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Chetri S. The culmination of multidrug-resistant efflux pumps vs. meager antibiotic arsenal era: Urgent need for an improved new generation of EPIs. Front Microbiol 2023; 14:1149418. [PMID: 37138605 PMCID: PMC10149990 DOI: 10.3389/fmicb.2023.1149418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 03/13/2023] [Indexed: 05/05/2023] Open
Abstract
Efflux pumps function as an advanced defense system against antimicrobials by reducing the concentration of drugs inside the bacteria and extruding the substances outside. Various extraneous substances, including antimicrobials, toxic heavy metals, dyes, and detergents, have been removed by this protective barrier composed of diverse transporter proteins found in between the cell membrane and the periplasm within the bacterial cell. In this review, multiple efflux pump families have been analytically and widely outlined, and their potential applications have been discussed in detail. Additionally, this review also discusses a variety of biological functions of efflux pumps, including their role in the formation of biofilms, quorum sensing, their survivability, and the virulence in bacteria, and the genes/proteins associated with efflux pumps have also been explored for their potential relevance to antimicrobial resistance and antibiotic residue detection. A final discussion centers around efflux pump inhibitors, particularly those derived from plants.
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2
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Huang L, Wu C, Gao H, Xu C, Dai M, Huang L, Hao H, Wang X, Cheng G. Bacterial Multidrug Efflux Pumps at the Frontline of Antimicrobial Resistance: An Overview. Antibiotics (Basel) 2022; 11:antibiotics11040520. [PMID: 35453271 PMCID: PMC9032748 DOI: 10.3390/antibiotics11040520] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/01/2022] [Accepted: 04/08/2022] [Indexed: 02/06/2023] Open
Abstract
Multidrug efflux pumps function at the frontline to protect bacteria against antimicrobials by decreasing the intracellular concentration of drugs. This protective barrier consists of a series of transporter proteins, which are located in the bacterial cell membrane and periplasm and remove diverse extraneous substrates, including antimicrobials, organic solvents, toxic heavy metals, etc., from bacterial cells. This review systematically and comprehensively summarizes the functions of multiple efflux pumps families and discusses their potential applications. The biological functions of efflux pumps including their promotion of multidrug resistance, biofilm formation, quorum sensing, and survival and pathogenicity of bacteria are elucidated. The potential applications of efflux pump-related genes/proteins for the detection of antibiotic residues and antimicrobial resistance are also analyzed. Last but not least, efflux pump inhibitors, especially those of plant origin, are discussed.
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3
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Alav I, Kobylka J, Kuth MS, Pos KM, Picard M, Blair JMA, Bavro VN. Structure, Assembly, and Function of Tripartite Efflux and Type 1 Secretion Systems in Gram-Negative Bacteria. Chem Rev 2021; 121:5479-5596. [PMID: 33909410 PMCID: PMC8277102 DOI: 10.1021/acs.chemrev.1c00055] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Indexed: 12/11/2022]
Abstract
Tripartite efflux pumps and the related type 1 secretion systems (T1SSs) in Gram-negative organisms are diverse in function, energization, and structural organization. They form continuous conduits spanning both the inner and the outer membrane and are composed of three principal components-the energized inner membrane transporters (belonging to ABC, RND, and MFS families), the outer membrane factor channel-like proteins, and linking the two, the periplasmic adaptor proteins (PAPs), also known as the membrane fusion proteins (MFPs). In this review we summarize the recent advances in understanding of structural biology, function, and regulation of these systems, highlighting the previously undescribed role of PAPs in providing a common architectural scaffold across diverse families of transporters. Despite being built from a limited number of basic structural domains, these complexes present a staggering variety of architectures. While key insights have been derived from the RND transporter systems, a closer inspection of the operation and structural organization of different tripartite systems reveals unexpected analogies between them, including those formed around MFS- and ATP-driven transporters, suggesting that they operate around basic common principles. Based on that we are proposing a new integrated model of PAP-mediated communication within the conformational cycling of tripartite systems, which could be expanded to other types of assemblies.
