1
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Roy S, Booth CE, Powell-Pierce AD, Schulz AM, Skare JT, Garcia BL. Conformational dynamics of complement protease C1r inhibitor proteins from Lyme disease- and relapsing fever-causing spirochetes. J Biol Chem 2023; 299:104972. [PMID: 37380082 PMCID: PMC10413161 DOI: 10.1016/j.jbc.2023.104972] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/16/2023] [Accepted: 06/19/2023] [Indexed: 06/30/2023] Open
Abstract
Borrelial pathogens are vector-borne etiological agents known to cause Lyme disease, relapsing fever, and Borrelia miyamotoi disease. These spirochetes each encode several surface-localized lipoproteins that bind components of the human complement system to evade host immunity. One borrelial lipoprotein, BBK32, protects the Lyme disease spirochete from complement-mediated attack via an alpha helical C-terminal domain that interacts directly with the initiating protease of the classical complement pathway, C1r. In addition, the B. miyamotoi BBK32 orthologs FbpA and FbpB also inhibit C1r, albeit via distinct recognition mechanisms. The C1r-inhibitory activities of a third ortholog termed FbpC, which is found exclusively in relapsing fever-causing spirochetes, remains unknown. Here, we report the crystal structure of the C-terminal domain of Borrelia hermsii FbpC to a limiting resolution of 1.5 Å. We used surface plasmon resonance and assays of complement function to demonstrate that FbpC retains potent BBK32-like anticomplement activities. Based on the structure of FbpC, we hypothesized that conformational dynamics of the complement inhibitory domains of borrelial C1r inhibitors may differ. To test this, we utilized the crystal structures of the C-terminal domains of BBK32, FbpA, FbpB, and FbpC to carry out molecular dynamics simulations, which revealed borrelial C1r inhibitors adopt energetically favored open and closed states defined by two functionally critical regions. Taken together, these results advance our understanding of how protein dynamics contribute to the function of bacterial immune evasion proteins and reveal a surprising plasticity in the structures of borrelial C1r inhibitors.
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Affiliation(s)
- Sourav Roy
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Charles E Booth
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Alexandra D Powell-Pierce
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Bryan, Texas, USA
| | - Anna M Schulz
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA
| | - Jon T Skare
- Department of Microbial Pathogenesis and Immunology, School of Medicine, Texas A&M University, Bryan, Texas, USA.
| | - Brandon L Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, USA.
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2
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He H, Pramanik AS, Swanson SK, Johnson DK, Florens L, Zückert WR. A Borrelia burgdorferi LptD homolog is required for flipping of surface lipoproteins through the spirochetal outer membrane. Mol Microbiol 2023; 119:752-767. [PMID: 37170643 PMCID: PMC10330739 DOI: 10.1111/mmi.15072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/13/2023]
Abstract
Borrelia spirochetes are unique among diderm bacteria in their lack of lipopolysaccharide (LPS) in the outer membrane (OM) and their abundance of surface-exposed lipoproteins with major roles in transmission, virulence, and pathogenesis. Despite their importance, little is known about how surface lipoproteins are translocated through the periplasm and the OM. Here, we characterized Borrelia burgdorferi BB0838, a distant homolog of the OM LPS assembly protein LptD. Using a CRISPR interference approach, we showed that BB0838 is required for cell growth and envelope stability. Upon BB0838 knockdown, surface lipoprotein OspA was retained in the inner leaflet of the OM, as determined by its inaccessibility to in situ proteolysis but its presence in OM vesicles. The topology of the OM porin/adhesin P66 remained unaffected. Quantitative mass spectrometry of the B. burgdorferi membrane-associated proteome confirmed the selective periplasmic retention of surface lipoproteins under BB0838 knockdown conditions. Additional analysis identified a single in situ protease-accessible BB0838 peptide that mapped to a predicted β-barrel surface loop. Alphafold Multimer modeled a B. burgdorferi LptB2 FGCAD complex spanning the periplasm. Together, this suggests that BB0838/LptDBb facilitates the essential terminal step in spirochetal surface lipoprotein secretion, using an orthologous OM component of a pathway that secretes LPS in proteobacteria.
