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Galarion LH, Mitchell JK, Randall CP, O’Neill AJ. An extensively validated whole-cell biosensor for specific, sensitive and high-throughput detection of antibacterial inhibitors targeting cell-wall biosynthesis. J Antimicrob Chemother 2023; 78:646-655. [PMID: 36626387 PMCID: PMC9978594 DOI: 10.1093/jac/dkac429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 12/02/2022] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Whole-cell biosensor strains are powerful tools for antibacterial drug discovery, in principle allowing the identification of inhibitors acting on specific, high-value target pathways. Whilst a variety of biosensors have been described for detecting cell-wall biosynthesis inhibitors (CWBIs), these strains typically lack specificity and/or sensitivity, and have for the most part not been rigorously evaluated as primary screening tools. Here, we describe several Staphylococcus aureus CWBI biosensors and show that specific and sensitive biosensor-based discovery of CWBIs is achievable. METHODS Biosensors comprised lacZ reporter fusions with S. aureus promoters (PgltB, PilvD, PmurZ, PoppB, PORF2768, PsgtB) that are subject to up-regulation following inhibition of cell-wall biosynthesis. Induction of biosensors was detected by measuring expression of β-galactosidase using fluorogenic or luminogenic substrates. RESULTS Three of the six biosensors tested (those based on PgltB, PmurZ, PsgtB) exhibited apparently specific induction of β-galactosidase expression in the presence of CWBIs. Further validation of one of these (PmurZ) using an extensive array of positive and negative control compounds and conditional mutants established that it responded appropriately and uniquely to inhibition of cell-wall biosynthesis. Using this biosensor, we established, validated and deployed a high-throughput assay that identified a potentially novel CWBI from a screen of >9000 natural product extracts. CONCLUSIONS Our extensively validated PmurZ biosensor strain offers specific and sensitive detection of CWBIs, and is well-suited for high-throughput screening; it therefore represents a valuable tool for antibacterial drug discovery.
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Affiliation(s)
- Luiza H Galarion
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Jennifer K Mitchell
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Christopher P Randall
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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2
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Fungal Depsides-Naturally Inspiring Molecules: Biosynthesis, Structural Characterization, and Biological Activities. Metabolites 2021; 11:metabo11100683. [PMID: 34677398 PMCID: PMC8540757 DOI: 10.3390/metabo11100683] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/05/2021] [Accepted: 10/02/2021] [Indexed: 11/23/2022] Open
Abstract
Fungi represent a huge reservoir of structurally diverse bio-metabolites. Although there has been a marked increase in the number of isolated fungal metabolites over the past years, many hidden metabolites still need to be discovered. Depsides are a group of polyketides consisting of two or more ester-linked hydroxybenzoic acid moieties. They possess valuable bioactive properties, such as anticancer, antidiabetic, antibacterial, antiviral, anti-inflammatory, antifungal, antifouling, and antioxidant qualities, as well as various human enzyme-inhibitory activities. This review provides an overview of the reported data on fungal depsides, including their sources, biosynthesis, physical and spectral data, and bioactivities in the period from 1975 to 2020. Overall, 110 metabolites and more than 122 references are confirmed. This is the first review of these multi-faceted metabolites from fungi.
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3
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Ibrahim SRM, Altyar AE, Mohamed SGA, Mohamed GA. Genus Thielavia: phytochemicals, industrial importance and biological relevance. Nat Prod Res 2021; 36:5108-5123. [PMID: 33949258 DOI: 10.1080/14786419.2021.1919105] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Thielavia species (Chaetomiaceae) are a wealthy source of enzymes such as laccases, cutinases, glucuronoyl esterases, feruloyl esterases, 1,4-β-endoglucanase and lytic polysaccharide monooxygenases that reported to have various biotechnological and industrial applications in dye decolorization, bio-refinery, biomass utilization, ester biosynthesis and biodegradation. Different metabolites have been reported from this genus as depsides, azaphilones, pyrazines, naphthodianthrones and anthraquinones derivatives. These metabolites have attracted research interest due to their fascinating structures and diverse bioactivities, including antimicrobial, cytotoxic, antioxidant, anti-diabetic, and superoxide anion generation, phospholipase, prostaglandins synthesis and proteasome inhibitory activities. Therefore, these compounds can be taken into account as candidates for the development of effective and novel pharmaceutical leads. The current review represents the relevant information for the Thielavia genus, in particular, its phytoconstituents and their pharmacological activities, as well as the biotechnological applications of Thielavia species published from 1981 till now. More than 40 metabolites are described and - 71 references are cited.