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Affiliation(s)
- Ilyas Alav
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Jessica Kobylka
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Miriam S. Kuth
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Klaas M. Pos
- Institute
of Biochemistry, Biocenter, Goethe Universität
Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Martin Picard
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS
UMR 7099, Université de Paris, 75005 Paris, France
- Fondation
Edmond de Rothschild pour le développement de la recherche
Scientifique, Institut de Biologie Physico-Chimique, 75005 Paris, France
| | - Jessica M. A. Blair
- Institute
of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Vassiliy N. Bavro
- School
of Life Sciences, University of Essex, Colchester, CO4 3SQ United Kingdom
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4
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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: 66] [Impact Index Per Article: 22.0] [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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5
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Bailly C. Medicinal applications and molecular targets of dequalinium chloride. Biochem Pharmacol 2021; 186:114467. [PMID: 33577890 DOI: 10.1016/j.bcp.2021.114467] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 12/23/2022]
Abstract
For more than 60 years dequalinium chloride (DQ) has been used as anti-infective drug, mainly to treat local infections. It is a standard drug to treat bacterial vaginosis and an active ingredient of sore-throat lozenges. As a lipophilic bis-quaternary ammonium molecule, the drug displays membrane effects and selectively targets mitochondria to deplete DNA and to block energy production in cells. But beyond its mitochondriotropic property, DQ can interfere with the correct functioning of diverse proteins. A dozen of DQ protein targets have been identified and their implication in the antibacterial, antiviral, antifungal, antiparasitic and anticancer properties of the drug is discussed here. The anticancer effects of DQ combine a mitochondrial action, a selective inhibition of kinases (PKC-α/β, Cdc7/Dbf4), and a modulation of Ca2+-activated K+ channels. At the bacterial level, DQ interacts with different multidrug transporters (QacR, AcrB, EmrE) and with the transcriptional regulator RamR. Other proteins implicated in the antiviral (MPER domain of gp41 HIV-1) and antiparasitic (chitinase A from Vibrio harveyi) activities have been identified. DQ also targets α -synuclein oligomers to restrict protofibrils formation implicated in some neurodegenerative disorders. In addition, DQ is a typical bolaamphiphile molecule, well suited to form liposomes and nanoparticules useful for drug entrapment and delivery (DQAsomes and others). Altogether, the review highlights the many pharmacological properties and therapeutic benefits of this old 'multi-talented' drug, which may be exploited further. Its multiple sites of actions in cells should be kept in mind when using DQ in experimental research.
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6
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Yu X, Wei H, Liu X, Liu D, Fan A, Su H. Enhanced resistance of Trichoderma harzianum LZDX-32-08 to hygromycin B induced by sea salt. Biotechnol Lett 2020; 43:213-222. [PMID: 32851464 DOI: 10.1007/s10529-020-02994-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/18/2020] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To determine the effect of sea salt on the resistance of Trichoderma harzianum LZDX-32-08 to hygromycin B and speculate the possible mechanisms involved via transcriptome analysis. RESULTS Sea salt addition in media to simulate marine environment significantly increased the tolerance of marine-derived fungus Trichoderma harzianum LZDX-32-08 to hygromycin B from 40 to 500 μg/ml. Meanwhile, sea salt addition also elicited the hygromycin B resistance of 5 other marine or terrestrial fungi. Transcriptomic analyses of T. harzianum cultivated on PDA, PDA supplemented with sea salt and PDA with both sea salt and hygromycin B revealed that genes coding for P-type ATPases, multidrug resistance related transporters and acetyltransferases were up-regulated, while genes coding for Ca2+/H+ antiporter and 1,3-glucosidase were down-regulated, indicating probable increased efflux and inactivation of hygromycin B as well as enhanced biofilm formation, which could jointly contribute to the drug resistance. CONCLUSIONS Marine environment or high ion concentration in the environment could be an importance inducer for antifungal resistance. Possible mechanisms and related key genes were proposed for understanding the molecular basis and overcoming this resistance.