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Affiliation(s)
- Huan He
- University of Kansas School of Medicine, Department of Microbiology, Molecular Genetics and Immunology, Kansas City, Kansas, USA
| | - Ankita S. Pramanik
- University of Kansas School of Medicine, Department of Microbiology, Molecular Genetics and Immunology, Kansas City, Kansas, USA
| | | | - David K. Johnson
- University of Kansas, Computational Chemical Biology Core, Lawrence, Kansas, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, Kansas City, Missouri, USA
| | - Wolfram R. Zückert
- University of Kansas School of Medicine, Department of Microbiology, Molecular Genetics and Immunology, Kansas City, Kansas, USA
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3
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Roy S, Booth CE, Powell-Pierce AD, Schulz AM, Skare JT, Garcia BL. "Conformational dynamics of C1r inhibitor proteins from Lyme disease and relapsing fever spirochetes". BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.01.530473. [PMID: 36909632 PMCID: PMC10002728 DOI: 10.1101/2023.03.01.530473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Borrelial pathogens are vector-borne etiological agents of Lyme disease, relapsing fever, and Borrelia miyamotoi disease. These spirochetes each encode several surface-localized lipoproteins that bind to components of the human complement system. BBK32 is an example of a borrelial lipoprotein that protects the Lyme disease spirochete from complement-mediated attack. The complement inhibitory activity of BBK32 arises from an alpha helical C-terminal domain that interacts directly with the initiating protease of the classical pathway, C1r. Borrelia miyamotoi spirochetes encode BBK32 orthologs termed FbpA and FbpB, and these proteins also inhibit C1r, albeit via distinct recognition mechanisms. The C1r-inhibitory activities of a third ortholog termed FbpC, which is found exclusively in relapsing fever spirochetes, remains unknown. Here we report the crystal structure of the C-terminal domain of B. hermsii FbpC to a limiting resolution of 1.5 Å. Surface plasmon resonance studies and assays of complement function demonstrate that FbpC retains potent BBK32-like anti-complement activities. Based on the structure of FbpC, we hypothesized that conformational dynamics of the complement inhibitory domains of borrelial C1r inhibitors may differ. To test this, we utilized the crystal structures of the C-terminal domains of BBK32, FbpA, FbpB, and FbpC to carry out 1 µs molecular dynamics simulations, which revealed borrelial C1r inhibitors adopt energetically favored open and closed states defined by two functionally critical regions. This study advances our understanding of how protein dynamics contribute to the function of bacterial immune evasion proteins and reveals a surprising plasticity in the structures of borrelial C1r inhibitors.
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Affiliation(s)
- Sourav Roy
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Charles E. Booth
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Alexandra D. Powell-Pierce
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States of America
| | - Anna M. Schulz
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Jon T. Skare
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, TX, United States of America
- Correspondence to Jon T. Skare and () and Brandon L. Garcia ()
| | - Brandon L. Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
- Correspondence to Jon T. Skare and () and Brandon L. Garcia ()
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4
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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: 95] [Impact Index Per Article: 31.7] [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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5
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Murakami S, Okada U, van Veen HW. Tripartite transporters as mechanotransmitters in periplasmic alternating-access mechanisms. FEBS Lett 2020; 594:3908-3919. [PMID: 32936941 DOI: 10.1002/1873-3468.13929] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/18/2022]
Abstract
To remove xenobiotics from the periplasmic space, Gram-negative bacteria utilise unique tripartite efflux systems in which a molecular engine in the plasma membrane connects to periplasmic and outer membrane subunits. Substrates bind to periplasmic sections of the engine or sometimes to the periplasmic subunits. Then, the tripartite machines undergo conformational changes that allow the movement of the substrates down the substrate translocation pathway to the outside of the cell. The transmembrane (TM) domains of the tripartite resistance-nodulation-drug-resistance (RND) transporters drive these conformational changes by converting proton motive force into mechanical motion. Similarly, the TM domains of tripartite ATP-binding cassette (ABC) transporters transmit mechanical movement associated with nucleotide binding and hydrolysis at the nucleotide-binding domains to the relevant subunits in the periplasm. In this way, metabolic energy is coupled to periplasmic alternating-access mechanisms to achieve substrate transport across the outer membrane.
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Affiliation(s)
- Satoshi Murakami
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Ui Okada
- Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
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6
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Greene NP, Kaplan E, Crow A, Koronakis V. Antibiotic Resistance Mediated by the MacB ABC Transporter Family: A Structural and Functional Perspective. Front Microbiol 2018; 9:950. [PMID: 29892271 PMCID: PMC5985334 DOI: 10.3389/fmicb.2018.00950] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 04/24/2018] [Indexed: 12/18/2022] Open
Abstract
The MacB ABC transporter forms a tripartite efflux pump with the MacA adaptor protein and TolC outer membrane exit duct to expel antibiotics and export virulence factors from Gram-negative bacteria. Here, we review recent structural and functional data on MacB and its homologs. MacB has a fold that is distinct from other structurally characterized ABC transporters and uses a unique molecular mechanism termed mechanotransmission. Unlike other bacterial ABC transporters, MacB does not transport substrates across the inner membrane in which it is based, but instead couples cytoplasmic ATP hydrolysis with transmembrane conformational changes that are used to perform work in the extra-cytoplasmic space. In the MacAB-TolC tripartite pump, mechanotransmission drives efflux of antibiotics and export of a protein toxin from the periplasmic space via the TolC exit duct. Homologous tripartite systems from pathogenic bacteria similarly export protein-like signaling molecules, virulence factors and siderophores. In addition, many MacB-like ABC transporters do not form tripartite pumps, but instead operate in diverse cellular processes including antibiotic sensing, cell division and lipoprotein trafficking.