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Affiliation(s)
- Sabrin R M Ibrahim
- Batterjee Medical College, Preparatory Year Program, Jeddah, Saudi Arabia.,Department of Pharmacognosy, Faculty of Pharmacy, Assiut University, Assiut, Egypt
| | - Ahmed E Altyar
- Department of Pharmacy Practice, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Gamal A Mohamed
- Department of Natural Products and Alternative Medicine, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia.,Department of Pharmacognosy, Faculty of Pharmacy, Al-Azhar University, Assiut, Egypt
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4
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Phillips-Jones MK, Harding SE. Antimicrobial resistance (AMR) nanomachines-mechanisms for fluoroquinolone and glycopeptide recognition, efflux and/or deactivation. Biophys Rev 2018; 10:347-362. [PMID: 29525835 PMCID: PMC5899746 DOI: 10.1007/s12551-018-0404-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 02/05/2018] [Indexed: 12/11/2022] Open
Abstract
In this review, we discuss mechanisms of resistance identified in bacterial agents Staphylococcus aureus and the enterococci towards two priority classes of antibiotics-the fluoroquinolones and the glycopeptides. Members of both classes interact with a number of components in the cells of these bacteria, so the cellular targets are also considered. Fluoroquinolone resistance mechanisms include efflux pumps (MepA, NorA, NorB, NorC, MdeA, LmrS or SdrM in S. aureus and EfmA or EfrAB in the enterococci) for removal of fluoroquinolone from the intracellular environment of bacterial cells and/or protection of the gyrase and topoisomerase IV target sites in Enterococcus faecalis by Qnr-like proteins. Expression of efflux systems is regulated by GntR-like (S. aureus NorG), MarR-like (MgrA, MepR) regulators or a two-component signal transduction system (TCS) (S. aureus ArlSR). Resistance to the glycopeptide antibiotic teicoplanin occurs via efflux regulated by the TcaR regulator in S. aureus. Resistance to vancomycin occurs through modification of the D-Ala-D-Ala target in the cell wall peptidoglycan and removal of high affinity precursors, or by target protection via cell wall thickening. Of the six Van resistance types (VanA-E, VanG), the VanA resistance type is considered in this review, including its regulation by the VanSR TCS. We describe the recent application of biophysical approaches such as the hydrodynamic technique of analytical ultracentrifugation and circular dichroism spectroscopy to identify the possible molecular effector of the VanS receptor that activates expression of the Van resistance genes; both approaches demonstrated that vancomycin interacts with VanS, suggesting that vancomycin itself (or vancomycin with an accessory factor) may be an effector of vancomycin resistance. With 16 and 19 proteins or protein complexes involved in fluoroquinolone and glycopeptide resistances, respectively, and the complexities of bacterial sensing mechanisms that trigger and regulate a wide variety of possible resistance mechanisms, we propose that these antimicrobial resistance mechanisms might be considered complex 'nanomachines' that drive survival of bacterial cells in antibiotic environments.
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Affiliation(s)
- Mary K Phillips-Jones
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, Loughborough, Leicestershire, UK.
| | - Stephen E Harding
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, Loughborough, Leicestershire, UK
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5
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Han Z, Li YX, Liu LL, Lu L, Guo XR, Zhang XX, Zhang XY, Qi SH, Xu Y, Qian PY. Thielavins W-Z₇, New Antifouling Thielavins from the Marine-Derived Fungus Thielavia sp. UST030930-004. Mar Drugs 2017; 15:md15050128. [PMID: 28468259 PMCID: PMC5450534 DOI: 10.3390/md15050128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 04/25/2017] [Accepted: 04/26/2017] [Indexed: 01/22/2023] Open
Abstract
Eleven new depsides—thielavins W–Z (1–4) and thielavins Z1–Z7 (5–11)—and also four known thielavins—A, H, J, and K (12–15)—were isolated from the ethyl acetate extract of a marine-derived fungal strain Thielavia sp UST030930-004. All of these compounds were evaluated for antifouling activity against cyprids of the barnacle Balanus (=Amphibalanus) amphitrite. The results showed that compounds 1–3 and 6–13 were active, with EC50 values ranging from 2.95 ± 0.59 to 69.19 ± 9.51 μM, respectively. The inhibitive effect of compounds 1–3 and 7 was reversible. This is the first description of the antifouling activity of thielavins against barnacle cyprids.