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Affiliation(s)
- Xijia Yu
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, North Third Ring Road 15, Chaoyang District, Beijing, 100029, People's Republic of China
| | - Huiling Wei
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, North Third Ring Road 15, Chaoyang District, Beijing, 100029, People's Republic of China
| | - Xianrui Liu
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, North Third Ring Road 15, Chaoyang District, Beijing, 100029, People's Republic of China
| | - Dong Liu
- State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100191, People's Republic of China
| | - Aili Fan
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, North Third Ring Road 15, Chaoyang District, Beijing, 100029, People's Republic of China.
| | - Haijia Su
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, North Third Ring Road 15, Chaoyang District, Beijing, 100029, People's Republic of China
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7
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Mazzolari A, Gervasoni S, Pedretti A, Fumagalli L, Matucci R, Vistoli G. Repositioning Dequalinium as Potent Muscarinic Allosteric Ligand by Combining Virtual Screening Campaigns and Experimental Binding Assays. Int J Mol Sci 2020; 21:ijms21175961. [PMID: 32825082 PMCID: PMC7503225 DOI: 10.3390/ijms21175961] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 12/12/2022] Open
Abstract
Structure-based virtual screening is a truly productive repurposing approach provided that reliable target structures are available. Recent progresses in the structural resolution of the G-Protein Coupled Receptors (GPCRs) render these targets amenable for structure-based repurposing studies. Hence, the present study describes structure-based virtual screening campaigns with a view to repurposing known drugs as potential allosteric (and/or orthosteric) ligands for the hM2 muscarinic subtype which was indeed resolved in complex with an allosteric modulator thus allowing a precise identification of this binding cavity. First, a docking protocol was developed and optimized based on binding space concept and enrichment factor optimization algorithm (EFO) consensus approach by using a purposely collected database including known allosteric modulators. The so-developed consensus models were then utilized to virtually screen the DrugBank database. Based on the computational results, six promising molecules were selected and experimentally tested and four of them revealed interesting affinity data; in particular, dequalinium showed a very impressive allosteric modulation for hM2. Based on these results, a second campaign was focused on bis-cationic derivatives and allowed the identification of other two relevant hM2 ligands. Overall, the study enhances the understanding of the factors governing the hM2 allosteric modulation emphasizing the key role of ligand flexibility as well as of arrangement and delocalization of the positively charged moieties.
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Affiliation(s)
- Angelica Mazzolari
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Silvia Gervasoni
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Alessandro Pedretti
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Laura Fumagalli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
| | - Rosanna Matucci
- Dipartimento di Neuroscienze, Psicologia, Area del Farmaco e Salute del Bambino (NEUROFARBA), Sezione di Farmacologia e Tossicologia, Università degli Studi di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy;
| | - Giulio Vistoli
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli, 25, I-20133 Milano, Italy; (A.M.); (S.G.); (A.P.); (L.F.)
- Correspondence: ; Tel.: +39-02-5019349
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8
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Structure and mechanism of a redesigned multidrug transporter from the Major Facilitator Superfamily. Sci Rep 2020; 10:3949. [PMID: 32127561 PMCID: PMC7054563 DOI: 10.1038/s41598-020-60332-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/06/2020] [Indexed: 01/07/2023] Open
Abstract
The rapid increase of multidrug resistance poses urgent threats to human health. Multidrug transporters prompt multidrug resistance by exporting different therapeutics across cell membranes, often by utilizing the H+ electrochemical gradient. MdfA from Escherichia coli is a prototypical H+ -dependent multidrug transporter belonging to the Major Facilitator Superfamily. Prior studies revealed unusual flexibility in the coupling between multidrug binding and deprotonation in MdfA, but the mechanistic basis for this flexibility was obscure. Here we report the X-ray structures of a MdfA mutant E26T/D34M/A150E, wherein the multidrug-binding and protonation sites were revamped, separately bound to three different substrates at resolutions up to 2.0 Å. To validate the functional relevance of these structures, we conducted mutational and biochemical studies. Our data elucidated intermediate states during antibiotic recognition and suggested structural changes that accompany the substrate-evoked deprotonation of E26T/D34M/A150E. These findings help to explain the mechanistic flexibility in drug/H+ coupling observed in MdfA and may inspire therapeutic development to preempt efflux-mediated antimicrobial resistance.
