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Schuldiner S. On the link between antibiotic resistance, diabetes, and wastewater. J Gen Physiol 2024; 156:e202313533. [PMID: 38294433 PMCID: PMC10829510 DOI: 10.1085/jgp.202313533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024] Open
Abstract
The study by Lucero et al. (https://doi.org/10.1085/jgp.202313464) sheds light on the remarkable capabilities of bacterial transporters to adapt to new selective pressures. Their findings provide insight into the mechanism of a subtype of SMR transporters.
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Affiliation(s)
- Shimon Schuldiner
- Department of Biological Chemistry, Institute of Life Sciences, Edmond J. Safra Campus, Hebrew University of Jerusalem, Jerusalem, Israel
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2
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Drew D, North RA, Nagarathinam K, Tanabe M. Structures and General Transport Mechanisms by the Major Facilitator Superfamily (MFS). Chem Rev 2021; 121:5289-5335. [PMID: 33886296 PMCID: PMC8154325 DOI: 10.1021/acs.chemrev.0c00983] [Citation(s) in RCA: 148] [Impact Index Per Article: 49.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
The major facilitator superfamily (MFS) is the largest known superfamily of secondary active transporters. MFS transporters are responsible for transporting a broad spectrum of substrates, either down their concentration gradient or uphill using the energy stored in the electrochemical gradients. Over the last 10 years, more than a hundred different MFS transporter structures covering close to 40 members have provided an atomic framework for piecing together the molecular basis of their transport cycles. Here, we summarize the remarkable promiscuity of MFS members in terms of substrate recognition and proton coupling as well as the intricate gating mechanisms undergone in achieving substrate translocation. We outline studies that show how residues far from the substrate binding site can be just as important for fine-tuning substrate recognition and specificity as those residues directly coordinating the substrate, and how a number of MFS transporters have evolved to form unique complexes with chaperone and signaling functions. Through a deeper mechanistic description of glucose (GLUT) transporters and multidrug resistance (MDR) antiporters, we outline novel refinements to the rocker-switch alternating-access model, such as a latch mechanism for proton-coupled monosaccharide transport. We emphasize that a full understanding of transport requires an elucidation of MFS transporter dynamics, energy landscapes, and the determination of how rate transitions are modulated by lipids.
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Affiliation(s)
- David Drew
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Rachel A. North
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Kumar Nagarathinam
- Center
of Structural and Cell Biology in Medicine, Institute of Biochemistry, University of Lübeck, D-23538, Lübeck, Germany
| | - Mikio Tanabe
- Structural
Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan
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3
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Henderson PJF, Maher C, Elbourne LDH, Eijkelkamp BA, Paulsen IT, Hassan KA. Physiological Functions of Bacterial "Multidrug" Efflux Pumps. Chem Rev 2021; 121:5417-5478. [PMID: 33761243 DOI: 10.1021/acs.chemrev.0c01226] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacterial multidrug efflux pumps have come to prominence in human and veterinary pathogenesis because they help bacteria protect themselves against the antimicrobials used to overcome their infections. However, it is increasingly realized that many, probably most, such pumps have physiological roles that are distinct from protection of bacteria against antimicrobials administered by humans. Here we undertake a broad survey of the proteins involved, allied to detailed examples of their evolution, energetics, structures, chemical recognition, and molecular mechanisms, together with the experimental strategies that enable rapid and economical progress in understanding their true physiological roles. Once these roles are established, the knowledge can be harnessed to design more effective drugs, improve existing microbial production of drugs for clinical practice and of feedstocks for commercial exploitation, and even develop more sustainable biological processes that avoid, for example, utilization of petroleum.
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Affiliation(s)
- Peter J F Henderson
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Claire Maher
- School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, New South Wales, Australia
| | - Liam D H Elbourne
- Department of Biomolecular Sciences, Macquarie University, Sydney 2109, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
| | - Bart A Eijkelkamp
- College of Science and Engineering, Flinders University, Bedford Park 5042, South Australia, Australia
| | - Ian T Paulsen
- Department of Biomolecular Sciences, Macquarie University, Sydney 2109, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
| | - Karl A Hassan
- School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
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4
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A Major Facilitator Superfamily (MFS) Efflux Pump, SCO4121, from Streptomyces coelicolor with Roles in Multidrug Resistance and Oxidative Stress Tolerance and Its Regulation by a MarR Regulator. Appl Environ Microbiol 2021; 87:AEM.02238-20. [PMID: 33483304 DOI: 10.1128/aem.02238-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 01/12/2021] [Indexed: 12/12/2022] Open
Abstract
Overexpression of efflux pumps is one of the major determinants of resistance in bacteria. Streptomyces species harbor a large array of efflux pumps that are transcriptionally silenced under laboratory conditions. However, their dissemination results in multidrug resistance in different clinical pathogens. In this study, we have identified an efflux pump from Streptomyces coelicolor, SCO4121, belonging to the major facilitator superfamily (MFS) family of transporters and characterized its role in antibiotic resistance. SCO4121 provided resistance to multiple dissimilar drugs upon overexpression in both native and heterologous hosts. Further, deletion of SCO4121 resulted in increased sensitivity toward ciprofloxacin and chloramphenicol, suggesting the pump to be a major transporter of these substrates. Apart from providing multidrug resistance, SCO4121 imparted increased tolerance against the strong oxidant HOCl. In wild-type Streptomyces coelicolor cells, these drugs were found to transcriptionally regulate the pump in a concentration-dependent manner. Additionally, we identified SCO4122, a MarR regulator that positively regulates SCO4121 in response to various drugs and the oxidant HOCl. Thus, through these studies we present the multiple roles of SCO4121 in S. coelicolor and highlight the intricate mechanisms via which it is regulated in response to antibiotics and oxidative stress.IMPORTANCE One of the key mechanisms of drug resistance in bacteria is overexpression of efflux pumps. Streptomyces species are a reservoir of a large number of efflux pumps, potentially to provide resistance to both endogenous and nonendogenous antibiotics. While many of these pumps are not expressed under standard laboratory conditions, they result in resistance to multiple drugs when spread to other bacterial pathogens through horizontal gene transfer. In this study, we have identified a widely conserved efflux pump SCO4121 from Streptomyces coelicolor with roles in both multidrug resistance and oxidative stress tolerance. We also report the presence of an adjacent MarR regulator, SCO4122, which positively regulates SCO4121 in the presence of diverse substrates in a redox-responsive manner. This study highlights that soil bacteria such as Streptomyces can reveal novel mechanisms of antibiotic resistance that may potentially emerge in clinically important bacteria.
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Han F, He X, Chen W, Gai H, Bai X, He Y, Takeshima K, Ohwada T, Wei M, Xie F. Involvement of a Novel TetR-Like Regulator (BdtR) of Bradyrhizobium diazoefficiens in the Efflux of Isoflavonoid Genistein. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:1411-1423. [PMID: 32924759 DOI: 10.1094/mpmi-08-20-0243-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A wide variety of leguminous plant-released (iso)flavonoids, such as genistein, are potential inducers of the nodulation (nod) genes of endosymbiotic rhizobia for the production of Nod factors, which are vital signaling molecules for triggering the symbiotic process. However, these (iso)flavonoids are generally thought to be toxic to the bacterial partner to varying degrees. Here, a novel TetR-like regulator gene of the soybean symbiont Bradyrhizobium diazoefficiens USDA110, bdtR (systematic designation blr7023), was characterized. It was found to be rapidly and preferentially induced by genistein, and its mutation resulted in significantly increased expression of the neighboring bll7019-bll7021 genes, encoding a multidrug resistance efflux pump system, in the absence of this isoflavonoid. Then, the transcriptional start site of BdtR was determined, and it was revealed that BdtR acted as a transcriptional repressor of the above efflux system through the binding of an AT-rich operator, which could be completely prevented by genistein. In addition, the ΔbdtR deletion mutant strain showed higher accumulation of extracellular genistein and became less susceptible to the isoflavonoid. In contrast, the inactivation of BdtR led to the significantly decreased induction of a nodulation gene (nodY) independent of the expression of nodD1 and nodW and to much weaker nodulation competitiveness. Taken together, the results show that BdtR plays an early sensing role in maintaining the intracellular homeostasis of genistein, helping to alleviate its toxic effect on this bacterium by negatively regulating neighboring genes encoding an efflux pump system while being essentially required for nodule occupancy competitiveness.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Fang Han
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Xueqian He
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Wenwen Chen
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Haoyu Gai
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Xuemei Bai
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Yongxing He
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Keisuke Takeshima
- Department of Food Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Takuji Ohwada
- Department of Food Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan
| | - Min Wei
- State Key Laboratory of Grassland Agro-Ecosystems, Institute of Arid Agroecology, School of Life Sciences, Lanzhou University, No. 222, South Tianshui Road, Lanzhou 730000, China
| | - Fang Xie
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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6
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Li C, Chen J, Li SC. Understanding Horizontal Gene Transfer network in human gut microbiota. Gut Pathog 2020; 12:33. [PMID: 32670414 PMCID: PMC7346641 DOI: 10.1186/s13099-020-00370-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 06/23/2020] [Indexed: 12/19/2022] Open
Abstract
Background Horizontal Gene Transfer (HGT) is the process of transferring genetic materials between species. Through sharing genetic materials, microorganisms in the human microbiota form a network. The network can provide insights into understanding the microbiota. Here, we constructed the HGT networks from the gut microbiota sequencing data and performed network analysis to characterize the HGT networks of gut microbiota. Results We constructed the HGT network and perform the network analysis to two typical gut microbiota datasets, a 283-sample dataset of Mother-to-Child and a 148-sample dataset of longitudinal inflammatory bowel disease (IBD) metagenome. The results indicated that (1) the HGT networks are scale-free. (2) The networks expand their complexities, sizes, and edge numbers, accompanying the early stage of lives; and microbiota established in children shared high similarity as their mother (p-value = 0.0138), supporting the transmission of microbiota from mother to child. (3) Groups harbor group-specific network edges, and network communities, which can potentially serve as biomarkers. For instances, IBD patient group harbors highly abundant communities of Proteobacteria (p-value = 0.0194) and Actinobacteria (p-value = 0.0316); children host highly abundant communities of Proteobacteria (p-value = 2.8785\documentclass[12pt]{minimal}
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\begin{document}$$e^{-7}$$\end{document}e-7). IBD patient networks contain more HGT edges in pathogenic genus, including Mycobacterium, Sutterella, and Pseudomonas. Children’s networks contain more edges from Bifidobacterium and Escherichia. Conclusion Hence, we proposed the HGT network constructions from the gut microbiota sequencing data. The HGT networks capture the host state and the response of microbiota to the environmental and host changes, and they are essential to understand the human microbiota.
