM and structural proteomics. EMBO Rep 2024; 25:1513-1540. [PMID: 38351373 PMCID: PMC10933263 DOI: 10.1038/s44319-024-00076-y] [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: 10/18/2023] [Revised: 01/17/2024] [Accepted: 01/19/2024] [Indexed: 02/19/2024] Open
Abstract
Membrane adenylyl cyclase AC8 is regulated by G proteins and calmodulin (CaM), mediating the crosstalk between the cAMP pathway and Ca2+ signalling. Despite the importance of AC8 in physiology, the structural basis of its regulation by G proteins and CaM is not well defined. Here, we report the 3.5 Å resolution cryo-EM structure of the bovine AC8 bound to the stimulatory Gαs protein in the presence of Ca2+/CaM. The structure reveals the architecture of the ordered AC8 domains bound to Gαs and the small molecule activator forskolin. The extracellular surface of AC8 features a negatively charged pocket, a potential site for unknown interactors. Despite the well-resolved forskolin density, the captured state of AC8 does not favour tight nucleotide binding. The structural proteomics approaches, limited proteolysis and crosslinking mass spectrometry (LiP-MS and XL-MS), allowed us to identify the contact sites between AC8 and its regulators, CaM, Gαs, and Gβγ, as well as to infer the conformational changes induced by these interactions. Our results provide a framework for understanding the role of flexible regions in the mechanism of AC regulation.
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Affiliation(s)
- Basavraj Khanppnavar
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Dina Schuster
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Pia Lavriha
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Federico Uliana
- Department of Biology, Institute of Biological Chemistry, ETH Zurich, Zurich, Switzerland
| | - Merve Özel
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Ved Mehta
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Alexander Leitner
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Paola Picotti
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Volodymyr M Korkhov
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland.
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
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Kathayat D, VanderVen BC. Exploiting cAMP signaling in Mycobacterium tuberculosis for drug discovery. Trends Microbiol 2024:S0966-842X(24)00008-8. [PMID: 38360432 DOI: 10.1016/j.tim.2024.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/21/2024] [Accepted: 01/23/2024] [Indexed: 02/17/2024]
Abstract
Mycobacterium tuberculosis (Mtb) replicates within host macrophages by adapting to the stressful and nutritionally constrained environments in these cells. Exploiting these adaptations for drug discovery has revealed that perturbing cAMP signaling can restrict Mtb growth in macrophages. Specifically, compounds that agonize or stimulate the bacterial enzyme, Rv1625c/Cya, induce cAMP synthesis and this interferes with the ability of Mtb to metabolize cholesterol. In murine tuberculosis (TB) infection models, Rv1625c/Cya agonists contribute to reducing relapse and shortening combination treatments, highlighting the therapeutic potential for this class of compounds. More recently, cAMP signaling has been implicated in regulating fatty acid utilization by Mtb. Thus, a new model is beginning to emerge in which cAMP regulates the utilization of host lipids by Mtb during infection, and this could provide new targets for TB drug development. Here, we summarize the current understanding of cAMP signaling in Mtb with a focus on our understanding of how cAMP signaling impacts Mtb physiology during infection. We also discuss additional cAMP-related drug targets in Mtb and other bacterial pathogens that may have therapeutic potential.
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Affiliation(s)
- Dipak Kathayat
- Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Brian C VanderVen
- Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA.
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Schuster D, Khanppnavar B, Kantarci I, Mehta V, Korkhov VM. Structural insights into membrane adenylyl cyclases, initiators of cAMP signaling. Trends Biochem Sci 2024; 49:156-168. [PMID: 38158273 DOI: 10.1016/j.tibs.2023.12.002] [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: 09/11/2023] [Revised: 12/04/2023] [Accepted: 12/04/2023] [Indexed: 01/03/2024]
Abstract
Membrane adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. As effector proteins of G protein-coupled receptors and other signaling pathways, ACs receive and amplify signals from the cell surface, translating them into biochemical reactions in the intracellular space and integrating different signaling pathways. Despite their importance in signal transduction and physiology, our knowledge about the structure, function, regulation, and molecular interactions of ACs remains relatively scarce. In this review, we summarize recent advances in our understanding of these membrane enzymes.
