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Hoffmann A, Steffens U, Maček B, Franz-Wachtel M, Nieselt K, Harbig TA, Scherlach K, Hertweck C, Sahl HG, Bierbaum G. The unusual mode of action of the polyketide glycoside antibiotic cervimycin C. mSphere 2024; 9:e0076423. [PMID: 38722162 PMCID: PMC11237698 DOI: 10.1128/msphere.00764-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 03/28/2024] [Indexed: 05/30/2024] Open
Abstract
Cervimycins A-D are bis-glycosylated polyketide antibiotics produced by Streptomyces tendae HKI 0179 with bactericidal activity against Gram-positive bacteria. In this study, cervimycin C (CmC) treatment caused a spaghetti-like phenotype in Bacillus subtilis 168, with elongated curved cells, which stayed joined after cell division, and exhibited a chromosome segregation defect, resulting in ghost cells without DNA. Electron microscopy of CmC-treated Staphylococcus aureus (3 × MIC) revealed swollen cells, misshapen septa, cell wall thickening, and a rough cell wall surface. Incorporation tests in B. subtilis indicated an effect on DNA biosynthesis at high cervimycin concentrations. Indeed, artificial downregulation of the DNA gyrase subunit B gene (gyrB) increased the activity of cervimycin in agar diffusion tests, and, in high concentrations (starting at 62.5 × MIC), the antibiotic inhibited S. aureus DNA gyrase supercoiling activity in vitro. To obtain a more global view on the mode of action of CmC, transcriptomics and proteomics of cervimycin treated versus untreated S. aureus cells were performed. Interestingly, 3 × MIC of cervimycin did not induce characteristic responses, which would indicate disturbance of the DNA gyrase activity in vivo. Instead, cervimycin induced the expression of the CtsR/HrcA heat shock operon and the expression of autolysins, exhibiting similarity to the ribosome-targeting antibiotic gentamicin. In summary, we identified the DNA gyrase as a target, but at low concentrations, electron microscopy and omics data revealed a more complex mode of action of cervimycin, which comprised induction of the heat shock response, indicating protein stress in the cell.IMPORTANCEAntibiotic resistance of Gram-positive bacteria is an emerging problem in modern medicine, and new antibiotics with novel modes of action are urgently needed. Secondary metabolites from Streptomyces species are an important source of antibiotics, like the cervimycin complex produced by Streptomyces tendae HKI 0179. The phenotypic response of Bacillus subtilis and Staphylococcus aureus toward cervimycin C indicated a chromosome segregation and septum formation defect. This effect was at first attributed to an interaction between cervimycin C and the DNA gyrase. However, omics data of cervimycin treated versus untreated S. aureus cells indicated a different mode of action, because the stress response did not include the SOS response but resembled the response toward antibiotics that induce mistranslation or premature chain termination and cause protein stress. In summary, these results point toward a possibly novel mechanism that generates protein stress in the cells and subsequently leads to defects in cell and chromosome segregation.
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Affiliation(s)
- Alina Hoffmann
- University Hospital Bonn, Institute of Medical Microbiology, Immunology and Parasitology, Bonn, Germany
| | - Ursula Steffens
- University Hospital Bonn, Institute of Medical Microbiology, Immunology and Parasitology, Bonn, Germany
| | - Boris Maček
- University of Tübingen, Proteome Center Tübingen, Tübingen, Germany
| | | | - Kay Nieselt
- University of Tübingen, Interfaculty Institute for Bioinformatics and Medical Informatics, Tübingen, Germany
| | - Theresa Anisja Harbig
- University of Tübingen, Interfaculty Institute for Bioinformatics and Medical Informatics, Tübingen, Germany
| | - Kirstin Scherlach
- Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
| | - Christian Hertweck
- Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (HKI), Jena, Germany
- Friedrich Schiller University Jena, Institute of Microbiology, Faculty of Biological Sciences, Jena, Germany
| | - Hans-Georg Sahl
- University of Bonn, Institute for Pharmaceutical Microbiology, Bonn, Germany
| | - Gabriele Bierbaum
- University Hospital Bonn, Institute of Medical Microbiology, Immunology and Parasitology, Bonn, Germany
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2
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Conformational space exploration of cryo-EM structures by variability refinement. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184133. [PMID: 36738875 DOI: 10.1016/j.bbamem.2023.184133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/27/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023]
Abstract
Cryo-EM observation of biological samples enables visualization of sample heterogeneity, in the form of discrete states that are separable, or continuous heterogeneity as a result of local protein motion before flash freezing. Variability analysis of this continuous heterogeneity describes the variance between a particle stack and a volume, and results in a map series describing the various steps undertaken by the sample in the particle stack. While this observation is absolutely stunning, it is very hard to pinpoint structural details to elements of the maps. In order to bridge the gap between observation and explanation, we designed a tool that refines an ensemble of structures into all the maps from variability analysis. Using this bundle of structures, it is easy to spot variable parts of the structure, as well as the parts that are not moving. Comparison with molecular dynamics simulations highlights the fact that the movements follow the same directions, albeit with different amplitudes. Ligand can also be investigated using this method. Variability refinement is available in the Phenix software suite, accessible under the program name phenix.varref.