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Affiliation(s)
- Chen Li
- Department of Computer Science, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Jiaxing Chen
- Department of Computer Science, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Shuai Cheng Li
- Department of Computer Science, City University of Hong Kong, Hong Kong, Hong Kong SAR, China
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Lu HP, Liu PY, Wang YB, Hsieh JF, Ho HC, Huang SW, Lin CY, Hsieh CH, Yu HT. Functional Characteristics of the Flying Squirrel's Cecal Microbiota under a Leaf-Based Diet, Based on Multiple Meta-Omic Profiling. Front Microbiol 2018; 8:2622. [PMID: 29354108 PMCID: PMC5758534 DOI: 10.3389/fmicb.2017.02622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 12/15/2017] [Indexed: 12/14/2022] Open
Abstract
Mammalian herbivores rely on microbial activities in an expanded gut chamber to convert plant biomass into absorbable nutrients. Distinct from ruminants, small herbivores typically have a simple stomach but an enlarged cecum to harbor symbiotic microbes; however, knowledge of this specialized gut structure and characteristics of its microbial contents is limited. Here, we used leaf-eating flying squirrels as a model to explore functional characteristics of the cecal microbiota adapted to a high-fiber, toxin-rich diet. Specifically, environmental conditions across gut regions were evaluated by measuring mass, pH, feed particle size, and metabolomes. Then, parallel metagenomes and metatranscriptomes were used to detect microbial functions corresponding to the cecal environment. Based on metabolomic profiles, >600 phytochemical compounds were detected, although many were present only in the foregut and probably degraded or transformed by gut microbes in the hindgut. Based on metagenomic (DNA) and metatranscriptomic (RNA) profiles, taxonomic compositions of the cecal microbiota were dominated by bacteria of the Firmicutes taxa; they contained major gene functions related to degradation and fermentation of leaf-derived compounds. Based on functional compositions, genes related to multidrug exporters were rich in microbial genomes, whereas genes involved in nutrient importers were rich in microbial transcriptomes. In addition, genes encoding chemotaxis-associated components and glycoside hydrolases specific for plant beta-glycosidic linkages were abundant in both DNA and RNA. This exploratory study provides findings which may help to form molecular-based hypotheses regarding functional contributions of symbiotic gut microbiota in small herbivores with folivorous dietary habits.
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Affiliation(s)
- Hsiao-Pei Lu
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Po-Yu Liu
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University & Academia Sinica, Taipei, Taiwan
| | - Yu-bin Wang
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Institute of Information Science, Academia Sinica, Taipei, Taiwan
| | - Ji-Fan Hsieh
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Han-Chen Ho
- Department of Anatomy, Tzu Chi University, Hualien, Taiwan
| | - Shiao-Wei Huang
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chung-Yen Lin
- Institute of Information Science, Academia Sinica, Taipei, Taiwan
| | - Chih-hao Hsieh
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
- Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan
- National Center for Theoretical Sciences, Taipei, Taiwan
| | - Hon-Tsen Yu
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University & Academia Sinica, Taipei, Taiwan
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8
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Spengler G, Kincses A, Gajdács M, Amaral L. New Roads Leading to Old Destinations: Efflux Pumps as Targets to Reverse Multidrug Resistance in Bacteria. Molecules 2017; 22:molecules22030468. [PMID: 28294992 PMCID: PMC6155429 DOI: 10.3390/molecules22030468] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 01/05/2023] Open
Abstract
Multidrug resistance (MDR) has appeared in response to selective pressures resulting from the incorrect use of antibiotics and other antimicrobials. This inappropriate application and mismanagement of antibiotics have led to serious problems in the therapy of infectious diseases. Bacteria can develop resistance by various mechanisms and one of the most important factors resulting in MDR is efflux pump-mediated resistance. Because of the importance of the efflux-related multidrug resistance the development of new therapeutic approaches aiming to inhibit bacterial efflux pumps is a promising way to combat bacteria having over-expressed MDR efflux systems. The definition of an efflux pump inhibitor (EPI) includes the ability to render the bacterium increasingly more sensitive to a given antibiotic or even reverse the multidrug resistant phenotype. In the recent years numerous EPIs have been developed, although so far their clinical application has not yet been achieved due to their in vivo toxicity and side effects. In this review, we aim to give a short overview of efflux mediated resistance in bacteria, EPI compounds of plant and synthetic origin, and the possible methods to investigate and screen EPI compounds in bacterial systems.
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Affiliation(s)
- Gabriella Spengler
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Annamária Kincses
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Márió Gajdács
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
| | - Leonard Amaral
- Department of Medical Microbiology and Immunobiology, Faculty of Medicine, University of Szeged, 6720 Szeged, Hungary.
- Travel Medicine, Institute of Hygiene and Tropical Medicine, Universidade Nova de Lisboa, 1349-008 Lisbon, Portugal.
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9
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Ongley SE, Pengelly JJL, Neilan BA. Elevated Na(+) and pH influence the production and transport of saxitoxin in the cyanobacteria Anabaena circinalis AWQC131C and Cylindrospermopsis raciborskii T3. Environ Microbiol 2015; 18:427-38. [PMID: 26347118 DOI: 10.1111/1462-2920.13048] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Saxitoxins (STX), neurotoxic alkaloids, fall under the umbrella of paralytic shellfish toxins produced by marine dinoflagellates and freshwater cyanobacteria. The genes responsible for the production of STX have been proposed, but factors that influence their expression and induce toxin efflux remain unclear. Here we characterize the putative STX NorM-like MATE transporters SxtF and SxtM. Complementation of the antibiotic-sensitive strain Escherichia coli KAM32 with these transporters decreased fluoroquinolone sensitivity, indicating that while becoming evolutionary specialized for STX transport these transporters retain relaxed specificity typical of this class. The transcriptional response of STX biosynthesis (sxtA) along with that of the STX transporters (sxtM and sxtF from Cylindrospermopsis raciborskii T3, and sxtM from Anabaena circinalis AWQC131C) were assessed in response to ionic stress. These data, coupled with a measure of toxin intracellular to extracellular ratios, provide an insight into the physiology of STX export. Cylindrospermopsis raciborskii and Anabaena circinalis exhibited opposing responses under conditions of ionic stress. High Na(+) (10 mM) induced moderate alterations of transcription and STX localization, whereas high pH (pH 9) stimulated the greatest physiological response. Saxitoxin production and cellular localization are responsive to ionic strength, indicating a role of this molecule in the maintenance of cellular homeostasis.
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Affiliation(s)
- Sarah E Ongley
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Jasper J L Pengelly
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Brett A Neilan
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
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Paul S, Alegre KO, Holdsworth SR, Rice M, Brown JA, McVeigh P, Kelly SM, Law CJ. A single-component multidrug transporter of the major facilitator superfamily is part of a network that protects Escherichia coli from bile salt stress. Mol Microbiol 2014; 92:872-84. [PMID: 24684269 PMCID: PMC4235344 DOI: 10.1111/mmi.12597] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2014] [Indexed: 01/16/2023]
Abstract
Resistance to high concentrations of bile salts in the human intestinal tract is vital for the survival of enteric bacteria such as Escherichia coli. Although the tripartite AcrAB-TolC efflux system plays a significant role in this resistance, it is purported that other efflux pumps must also be involved. We provide evidence from a comprehensive suite of experiments performed at two different pH values (7.2 and 6.0) that reflect pH conditions that E. coli may encounter in human gut that MdtM, a single-component multidrug resistance transporter of the major facilitator superfamily, functions in bile salt resistance in E. coli by catalysing secondary active transport of bile salts out of the cell cytoplasm. Furthermore, assays performed on a chromosomal ΔacrB mutant transformed with multicopy plasmid encoding MdtM suggested a functional synergism between the single-component MdtM transporter and the tripartite AcrAB-TolC system that results in a multiplicative effect on resistance. Substrate binding experiments performed on purified MdtM demonstrated that the transporter binds to cholate and deoxycholate with micromolar affinity, and transport assays performed on inverted vesicles confirmed the capacity of MdtM to catalyse electrogenic bile salt/H(+) antiport.