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Affiliation(s)
- Zhuang Han
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, 28 Luhuitou Road, Sanya 572000, China.
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
| | - Yong-Xin Li
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
| | - Ling-Li Liu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
| | - Liang Lu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
| | - Xian-Rong Guo
- Imaging & Characterization Core lab, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
| | - Xi-Xiang Zhang
- Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
| | - Xiao-Yong Zhang
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
| | - Shu-Hua Qi
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
| | - Ying Xu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
- College of Life Science, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060, China.
| | - Pei-Yuan Qian
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
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6
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Phillips-Jones MK, Channell G, Kelsall CJ, Hughes CS, Ashcroft AE, Patching SG, Dinu V, Gillis RB, Adams GG, Harding SE. Hydrodynamics of the VanA-type VanS histidine kinase: an extended solution conformation and first evidence for interactions with vancomycin. Sci Rep 2017; 7:46180. [PMID: 28397853 PMCID: PMC5387412 DOI: 10.1038/srep46180] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 03/10/2017] [Indexed: 11/08/2022] Open
Abstract
VanA-type resistance to glycopeptide antibiotics in clinical enterococci is regulated by the VanSARA two-component signal transduction system. The nature of the molecular ligand that is recognised by the VanSA sensory component has not hitherto been identified. Here we employ purified, intact and active VanSA membrane protein (henceforth referred to as VanS) in analytical ultracentrifugation experiments to study VanS oligomeric state and conformation in the absence and presence of vancomycin. A combination of sedimentation velocity and sedimentation equilibrium in the analytical ultracentrifuge (SEDFIT, SEDFIT-MSTAR and MULTISIG analysis) showed that VanS in the absence of the ligand is almost entirely monomeric (molar mass M = 45.7 kDa) in dilute aqueous solution with a trace amount of high molar mass material (M ~ 200 kDa). The sedimentation coefficient s suggests the monomer adopts an extended conformation in aqueous solution with an equivalent aspect ratio of ~(12 ± 2). In the presence of vancomycin over a 33% increase in the sedimentation coefficient is observed with the appearance of additional higher s components, demonstrating an interaction, an observation consistent with our circular dichroism measurements. The two possible causes of this increase in s - either a ligand induced dimerization and/or compaction of the monomer are considered.
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Affiliation(s)
- Mary K. Phillips-Jones
- School of Pharmacy & Biomedical Sciences, Membranes, Membrane Proteins & Peptides Research Group, University of Central Lancashire, Preston, PR1 2HE, United Kingdom
| | - Guy Channell
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD United Kingdom
| | - Claire J. Kelsall
- School of Pharmacy & Biomedical Sciences, Membranes, Membrane Proteins & Peptides Research Group, University of Central Lancashire, Preston, PR1 2HE, United Kingdom
| | - Charlotte S. Hughes
- School of Pharmacy & Biomedical Sciences, Membranes, Membrane Proteins & Peptides Research Group, University of Central Lancashire, Preston, PR1 2HE, United Kingdom
- Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0FA, United Kingdom
| | - Alison E. Ashcroft
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Simon G. Patching
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Vlad Dinu
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD United Kingdom
| | - Richard B. Gillis
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD United Kingdom
- School of Health Sciences, University of Nottingham, Nottingham, NG7 2HA United Kingdom
| | - Gary G. Adams
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD United Kingdom
- School of Health Sciences, University of Nottingham, Nottingham, NG7 2HA United Kingdom
| | - Stephen E. Harding
- National Centre for Macromolecular Hydrodynamics, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD United Kingdom
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7