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Cervimycin-Resistant Staphylococcus aureus Strains Display Vancomycin-Intermediate Resistant Phenotypes. Microbiol Spectr 2022; 10:e0256722. [PMID: 36173303 PMCID: PMC9603734 DOI: 10.1128/spectrum.02567-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Resistance to antibiotics is an increasing problem and necessitates novel antibacterial therapies. The polyketide antibiotics cervimycin A to D are natural products of Streptomyces tendae HKI 0179 with promising activity against multidrug-resistant staphylococci and vancomycin-resistant enterococci. To initiate mode of action studies, we selected cervimycin C- and D-resistant (CmR) Staphylococcus aureus strains. Genome sequencing of CmR mutants revealed amino acid exchanges in the essential histidine kinase WalK, the Clp protease proteolytic subunit ClpP or the Clp ATPase ClpC, and the heat shock protein DnaK. Interestingly, all characterized CmR mutants harbored a combination of mutations in walK and clpP or clpC. In vitro and in vivo analyses showed that the mutations in the Clp proteins abolished ClpP or ClpC activity, and the deletion of clpP rendered S. aureus but not all Bacillus subtilis strains cervimycin-resistant. The essential gene walK was the second mutational hotspot in the CmR S. aureus strains, which decreased WalK activity in vitro and generated a vancomycin-intermediate resistant phenotype, with a thickened cell wall, a lower growth rate, and reduced cell lysis. Transcriptomic and proteomic analyses revealed massive alterations in the CmR strains compared to the parent strain S. aureus SG511, with major shifts in the heat shock regulon, the metal ion homeostasis, and the carbohydrate metabolism. Taken together, mutations in the heat shock genes clpP, clpC, and dnaK, and the walK kinase gene in CmR mutants induced a vancomycin-intermediate resistant phenotype in S. aureus, suggesting cell wall metabolism or the Clp protease system as primary target of cervimycin. IMPORTANCE Staphylococcus aureus is a frequent cause of infections in both the community and hospital setting. Resistance development of S. aureus to various antibiotics is a severe problem for the treatment of this pathogen worldwide. New powerful antimicrobial agents against Gram-positives are needed, since antibiotics like vancomycin fail to cure vancomycin-intermediate resistant S. aureus (VISA) and vancomycin-resistant enterococci (VRE) infections. One candidate substance with promising activity against these organisms is cervimycin, which is an antibiotic complex with a yet unknown mode of action. In our study, we provide first insights into the mode of action of cervimycins. By characterizing cervimycin-resistant S. aureus strains, we revealed the Clp system and the essential kinase WalK as mutational hotspots for cervimycin resistance in S. aureus. It further emerged that cervimycin-resistant S. aureus strains show a VISA phenotype, indicating a role of cervimycin in perturbing the bacterial cell envelope.