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Affiliation(s)
- Dina Schuster
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland; Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Switzerland; Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Switzerland
| | - Basavraj Khanppnavar
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland; Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Switzerland
| | - Ilayda Kantarci
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Ved Mehta
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Volodymyr M Korkhov
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland; Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Switzerland.
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Butler MS, Henderson IR, Capon RJ, Blaskovich MAT. Antibiotics in the clinical pipeline as of December 2022. J Antibiot (Tokyo) 2023; 76:431-473. [PMID: 37291465 PMCID: PMC10248350 DOI: 10.1038/s41429-023-00629-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 04/20/2023] [Accepted: 04/25/2023] [Indexed: 06/10/2023]
Abstract
The need for new antibacterial drugs to treat the increasing global prevalence of drug-resistant bacterial infections has clearly attracted global attention, with a range of existing and upcoming funding, policy, and legislative initiatives designed to revive antibacterial R&D. It is essential to assess whether these programs are having any real-world impact and this review continues our systematic analyses that began in 2011. Direct-acting antibacterials (47), non-traditional small molecule antibacterials (5), and β-lactam/β-lactamase inhibitor combinations (10) under clinical development as of December 2022 are described, as are the three antibacterial drugs launched since 2020. Encouragingly, the increased number of early-stage clinical candidates observed in the 2019 review increased in 2022, although the number of first-time drug approvals from 2020 to 2022 was disappointingly low. It will be critical to monitor how many Phase-I and -II candidates move into Phase-III and beyond in the next few years. There was also an enhanced presence of novel antibacterial pharmacophores in early-stage trials, and at least 18 of the 26 phase-I candidates were targeted to treat Gram-negative bacteria infections. Despite the promising early-stage antibacterial pipeline, it is essential to maintain funding for antibacterial R&D and to ensure that plans to address late-stage pipeline issues succeed.
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Affiliation(s)
- Mark S Butler
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, 4072, Australia.
| | - Ian R Henderson
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, 4072, Australia
| | - Robert J Capon
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, 4072, Australia
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, 4072, Australia.
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Cyclic AMP-Mediated Inhibition of Cholesterol Catabolism in Mycobacterium tuberculosis by the Novel Drug Candidate GSK2556286. Antimicrob Agents Chemother 2023; 67:e0129422. [PMID: 36602336 PMCID: PMC9872607 DOI: 10.1128/aac.01294-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Despite the deployment of combination tuberculosis (TB) chemotherapy, efforts to identify shorter, nonrelapsing treatments have resulted in limited success. Recent evidence indicates that GSK2556286 (GSK286), which acts via Rv1625c, a membrane-bound adenylyl cyclase in Mycobacterium tuberculosis, shortens treatment in rodents relative to standard of care drugs. Moreover, GSK286 can replace linezolid in the three-drug, Nix-TB regimen. Given its therapeutic potential, we sought to better understand the mechanism of action of GSK286. The compound blocked growth of M. tuberculosis in cholesterol media and increased intracellular cAMP levels ~50-fold. GSK286 did not inhibit growth of an rv1625c transposon mutant in cholesterol media and did not induce cyclic AMP (cAMP) production in this mutant, suggesting that the compound acts on this adenylyl cyclase. GSK286 also induced cAMP production in Rhodococcus jostii RHA1, a cholesterol-catabolizing actinobacterium, when Rv1625c was heterologously expressed. However, these elevated levels of cAMP did not inhibit growth of R. jostii RHA1 in cholesterol medium. Mutations in rv1625c conferred cross-resistance to GSK286 and the known Rv1625c agonist, mCLB073. Metabolic profiling of M. tuberculosis cells revealed that elevated cAMP levels, induced using either an agonist or a genetic tool, did not significantly affect pools of steroid metabolites in cholesterol-incubated cells. Finally, the inhibitory effect of agonists was not dependent on the N-acetyltransferase MtPat. Together, these data establish that GSK286 is an Rv1625c agonist and sheds light on how cAMP signaling can be manipulated as a novel antibiotic strategy to shorten TB treatments. Nevertheless, the detailed mechanism of action of these compounds remains to be elucidated.
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