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Loutet SA, El-Halfawy OM, Jassem AN, López JMS, Medarde AF, Speert DP, Davies JE, Valvano MA. Identification of synergists that potentiate the action of polymyxin B against Burkholderia cenocepacia. Int J Antimicrob Agents 2015; 46:376-80. [PMID: 26187366 DOI: 10.1016/j.ijantimicag.2015.05.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/19/2015] [Accepted: 05/11/2015] [Indexed: 10/23/2022]
Abstract
Burkholderia cenocepacia and other members of the Burkholderia cepacia complex (BCC) are highly multidrug-resistant bacteria that cause severe pulmonary infections in patients with cystic fibrosis. A screen of 2686 compounds derived from marine organisms identified molecules that could synergise with polymyxin B (PMB) to inhibit the growth of B. cenocepacia. At 1 μg/mL, five compounds synergised with PMB and inhibited the growth of B. cenocepacia by ≥70% compared with growth in PMB alone. Follow-up testing revealed that one compound from the screen, the aminocoumarin antibiotic novobiocin, synergised with PMB and colistin against tobramycin-resistant clinical isolates of B. cenocepacia and Burkholderia multivorans. In parallel, we show that novobiocin sensitivity is common among BCC species and that these bacteria are even more susceptible to an alternative aminocoumarin, clorobiocin, which also had an additive effect with PMB against B. cenocepacia. These studies support using aminocoumarin antibiotics to treat BCC infections and show that synergisers can be found to increase the efficacy of antimicrobial peptides and polymyxins against BCC bacteria.
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Affiliation(s)
- Slade A Loutet
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada; Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Omar M El-Halfawy
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada; Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Agatha N Jassem
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | | | | | - David P Speert
- Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada; Department of Pathology, University of British Columbia, Vancouver, BC, Canada
| | - Julian E Davies
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Miguel A Valvano
- Centre for Human Immunology, Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada; Centre for Infection and Immunity, Queen's University Belfast, Belfast, UK.
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8
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Discovery of novel cell wall-active compounds using P ywaC, a sensitive reporter of cell wall stress, in the model gram-positive bacterium Bacillus subtilis. Antimicrob Agents Chemother 2014; 58:3261-9. [PMID: 24687489 DOI: 10.1128/aac.02352-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The emergence of antibiotic resistance in recent years has radically reduced the clinical efficacy of many antibacterial treatments and now poses a significant threat to public health. One of the earliest studied well-validated targets for antimicrobial discovery is the bacterial cell wall. The essential nature of this pathway, its conservation among bacterial pathogens, and its absence in human biology have made cell wall synthesis an attractive pathway for new antibiotic drug discovery. Herein, we describe a highly sensitive screening methodology for identifying chemical agents that perturb cell wall synthesis, using the model of the Gram-positive bacterium Bacillus subtilis. We report on a cell-based pilot screen of 26,000 small molecules to look for cell wall-active chemicals in real time using an autonomous luminescence gene cluster driven by the promoter of ywaC, which encodes a guanosine tetra(penta)phosphate synthetase that is expressed under cell wall stress. The promoter-reporter system was generally much more sensitive than growth inhibition testing and responded almost exclusively to cell wall-active antibiotics. Follow-up testing of the compounds from the pilot screen with secondary assays to verify the mechanism of action led to the discovery of 9 novel cell wall-active compounds.
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9
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Brockmeyer F, Schoemaker R, Schmidtmann M, Martens J. Multicomponent reaction for the first synthesis of 2,2-dialkyl- and 2-alkyl-2-aralkyl-5,6-diaryl-2H-1,3-thiazines as scaffolds for various 3,4-dihydro-2H-1,3-thiazine derivatives. Org Biomol Chem 2014; 12:5168-81. [DOI: 10.1039/c4ob00866a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
2H-1,3-thiazines, prepared via a novel and efficient multicomponent reaction, can be used as scaffolds for the synthesis of diverse 3,4-dihydro-2H-1,3-thiazines.