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Lacabanne D, Wiegand T, Di Cesare M, Orelle C, Ernst M, Jault JM, Meier BH, Böckmann A. Solid-State NMR Reveals Asymmetric ATP Hydrolysis in the Multidrug ABC Transporter BmrA. J Am Chem Soc 2022; 144:12431-12442. [PMID: 35776907 PMCID: PMC9284561 DOI: 10.1021/jacs.2c04287] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
The detailed mechanism
of ATP hydrolysis in ATP-binding cassette
(ABC) transporters is still not fully understood. Here, we employed 31P solid-state NMR to probe the conformational changes and
dynamics during the catalytic cycle by locking the multidrug ABC transporter
BmrA in prehydrolytic, transition, and posthydrolytic states, using
a combination of mutants and ATP analogues. The 31P spectra
reveal that ATP binds strongly in the prehydrolytic state to both
ATP-binding sites as inferred from the analysis of the nonhydrolytic
E504A mutant. In the transition state of wild-type BmrA, the symmetry
of the dimer is broken and only a single site is tightly bound to
ADP:Mg2+:vanadate, while the second site is more ‘open’
allowing exchange with the nucleotides in the solvent. In the posthydrolytic
state, weak binding, as characterized by chemical exchange with free
ADP and by asymmetric 31P–31P two-dimensional
(2D) correlation spectra, is observed for both sites. Revisiting the 13C spectra in light of these findings confirms the conformational
nonequivalence of the two nucleotide-binding sites in the transition
state. Our results show that following ATP binding, the symmetry of
the ATP-binding sites of BmrA is lost in the ATP-hydrolysis step,
but is then recovered in the posthydrolytic ADP-bound state.
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Affiliation(s)
| | - Thomas Wiegand
- Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Margot Di Cesare
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS/University of Lyon, 7, passage du Vercors, 69367 Lyon, France
| | - Cédric Orelle
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS/University of Lyon, 7, passage du Vercors, 69367 Lyon, France
| | - Matthias Ernst
- Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Jean-Michel Jault
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS/University of Lyon, 7, passage du Vercors, 69367 Lyon, France
| | - Beat H Meier
- Physical Chemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Anja Böckmann
- Molecular Microbiology and Structural Biochemistry, UMR5086 CNRS/University of Lyon, 7, passage du Vercors, 69367 Lyon, France
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5
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Structural insights into the catalytic cycle of a bacterial multidrug ABC efflux pump. J Mol Biol 2022; 434:167541. [DOI: 10.1016/j.jmb.2022.167541] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/02/2022] [Accepted: 03/09/2022] [Indexed: 12/19/2022]
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Chaptal V, Zampieri V, Wiseman B, Orelle C, Martin J, Nguyen KA, Gobet A, Di Cesare M, Magnard S, Javed W, Eid J, Kilburg A, Peuchmaur M, Marcoux J, Monticelli L, Hogbom M, Schoehn G, Jault JM, Boumendjel A, Falson P. Substrate-bound and substrate-free outward-facing structures of a multidrug ABC exporter. SCIENCE ADVANCES 2022; 8:eabg9215. [PMID: 35080979 DOI: 10.1101/2021.03.12.435132] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecular features of drug release are so far unknown. Here, we resolved three ATP-Mg2+-bound outward-facing conformations of the Bacillus subtilis (homodimeric) BmrA by x-ray crystallography and single-particle cryo-electron microscopy (EM) in detergent solution, one of them with rhodamine 6G (R6G), a substrate exported by BmrA when overexpressed in B. subtilis. Two R6G molecules bind to the drug-binding cavity at the level of the outer leaflet, between transmembrane (TM) helices 1-2 of one monomer and TM5'-6' of the other. They induce a rearrangement of TM1-2, highlighting a local flexibility that we confirmed by hydrogen/deuterium exchange and molecular dynamics simulations. In the absence of R6G, simulations show a fast postrelease occlusion of the cavity driven by hydrophobicity, while when present, R6G can move within the cavity, maintaining it open.