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Affiliation(s)
- Stephanie Paul
- Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK
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11
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Sherlach KS, Roepe PD. "Drug resistance associated membrane proteins". Front Physiol 2014; 5:108. [PMID: 24688472 PMCID: PMC3960488 DOI: 10.3389/fphys.2014.00108] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/03/2014] [Indexed: 01/23/2023] Open
Affiliation(s)
- Katy S Sherlach
- Department of Chemistry and Department of Biochemistry and Cellular and Molecular Biology, Georgetown University Washington, DC, USA
| | - Paul D Roepe
- Department of Chemistry and Department of Biochemistry and Cellular and Molecular Biology, Georgetown University Washington, DC, USA
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12
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Listeria monocytogenes multidrug resistance transporters and cyclic di-AMP, which contribute to type I interferon induction, play a role in cell wall stress. J Bacteriol 2013; 195:5250-61. [PMID: 24056102 DOI: 10.1128/jb.00794-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular bacterial pathogen Listeria monocytogenes activates a robust type I interferon response upon infection. This response is partially dependent on the multidrug resistance (MDR) transporter MdrM and relies on cyclic-di-AMP (c-di-AMP) secretion, yet the functions of MdrM and cyclic-di-AMP that lead to this response are unknown. Here we report that it is not MdrM alone but a cohort of MDR transporters that together contribute to type I interferon induction during infection. In a search for a physiological function of these transporters, we revealed that they play a role in cell wall stress responses. A mutant with deletion of four transporter genes (ΔmdrMTAC) was found to be sensitive to sublethal concentrations of vancomycin due to an inability to produce and shed peptidoglycan under this stress. Remarkably, c-di-AMP is involved in this phenotype, as overexpression of the c-di-AMP phosphodiesterase (PdeA) resulted in increased susceptibility of the ΔmdrMTAC mutant to vancomycin, whereas overexpression of the c-di-AMP diadenylate cyclase (DacA) reduced susceptibility to this drug. These observations suggest a physiological association between c-di-AMP and the MDR transporters and support the model that MDR transporters mediate c-di-AMP secretion to regulate peptidoglycan synthesis in response to cell wall stress.
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13
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Holdsworth SR, Law CJ. Multidrug resistance protein MdtM adds to the repertoire of antiporters involved in alkaline pH homeostasis in Escherichia coli. BMC Microbiol 2013; 13:113. [PMID: 23701827 PMCID: PMC3668916 DOI: 10.1186/1471-2180-13-113] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 05/20/2013] [Indexed: 12/04/2022] Open
Abstract
Background In neutralophilic bacteria, monovalent metal cation/H+ antiporters play a key role in pH homeostasis. In Escherichia coli, only four antiporters (NhaA, NhaB, MdfA and ChaA) are identified to function in maintenance of a stable cytoplasmic pH under conditions of alkaline stress. We hypothesised that the multidrug resistance protein MdtM, a recently characterised homologue of MdfA and a member of the major facilitator superfamily, also functions in alkaline pH homeostasis. Results Assays that compared the growth of an E. coli ΔmdtM deletion mutant transformed with a plasmid encoding wild-type MdtM or the dysfunctional MdtM D22A mutant at different external alkaline pH values (ranging from pH 8.5 to 10) revealed a potential contribution by MdtM to alkaline pH tolerance, but only when millimolar concentrations of sodium or potassium was present in the growth medium. Fluorescence-based activity assays using inverted vesicles generated from transformants of antiporter-deficient (ΔnhaA, ΔnhaB, ΔchaA) E. coli TO114 cells defined MdtM as a low-affinity antiporter that catalysed electrogenic exchange of Na+, K+, Rb+ or Li+ for H+. The K+/H+ antiport reaction had a pH optimum at 9.0, whereas the Na+/H+ exchange activity was optimum at pH 9.25. Measurement of internal cellular pH confirmed MdtM as contributing to maintenance of a stable cytoplasmic pH, acid relative to the external pH, under conditions of alkaline stress. Conclusions Taken together, the results support a role for MdtM in alkaline pH tolerance. MdtM can therefore be added to the currently limited list of antiporters known to function in pH homeostasis in the model organism E. coli.
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Affiliation(s)
- Scarlett R Holdsworth
- Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
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Alvarez-Ortega C, Olivares J, Martínez JL. RND multidrug efflux pumps: what are they good for? Front Microbiol 2013; 4:7. [PMID: 23386844 PMCID: PMC3564043 DOI: 10.3389/fmicb.2013.00007] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 01/07/2013] [Indexed: 01/27/2023] Open
Abstract
Multidrug efflux pumps are chromosomally encoded genetic elements capable of mediating resistance to toxic compounds in several life forms. In bacteria, these elements are involved in intrinsic and acquired resistance to antibiotics. Unlike other well-known horizontally acquired antibiotic resistance determinants, genes encoding for multidrug efflux pumps belong to the core of bacterial genomes and thus have evolved over millions of years. The selective pressure stemming from the use of antibiotics to treat bacterial infections is relatively recent in evolutionary terms. Therefore, it is unlikely that these elements have evolved in response to antibiotics. In the last years, several studies have identified numerous functions for efflux pumps that go beyond antibiotic extrusion. In this review we present some examples of these functions that range from bacterial interactions with plant or animal hosts, to the detoxification of metabolic intermediates or the maintenance of cellular homeostasis.
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Affiliation(s)
- Carolina Alvarez-Ortega
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas Madrid, Spain
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15
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Gabani P, Prakash D, Singh OV. Emergence of antibiotic-resistant extremophiles (AREs). Extremophiles 2012; 16:697-713. [PMID: 22907125 DOI: 10.1007/s00792-012-0475-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 08/02/2012] [Indexed: 12/14/2022]
Abstract
Excessive use of antibiotics in recent years has produced bacteria that are resistant to a wide array of antibiotics. Several genetic and non-genetic elements allow microorganisms to adapt and thrive under harsh environmental conditions such as lethal doses of antibiotics. We attempt to classify these microorganisms as antibiotic-resistant extremophiles (AREs). AREs develop strategies to gain greater resistance to antibiotics via accumulation of multiple genes or plasmids that harbor genes for multiple drug resistance (MDR). In addition to their altered expression of multiple genes, AREs also survive by producing enzymes such as penicillinase that inactivate antibiotics. It is of interest to identify the underlying molecular mechanisms by which the AREs are able to survive in the presence of wide arrays of high-dosage antibiotics. Technologically, "omics"-based approaches such as genomics have revealed a wide array of genes differentially expressed in AREs. Proteomics studies with 2DE, MALDI-TOF, and MS/MS have identified specific proteins, enzymes, and pumps that function in the adaptation mechanisms of AREs. This article discusses the molecular mechanisms by which microorganisms develop into AREs and how "omics" approaches can identify the genetic elements of these adaptation mechanisms. These objectives will assist the development of strategies and potential therapeutics to treat outbreaks of pathogenic microorganisms in the future.
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Affiliation(s)
- Prashant Gabani
- Division of Biological and Health Sciences, University of Pittsburgh, 300 Campus Drive, Bradford, PA 16701, USA
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16
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Functional and biochemical characterisation of the Escherichia coli major facilitator superfamily multidrug transporter MdtM. Biochimie 2012; 94:1334-46. [DOI: 10.1016/j.biochi.2012.03.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Accepted: 03/01/2012] [Indexed: 01/22/2023]
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17
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Simm R, Vörös A, Ekman JV, Sødring M, Nes I, Kroeger JK, Saidijam M, Bettaney KE, Henderson PJF, Salkinoja-Salonen M, Kolstø AB. BC4707 is a major facilitator superfamily multidrug resistance transport protein from Bacillus cereus implicated in fluoroquinolone tolerance. PLoS One 2012; 7:e36720. [PMID: 22615800 PMCID: PMC3353944 DOI: 10.1371/journal.pone.0036720] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 04/12/2012] [Indexed: 01/03/2023] Open
Abstract
Transcriptional profiling highlighted a subset of genes encoding putative multidrug transporters in the pathogen Bacillus cereus that were up-regulated during stress produced by bile salts. One of these multidrug transporters (BC4707) was selected for investigation. Functional characterization of the BC4707 protein in Escherichia coli revealed a role in the energized efflux of xenobiotics. Phenotypic analyses after inactivation of the gene bc4707 in Bacillus cereus ATCC14579 suggested a more specific, but modest role in the efflux of norfloxacin. In addition to this, transcriptional analyses showed that BC4707 is also expressed during growth of B. cereus under non-stressful conditions where it may have a role in the normal physiology of the bacteria. Altogether, the results indicate that bc4707, which is part of the core genome of the B. cereus group of bacteria, encodes a multidrug resistance efflux protein that is likely involved in maintaining intracellular homeostasis during growth of the bacteria.