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9
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Abstract
Infections arising from multidrug-resistant pathogenic bacteria are spreading rapidly throughout the world and threaten to become untreatable. The origins of resistance are numerous and complex, but one underlying factor is the capacity of bacteria to rapidly export drugs through the intrinsic activity of efflux pumps. In this Review, we describe recent advances that have increased our understanding of the structures and molecular mechanisms of multidrug efflux pumps in bacteria. Clinical and laboratory data indicate that efflux pumps function not only in the drug extrusion process but also in virulence and the adaptive responses that contribute to antimicrobial resistance during infection. The emerging picture of the structure, function and regulation of efflux pumps suggests opportunities for countering their activities.
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10
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Wu HH, Symersky J, Lu M. Structure of an engineered multidrug transporter MdfA reveals the molecular basis for substrate recognition. Commun Biol 2019; 2:210. [PMID: 31240248 PMCID: PMC6572762 DOI: 10.1038/s42003-019-0446-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 04/30/2019] [Indexed: 02/05/2023] Open
Abstract
MdfA is a prototypical H+-coupled multidrug transporter that is characterized by extraordinarily broad substrate specificity. The involvement of specific H-bonds in MdfA-drug interactions and the simplicity of altering the substrate specificity of MdfA contradict the promiscuous nature of multidrug recognition, presenting a baffling conundrum. Here we show the X-ray structures of MdfA variant I239T/G354E in complexes with three electrically different ligands, determined at resolutions up to 2.2 Å. Our structures reveal that I239T/G354E interacts with these compounds differently from MdfA and that I239T/G354E possesses two discrete, non-overlapping substrate-binding sites. Our results shed new light on the molecular design of multidrug-binding and protonation sites and highlight the importance of often-neglected, long-range charge-charge interactions in multidrug recognition. Beyond helping to solve the ostensible conundrum of multidrug recognition, our findings suggest the mechanistic difference between substrate and inhibitor for any H+-dependent multidrug transporter, which may open new vistas on curtailing efflux-mediated multidrug resistance.
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Affiliation(s)
- Hsin-Hui Wu
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064 USA
| | - Jindrich Symersky
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064 USA
| | - Min Lu
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064 USA
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11
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Majumder P, Khare S, Athreya A, Hussain N, Gulati A, Penmatsa A. Dissection of Protonation Sites for Antibacterial Recognition and Transport in QacA, a Multi-Drug Efflux Transporter. J Mol Biol 2019; 431:2163-2179. [PMID: 30910733 PMCID: PMC7212025 DOI: 10.1016/j.jmb.2019.03.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 01/05/2023]
Abstract
QacA is a drug:H+ antiporter with 14 transmembrane helices that confers antibacterial resistance to methicillin-resistant Staphylococcus aureus strains, with homologs in other pathogenic organisms. It is a highly promiscuous antiporter, capable of H+-driven efflux of a wide array of cationic antibacterial compounds and dyes. Our study, using a homology model of QacA, reveals a group of six protonatable residues in its vestibule. Systematic mutagenesis resulted in the identification of D34 (TM1), and a cluster of acidic residues in TM13 including E407 and D411 and D323 in TM10, as being crucial for substrate recognition and transport of monovalent and divalent cationic antibacterial compounds. The transport and binding properties of QacA and its mutants were explored using whole cells, inside-out vesicles, substrate-induced H+ release and microscale thermophoresis-based assays. The activity of purified QacA was also observed using proteoliposome-based substrate-induced H+ transport assay. Our results identify two sites, D34 and D411 as vital players in substrate recognition, while E407 facilitates substrate efflux as a protonation site. We also observe that E407 plays an additional role as a substrate recognition site for the transport of dequalinium, a divalent quaternary ammonium compound. These observations rationalize the promiscuity of QacA for diverse substrates. The study unravels the role of acidic residues in QacA with implications for substrate recognition, promiscuity and processive transport in multidrug efflux transporters, related to QacA.
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Affiliation(s)
- Puja Majumder
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Shashank Khare
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Arunabh Athreya
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Nazia Hussain
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Ashutosh Gulati
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Aravind Penmatsa
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India.