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Affiliation(s)
- Vincent Chaptal
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Veronica Zampieri
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Benjamin Wiseman
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Cédric Orelle
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Juliette Martin
- Modeling Biological Macromolecules Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Kim-Anh Nguyen
- University of Grenoble Alpes, INSERM, LRB, 38000 Grenoble, France
| | - Alexia Gobet
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Margot Di Cesare
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Sandrine Magnard
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Waqas Javed
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Jad Eid
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Arnaud Kilburg
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Marine Peuchmaur
- University of Grenoble Alpes, CNRS, DPM UMR 5063, 38041 Grenoble, France
| | - Julien Marcoux
- Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089, Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Luca Monticelli
- Modeling Biological Macromolecules Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Martin Hogbom
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Guy Schoehn
- University of Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France
| | - Jean-Michel Jault
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | | | - Pierre Falson
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
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7
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Chaptal V, Zampieri V, Wiseman B, Orelle C, Martin J, Nguyen KA, Gobet A, Di Cesare M, Magnard S, Javed W, Eid J, Kilburg A, Peuchmaur M, Marcoux J, Monticelli L, Hogbom M, Schoehn G, Jault JM, Boumendjel A, Falson P. Substrate-bound and substrate-free outward-facing structures of a multidrug ABC exporter. SCIENCE ADVANCES 2022; 8:eabg9215. [PMID: 35080979 PMCID: PMC8791611 DOI: 10.1126/sciadv.abg9215] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Multidrug ABC transporters translocate drugs across membranes by a mechanism for which the molecular features of drug release are so far unknown. Here, we resolved three ATP-Mg2+-bound outward-facing conformations of the Bacillus subtilis (homodimeric) BmrA by x-ray crystallography and single-particle cryo-electron microscopy (EM) in detergent solution, one of them with rhodamine 6G (R6G), a substrate exported by BmrA when overexpressed in B. subtilis. Two R6G molecules bind to the drug-binding cavity at the level of the outer leaflet, between transmembrane (TM) helices 1-2 of one monomer and TM5'-6' of the other. They induce a rearrangement of TM1-2, highlighting a local flexibility that we confirmed by hydrogen/deuterium exchange and molecular dynamics simulations. In the absence of R6G, simulations show a fast postrelease occlusion of the cavity driven by hydrophobicity, while when present, R6G can move within the cavity, maintaining it open.
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Affiliation(s)
- Vincent Chaptal
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Veronica Zampieri
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Benjamin Wiseman
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Cédric Orelle
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Juliette Martin
- Modeling Biological Macromolecules Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Kim-Anh Nguyen
- University of Grenoble Alpes, INSERM, LRB, 38000 Grenoble, France
| | - Alexia Gobet
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Margot Di Cesare
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Sandrine Magnard
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Waqas Javed
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Jad Eid
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Arnaud Kilburg
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Marine Peuchmaur
- University of Grenoble Alpes, CNRS, DPM UMR 5063, 38041 Grenoble, France
| | - Julien Marcoux
- Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089, Université de Toulouse, CNRS, UPS, 31000 Toulouse, France
| | - Luca Monticelli
- Modeling Biological Macromolecules Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | - Martin Hogbom
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Guy Schoehn
- University of Grenoble Alpes, CEA, CNRS, IBS, F-38000 Grenoble, France
| | - Jean-Michel Jault
- Bacterial Nucleotide-Binding Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
| | | | - Pierre Falson
- Drug Resistance and Membrane Proteins Group, Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, IBCP, 7, passage du Vercors, 69367 Lyon, France
- Corresponding author.
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8
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Gobet A, Jaxel C, Magnard S, Garrigos M, Orlowski S, Jamin N, Falson P, Chaptal V. Overexpression of the ABC Transporter BmrA Within Intracellular Caveolae in Escherichia coli. Methods Mol Biol 2022; 2507:79-89. [PMID: 35773578 DOI: 10.1007/978-1-0716-2368-8_5] [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: 06/15/2023]
Abstract
We describe here the overproduction and oriented membrane insertion of membrane protein inside intracellular vesicles named heterologous caveolae within E. coli. The method is described with BmrA, a multidrug efflux pump from Bacillus subtilis. BmrA is produced in these vesicles, thanks to the coexpression with the canine caveolin-1β, one of the two isoforms of caveolin-1. Enriched by sucrose gradient, the caveolae-containing fraction allows to probe the ATPase and Hoechst 33342 transport activities, the latter displaying a higher specific activity than the same without caveolin-1β.
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Affiliation(s)
- Alexia Gobet
- Drug Resistance and Membrane Proteins Team, CNRS - Lyon 1 University UMR 5086, Institut de Biologie et Chimie des Protéines, Lyon, France
| | - Christine Jaxel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Sandrine Magnard
- Drug Resistance and Membrane Proteins Team, CNRS - Lyon 1 University UMR 5086, Institut de Biologie et Chimie des Protéines, Lyon, France
| | - Manuel Garrigos
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphane Orlowski
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Nadège Jamin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.
| | - Pierre Falson
- Drug Resistance and Membrane Proteins Team, CNRS - Lyon 1 University UMR 5086, Institut de Biologie et Chimie des Protéines, Lyon, France.
| | - Vincent Chaptal
- Drug Resistance and Membrane Proteins Team, CNRS - Lyon 1 University UMR 5086, Institut de Biologie et Chimie des Protéines, Lyon, France.