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Affiliation(s)
- Fabian Brockmeyer
- Institut für Chemie
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg, Germany
| | - Robin Schoemaker
- Institut für Chemie
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg, Germany
| | - Marc Schmidtmann
- Institut für Chemie
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg, Germany
| | - Jürgen Martens
- Institut für Chemie
- Carl von Ossietzky Universität Oldenburg
- 26111 Oldenburg, Germany
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10
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In vivo studies suggest that induction of VanS-dependent vancomycin resistance requires binding of the drug to D-Ala-D-Ala termini in the peptidoglycan cell wall. Antimicrob Agents Chemother 2013; 57:4470-80. [PMID: 23836175 DOI: 10.1128/aac.00523-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
VanRS two-component regulatory systems are key elements required for the transcriptional activation of inducible vancomycin resistance genes in bacteria, but the precise nature of the ligand signal that activates these systems has remained undefined. Using the resistance system in Streptomyces coelicolor as a model, we have undertaken a series of in vivo studies which indicate that the VanS sensor kinase in VanB-type resistance systems is activated by vancomycin in complex with the d-alanyl-d-alanine (d-Ala-d-Ala) termini of cell wall peptidoglycan (PG) precursors. Complementation of an essential d-Ala-d-Ala ligase activity by constitutive expression of vanA encoding a bifunctional d-Ala-d-Ala and d-alanyl-d-lactate (d-Ala-d-Lac) ligase activity allowed construction of strains that synthesized variable amounts of PG precursors containing d-Ala-d-Ala. Assays quantifying the expression of genes under VanRS control showed that the response to vancomycin in these strains correlated with the abundance of d-Ala-d-Ala-containing PG precursors; strains producing a lower proportion of PG precursors terminating in d-Ala-d-Ala consistently exhibited a lower response to vancomycin. Pretreatment of wild-type cells with vancomycin or teicoplanin to saturate and mask the d-Ala-d-Ala binding sites in nascent PG also blocked the transcriptional response to subsequent vancomycin exposure, and desleucyl vancomycin, a vancomycin analogue incapable of interacting with d-Ala-d-Ala residues, failed to induce van gene expression. Activation of resistance by a vancomycin-d-Ala-d-Ala PG complex predicts a limit to the proportion of PG that can be derived from precursors terminating in d-Ala-d-Lac, a restriction also enforced by the bifunctional activity of the VanA ligase.
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11
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Singh SB, Young K, Miesel L. Screening strategies for discovery of antibacterial natural products. Expert Rev Anti Infect Ther 2013; 9:589-613. [PMID: 21819327 DOI: 10.1586/eri.11.81] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Microbial-derived natural products have been a traditional source of antibiotics and antibiotic leads and continue to be effective sources of antibiotics today. The most important of these discoveries were made about 50 years ago. Chemical modifications of natural products discovered during those years continue to produce new clinical agents but their value is now, unfortunately, fading away owing to the exhaustion of opportunities of chemical modifications. The discovery of new natural antibiotics is directly linked to new screening technologies, particularly technologies that can help to eliminate the rediscovery of known antibiotics. In this article, we have reviewed the screening technologies from recent literature as well as originating from authors laboratories that were used for the screening of natural products. The article covers the entire spectrum of screening strategies, including classical empiric whole-cell assays to more sophisticated antisense based hypersensitive Staphylococcus aureus Fitness Test assays designed to screen all targets simultaneously. These technologies have led to the discovery of a series of natural product antibiotics, which have been summarized, including the discovery of platensimycin, platencin, nocathiacins, philipimycin, cyclothialidine and muryamycins. It is quite clear that natural products provide a tremendous opportunity to discover new antibiotics when combined with new hyper-sensitive whole-cell technologies.
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Affiliation(s)
- Sheo B Singh
- Merck Research Laboratories, Rahway, NJ 07065, USA.
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12
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Ostash B, Walker S. Moenomycin family antibiotics: chemical synthesis, biosynthesis, and biological activity. Nat Prod Rep 2010; 27:1594-617. [PMID: 20730219 PMCID: PMC2987538 DOI: 10.1039/c001461n] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The review (with 214 references cited) is devoted to moenomycins, the only known group of antibiotics that directly inhibit bacterial peptidoglycan glycosytransferases. Naturally occurring moenomycins and chemical and biological approaches to their derivatives are described. The biological properties of moenomycins and plausible mechanisms of bacterial resistance to them are also covered here, portraying a complete picture of the chemistry and biology of these fascinating natural products
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Affiliation(s)
- Bohdan Ostash
- Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave., Armenise Bldg. 2, Rm 630, Boston, MA 02115, USA
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13
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A vancomycin photoprobe identifies the histidine kinase VanSsc as a vancomycin receptor. Nat Chem Biol 2010; 6:327-9. [PMID: 20383152 DOI: 10.1038/nchembio.350] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Accepted: 03/09/2010] [Indexed: 11/08/2022]
Abstract
Inducible resistance to the glycopeptide antibiotic vancomycin requires expression of vanH, vanA and vanX, controlled by a two-component regulatory system consisting of a receptor histidine kinase, VanS, and a response regulator, VanR. The identity of the VanS receptor ligand has been debated. Using a synthesized vancomycin photoaffinity probe, we show that vancomycin directly binds Streptomyces coelicolor VanS (VanSsc) and this binding is correlated with resistance and required for vanH, vanA and vanX gene expression.