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Affiliation(s)
- Roger Simm
- Laboratory for Microbial Dynamics, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Aniko Vörös
- Laboratory for Microbial Dynamics, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Jaakko V. Ekman
- Department of Biosciences, Biocenter 1, University of Helsinki, Helsinki, Finland
| | - Marianne Sødring
- Laboratory for Microbial Dynamics, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Ingerid Nes
- Laboratory for Microbial Dynamics, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Jasmin K. Kroeger
- Laboratory for Microbial Dynamics, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Massoud Saidijam
- Astbury Centre for Structural Molecular Biology, Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom
- School of Medicine, Hamedan University of Medical Sciences, Hamedan, Iran
| | - Kim E. Bettaney
- Astbury Centre for Structural Molecular Biology, Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom
| | - Peter J. F. Henderson
- Astbury Centre for Structural Molecular Biology, Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom
| | | | - Anne-Brit Kolstø
- Laboratory for Microbial Dynamics, Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
- * E-mail:
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Teijeira F, Ullán R, Fernández-Aguado M, Martín J. CefR modulates transporters of beta-lactam intermediates preventing the loss of penicillins to the broth and increases cephalosporin production in Acremonium chrysogenum. Metab Eng 2011; 13:532-43. [DOI: 10.1016/j.ymben.2011.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/10/2011] [Accepted: 06/13/2011] [Indexed: 11/27/2022]
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19
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Ghosh S, Cremers CM, Jakob U, Love NG. Chlorinated phenols control the expression of the multidrug resistance efflux pump MexAB-OprM in Pseudomonas aeruginosa by interacting with NalC. Mol Microbiol 2011; 79:1547-56. [PMID: 21231970 DOI: 10.1111/j.1365-2958.2011.07544.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NalC is a TetR type regulator that represses the multidrug efflux pump MexAB-OprM in Pseudomonas aeruginosa. Here we explain the mechanism of NalC-mediated regulation of MexAB-OprM. We show that NalC non-covalently binds chlorinated phenols and chemicals containing chlorophenol side-chains such as triclosan. NalC-chlorinated phenol binding results in its dissociation from promoter DNA and upregulation of NalC's downstream targets, including the MexR antirepressor ArmR. ArmR upregulation and MexR-ArmR complex formation have previously been shown to upregulate MexAB-OprM. In vivo mexB and armR expression analyses were used to corroborate in vitro NalC-chlorinated phenol binding. We also show that the interaction between chlorinated phenols and NalC is reversible, such that removal of these chemicals restored NalC promoter DNA binding. Thus, the NalC-chlorinated phenol interaction is likely a pertinent physiological mechanism that P. aeruginosa uses to control expression of the MexAB-OprM efflux pump.
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Affiliation(s)
- Sudeshna Ghosh
- Department of Civil and Environmental Engineering, University of Michigan, 2350 Hayward Street, 2340 GG Brown, Ann Arbor, MI 48109-2125, USA
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20
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Woodward JJ, Iavarone AT, Portnoy DA. c-di-AMP secreted by intracellular Listeria monocytogenes activates a host type I interferon response. Science 2010; 328:1703-5. [PMID: 20508090 DOI: 10.1126/science.1189801] [Citation(s) in RCA: 611] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Intracellular bacterial pathogens, such as Listeria monocytogenes, are detected in the cytosol of host immune cells. Induction of this host response is often dependent on microbial secretion systems and, in L. monocytogenes, is dependent on multidrug efflux pumps (MDRs). Using L. monocytogenes mutants that overexpressed MDRs, we identified cyclic diadenosine monophosphate (c-di-AMP) as a secreted molecule able to trigger the cytosolic host response. Overexpression of the di-adenylate cyclase, dacA (lmo2120), resulted in elevated levels of the host response during infection. c-di-AMP thus represents a putative bacterial secondary signaling molecule that triggers a cytosolic pathway of innate immunity and is predicted to be present in a wide variety of bacteria and archea.
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Affiliation(s)
- Joshua J Woodward
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720, USA
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21
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Analysis of membrane proteins in metagenomics: networks of correlated environmental features and protein families. Genome Res 2010; 20:960-71. [PMID: 20430783 DOI: 10.1101/gr.102814.109] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Recent metagenomics studies have begun to sample the genomic diversity among disparate habitats and relate this variation to features of the environment. Membrane proteins are an intuitive, but thus far overlooked, choice in this type of analysis as they directly interact with the environment, receiving signals from the outside and transporting nutrients. Using global ocean sampling (GOS) data, we found nearly approximately 900,000 membrane proteins in large-scale metagenomic sequence, approximately a fifth of which are completely novel, suggesting a large space of hitherto unexplored protein diversity. Using GPS coordinates for the GOS sites, we extracted additional environmental features via interpolation from the World Ocean Database, the National Center for Ecological Analysis and Synthesis, and empirical models of dust occurrence. This allowed us to study membrane protein variation in terms of natural features, such as phosphate and nitrate concentrations, and also in terms of human impacts, such as pollution and climate change. We show that there is widespread variation in membrane protein content across marine sites, which is correlated with changes in both oceanographic variables and human factors. Furthermore, using these data, we developed an approach, protein families and environment features network (PEN), to quantify and visualize the correlations. PEN identifies small groups of covarying environmental features and membrane protein families, which we call "bimodules." Using this approach, we find that the affinity of phosphate transporters is related to the concentration of phosphate and that the occurrence of iron transporters is connected to the amount of shipping, pollution, and iron-containing dust.
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Abstract
Large amounts of antibiotics used for human therapy, as well as for farm animals and even for fish in aquaculture, resulted in the selection of pathogenic bacteria resistant to multiple drugs. Multidrug resistance in bacteria may be generated by one of two mechanisms. First, these bacteria may accumulate multiple genes, each coding for resistance to a single drug, within a single cell. This accumulation occurs typically on resistance (R) plasmids. Second, multidrug resistance may also occur by the increased expression of genes that code for multidrug efflux pumps, extruding a wide range of drugs. This review discusses our current knowledge on the molecular mechanisms involved in both types of resistance.
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Affiliation(s)
- Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
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23
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A coordinated network of transporters with overlapping specificities provides a robust survival strategy. Proc Natl Acad Sci U S A 2009; 106:9051-6. [PMID: 19451626 DOI: 10.1073/pnas.0902400106] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multidrug transporters provide a survival strategy for living organisms. As expected given their central role in survival, these transporters are ubiquitous, and in many genomes, several genes coding for putative transporters have been identified. However, in an organism such as Escherichia coli mutations in genes coding for transporters other than the major AcrAB-TolC multidrug efflux transporter have only a marginal effect on phenotype. Thus, whether the physiological role of the transporters identified is indeed drug export has been questioned. We show here that the minor effect of single mutations is due to the overlapping functionality of several transporters. This was revealed by generating multiple chromosomal deletion mutations in genes coding for transporters that share the same substrate and testing their effect on the resistance phenotype. In addition, complementation studies imply that AcrAB-TolC confers robust resistance provided that single-component transporters in the plasma membrane are functional. This finding supports the contention that hydrophobic drugs are removed in a 2-stage process: AcrAB-TolC removes substrates from the periplasmic space, while single-component transporters remove them from the cell. The overlapping specificities of the transporters ensure coverage of a wide range of xenobiotics and provide robustness in the response to environmental stress. This strategy also confers evolvability to the organism by reducing constraints on change and allowing the accumulation of nonlethal variation.
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EmrE, a model for studying evolution and mechanism of ion-coupled transporters. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:748-62. [DOI: 10.1016/j.bbapap.2008.12.018] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/16/2008] [Accepted: 12/17/2008] [Indexed: 11/23/2022]
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25
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Torres C, Galián C, Freiberg C, Fantino JR, Jault JM. The YheI/YheH heterodimer from Bacillus subtilis is a multidrug ABC transporter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:615-22. [DOI: 10.1016/j.bbamem.2008.12.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 12/12/2008] [Accepted: 12/22/2008] [Indexed: 12/12/2022]
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26
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van Dillewijn P, Sanjuán J, Olivares J, Soto MJ. The tep1 gene of Sinorhizobium meliloti coding for a putative transmembrane efflux protein and N-acetyl glucosamine affect nod gene expression and nodulation of alfalfa plants. BMC Microbiol 2009; 9:17. [PMID: 19173735 PMCID: PMC2637885 DOI: 10.1186/1471-2180-9-17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 01/27/2009] [Indexed: 11/24/2022] Open
Abstract
Background Soil bacteria collectively known as Rhizobium, characterized by their ability to establish beneficial symbiosis with legumes, share several common characteristics with pathogenic bacteria when infecting the host plant. Recently, it was demonstrated that a fadD mutant of Sinorhizobium meliloti is altered in the control of swarming, a type of co-ordinated movement previously associated with pathogenicity, and is also impaired in nodulation efficiency on alfalfa roots. In the phytopathogen Xanthomonas campestris, a fadD homolog (rpfB) forms part of a cluster of genes involved in the regulation of pathogenicity factors. In this work, we have investigated the role in swarming and symbiosis of SMc02161, a S. meliloti fadD-linked gene. Results The SMc02161 locus in S. meliloti shows similarities with members of the Major Facilitator Superfamily (MFS) of transporters. A S. meliloti null-mutant shows increased sensitivity to chloramphenicol. This indication led us to rename the locus tep1 for transmembrane efflux protein. The lack of tep1 does not affect the appearance of swarming motility. Interestingly, nodule formation efficiency on alfalfa plants is improved in the tep1 mutant during the first days of the interaction though nod gene expression is lower than in the wild type strain. Curiously, a nodC mutation or the addition of N-acetyl glucosamine to the wild type strain lead to similar reductions in nod gene expression as in the tep1 mutant. Moreover, aminosugar precursors of Nod factors inhibit nodulation. Conclusion tep1 putatively encodes a transmembrane protein which can confer chloramphenicol resistance in S. meliloti by expelling the antibiotic outside the bacteria. The improved nodulation of alfalfa but reduced nod gene expression observed in the tep1 mutant suggests that Tep1 transports compounds which influence nodulation. In contrast to Bradyrhizobium japonicum, we show that in S. meliloti there is no feedback regulation of nodulation genes. Moreover, the Nod factor precursor, N-acetyl glucosamine reduces nod gene expression and nodulation efficiency when present at millimolar concentrations. A role for Tep1 in the efflux of Nod factor precursors could explain the phenotypes associated with tep1 inactivation.