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Oepen K, Özbek H, Schüffler A, Liermann JC, Thines E, Schneider D. Myristic Acid Inhibits the Activity of the Bacterial ABC Transporter BmrA. Int J Mol Sci 2021; 22:ijms222413565. [PMID: 34948362 PMCID: PMC8707315 DOI: 10.3390/ijms222413565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/07/2021] [Accepted: 12/14/2021] [Indexed: 12/12/2022] Open
Abstract
ATP-binding cassette (ABC) transporters are conserved in all kingdoms of life, where they transport substrates against a concentration gradient across membranes. Some ABC transporters are known to cause multidrug resistances in humans and are able to transport chemotherapeutics across cellular membranes. Similarly, BmrA, the ABC transporter of Bacillus subtilis, is involved in excretion of certain antibiotics out of bacterial cells. Screening of extract libraries isolated from fungi revealed that the C14 fatty acid myristic acid has an inhibitory effect on the BmrA ATPase as well as the transport activity. Thus, a natural membrane constituent inhibits the BmrA activity, a finding with physiological consequences as to the activity and regulation of ABC transporter activities in biological membranes.
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Affiliation(s)
- Kristin Oepen
- Department of Chemistry, Johannes Gutenberg-University, 55128 Mainz, Germany; (K.O.); (J.C.L.)
| | - Hüseyin Özbek
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), 55128 Mainz, Germany; (H.Ö.); (A.S.); (E.T.)
| | - Anja Schüffler
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), 55128 Mainz, Germany; (H.Ö.); (A.S.); (E.T.)
| | - Johannes C. Liermann
- Department of Chemistry, Johannes Gutenberg-University, 55128 Mainz, Germany; (K.O.); (J.C.L.)
| | - Eckhard Thines
- Institut für Biotechnologie und Wirkstoff-Forschung gGmbH (IBWF), 55128 Mainz, Germany; (H.Ö.); (A.S.); (E.T.)
- Institute of Molecular Physiology, Johannes Gutenberg-University, 55128 Mainz, Germany
| | - Dirk Schneider
- Department of Chemistry, Johannes Gutenberg-University, 55128 Mainz, Germany; (K.O.); (J.C.L.)
- Institute of Molecular Physiology, Johannes Gutenberg-University, 55128 Mainz, Germany
- Correspondence: ; Tel.: +49-6131-39-25833
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10
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Rismondo J, Schulz LM. Not Just Transporters: Alternative Functions of ABC Transporters in Bacillus subtilis and Listeria monocytogenes. Microorganisms 2021; 9:microorganisms9010163. [PMID: 33450852 PMCID: PMC7828314 DOI: 10.3390/microorganisms9010163] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/07/2021] [Accepted: 01/10/2021] [Indexed: 12/24/2022] Open
Abstract
ATP-binding cassette (ABC) transporters are usually involved in the translocation of their cognate substrates, which is driven by ATP hydrolysis. Typically, these transporters are required for the import or export of a wide range of substrates such as sugars, ions and complex organic molecules. ABC exporters can also be involved in the export of toxic compounds such as antibiotics. However, recent studies revealed alternative detoxification mechanisms of ABC transporters. For instance, the ABC transporter BceAB of Bacillus subtilis seems to confer resistance to bacitracin via target protection. In addition, several transporters with functions other than substrate export or import have been identified in the past. Here, we provide an overview of recent findings on ABC transporters of the Gram-positive organisms B. subtilis and Listeria monocytogenes with transport or regulatory functions affecting antibiotic resistance, cell wall biosynthesis, cell division and sporulation.
