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Hoang KV, Adcox HE, Fitch JR, Gordon DM, Curry HM, Schlesinger LS, White P, Gunn JS. AR-13, a Celecoxib Derivative, Directly Kills Francisella In Vitro and Aids Clearance and Mouse Survival In Vivo. Front Microbiol 2017; 8:1695. [PMID: 28955308 PMCID: PMC5600997 DOI: 10.3389/fmicb.2017.01695] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/23/2017] [Indexed: 12/15/2022] Open
Abstract
Francisella tularensis (F. tularensis) is the causative agent of tularemia and is classified as a Tier 1 select agent. No licensed vaccine is currently available in the United States and treatment of tularemia is confined to few antibiotics. In this study, we demonstrate that AR-13, a derivative of the cyclooxygenase-2 inhibitor celecoxib, exhibits direct in vitro bactericidal killing activity against Francisella including a type A strain of F. tularensis (SchuS4) and the live vaccine strain (LVS), as well as toward the intracellular proliferation of LVS in macrophages, without causing significant host cell toxicity. Identification of an AR-13-resistant isolate indicates that this compound has an intracellular target(s) and that efflux pumps can mediate AR-13 resistance. In the mouse model of tularemia, AR-13 treatment protected 50% of the mice from lethal LVS infection and prolonged survival time from a lethal dose of F. tularensis SchuS4. Combination of AR-13 with a sub-optimal dose of gentamicin protected 60% of F. tularensis SchuS4-infected mice from death. Taken together, these data support the translational potential of AR-13 as a lead compound for the further development of new anti-Francisella agents.
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Affiliation(s)
- Ky V Hoang
- Center for Microbial Interface Biology, Department of Microbial Infection and Immunity, The Ohio State University, ColumbusOH, United States
| | - Haley E Adcox
- Center for Microbial Interface Biology, Department of Microbial Infection and Immunity, The Ohio State University, ColumbusOH, United States
| | - James R Fitch
- The Institute for Genomic Medicine, Nationwide Children's Hospital, ColumbusOH, United States
| | - David M Gordon
- The Institute for Genomic Medicine, Nationwide Children's Hospital, ColumbusOH, United States
| | - Heather M Curry
- Center for Microbial Interface Biology, Department of Microbial Infection and Immunity, The Ohio State University, ColumbusOH, United States
| | - Larry S Schlesinger
- Center for Microbial Interface Biology, Department of Microbial Infection and Immunity, The Ohio State University, ColumbusOH, United States
| | - Peter White
- The Institute for Genomic Medicine, Nationwide Children's Hospital, ColumbusOH, United States.,Department of Pediatrics, The Ohio State University College of Medicine, ColumbusOH, United States
| | - John S Gunn
- Center for Microbial Interface Biology, Department of Microbial Infection and Immunity, The Ohio State University, ColumbusOH, United States
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Grinnage-Pulley T, Mu Y, Dai L, Zhang Q. Dual Repression of the Multidrug Efflux Pump CmeABC by CosR and CmeR in Campylobacter jejuni. Front Microbiol 2016; 7:1097. [PMID: 27468281 PMCID: PMC4943160 DOI: 10.3389/fmicb.2016.01097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 06/30/2016] [Indexed: 12/15/2022] Open
Abstract
During transmission and intestinal colonization, Campylobacter jejuni, a major foodborne human pathogen, experiences oxidative stress. CosR, a response regulator in C. jejuni, modulates the oxidative stress response and represses expression of the CmeABC multidrug efflux pump. CmeABC, a key component in resistance to toxic compounds including antimicrobials and bile salts, is also under negative regulation by CmeR, a TetR family transcriptional regulator. How CosR and CmeR interact in binding to the cmeABC promoter and how CosR senses oxidative stress are still unknown. To answer these questions, we conducted various experiments utilizing electrophoretic mobility shift assays and transcriptional fusion assays. CosR and CmeR bound independently to two separate sites of the cmeABC promoter, simultaneously repressing cmeABC expression. This dual binding of CosR and CmeR is optimal with a 17 base pair space between the two binding sites as mutations that shortened the distance between the binding sites decreased binding by CmeR and enhanced cmeABC expression. Additionally, the single cysteine residue (C218) of CosR was sensitive to oxidation, which altered the DNA-binding activity of CosR and dissociated CosR from the cmeABC promoter as determined by electrophoretic mobility shift assay. Replacement of C218 with serine rendered CosR insensitive to oxidation, suggesting a potential role of C218 in sensing oxidative stress and providing a possible mechanism for CosR-mediated response to oxidative stress. These findings reveal a dual regulatory role of CosR and CmeR in modulating cmeABC expression and suggest a potential mechanism that may explain overexpression of cmeABC in response to oxidative stress. Differential expression of cmeABC mediated by CmeR and CosR in response to different signals may facilitate adaptation of Campylobacter to various environmental conditions.