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12
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smFRET Probing Reveals Substrate-Dependent Conformational Dynamics of E. coli Multidrug MdfA. Biophys J 2019; 116:2296-2303. [PMID: 31146923 DOI: 10.1016/j.bpj.2019.04.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 04/10/2019] [Accepted: 04/23/2019] [Indexed: 11/21/2022] Open
Abstract
Bacterial multidrug-resistance transporters of the major facilitator superfamily are distinguished by their extraordinary ability to bind structurally diverse substrates, thus serving as a highly efficient tool to protect cells from multiple toxic substances present in their environment, including antibiotic drugs. However, details of the dynamic conformational changes of the transport cycle involved remain to be elucidated. Here, we used the single-molecule fluorescence resonance energy transfer technique to investigate the conformational behavior of the Escherichia coli multidrug transporter MdfA under conditions of different substrates, pH, and alkali metal ions. Our data show that different substrates exhibit distinct effects on both the conformational distribution and transition rate between two major conformations. Although the cationic substrate tetraphenylphosphonium favors the outward-facing conformation, it has less effect on the transition rate. In contrast, binding of the electroneutral substrate chloramphenicol tends to stabilize the inward-facing conformation and decreases the transition rate. Therefore, our study supports the notion that the MdfA transporter uses distinct mechanisms to transport electroneutral and cationic substrates.
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13
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Foong WE, Tam HK, Crames JJ, Averhoff B, Pos KM. The chloramphenicol/H+ antiporter CraA of Acinetobacter baumannii AYE reveals a broad substrate specificity. J Antimicrob Chemother 2019; 74:1192-1201. [DOI: 10.1093/jac/dkz024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/23/2018] [Accepted: 01/08/2019] [Indexed: 12/15/2022] Open
Affiliation(s)
- Wuen Ee Foong
- Institute of Biochemistry, Goethe‐University Frankfurt, Max‐von‐Laue‐Str. 9, Frankfurt am Main, Germany
| | - Heng-Keat Tam
- Institute of Biochemistry, Goethe‐University Frankfurt, Max‐von‐Laue‐Str. 9, Frankfurt am Main, Germany
| | - Jan J Crames
- Institute of Biochemistry, Goethe‐University Frankfurt, Max‐von‐Laue‐Str. 9, Frankfurt am Main, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Klaas M Pos
- Institute of Biochemistry, Goethe‐University Frankfurt, Max‐von‐Laue‐Str. 9, Frankfurt am Main, Germany
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14
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Wand ME, Jamshidi S, Bock LJ, Rahman KM, Sutton JM. SmvA is an important efflux pump for cationic biocides in Klebsiella pneumoniae and other Enterobacteriaceae. Sci Rep 2019; 9:1344. [PMID: 30718598 PMCID: PMC6362122 DOI: 10.1038/s41598-018-37730-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/04/2018] [Indexed: 01/13/2023] Open
Abstract
The multidrug resistant (MDR) opportunistic pathogen Klebsiella pneumoniae has previously been shown to adapt to chlorhexidine by increasing expression of the MFS efflux pump smvA. Here we show that loss of the regulator SmvR, through adaptation to chlorhexidine, results in increased resistance to a number of cationic biocides in K. pneumoniae and other members of the Enterobacteriaceae. Clinical Enterobacteriaceae isolates which lack smvA and smvR also have an increased susceptibility to chlorhexidine. When smvA from Salmonella and K. pneumoniae are expressed in Escherichia coli, which lacks a homologue to SmvAR, resistance to chlorhexidine increased (4-fold) but plasmid carriage of smvA alone was detrimental to the cell. Challenge of K. pneumoniae with chlorhexidine and another cationic biocide, octenidine, resulted in increased expression of smvA (approx. 70 fold). Adaptation to octenidine was achieved through mutating key residues in SmvA (A363V; Y391N) rather than abolishing the function of SmvR, as with chlorhexidine adaptation. Molecular modelling was able to predict that octenidine interacted more strongly with these mutated SmvA forms. These results show that SmvA is a major efflux pump for cationic biocides in several bacterial species and that increased efflux through SmvA can lead to increased chlorhexidine and octenidine tolerance.