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Feng Z, Liu D, Liu Z, Liang Y, Wang Y, Liu Q, Liu Z, Zang Z, Cui Y. Cloning and Functional Characterization of Putative Escherichia coli ABC Multidrug Efflux Transporter YddA. J Microbiol Biotechnol 2020; 30:982-995. [PMID: 32347079 PMCID: PMC9728188 DOI: 10.4014/jmb.2003.03003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/23/2020] [Indexed: 12/15/2022]
Abstract
A putative multidrug efflux gene, yddA, was cloned from the Escherichia coli K-12 strain. A drugsensitive strain of E. coli missing the main multidrug efflux pump AcrB was constructed as a host and the yddA gene was knocked out in wild-type (WT) and drug-sensitive E. coliΔacrB to study the yddA function. Sensitivity to different substrates of WT E.coli, E. coliΔyddA, E. coliΔacrB and E. coliΔacrBΔyddA strains was compared with minimal inhibitory concentration (MIC) assays and fluorescence tests. MIC assay and fluorescence test results showed that YddA protein was a multidrug efflux pump that exported multiple substrates. Three inhibitors, ortho-vanadate, carbonyl cyanide m-chlorophenylhydrazone (CCCP), and reserpine, were used in fluorescence tests. Ortho-vanadate and reserpine significantly inhibited the efflux and increased accumulation of ethidium bromide and norfloxacin, while CCCP had no significant effect on YddA-regulated efflux. The results indicated that YddA relies on energy released from ATP hydrolysis to transfer the substrates and YddA is an ABC-type multidrug exporter. Functional study of unknown ATP-binding cassette (ABC) superfamily transporters in the model organism E. coli is conducive to discovering new multidrug resistance-reversal targets and providing references for studying other ABC proteins of unknown function.
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Affiliation(s)
- Zhenyue Feng
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China,College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Defu Liu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Ziwen Liu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Yimin Liang
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Yanhong Wang
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Qingpeng Liu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Zhenhua Liu
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Zhongjing Zang
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China
| | - Yudong Cui
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China,College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, P.R. China,Corresponding author Phone/Fax: +459-6031177 E-mail:
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12
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Multidrug ABC transporters in bacteria. Res Microbiol 2019; 170:381-391. [DOI: 10.1016/j.resmic.2019.06.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 06/12/2019] [Accepted: 06/17/2019] [Indexed: 12/23/2022]
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13
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Lacabanne D, Orelle C, Lecoq L, Kunert B, Chuilon C, Wiegand T, Ravaud S, Jault JM, Meier BH, Böckmann A. Flexible-to-rigid transition is central for substrate transport in the ABC transporter BmrA from Bacillus subtilis. Commun Biol 2019; 2:149. [PMID: 31044174 PMCID: PMC6488656 DOI: 10.1038/s42003-019-0390-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 03/15/2019] [Indexed: 01/15/2023] Open
Abstract
ATP-binding-cassette (ABC) transporters are molecular pumps that translocate molecules across the cell membrane by switching between inward-facing and outward-facing states. To obtain a detailed understanding of their mechanism remains a challenge to structural biology, as these proteins are notoriously difficult to study at the molecular level in their active, membrane-inserted form. Here we use solid-state NMR to investigate the multidrug ABC transporter BmrA reconstituted in lipids. We identify the chemical-shift differences between the inward-facing, and outward-facing state induced by ATP:Mg2+:Vi addition. Analysis of an X-loop mutant, for which we show that ATPase and transport activities are uncoupled, reveals an incomplete transition to the outward-facing state upon ATP:Mg2+:Vi addition, notably lacking the decrease in dynamics of a defined set of residues observed in wild-type BmrA. This suggests that this stiffening is required for an efficient transmission of the conformational changes to allow proper transport of substrate by the pump.