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Affiliation(s)
- Pieter van Dillewijn
- Departamento de Protección Ambiental, Estación Experimental del Zaidín, CSIC, Granada, Spain.
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27
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Martinez JL, Sánchez MB, Martínez-Solano L, Hernandez A, Garmendia L, Fajardo A, Alvarez-Ortega C. Functional role of bacterial multidrug efflux pumps in microbial natural ecosystems. FEMS Microbiol Rev 2009; 33:430-49. [PMID: 19207745 DOI: 10.1111/j.1574-6976.2008.00157.x] [Citation(s) in RCA: 306] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Multidrug efflux pumps have emerged as relevant elements in the intrinsic and acquired antibiotic resistance of bacterial pathogens. In contrast with other antibiotic resistance genes that have been obtained by virulent bacteria through horizontal gene transfer, genes coding for multidrug efflux pumps are present in the chromosomes of all living organisms. In addition, these genes are highly conserved (all members of the same species contain the same efflux pumps) and their expression is tightly regulated. Together, these characteristics suggest that the main function of these systems is not resisting the antibiotics used in therapy and that they should have other roles relevant to the behavior of bacteria in their natural ecosystems. Among the potential roles, it has been demonstrated that efflux pumps are important for processes of detoxification of intracellular metabolites, bacterial virulence in both animal and plant hosts, cell homeostasis and intercellular signal trafficking.
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Affiliation(s)
- Jose Luis Martinez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Cantoblanco, Madrid, Spain.
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28
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Sigal N, Fluman N, Siemion S, Bibi E. The secondary multidrug/proton antiporter MdfA tolerates displacements of an essential negatively charged side chain. J Biol Chem 2009; 284:6966-71. [PMID: 19129186 DOI: 10.1074/jbc.m808877200] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The largest family of solute transporters includes ion motive force-driven secondary transporters. Several well characterized solute-specific transport systems in this group have at least one irreplaceable acidic residue that plays a critical role in energy coupling during transport. Previous studies have established the importance of acidic residues in substrate recognition by major facilitator superfamily secondary multidrug transporters, but their role in the transport mechanism remained unknown. We have been investigating the involvement of acidic residues in the mechanism of MdfA, an Escherichia coli secondary multidrug/proton antiporter. We demonstrated that no single negatively charged side chain plays an irreplaceable role in MdfA. Accordingly, we hypothesized that MdfA might be able to utilize at least two acidic residues alternatively. In this study, we present evidence that indeed, unlike solute-specific secondary transporters, MdfA tolerates displacements of an essential negative charge to various locations in the putative drug translocation pathway. The results suggest that MdfA utilizes a proton translocation strategy that is less sensitive to perturbations in the geometry of the proton-binding site, further illustrating the exceptional structural promiscuity of multidrug transporters.
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Affiliation(s)
- Nadejda Sigal
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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29
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Fluman N, Bibi E. Bacterial multidrug transport through the lens of the major facilitator superfamily. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1794:738-47. [PMID: 19103310 DOI: 10.1016/j.bbapap.2008.11.020] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 11/21/2008] [Accepted: 11/24/2008] [Indexed: 10/21/2022]
Abstract
Multidrug transporters are membrane proteins that expel a wide spectrum of cytotoxic compounds from the cell. Through this function, they render cells resistant to multiple drugs. These transporters are found in many different families of transport proteins, of which the largest is the major facilitator superfamily. Multidrug transporters from this family are highly represented in bacteria and studies of them have provided important insight into the mechanism underlying multidrug transport. This review summarizes the work carried out on these interesting proteins and underscores the differences and similarities to other transport systems.
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Affiliation(s)
- Nir Fluman
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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30
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Sá-Correia I, dos Santos SC, Teixeira MC, Cabrito TR, Mira NP. Drug:H+ antiporters in chemical stress response in yeast. Trends Microbiol 2008; 17:22-31. [PMID: 19062291 DOI: 10.1016/j.tim.2008.09.007] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 08/03/2008] [Accepted: 09/19/2008] [Indexed: 10/21/2022]
Abstract
The emergence of widespread multidrug resistance (MDR) is a serious challenge for therapeutics, food-preservation and crop protection. Frequently, MDR is a result of the action of drug-efflux pumps, which are able to catalyze the extrusion of unrelated chemical compounds. This review summarizes the current knowledge on the Saccharomyces cerevisiae drug:H+ antiporters of the major facilitator superfamily (MFS), a group of MDR transporters that is still characterized poorly in eukaryotes. Particular focus is given here to the physiological role and expression regulation of these transporters, while we provide a unified view of new data emerging from functional genomics approaches. Although traditionally described as drug pumps, evidence reviewed here corroborates the hypothesis that several MFS-MDR transporters might have a natural substrate and that drug transport might occur only fortuitously or opportunistically. Their role in MDR might even result from the transport of endogenous metabolites that affect the partition of cytotoxic compounds indirectly. Finally, the extrapolation of the gathered knowledge on the MDR phenomenon in yeast to pathogenic fungi and higher eukaryotes is discussed.
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Affiliation(s)
- Isabel Sá-Correia
- Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, 1049-001 Lisboa, Portugal.
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31
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Lee LF, Chen YJ, Kirby R, Chen C, Chen CW. A multidrug efflux system is involved in colony growth in Streptomyces lividans. MICROBIOLOGY-SGM 2007; 153:924-934. [PMID: 17379703 DOI: 10.1099/mic.0.2006/000018-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Multidrug resistance (MDR) genes are abundant in Streptomyces genomes, and yet these bacteria are generally drug sensitive under routine laboratory conditions, indicating low or no expression of these genes. Drug-resistant mutations have been isolated that lie in regulatory genes adjacent to the MDR genes, suggesting that resistance arises by derepression. This study identified a divergently oriented pair consisting of a TetR-family regulator (ebrS) and a major facilitator-family MDR pump (ebrC) gene in Streptomyces lividans, which is widely conserved in Streptomyces species. EbrS represses transcription of ebrC as well as its own transcription. Deletion of ebrS causes overexpression of ebrC, resulting in elevated resistance to many drugs. The ebrS and ebrC promoters were used in a reporter system to test inducibility by various chemicals. Among the 15 compounds (including five EbrC target drugs) tested, none induced ebrC transcription. On the other hand, the ebrS promoter was induced by rifampicin and high concentrations of calcium and magnesium. Deletion of ebrS-ebrC did not change rifampicin sensitivity, indicating that the EbrC pump is not involved in rifampicin efflux. Moreover, deletion of ebrC caused retardation of colony growth on selected media, and the defect could be suppressed by supplementation with high concentrations of Ca(2+), Mg(2+), Na(+) or K(+). Based on these results, it is proposed that the primary biological role of most MDR systems in Streptomyces species is not removal of extrinsic drugs, but rather export of specific toxic compounds endogenously synthesized during growth.