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Affiliation(s)
- Matthew E Wand
- Public Health England, National Infection Service, Porton Down, Salisbury, Wiltshire, SP4 0JG, UK.
| | - Shirin Jamshidi
- School of Cancer and Pharmaceutical Science, King's College London, London, SE1 9NH, UK
| | - Lucy J Bock
- Public Health England, National Infection Service, Porton Down, Salisbury, Wiltshire, SP4 0JG, UK
| | | | - J Mark Sutton
- Public Health England, National Infection Service, Porton Down, Salisbury, Wiltshire, SP4 0JG, UK
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15
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Zomot E, Yardeni EH, Vargiu AV, Tam HK, Malloci G, Ramaswamy VK, Perach M, Ruggerone P, Pos KM, Bibi E. A New Critical Conformational Determinant of Multidrug Efflux by an MFS Transporter. J Mol Biol 2018. [PMID: 29530612 DOI: 10.1016/j.jmb.2018.02.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Secondary multidrug (Mdr) transporters utilize ion concentration gradients to actively remove antibiotics and other toxic compounds from cells. The model Mdr transporter MdfA from Escherichia coli exchanges dissimilar drugs for protons. The transporter should open at the cytoplasmic side to enable access of drugs into the Mdr recognition pocket. Here we show that the cytoplasmic rim around the Mdr recognition pocket represents a previously overlooked important regulatory determinant in MdfA. We demonstrate that increasing the positive charge of the electrically asymmetric rim dramatically inhibits MdfA activity and sometimes even leads to influx of planar, positively charged compounds, resulting in drug sensitivity. Our results suggest that unlike the mutants with the electrically modified rim, the membrane-embedded wild-type MdfA exhibits a significant probability of an inward-closed conformation, which is further increased by drug binding. Since MdfA binds drugs from its inward-facing environment, these results are intriguing and raise the possibility that the transporter has a sensitive, drug-induced conformational switch, which favors an inward-closed state.
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Affiliation(s)
- Elia Zomot
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eliane Hadas Yardeni
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Heng-Keat Tam
- Institute of Biochemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Giuliano Malloci
- Department of Physics, University of Cagliari, 09042 Monserrato (CA), Italy
| | | | - Michal Perach
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Paolo Ruggerone
- Department of Physics, University of Cagliari, 09042 Monserrato (CA), Italy
| | - Klaas Martinus Pos
- Institute of Biochemistry, Goethe University Frankfurt, 60438 Frankfurt, Germany
| | - Eitan Bibi
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
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16
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Zwama M, Yamasaki S, Nakashima R, Sakurai K, Nishino K, Yamaguchi A. Multiple entry pathways within the efflux transporter AcrB contribute to multidrug recognition. Nat Commun 2018; 9:124. [PMID: 29317622 PMCID: PMC5760665 DOI: 10.1038/s41467-017-02493-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 12/04/2017] [Indexed: 11/13/2022] Open
Abstract
AcrB is the major multidrug exporter in Escherichia coli. Although several substrate-entrances have been identified, the specificity of these various transport paths remains unclear. Here we present evidence for a substrate channel (channel 3) from the central cavity of the AcrB trimer, which is connected directly to the deep pocket without first passing the switch-loop and the proximal pocket . Planar aromatic cations, such as ethidium, prefer channel 3 to channels 1 and 2. The efflux through channel 3 increases by targeted mutations and is not in competition with the export of drugs such as minocycline and erythromycin through channels 1 and 2. A switch-loop mutant, in which the pathway from the proximal to the deep pocket is hindered, can export only channel 3-utilizing drugs. The usage of multiple entrances thus contributes to the recognition and transport of a wide range of drugs with different physicochemical properties. Multidrug transporters possess several drug binding sites. Here the authors describe a transport path specific for planar aromatic cations in the E. coli multi-drug transporter AcrB.
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Affiliation(s)
- Martijn Zwama
- Laboratory of Cell Membrane Structural Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan.,Department of Biomolecular Science and Regulation, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan.,Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Seiji Yamasaki
- Department of Biomolecular Science and Regulation, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan
| | - Ryosuke Nakashima
- Laboratory of Cell Membrane Structural Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan
| | - Keisuke Sakurai
- Laboratory of Cell Membrane Structural Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan
| | - Kunihiko Nishino
- Department of Biomolecular Science and Regulation, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan
| | - Akihito Yamaguchi
- Laboratory of Cell Membrane Structural Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, 567-0047, Japan.