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14
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Vancomycin resistance VanS/VanR two-component systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 631:200-13. [PMID: 18792691 DOI: 10.1007/978-0-387-78885-2_14] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Vancomycin is a member of the glycopeptide class of antibiotics. Vancomycin resistance (van) gene clusters are found in human pathogens such as Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus, glycopeptide-producing actinomycetes such as Amycolotopsis orientalis, Actinoplanes teichomyceticus and Streptomyces toyocaensis and the nonglycopeptide producing actinomycete Streptomyces coelicolor. Expression of the van genes is activated by the VanS/VanR two-component system in response to extracellular glycopeptide antibiotic. Two major types of inducible vancomycin resistance are found in pathogenic bacteria; VanA strains are resistant to vancomycin itself and also to the lipidated glycopeptide teicoplanin, while VanB strains are resistant to vancomycin but sensitive to teicoplanin. Here we discuss the enzymes the van genes encode, the range of different VanS/VanR two-component systems, the biochemistry of VanS/VanR, the nature of the effector ligand(s) recognised by VanS and the evolution of the van cluster.
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15
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De Pascale G, Grigoriadou C, Losi D, Ciciliato I, Sosio M, Donadio S. Validation for high-throughput screening of a VanRS-based reporter gene assay for bacterial cell wall inhibitors. J Appl Microbiol 2008; 103:133-40. [PMID: 17584459 DOI: 10.1111/j.1365-2672.2006.03231.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIMS The present study was undertaken to validate, for antibiotic discovery, a reporter gene assay based on a Bacillus subtilis strain expressing the Enterococcusfaecium vanRS genes and a vanH-lacZ fusion, which produced beta-galactosidase activity in the presence of cell wall inhibitors (CWI) and lysozyme. METHODS AND RESULTS The reporter assay was miniaturized, automated and validated with antibiotics and tested against portions of chemical and microbial extract libraries. The assay is simple, fast and reproducible and can detect all CWI, sometimes at concentrations lower than those necessary to inhibit bacterial growth. However, some membrane-interfering compounds also generate comparable signals. While most CWI elicit a signal that is transcription-dependent and abolished in an osmoprotective medium, transcription is not required for beta-galactosidase activity brought about by the membrane-interfering compounds. CONCLUSIONS At least two distinct mechanisms appear to lead to enzymatic activity in the reporter strain. Effective counterscreens can be designed to discard the undesired classes of compounds. SIGNIFICANCE AND IMPACT OF THE STUDY Extensive validation is required before introducing a reporter assay in high-throughput screening. However, the ease of operation and manipulation makes the reporter assays powerful tools for antibiotic discovery.