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Affiliation(s)
- Tara Grinnage-Pulley
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
| | - Yang Mu
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
| | - Lei Dai
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
| | - Qijing Zhang
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames IA, USA
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Monlezun L, Phan G, Benabdelhak H, Lascombe MB, Enguéné VYN, Picard M, Broutin I. New OprM structure highlighting the nature of the N-terminal anchor. Front Microbiol 2015; 6:667. [PMID: 26191054 PMCID: PMC4486845 DOI: 10.3389/fmicb.2015.00667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 06/19/2015] [Indexed: 01/11/2023] Open
Abstract
Among the different mechanisms used by bacteria to resist antibiotics, active efflux plays a major role. In Gram-negative bacteria, active efflux is carried out by tripartite efflux pumps that form a macromolecular assembly spanning both membranes of the cellular wall. At the outer membrane level, a well-conserved outer membrane factor (OMF) protein acts as an exit duct, but its sequence varies greatly among different species. The OMFs share a similar tri-dimensional structure that includes a beta-barrel pore domain that stabilizes the channel within the membrane. In addition, OMFs are often subjected to different N-terminal post-translational modifications (PTMs), such as an acylation with a lipid. The role of additional N-terminal anchors is all the more intriguing since it is not always required among the OMFs family. Understanding this optional PTM could open new research lines in the field of antibiotics resistance. In Escherichia coli, it has been shown that CusC is modified with a tri-acylated lipid, whereas TolC does not show any modification. In the case of OprM from Pseudomonas aeruginosa, the N-terminal modification remains a matter of debate, therefore, we used several approaches to investigate this issue. As definitive evidence, we present a new X-ray structure at 3.8 Å resolution that was solved in a new space group, making it possible to model the N-terminal residue as a palmitoylated cysteine.
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Affiliation(s)
- Laura Monlezun
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR 8015, Faculté de Pharmacie, Université Paris Descartes Paris, France
| | - Gilles Phan
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR 8015, Faculté de Pharmacie, Université Paris Descartes Paris, France
| | - Houssain Benabdelhak
- Laboratoire d'Imagerie Biomédicale, Sorbonne Universités, Université Pierre et Marie Curie Paris 6, CNRS UMR 7371, INSERM U1146 Paris, France
| | - Marie-Bernard Lascombe
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR 8015, Faculté de Pharmacie, Université Paris Descartes Paris, France
| | - Véronique Y N Enguéné
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR 8015, Faculté de Pharmacie, Université Paris Descartes Paris, France
| | - Martin Picard
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR 8015, Faculté de Pharmacie, Université Paris Descartes Paris, France
| | - Isabelle Broutin
- Laboratoire de Cristallographie et RMN Biologiques, CNRS UMR 8015, Faculté de Pharmacie, Université Paris Descartes Paris, France
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Abstract
Several members of the genus Burkholderia are prominent pathogens. Infections caused by these bacteria are difficult to treat because of significant antibiotic resistance. Virtually all Burkholderia species are also resistant to polymyxin, prohibiting use of drugs like colistin that are available for treatment of infections caused by most other drug resistant Gram-negative bacteria. Despite clinical significance and antibiotic resistance of Burkholderia species, characterization of efflux pumps lags behind other non-enteric Gram-negative pathogens such as Acinetobacter baumannii and Pseudomonas aeruginosa. Although efflux pumps have been described in several Burkholderia species, they have been best studied in Burkholderia cenocepacia and B. pseudomallei. As in other non-enteric Gram-negatives, efflux pumps of the resistance nodulation cell division (RND) family are the clinically most significant efflux systems in these two species. Several efflux pumps were described in B. cenocepacia, which when expressed confer resistance to clinically significant antibiotics, including aminoglycosides, chloramphenicol, fluoroquinolones, and tetracyclines. Three RND pumps have been characterized in B. pseudomallei, two of which confer either intrinsic or acquired resistance to aminoglycosides, macrolides, chloramphenicol, fluoroquinolones, tetracyclines, trimethoprim, and in some instances trimethoprim+sulfamethoxazole. Several strains of the host-adapted B. mallei, a clone of B. pseudomallei, lack AmrAB-OprA, and are therefore aminoglycoside and macrolide susceptible. B. thailandensis is closely related to B. pseudomallei, but non-pathogenic to humans. Its pump repertoire and ensuing drug resistance profile parallels that of B. pseudomallei. An efflux pump in B. vietnamiensis plays a significant role in acquired aminoglycoside resistance. Summarily, efflux pumps are significant players in Burkholderia drug resistance.
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Affiliation(s)
- Nicole L Podnecky
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biological Sciences, Colorado State University Fort Collins, CO, USA
| | - Katherine A Rhodes
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biological Sciences, Colorado State University Fort Collins, CO, USA ; Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, Institute for Therapeutic Innovation, University of Florida Gainesville, FL, USA
| | - Herbert P Schweizer
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biological Sciences, Colorado State University Fort Collins, CO, USA ; Department of Molecular Genetics and Microbiology, College of Medicine, Emerging Pathogens Institute, Institute for Therapeutic Innovation, University of Florida Gainesville, FL, USA
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