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17
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Zhang XC, Liu M, Lu G, Heng J. Thermodynamic secrets of multidrug resistance: A new take on transport mechanisms of secondary active antiporters. Protein Sci 2017; 27:595-613. [PMID: 29193407 DOI: 10.1002/pro.3355] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 12/17/2022]
Abstract
Multidrug resistance (MDR) presents a growing challenge to global public health. Drug extrusion transporters play a critical part in MDR; thus, their mechanisms of substrate recognition are being studied in great detail. In this work, we review common structural features of key transporters involved in MDR. Based on our membrane potential-driving hypothesis, we propose a general energy-coupling mechanism for secondary-active antiporters. This putative mechanism provides a common framework for understanding poly-specificity of most-if not all-MDR transporters.
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Affiliation(s)
- Xuejun C Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Min Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guangyuan Lu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jie Heng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing, 100101, China
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18
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Abstract
EmrE is a small multidrug resistance transporter found in Escherichia coli that confers resistance to toxic polyaromatic cations due to its proton-coupled antiport of these substrates. Here we show that EmrE breaks the rules generally deemed essential for coupled antiport. NMR spectra reveal that EmrE can simultaneously bind and cotransport proton and drug. The functional consequence of this finding is an exceptionally promiscuous transporter: not only can EmrE export diverse drug substrates, it can couple antiport of a drug to either one or two protons, performing both electrogenic and electroneutral transport of a single substrate. We present a free-exchange model for EmrE antiport that is consistent with these results and recapitulates ∆pH-driven concentrative drug uptake. Kinetic modeling suggests that free exchange by EmrE sacrifices coupling efficiency but boosts initial transport speed and drug release rate, which may facilitate efficient multidrug efflux.
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19
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Yardeni EH, Zomot E, Bibi E. The fascinating but mysterious mechanistic aspects of multidrug transport by MdfA from Escherichia coli. Res Microbiol 2017; 169:455-460. [PMID: 28951231 DOI: 10.1016/j.resmic.2017.09.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/24/2017] [Accepted: 09/13/2017] [Indexed: 10/18/2022]
Abstract
MdfA is an interesting member of a large group of secondary multidrug (Mdr) transporters. Through genetic, biochemical and biophysical studies of MdfA, many challenging aspects of the multidrug transport phenomenon have been addressed. This includes its ability to interact with chemically unrelated drugs and how it utilizes energy to drive efflux of compounds that are not only structurally, but also electrically, different. Admittedly, however, despite all efforts and a recent pioneering structural contribution, several important mechanistic issues of the promiscuous capabilities of MdfA still seek better molecular and dynamic understanding.
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Affiliation(s)
- Eliane H Yardeni
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Elia Zomot
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eitan Bibi
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
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20
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The role played by drug efflux pumps in bacterial multidrug resistance. Essays Biochem 2017; 61:127-139. [DOI: 10.1042/ebc20160064] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/22/2017] [Accepted: 01/24/2017] [Indexed: 01/19/2023]
Abstract
Antimicrobial resistance is a current major challenge in chemotherapy and infection control. The ability of bacterial and eukaryotic cells to recognize and pump toxic compounds from within the cell to the environment before they reach their targets is one of the important mechanisms contributing to this phenomenon. Drug efflux pumps are membrane transport proteins that require energy to export substrates and can be selective for a specific drug or poly-specific that can export multiple structurally diverse drug compounds. These proteins can be classified into seven groups based on protein sequence homology, energy source and overall structure. Extensive studies on efflux proteins have resulted in a wealth of knowledge that has made possible in-depth understanding of the structures and mechanisms of action, substrate profiles, regulation and possible inhibition of many clinically important efflux pumps. This review focuses on describing known families of drug efflux pumps using examples that are well characterized structurally and/or biochemically.