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Affiliation(s)
- Li-Fong Lee
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, University System of Taiwan, Shih-Pai, Taipei, Taiwan
| | - Yueh-Jung Chen
- Department of Biological Science and Technology, Chung Hwa College of Medical Technology, Jen-Te Hsiang, Tainan Hsien, Taiwan
| | - Ralph Kirby
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, University System of Taiwan, Shih-Pai, Taipei, Taiwan
| | - Chi Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, University System of Taiwan, Shih-Pai, Taipei, Taiwan
| | - Carton W Chen
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, University System of Taiwan, Shih-Pai, Taipei, Taiwan
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Regulation of multidrug efflux systems involved in multidrug and metal resistance of Salmonella enterica serovar Typhimurium. J Bacteriol 2007; 189:9066-75. [PMID: 17933888 DOI: 10.1128/jb.01045-07] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Multidrug-resistant strains of Salmonella are now encountered frequently, and the rates of multidrug resistance have increased considerably in recent years. Here, we report that the two-component regulatory system BaeSR increases multidrug and metal resistance in Salmonella through the induction of drug efflux systems. Screening of random fragments of genomic DNA for the ability to increase beta-lactam resistance in Salmonella enterica led to the isolation of a plasmid containing baeR, which codes for the response regulator of BaeSR. When overexpressed, baeR significantly increased the resistance of the delta acrB strain to oxacillin, cloxacillin, and nafcillin. baeR overexpression conferred resistance to novobiocin and deoxycholate, as well as to beta-lactams in Salmonella. The increase in drug resistance caused by baeR overexpression was completely suppressed by deletion of the multifunctional outer membrane channel gene tolC. TolC interacts with different drug efflux systems. Among the nine drug efflux systems in Salmonella, quantitative real-time PCR analysis showed that BaeR induced the expression of acrD and mdtABC. Double deletion of these two genes completely suppressed BaeR-mediated multidrug resistance, whereas single deletion of either gene did not. The promoter regions of acrD and mdtABC harbor binding sites for the response regulator BaeR, which activates acrD and mdtABC transcription in response to indole, copper, and zinc. In addition to their role in multidrug resistance, we found that BaeSR, AcrD, and MdtABC contribute to copper and zinc resistance in Salmonella. Our results indicate that the BaeSR system increases multidrug and metal resistance in Salmonella by inducing the AcrD and MdtABC drug efflux systems. We found a previously uncharacterized physiological role for the AcrD and MdtABC multidrug efflux systems in metal resistance.
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33
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Quinn T, Bolla JM, Pagès JM, Fanning S. Antibiotic-resistant Campylobacter: could efflux pump inhibitors control infection? J Antimicrob Chemother 2006; 59:1230-6. [PMID: 17118938 DOI: 10.1093/jac/dkl470] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Campylobacter is the most common cause of bacterial gastroenteritis in the world. Poultry is the main reservoir of human infections. The widespread use of antibiotics in agriculture and veterinary medicine has resulted in the emergence of an increasing number of antibiotic-resistant Campylobacter strains that can be transmitted to humans through the food chain. Of particular concern to public health is the prevalence of resistance to macrolides and fluoroquinolones that are used in the treatment of life-threatening campylobacteriosis. The CmeABC efflux system has been shown to contribute to the intrinsic and acquired resistance to these antibiotics. In addition, by mediating resistance to bile, it is essential for colonization of the chicken gut in vivo. Inhibition of CmeABC may provide an effective means of reversing antibiotic resistance and decreasing the transmission of Campylobacter via the food chain. This would positively impact on public health by decreasing the morbidity, mortality and increased healthcare costs associated with the treatment of antibiotic-resistant Campylobacter.
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Affiliation(s)
- Teresa Quinn
- Centre for Food Safety, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin Belfield, Dublin 4, Ireland
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34
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Sigal N, Molshanski-Mor S, Bibi E. No single irreplaceable acidic residues in the Escherichia coli secondary multidrug transporter MdfA. J Bacteriol 2006; 188:5635-9. [PMID: 16855255 PMCID: PMC1540044 DOI: 10.1128/jb.00422-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The largest family of solute transporters (major facilitator superfamily [MFS]) includes proton-motive-force-driven secondary transporters. Several characterized MFS transporters utilize essential acidic residues that play a critical role in the energy-coupling mechanism during transport. Surprisingly, we show here that no single acidic residue plays an irreplaceable role in the Escherichia coli secondary multidrug transporter MdfA.
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Affiliation(s)
- Nadejda Sigal
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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35
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Lewinson O, Adler J, Sigal N, Bibi E. Promiscuity in multidrug recognition and transport: the bacterial MFS Mdr transporters. Mol Microbiol 2006; 61:277-84. [PMID: 16856936 DOI: 10.1111/j.1365-2958.2006.05254.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multidrug (Mdr) transport is an obstacle to the successful treatment of cancer and infectious diseases, and it is mediated by Mdr transporters that recognize and export an unusually broad spectrum of chemically dissimilar toxic compounds. Therefore, in addition to its clinical significance, the Mdr transport phenomenon presents intriguing and challenging mechanistic queries. Recent studies of secondary Mdr transporters of the major facilitator superfamily (MFS) have revealed that they are promiscuous not only regarding their substrate recognition profile, but also with respect to matters of energy utilization, electrical and chemical flexibility in the Mdr recognition pocket, and surprisingly, also in their physiological functions.
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Affiliation(s)
- Oded Lewinson
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, 76100, Israel
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36
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De Rossi E, Aínsa JA, Riccardi G. Role of mycobacterial efflux transporters in drug resistance: an unresolved question. FEMS Microbiol Rev 2006; 30:36-52. [PMID: 16438679 DOI: 10.1111/j.1574-6976.2005.00002.x] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Two mechanisms are thought to be involved in the natural drug resistance of mycobacteria: the mycobacterial cell wall permeability barrier and active multidrug efflux pumps. Genes encoding drug efflux transporters have been isolated from several mycobacterial species. These proteins transport tetracycline, fluoroquinolones, aminoglycosides and other compounds. Recent reports have suggested that efflux pumps may also be involved in transporting isoniazid, one of the main drugs used to treat tuberculosis. This review highlights recent advances in our understanding of efflux-mediated drug resistance in mycobacteria, including the distribution of efflux systems in these organisms, their substrate profiles and their contribution to drug resistance. The balance between the drug transport into the cell and drug efflux is not yet clearly understood, and further studies are required in mycobacteria.
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Affiliation(s)
- Edda De Rossi
- Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, Pavia, Italy
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37
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Terán W, Krell T, Ramos JL, Gallegos MT. Effector-Repressor Interactions, Binding of a Single Effector Molecule to the Operator-bound TtgR Homodimer Mediates Derepression. J Biol Chem 2006; 281:7102-9. [PMID: 16407274 DOI: 10.1074/jbc.m511095200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The RND family transporter TtgABC and its cognate repressor TtgR from Pseudomonas putida DOT-T1E were both shown to possess multidrug recognition properties. Structurally unrelated molecules such as chloramphenicol, butyl paraben, 1,3-dihydroxynaphthalene, and several flavonoids are substrates of TtgABC and activate pump expression by binding to the TtgR-operator complex. Isothermal titration calorimetry was employed to determine the thermodynamic parameters for the binding of these molecules to TtgR. Dissociation constants were in the range from 1 to 150 microm, the binding stoichiometry was one effector molecule per dimer of TtgR, and the process was driven by favorable enthalpy changes. Although TtgR exhibits a large multidrug binding profile, the plant-derived compounds phloretin and quercetin were shown to bind with the highest affinity (K(D) of around 1 microm), in contrast to other effectors (chloramphenicol and aromatic solvents) for which exhibited a more reduced affinity. Structure-function studies of effectors indicate that the presence of aromatic rings as well as hydroxyl groups are determinants for TtgR binding. The binding of TtgR to its operator DNA does not alter the protein effector profile nor the effector binding stoichiometry. Moreover, we demonstrate here for the first time that the binding of a single effector molecule to the DNA-bound TtgR homodimer induces the dissociation of the repressor-operator complex. This provides important insight into the molecular mechanism of effector-mediated derepression.
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Affiliation(s)
- Wilson Terán
- Department of Biochemistry, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Apartado de Correos 419, E-18008 Granada, Spain
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38
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Lynch AS. Efflux systems in bacterial pathogens: An opportunity for therapeutic intervention? An industry view. Biochem Pharmacol 2006; 71:949-56. [PMID: 16290174 DOI: 10.1016/j.bcp.2005.10.021] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 10/05/2005] [Accepted: 10/11/2005] [Indexed: 11/19/2022]
Abstract
The efflux systems of bacteria protect cells from antibiotics and biocides by actively transporting compounds out of the cytoplasm and/or periplasm and thereby limit their steady-state accumulation at their site(s) of action. The impact of efflux systems on the efficacy of antibiotics used in human medicine and animal husbandry is becoming increasingly apparent from the characterization of drug-resistant strains with altered drug efflux properties. In most instances, efflux-mediated antibiotic resistance arises from mutational events that result in their elevated expression and, in the case of efflux pumps with broad substrate specificity, can confer multi-drug resistance (MDR) to structurally unrelated antibiotics. Knowledge of the role of efflux systems in conferring antibiotic resistance has now been successfully exploited in the pharmaceutical industry and contributed, in part, to the development of new members of the macrolide and tetracycline classes of antibiotics that circumvent the efflux-based resistance mechanisms that have limited the clinical utility of their progenitors. The therapeutic utility of compounds that inhibit bacterial drug efflux pumps and therein potentiate the activity of a co-administered antibiotic agent remains to be validated in the clinical setting, but the approach holds promise for the future in improving the efficacy and/or extending the clinical utility of existing antibiotics. This review discusses the potential of further exploiting the knowledge of efflux-mediated antibiotic resistance in bacteria toward the discovery and development of new chemotherapeutic agents.
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Affiliation(s)
- A Simon Lynch
- Cumbre Inc., 1502 Viceroy Drive, Dallas, TX 75235-2304, USA.