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Affiliation(s)
- Denis Lacabanne
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Cédric Orelle
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Lauriane Lecoq
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Britta Kunert
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Claire Chuilon
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Thomas Wiegand
- Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Stéphanie Ravaud
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Jean-Michel Jault
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
| | - Beat H. Meier
- Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Anja Böckmann
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, 7, passage de Vercors, 69367 Lyon, France
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Chelliah R, Wei S, Park BJ, Park JH, Park YS, Kim SH, Jin YG, Oh DH. New perspectives on Mega plasmid sequence (poh1) in Bacillus thuringiensis ATCC 10792 harbouring antimicrobial, insecticidal and antibiotic resistance genes. Microb Pathog 2018; 126:14-18. [PMID: 30326263 DOI: 10.1016/j.micpath.2018.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 09/23/2018] [Accepted: 10/09/2018] [Indexed: 11/29/2022]
Abstract
Bacillus thuringiensis promotes the growth of numerous economically important crops. The present study presents the complete genome sequence for a mega plasmid present in the type strain of B. thuringiensis ATCC 10792, a typical spore-forming Gram-positive bacterium with insecticidal activity, and investigates its genetic characteristics. The genome was sequenced and assembled de novo using Pac-Bio sequencers and the Hierarchical Genome Assembly Process, respectively. Further genome annotation was performed, and a total of 489 proteins and a novel mega-plasmid (poh1) with 584,623 bps were identified. The organization of poh1 revealed the genes involved in the insecticidal toxin pathway. The genes responsible for antimicrobial, insecticidal and antibiotic activities were well conserved in poh1, indicating an intimate association with plant hosts. The poh1 plasmid contains the gene encoding a novel crystal protein kinase responsible for production of zeta toxin, which poisons insects and other Gram-negative bacteria through the global inhibition of peptidoglycan synthesis. Lantibiotics are a group of bacteriocins that include the biologically active antimicrobial peptide Paenibacillin. Further, poh1 also contains the genes that encode the gramicidin S prototypical antibiotic peptide and tetracycline resistance protein. In conclusion, the strain-specific genes of B. thuringiensis strain ATCC 10792 were identified through complete genome sequencing and bioinformatics data based on major pathogenic factors that contribute to further studies of the pathogenic mechanism and phenotype analyses.
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Affiliation(s)
- Ramachandran Chelliah
- Department of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwon-do, 24341, Republic of Korea
| | - Shuai Wei
- Department of Medical Biomaterials Engineering and Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon, Republic of Korea
| | - Byung-Jae Park
- Department of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwon-do, 24341, Republic of Korea
| | - Joong-Hyun Park
- Department of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwon-do, 24341, Republic of Korea
| | - Youn-Seo Park
- Department of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwon-do, 24341, Republic of Korea
| | - Se-Hun Kim
- Department of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwon-do, 24341, Republic of Korea
| | - Yong-Guo Jin
- National Research and Development Center for Egg Processing, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, PR China.
| | - Deog-Hwan Oh
- Department of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwon-do, 24341, Republic of Korea.
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Ghosh S, Kuisiene N, Cheeptham N. The cave microbiome as a source for drug discovery: Reality or pipe dream? Biochem Pharmacol 2016; 134:18-34. [PMID: 27867014 DOI: 10.1016/j.bcp.2016.11.018] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 11/15/2016] [Indexed: 01/04/2023]
Abstract
This review highlights cave habitats, cave microbiomes and their potential for drug discovery. Such studies face many challenges, including access to remote and pristine caves, and sample collection and transport. Inappropriate physical and chemical growth conditions in the laboratory for the isolation and cultivation of cave microorganisms pose many complications including length of cultivation; some cave microorganisms can take weeks and even months to grow. Additionally, DNA extraction from cave environmental samples may be difficult due to the high concentration of various minerals that are natural DNA blocking agents. Once cave microorganisms are grown in the lab, other problems often arise, such as maintenance of pure culture, consistency of antimicrobial activity and fermentation conditions for antimicrobial production. In this review, we suggest that, although based on what has been done in the field, there is potential in using cave microorganisms to produce antimicrobial agents, one needs to be highly committed and prepared.
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Affiliation(s)
- Soumya Ghosh
- Department of Biological Sciences, Faculty of Science, Thompson Rivers University, Kamloops, BC, Canada
| | - Nomeda Kuisiene
- Department of Microbiology and Biotechnology, Vilnius University, Lithuania
| | - Naowarat Cheeptham
- Department of Biological Sciences, Faculty of Science, Thompson Rivers University, Kamloops, BC, Canada.
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16
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Schindler BD, Kaatz GW. Multidrug efflux pumps of Gram-positive bacteria. Drug Resist Updat 2016; 27:1-13. [DOI: 10.1016/j.drup.2016.04.003] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/28/2016] [Accepted: 04/22/2016] [Indexed: 11/16/2022]
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17
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Elshahawi SI, Shaaban KA, Kharel MK, Thorson JS. A comprehensive review of glycosylated bacterial natural products. Chem Soc Rev 2015; 44:7591-697. [PMID: 25735878 PMCID: PMC4560691 DOI: 10.1039/c4cs00426d] [Citation(s) in RCA: 299] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15 940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.