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Hutchings MI, Hong HJ, Buttner MJ. The vancomycin resistance VanRS two-component signal transduction system of Streptomyces coelicolor. Mol Microbiol 2006; 59:923-35. [PMID: 16420361 DOI: 10.1111/j.1365-2958.2005.04953.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We took advantage of the vancomycin-dependent phenotype of Streptomyces coelicolor femX null mutants to isolate a collection of spontaneous, drug-independent femX suppressor mutants that expressed the vancomycin-resistance (van) genes constitutively. All of the suppressor mutations were in vanS but, unexpectedly, many were predicted to be loss-of-function mutations. Confirming this interpretation, a constructed vanS deletion mutation also resulted in constitutive expression of the van genes, suggesting that VanS negatively regulated VanR function in the absence of drug. In contrast, a vanS pta ackA triple mutant, which should not be able synthesize acetyl phosphate, failed to express the van genes, whereas a pta ackA double mutant showed wild-type, regulated induction of the van genes. These results suggest that in the absence of vancomycin, acetyl phosphate phosphorylates VanR, and VanS acts as a phosphatase to suppress the levels of VanR approximately P. On exposure to vancomycin, VanS activity switches from a phosphatase to a kinase and vancomycin resistance is induced. In S. coelicolor, the van genes are induced by both vancomycin and the glycopeptide A47934, whereas in Streptomyces toyocaensis (the A47934 producer) resistance is induced by A47934 but not by vancomycin. We exploited this distinction to replace the S. coelicolor vanRS genes with the vanRS genes from S. toyocaensis. The resulting strain acquired the inducer profile of S. toyocaensis, providing circumstantial evidence that the VanS effector ligand is the drug itself, and not an intermediate in cell wall biosynthesis that accumulates as result of drug action. Consistent with this suggestion, we found that non-glycopeptide inhibitors of the late steps in cell wall biosynthesis such as moenomycin A, bacitracin and ramoplanin were not inducers of the S. coelicolor VanRS system, in contrast to results obtained in enterococcal VanRS systems.
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Affiliation(s)
- Matthew I Hutchings
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK.
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Silver LL. Does the cell wall of bacteria remain a viable source of targets for novel antibiotics? Biochem Pharmacol 2005; 71:996-1005. [PMID: 16290173 DOI: 10.1016/j.bcp.2005.10.029] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2005] [Revised: 10/13/2005] [Accepted: 10/17/2005] [Indexed: 11/19/2022]
Abstract
Whether the bacterial cell wall remains a viable source of novel antibacterials is addressed here by reviewing screen and design strategies for discovery of antibacterials with a focus on their output. Inhibitors for which antibacterial activity has been shown to be due to specific inhibition of a reaction (antibacterially validated inhibitors) are known for 8 of the 14 conserved essential steps of the pathway. Antibacterially validated enzyme inhibitors exist for six of these steps. The possible obstacles to finding validated inhibitors of the remaining enzymes are discussed and some strategies are suggested.
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Affiliation(s)
- Lynn L Silver
- LL Silver Consulting (LLC), 3403 Park Place, Springfield, NJ 07081, USA.
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Cao M, Wang T, Ye R, Helmann JD. Antibiotics that inhibit cell wall biosynthesis induce expression of the Bacillus subtilis sigma(W) and sigma(M) regulons. Mol Microbiol 2002; 45:1267-76. [PMID: 12207695 DOI: 10.1046/j.1365-2958.2002.03050.x] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bacillus subtilis encodes seven extracytoplasmic function (ECF) sigma factors. The sigma(W) regulon includes functions involved in detoxification and protection against antimicrobials, whereas sigma(M) is essential for growth at high salt concentrations. We now report that antibiotics that inhibit cell wall biosynthesis induce both sigma(W) and sigma(M) regulons as monitored using DNA microarrays. Induction of selected sigma(W)-dependent genes was confirmed using lacZ reporter fusions and Northern blot analysis. The ability of vancomycin to induce the sigma(W) regulon is dependent on both sigma(W) and the cognate anti-sigma, RsiW, but is independent of the transition state regulator AbrB. These results suggest that the membrane-localized RsiW anti-sigma(W) factor mediates the transcriptional response to cell wall stress. Our findings are consistent with the idea that one function of ECF sigma factors is to coordinate antibiosis stress responses and cell envelope homeostasis.
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Affiliation(s)
- Min Cao
- Department of Microbiology, Cornell uhniversity, Ithaca, NY 14853-8101, USA
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Chopra I, Hesse L, O'Neill A. Exploiting current understanding of antibiotic action for discovery of new drugs. J Appl Microbiol 2002. [DOI: 10.1046/j.1365-2672.92.5s1.13.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Togashi K, Ko HR, Ahn JS, Osada H. Inhibition of telomerase activity by fungus metabolites, CRM646-A and thielavin B. Biosci Biotechnol Biochem 2001; 65:651-3. [PMID: 11330682 DOI: 10.1271/bbb.65.651] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We performed a screening program to identify telomerase inhibitors from our drug source obtained from fungus fermentations, and found that two compounds, CRM646-A and thielavin B, inhibited telomerase activity at doses of 3.2 and 32 microM, respectively. These compounds also inhibited the activity of viral reverse transcriptase at almost the same dose levels which inhibited telomerase activity.