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Lin J, Cagliero C, Guo B, Barton YW, Maurel MC, Payot S, Zhang Q. Bile salts modulate expression of the CmeABC multidrug efflux pump in Campylobacter jejuni. J Bacteriol 2005; 187:7417-24. [PMID: 16237025 PMCID: PMC1272998 DOI: 10.1128/jb.187.21.7417-7424.2005] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CmeABC, a multidrug efflux pump, is involved in the resistance of Campylobacter jejuni to a broad spectrum of antimicrobial agents and is essential for Campylobacter colonization in animal intestine by mediating bile resistance. Previously, we have shown that expression of this efflux pump is under the control of a transcriptional repressor named CmeR. Inactivation of CmeR or mutation in the cmeABC promoter (PcmeABC) region derepresses cmeABC, leading to overexpression of this efflux pump. However, it is unknown if the expression of cmeABC can be conditionally induced by the substrates it extrudes. In this study, we examined the expression of cmeABC in the presence of various antimicrobial compounds. Although the majority of the antimicrobials tested did not affect the expression of cmeABC, bile salts drastically elevated the expression of this efflux operon. The induction was observed with both conjugated and unconjugated bile salts and was in a dose- and time-dependent manner. Experiments using surface plasmon resonance demonstrated that bile salts inhibited the binding of CmeR to PcmeABC, suggesting that bile compounds are inducing ligands of CmeR. The interaction between bile salts and CmeR likely triggers conformational changes in CmeR, resulting in reduced binding affinity of CmeR to PcmeABC. Bile did not affect the transcription of cmeR, indicating that altered expression of cmeR is not a factor in bile-induced overexpression of cmeABC. In addition to the CmeR-dependent induction, some bile salts (e.g., taurocholate) also activated the expression of cmeABC by a CmeR-independent pathway. Consistent with the elevated production of CmeABC, the presence of bile salts in culture media resulted in increased resistance of Campylobacter to multiple antimicrobials. These findings reveal a new mechanism that modulates the expression of cmeABC and further support the notion that bile resistance is a natural function of CmeABC.
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Affiliation(s)
- Jun Lin
- Department of Veterinary Microbiology and Preventive Medicine, 1116 Veterinary Medicine Complex, Iowa State University, Ames, IA 50011, USA
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40
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Martín JF, Casqueiro J, Liras P. Secretion systems for secondary metabolites: how producer cells send out messages of intercellular communication. Curr Opin Microbiol 2005; 8:282-93. [PMID: 15939351 DOI: 10.1016/j.mib.2005.04.009] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 04/22/2005] [Indexed: 11/23/2022]
Abstract
Many secondary metabolites (e.g. antibiotics and mycotoxins) are toxic to the microorganisms that produce them. The clusters of genes that are responsible for the biosynthesis of secondary metabolites frequently contain genes for resistance to these toxic metabolites, such as different types of multiple drug resistance systems, to avoid suicide of the producer strains. Recently there has been research into the efflux systems of secondary metabolites in bacteria and in filamentous fungi, such as the large number of ATP-binding cassette transporters found in antibiotic-producing Streptomyces species and that are involved in penicillin secretion in Penicillium chrysogenum. A different group of efflux systems, the major facilitator superfamily exporters, occur very frequently in a variety of bacteria that produce pigments or antibiotics (e.g. the cephamycin and thienamycin producers) and in filamentous fungi that produce mycotoxins. Such efflux systems include the CefT exporters that mediate cephalosporin secretion in Acremonium chrysogenum. The evolutionary origin of these efflux systems and their relationship with current resistance determinants in pathogenic bacteria has been analyzed. Genetic improvement of the secretion systems of secondary metabolites in the producer strain has important industrial applications.
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Affiliation(s)
- Juan F Martín
- Area de Microbiología, Facultad de Ciencias Biológicas y Ambientales, Campus de Vegazana, s/n, 24071 León, Spain.
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41
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Lawrence LE, Barrett JF. Efflux pumps in bacteria: overview, clinical relevance, and potential pharmaceutical target. Expert Opin Investig Drugs 2005; 7:199-217. [PMID: 15991952 DOI: 10.1517/13543784.7.2.199] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Trends in microbial resistance suggest a dramatic increase in the frequency of reports of multi-drug efflux pumps in bacteria and fungi. Although it is difficult to determine whether this increase is due to the increased attention given to this resistance mechanism, or an increase in frequency, efflux pumps are becoming an important consideration in resistance emergence. These efflux pumps comprise at least four different classes in Gram-positive and Gram-negative bacteria, as well as in Streptomyces and fungi. As more efflux pumps are characterised and studied, both biochemically and structurally, the opportunity for intervention may arise.
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Affiliation(s)
- L E Lawrence
- Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492, USA
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42
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Krulwich TA, Lewinson O, Padan E, Bibi E. Do physiological roles foster persistence of drug/multidrug-efflux transporters? A case study. Nat Rev Microbiol 2005; 3:566-72. [PMID: 15953929 DOI: 10.1038/nrmicro1181] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Drug and multidrug resistance have greatly compromised the compounds that were once the mainstays of antibiotic therapy. This resistance often persists despite reductions in the use of antibiotics, indicating that the proteins encoded by antibiotic-resistance genes have alternative physiological roles that can foster such persistence in the absence of selective pressure by antibiotics. The recent observations that Tet(L), a tetracycline-efflux transporter, and MdfA, a multidrug-efflux transporter, both confer alkali tolerance offer a striking case study in support of this hypothesis.
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Affiliation(s)
- Terry A Krulwich
- Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, New York 10029, USA
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43
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Kriengkauykiat J, Porter E, Lomovskaya O, Wong-Beringer A. Use of an efflux pump inhibitor to determine the prevalence of efflux pump-mediated fluoroquinolone resistance and multidrug resistance in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2005; 49:565-70. [PMID: 15673734 PMCID: PMC547318 DOI: 10.1128/aac.49.2.565-570.2005] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2004] [Revised: 10/03/2004] [Accepted: 10/07/2004] [Indexed: 11/20/2022] Open
Abstract
Fluoroquinolone-resistance in Pseudomonas aeruginosa may be due to efflux pump overexpression (EPO) and/or target mutations. EPO can result in multidrug resistance (MDR) due to broad substrate specificity of the pumps. MC-04,124, an efflux pump inhibitor (EPI) shown to significantly potentiate activity of levofloxacin in P. aeruginosa, was used to examine the prevalence of EPO in clinical isolates. MICs were determined for ciprofloxacin, levofloxacin, moxifloxacin, and gatifloxacin with or without EPI and for other antipseudomonal agents by using broth microdilution against P. aeruginosa isolates from adults (n = 119) and children (n = 24). The prevalence of the EPO phenotype (>/=8-fold MIC decrease when tested with EPI) was compared among subgroups with different resistance profiles. The EPO phenotype was more prevalent among levofloxacin-resistant than levofloxacin-sensitive strains (61%, 48/79 versus 9%, 6/64). EPO was present in 60% of fluoroquinolone-resistant strains without cross-resistance, while it was present at variable frequencies among strains with cross-resistance to other agents: piperacillin-tazobactam (86%), ceftazidime (76%), cefepime (65%), imipenem (56%), gentamicin (55%), tobramycin (48%), and amikacin (27%). The magnitude of MIC decrease with an EPI paralleled the frequency of which the EPO phenotype was observed in different subgroups. EPI reduced the levofloxacin MIC by as much as 16-fold in eight strains for which MICs were 128 microg/ml. Efflux-mediated resistance appears to contribute significantly to fluoroquinolone resistance and MDR in P. aeruginosa. Our data support the fact that increased fluoroquinolone usage can negatively impact susceptibility of P. aeruginosa to multiple classes of antipseudomonal agents.
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Affiliation(s)
- Jane Kriengkauykiat
- University of Southern California, School of Pharmacy, 1985 Zonal Ave., Los Angeles, CA 90089, USA
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44
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Cao L, Srikumar R, Poole K. MexAB-OprM hyperexpression in NalC-type multidrug-resistant Pseudomonas aeruginosa: identification and characterization of the nalC gene encoding a repressor of PA3720-PA3719. Mol Microbiol 2005; 53:1423-36. [PMID: 15387820 DOI: 10.1111/j.1365-2958.2004.04210.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
MexAB-OprM is a multidrug efflux system that contributes to intrinsic and acquired multidrug resistance in Pseudomonas aeruginosa, the latter as a result of mutational hyperexpression of the mexAB-oprM operon. While efflux gene hyperexpression typically results from mutations in the linked mexR repressor gene, it also occurs independently of mexR mutations in so-called nalC mutants that demonstrate more modest mexAB-oprM expression and, thus, more modest multidrug resistance than do mexR strains. Using a transposon insertion mutagenesis approach, nalC mutant strains were selected and the disrupted gene, PA3721, identified. Amplification and sequencing of this gene from previously isolated spontaneous nalC mutants revealed the presence of mutations in all instances and as such, PA3721 has been renamed nalC. PA3721 (nalC) encodes a probable repressor of the TetR/AcrR family and occurs upstream of an apparent two-gene operon, PA3720-PA3719, whose expression was negatively regulated by PA3721. Thus, PA3720-PA3719 was hyperexpressed in transposon insertion and spontaneous nalC mutants. The loss of PA3719 but not of PA3720 expression in a spontaneous nalC mutant reduced MexAB-OprM expression to wild-type levels and compromised multidrug resistance, an indication that hyperexpression of PA3719 only was necessary for the nalC phenotype. Introduction of PA3719 into wild-type P. aeruginosa on a multicopy plasmid was, in fact, sufficient to promote elevated MexAB-OprM expression and multidrug resistance characteristic of a nalC strain. Thus, the nalC (PA3721) mutation serves only to enhance PA3720-PA3719 expression, with expression of PA3719 (encodes a 53 amino acid protein of predicted pI 10.4) directly or indirectly impacting MexAB-OprM expression. Intriguingly, nalC strains produce markedly elevated levels of stable MexR protein suggesting that PA3720-PA3719 hyperexpression somehow modulates MexR repressor activity. The deduced products of PA3720-PA3719 show no homology to sequences presently in the GenBank databases, however, and as such provide no clues as to how this might occur.