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21
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Computational modelling of efflux pumps and their inhibitors. Essays Biochem 2017; 61:141-156. [PMID: 28258237 DOI: 10.1042/ebc20160065] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 12/13/2016] [Accepted: 12/19/2016] [Indexed: 11/17/2022]
Abstract
Antimicrobial resistance is based on the multifarious strategies that bacteria adopt to face antibiotic therapies, making it a key public health concern of our era. Among these strategies, efflux pumps (EPs) contribute significantly to increase the levels and profiles of resistance by expelling a broad range of unrelated compounds - buying time for the organisms to develop specific resistance. In Gram-negative bacteria, many of these chromosomally encoded transporters form multicomponent 'pumps' that span both inner and outer membranes and are driven energetically by a primary or secondary transporter component.One of the strategies to reinvigorate the efficacy of antimicrobials is by joint administration with EP inhibitors (EPI), which either block the substrate binding and/or hinder any of the transport-dependent steps of the pump. In this review, we provide an overview of multidrug-resistance EPs, their inhibition strategies and the relevant findings from the various computational simulation studies reported to date with respect to deciphering the mechanism of action of inhibitors with the purpose of improving their rational design.
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22
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Oswald C, Tam HK, Pos KM. Transport of lipophilic carboxylates is mediated by transmembrane helix 2 in multidrug transporter AcrB. Nat Commun 2016; 7:13819. [PMID: 27982032 PMCID: PMC5171871 DOI: 10.1038/ncomms13819] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 11/01/2016] [Indexed: 12/16/2022] Open
Abstract
The deployment of multidrug efflux pumps is a powerful defence mechanism for Gram-negative bacterial cells when exposed to antimicrobial agents. The major multidrug efflux transport system in Escherichia coli, AcrAB–TolC, is a tripartite system using the proton-motive force as an energy source. The polyspecific substrate-binding module AcrB uses various pathways to sequester drugs from the periplasm and outer leaflet of the inner membrane. Here we report the asymmetric AcrB structure in complex with fusidic acid at a resolution of 2.5 Å and mutational analysis of the putative fusidic acid binding site at the transmembrane domain. A groove shaped by the interface between transmembrane helix 1 (TM1) and TM2 specifically binds fusidic acid and other lipophilic carboxylated drugs. We propose that these bound drugs are actively displaced by an upward movement of TM2 towards the AcrB periplasmic porter domain in response to protonation events in the transmembrane domain.
The AcrB module of the AcrAB-TolC multidrug efflux pump sequesters drugs from the periplasm and outer leaflet of the inner membrane. Here, Oswald et al. provide evidence that lipophilic carboxylated substrates bind to a groove between transmembrane helices TM1 and TM2, for further transport by an upward movement of TM2.
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Affiliation(s)
- Christine Oswald
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt am Main, Germany.,Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt am Main, Germany
| | - Heng-Keat Tam
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt am Main, Germany
| | - Klaas M Pos
- Institute of Biochemistry, Goethe University Frankfurt, Max-von-Laue-Strasse 9, D-60438 Frankfurt am Main, Germany
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23
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Structural basis for the blockade of MATE multidrug efflux pumps. Nat Commun 2015; 6:7995. [PMID: 26246409 PMCID: PMC4866600 DOI: 10.1038/ncomms8995] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 07/04/2015] [Indexed: 11/08/2022] Open
Abstract
Multidrug and toxic compound extrusion (MATE) transporters underpin multidrug resistance by using the H(+) or Na(+) electrochemical gradient to extrude different drugs across cell membranes. MATE transporters can be further parsed into the DinF, NorM and eukaryotic subfamilies based on their amino-acid sequence similarity. Here we report the 3.0 Å resolution X-ray structures of a protonation-mimetic mutant of an H(+)-coupled DinF transporter, as well as of an H(+)-coupled DinF and a Na(+)-coupled NorM transporters in complexes with verapamil, a small-molecule pharmaceutical that inhibits MATE-mediated multidrug extrusion. Combining structure-inspired mutational and functional studies, we confirm the biological relevance of our crystal structures, reveal the mechanistic differences among MATE transporters, and suggest how verapamil inhibits MATE-mediated multidrug efflux. Our findings offer insights into how MATE transporters extrude chemically and structurally dissimilar drugs and could inform the design of new strategies for tackling multidrug resistance.
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