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Affiliation(s)
- K Togashi
- Antibiotics Laboratory, RIKEN, Saitama, Japan
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21
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Arthur M, Quintiliani R. Regulation of VanA- and VanB-type glycopeptide resistance in enterococci. Antimicrob Agents Chemother 2001; 45:375-81. [PMID: 11158729 PMCID: PMC90301 DOI: 10.1128/aac.45.2.375-381.2001] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- M Arthur
- Laboratoire de Recherche Moléculaire sur les Antibiotiques, Université Pierre et Marie Curie, Paris VI, Paris, France.
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Baizman ER, Branstrom AA, Longley CB, Allanson N, Sofia MJ, Gange D, Goldman RC. Antibacterial activity of synthetic analogues based on the disaccharide structure of moenomycin, an inhibitor of bacterial transglycosylase. MICROBIOLOGY (READING, ENGLAND) 2000; 146 Pt 12:3129-3140. [PMID: 11101671 DOI: 10.1099/00221287-146-12-3129] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Moenomycin is a natural product glycolipid that inhibits the growth of a broad spectrum of Gram-positive bacteria. In Escherichia coli, moenomycin inhibits peptidoglycan synthesis at the transglycosylation stage, causes accumulation of cell-wall intermediates, and leads to lysis and cell death. However, unlike Esc. coli, where 5-6 log units of killing are observed, 0-2 log units of killing occurred when Gram-positive bacteria were treated with similar multiples of the MIC. In addition, bulk peptidoglycan synthesis in intact Gram-positive cells was resistant to the effects of moenomycin. In contrast, synthetic disaccharides based on the moenomycin disaccharide core structure were identified that were bactericidal to Gram-positive bacteria, inhibited cell-wall synthesis in intact cells, and were active on both sensitive and vancomycin-resistant enterococci. These disaccharide analogues do not inhibit the formation of N:-acetylglucosamine-ss-1, 4-MurNAc-pentapeptide-pyrophosphoryl-undecaprenol (lipid II), but do inhibit the polymerization of lipid II into peptidoglycan in Esc. coli. In addition, cell growth was required for bactericidal activity. The data indicate that synthetic disaccharide analogues of moenomycin inhibit cell-wall synthesis at the transglycosylation stage, and that their activity on Gram-positive bacteria differs from moenomycin due to differential targeting of the transglycosylation process. Inhibition of the transglycosylation process represents a promising approach to the design of new antibacterial agents active on drug-resistant bacteria.
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Affiliation(s)
- Eugene R Baizman
- Advanced Medicine East Inc., 8 Clarke Drive, Cranbury, NJ 08512, USA1
| | | | | | - Nigel Allanson
- Advanced Medicine East Inc., 8 Clarke Drive, Cranbury, NJ 08512, USA1
| | - Michael J Sofia
- Advanced Medicine East Inc., 8 Clarke Drive, Cranbury, NJ 08512, USA1
| | - David Gange
- Advanced Medicine East Inc., 8 Clarke Drive, Cranbury, NJ 08512, USA1
| | - Robert C Goldman
- Advanced Medicine East Inc., 8 Clarke Drive, Cranbury, NJ 08512, USA1
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Riedl S, Ohlsen K, Werner G, Witte W, Hacker J. Impact of flavophospholipol and vancomycin on conjugational transfer of vancomycin resistance plasmids. Antimicrob Agents Chemother 2000; 44:3189-92. [PMID: 11036050 PMCID: PMC101630 DOI: 10.1128/aac.44.11.3189-3192.2000] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influence of vancomycin and flavophospholipol (FPL) on the transfer rate of conjugative plasmids harboring the vancomycin resistance operon vanA was determined in several clinical and animal isolates of Enterococcus faecium. FPL significantly inhibited the frequency of transfer of conjugative VanA plasmids up to 70-fold. Vancomycin had no significant effect on the transfer rate of VanA plasmids.
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Affiliation(s)
- S Riedl
- Institute for Molecular Biology of Infectious Diseases, The University of Würzburg, D-97070 Würzburg, Germany
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