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Affiliation(s)
- Lily Cao
- Department of Microbiology and Immunology, Queen's University, Kingston, ON, Canada, K7L 3N6
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45
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Langton KP, Henderson PJF, Herbert RB. Antibiotic resistance: multidrug efflux proteins, a common transport mechanism? Nat Prod Rep 2005; 22:439-51. [PMID: 16047044 DOI: 10.1039/b413734p] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Kate P Langton
- Astbury Centre for Structural Molecular Biology, School of Biochemistry and Microbiology, University of Leeds, LS2 9JT, UK.
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46
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Lewinson O, Padan E, Bibi E. Alkalitolerance: a biological function for a multidrug transporter in pH homeostasis. Proc Natl Acad Sci U S A 2004; 101:14073-8. [PMID: 15371593 PMCID: PMC521123 DOI: 10.1073/pnas.0405375101] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
MdfA is an Escherichia coli multidrug-resistance transporter. Cells expressing MdfA from a multicopy plasmid exhibit multidrug resistance against a diverse group of toxic compounds. In this article, we show that, in addition to its role in multidrug resistance, MdfA confers extreme alkaline pH resistance and allows the growth of transformed cells under conditions that are close to those used normally by alkaliphiles (up to pH 10) by maintaining a physiological internal pH. MdfA-deleted E. coli cells are sensitive even to mild alkaline conditions, and the wild-type phenotype is restored fully by MdfA expressed from a plasmid. This activity of MdfA requires Na(+) or K(+). Fluorescence studies with inverted membrane vesicles demonstrate that MdfA catalyzes Na(+)- or K(+)-dependent proton transport, and experiments with reconstituted proteoliposomes confirm that MdfA is solely responsible for this phenomenon. Studies with multidrug resistance-defective MdfA mutants and competitive transport assays suggest that these activities of MdfA are related. Together, the results demonstrate that a single protein has an unprecedented capacity to turn E. coli from an obligatory neutrophile into an alkalitolerant bacterium, and they suggest a previously uncharacterized physiological role for MdfA in pH homeostasis.
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Affiliation(s)
- Oded Lewinson
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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47
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Lin J, Sahin O, Michel LO, Zhang Q. Critical role of multidrug efflux pump CmeABC in bile resistance and in vivo colonization of Campylobacter jejuni. Infect Immun 2003; 71:4250-9. [PMID: 12874300 PMCID: PMC165992 DOI: 10.1128/iai.71.8.4250-4259.2003] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CmeABC functions as a multidrug efflux pump contributing to the resistance of Campylobacter to a broad range of antimicrobials. In this study, we examined the role of CmeABC in bile resistance and its contribution to the adaptation of Campylobacter jejuni in the intestinal tract of the chicken, a natural host and a major reservoir for Campylobacter. Inactivation of cmeABC drastically decreased the resistance of Campylobacter to various bile salts. Addition of choleate (2 mM) in culture medium impaired the in vitro growth of the cmeABC mutants but had no effect on the growth of the wild-type strain. Bile concentration varied in the duodenum, jejunum, and cecum of chicken intestine, and the inhibitory effect of the intestinal extracts on the in vitro growth of Campylobacter was well correlated with the total bile concentration in the individual sections of chicken intestine. When inoculated into chickens, the wild-type strain colonized the birds as early as day 2 postinoculation with a density as high as 10(7) CFU/g of feces. In contrast, the cmeABC mutants failed to colonize any of the inoculated chickens throughout the study. The minimum infective dose for the cmeABC mutant was at least 2.6 x 10(4)-fold higher than that of the wild-type strain. Complementation of the cmeABC mutants with a wild-type cmeABC allele in trans fully restored the in vitro growth in bile-containing media and the in vivo colonization to the levels of the wild-type strain. Immunoblotting analysis indicated that CmeABC is expressed and immunogenic in chickens experimentally infected with C. jejuni. Together, these findings provide compelling evidence that CmeABC, by mediating resistance to bile salts in the intestinal tract, is required for successful colonization of C. jejuni in chickens. Inhibition of CmeABC function may not only control antibiotic resistance but also prevent the in vivo colonization of pathogenic Campylobacter.
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Affiliation(s)
- Jun Lin
- Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio 44691, USA
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48
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Abstract
Multidrug efflux transporters, found in all living cells and protecting them from multiple structurally dissimilar hydrophobic toxins, have fascinated researchers for decades and presented a number of puzzling questions. These transporters demonstrate a remarkably broad substrate specificity, which seemingly contradicts established dogmas of biochemistry. Although sharing highly unusual properties, in some unexplained way, they have arisen multiple times in the evolution of several families of membrane proteins. Furthermore, the number of multidrug transporters encoded in each genome is so large that their role in cellular physiology has remained un-certain. Recent advances in the structural analysis of a number of soluble multidrug-recognizing proteins show that these proteins possess large hydrophobic binding sites and bind their substrates through a combination of a hydrophobic effect and electrostatic attraction, rather than by establishing a precise network of hydrogen bonds and other specific interactions characteristic of traditionally studied enzymes and receptors. Low-resolution structural studies of multidrug transporters suggest that they possess similar large binding sites and may use similar simple principles of substrate recognition. This would explain not only their broad substrate specificity, but also their unusual evolutionary relationships and the apparent multiplicity in genomes of organisms of all evolutionary kingdoms. Although further structural studies will be needed to prove this hypothesis, it is already clear that the explanation of the puzzling phenomenon of multidrug efflux may not necessarily require any substantially new biochemical or biological principles.
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Affiliation(s)
- Alex A Neyfakh
- Center for Pharmaceutical Biotechnology (M/C 870), University of Illinois, 900 S Ashland Street, Chicago, IL 60607, USA.
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49
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Furrer JL, Sanders DN, Hook-Barnard IG, McIntosh MA. Export of the siderophore enterobactin in Escherichia coli: involvement of a 43 kDa membrane exporter. Mol Microbiol 2002; 44:1225-34. [PMID: 12068807 DOI: 10.1046/j.1365-2958.2002.02885.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The enterobactin system for iron transport in Escherichia coli is well characterized with the exception of the mechanism of enterobactin secretion to the extracellular environment. Escherichia coli membrane protein P43, encoded by ybdA in the chromosomal region of genes involved in enterobactin synthesis, shows strong homology to the 12-transmembrane segment major facilitator superfamily of export pumps. A P43-null mutation was created and siderophore nutrition assays, performed with a panel of E. coli strains expressing one or more outer membrane receptors for enterobactin-related compounds, demonstrated that the P43 mutant was unable to secrete enterobactin efficiently. Products released from the mutant strain were identified with thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), revealing that the P43 mutant secretes little, if any, enterobactin, but elevated levels of enterobactin breakdown products 2,3- dihydroxybenzoylserine (DHBS) monomer, dimer, and trimer. These data establish that P43 is a critical component of the E. coli enterobactin secretion machinery and provides a rationale for the designation of the previous genetic locus ybdA as entS to reflect its relevant biological function.
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Affiliation(s)
- Jason L Furrer
- Department of Molecular Microbiology and Immunology, University of Missouri-Columbia, Columbia, MO, USA
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50
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Teo JWP, Tan TMC, Poh CL. Genetic determinants of tetracycline resistance in Vibrio harveyi. Antimicrob Agents Chemother 2002; 46:1038-45. [PMID: 11897587 PMCID: PMC127092 DOI: 10.1128/aac.46.4.1038-1045.2002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Isolates of Vibrio harveyi, a prawn pathogen, have demonstrated multiple antibiotic resistance to commonly used antimicrobial agents, such as oxytetracycline. In this paper, we describe the cloning and characterization of two tetracycline resistance determinants from V. harveyi strain M3.4L. The first resistance determinant, cloned as a 4,590-bp fragment, was identical to tetA and flanking sequences encoded on transposon Tn10 from Shigella flexneri. The second determinant, cloned as a 3,358-bp fragment in pATJ1, contains two open reading frames, designated tet35 and txr. tet35 encodes a 369-amino-acid protein that was predicted to have nine transmembrane regions. It is a novel protein which has no homology to any other drug resistance protein but has low levels of homology (28%) to Na(+)/H(+) antiporters. Transposon mutagenesis showed that tet35 and txr were required for tetracycline resistance in a heterologous Escherichia coli host. Tetracycline accumulation studies indicate that E. coli carrying tet35 and txr can function as an energy-dependent tetracycline efflux pump but is less efficient than TetA.
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Affiliation(s)
- Jeanette W P Teo
- Programme in Environmental Microbiology, Department of Microbiology, Faculty of Medicine, National University of Singapore, Singapore
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