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Affiliation(s)
- Sherif I Elshahawi
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Khaled A Shaaban
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Madan K Kharel
- School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, Maryland, USA
| | - Jon S Thorson
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
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18
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Baylay AJ, Piddock LJV. Clinically relevant fluoroquinolone resistance due to constitutive overexpression of the PatAB ABC transporter in Streptococcus pneumoniae is conferred by disruption of a transcriptional attenuator. J Antimicrob Chemother 2014; 70:670-9. [PMID: 25411187 PMCID: PMC4319486 DOI: 10.1093/jac/dku449] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Constitutive overexpression of patAB has been observed in several unrelated fluoroquinolone-resistant laboratory mutants and clinical isolates; therefore, we sought to identify the cause of this overexpression. METHODS Constitutive patAB overexpression in two clinical isolates and a laboratory-selected mutant was investigated using a whole-genome transformation approach. To determine the effect of the detected terminator mutations, the WT and mutated patA leader sequences were cloned upstream of a GFP reporter. Finally, mutation of the opposing base in the stem-loop structure was carried out. RESULTS We identified three novel mutations causing up-regulation of patAB. All three of these were located in the upstream region of patA and affected the same Rho-independent transcriptional terminator structure. Each mutation was predicted to destabilize the terminator stem-loop to a different degree, and there was a strong correlation between predicted terminator stability and patAB expression level. Using a GFP reporter of patA transcription, these terminator mutations led to increased transcription of a downstream gene. For one mutant sequence, terminator stability could be restored by mutation of the opposing base in the stem-loop structure, demonstrating that transcriptional suppression of patAB is mediated by the terminator stem-loop structure. CONCLUSIONS This study showed that a mutation in a Rho-independent transcriptional terminator structure confers overexpression of patAB and fluoroquinolone resistance. Understanding how levels of the PatAB efflux pump are regulated increases our knowledge of pneumococcal biology and how the pneumococcus can respond to various stresses, including antimicrobials.
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Affiliation(s)
- Alison J Baylay
- Antimicrobials Research Group, School of Immunity and Infection, Institute of Microbiology and Infection and College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Laura J V Piddock
- Antimicrobials Research Group, School of Immunity and Infection, Institute of Microbiology and Infection and College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
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3D cryo-electron reconstruction of BmrA, a bacterial multidrug ABC transporter in an inward-facing conformation and in a lipidic environment. J Mol Biol 2014; 426:2059-69. [PMID: 24630999 DOI: 10.1016/j.jmb.2014.03.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 03/01/2014] [Accepted: 03/04/2014] [Indexed: 11/21/2022]
Abstract
ABC (ATP-binding cassette) membrane exporters are efflux transporters of a wide diversity of molecule across the membrane at the expense of ATP. A key issue regarding their catalytic cycle is whether or not their nucleotide-binding domains (NBDs) are physically disengaged in the resting state. To settle this controversy, we obtained structural data on BmrA, a bacterial multidrug homodimeric ABC transporter, in a membrane-embedded state. BmrA in the apostate was reconstituted in lipid bilayers forming a mixture of ring-shaped structures of 24 or 39 homodimers. Three-dimensional models of the ring-shaped structures of 24 or 39 homodimers were calculated at 2.3 nm and 2.5 nm resolution from cryo-electron microscopy, respectively. In these structures, BmrA adopts an inward-facing open conformation similar to that found in mouse P-glycoprotein structure with the NBDs separated by 3 nm. Both lipidic leaflets delimiting the transmembrane domains of BmrA were clearly resolved. In planar membrane sheets, the NBDs were even more separated. BmrA in an ATP-bound conformation was determined from two-dimensional crystals grown in the presence of ATP and vanadate. A projection map calculated at 1.6 nm resolution shows an open outward-facing conformation. Overall, the data are consistent with a mechanism of drug transport involving large conformational changes of BmrA and show that a bacterial ABC exporter can adopt at least two open inward conformations in lipid membrane.
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