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Affiliation(s)
- Nicholas P Greene
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Elise Kaplan
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Allister Crow
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Vassilis Koronakis
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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7
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Trans-envelope multidrug efflux pumps of Gram-negative bacteria and their synergism with the outer membrane barrier. Res Microbiol 2018; 169:351-356. [PMID: 29454787 DOI: 10.1016/j.resmic.2018.02.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/05/2018] [Accepted: 02/06/2018] [Indexed: 11/20/2022]
Abstract
Antibiotic resistance is a serious threat to public health. Significant efforts are currently directed toward containment of the spread of resistance, finding new therapeutic options concerning resistant human and animal pathogens, and addressing the gaps in the fundamental understanding of mechanisms of resistance. Experimental data and kinetic modeling revealed a major factor in resistance, the synergy between active efflux and the low permeability barrier of the outer membrane, which dramatically reduces the intracellular accumulation of many antibiotics. The structural and mechanistic particularities of trans-envelope efflux pumps amplify the effectiveness of cell envelopes as permeability barriers. An important feature of this synergism is that efflux pumps and the outer membrane barriers are mechanistically independent and select antibiotics based on different physicochemical properties. The synergism amplifies even weak polyspecificity of multidrug efflux pumps and creates a major hurdle in the discovery and development of new therapeutics against Gram-negative pathogens.
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8
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Urbina P, Bersch B, De Angelis F, Derfoufi KM, Prévost M, Goormaghtigh E, Vandenbussche G. Structural and Functional Investigation of the Ag+/Cu+ Binding Domains of the Periplasmic Adaptor Protein SilB from Cupriavidus metallidurans CH34. Biochemistry 2016; 55:2883-97. [DOI: 10.1021/acs.biochem.6b00022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Patricia Urbina
- Laboratory
for the Structure and Function of Biological Membranes, Center for
Structural Biology and Bioinformatics, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Beate Bersch
- Institut
de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France
| | - Fabien De Angelis
- Laboratory
for the Structure and Function of Biological Membranes, Center for
Structural Biology and Bioinformatics, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Kheiro-Mouna Derfoufi
- Laboratory
for the Structure and Function of Biological Membranes, Center for
Structural Biology and Bioinformatics, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Martine Prévost
- Laboratory
for the Structure and Function of Biological Membranes, Center for
Structural Biology and Bioinformatics, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Erik Goormaghtigh
- Laboratory
for the Structure and Function of Biological Membranes, Center for
Structural Biology and Bioinformatics, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
| | - Guy Vandenbussche
- Laboratory
for the Structure and Function of Biological Membranes, Center for
Structural Biology and Bioinformatics, Université Libre de Bruxelles, B-1050 Bruxelles, Belgium
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9
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An overview of bacterial efflux pumps and computational approaches to study efflux pump inhibitors. Future Med Chem 2016; 8:195-210. [DOI: 10.4155/fmc.15.173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Micro-organisms express a wide range of transmembrane pumps known as multidrug efflux pumps that improve the micro-organism's ability to survive in severe environments and contribute to resistance against antibiotic and antimicrobial agents. There is significant interest in developing efflux inhibitors as an adjunct to treatment with current and next generation of antibiotics. A greater understanding of drug recognition and transport by multidrug efflux pumps is needed to develop clinically useful inhibitors, given the breadth of molecules that can be effluxed by these systems. We summarize some structural and functional data that could provide insights into the inhibition of transport mechanisms of these intricate molecular nanomachines with a focus on the advances in computational approaches.
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10
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Du D, van Veen HW, Murakami S, Pos KM, Luisi BF. Structure, mechanism and cooperation of bacterial multidrug transporters. Curr Opin Struct Biol 2015; 33:76-91. [PMID: 26282926 DOI: 10.1016/j.sbi.2015.07.015] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/29/2015] [Accepted: 07/24/2015] [Indexed: 12/13/2022]
Abstract
Cells from all domains of life encode energy-dependent trans-membrane transporters that can expel harmful substances including clinically applied therapeutic agents. As a collective body, these transporters perform as a super-system that confers tolerance to an enormous range of harmful compounds and consequently aid survival in hazardous environments. In the Gram-negative bacteria, some of these transporters serve as energy-transducing components of tripartite assemblies that actively efflux drugs and other harmful compounds, as well as deliver virulence agents across the entire cell envelope. We draw together recent structural and functional data to present the current models for the transport mechanisms for the main classes of multi-drug transporters and their higher-order assemblies.
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Affiliation(s)
- Dijun Du
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Hendrik W van Veen
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Satoshi Murakami
- Division of Structure and Function of Biomolecules, Department of Life Science, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Klaas M Pos
- Institute of Biochemistry, Goethe Universität Frankfurt, Max-von-Laue-Straße 9, D-60438 Frankfurt, Germany
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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11
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Dyer A, Brown G, Stejskal L, Laity PR, Bingham RJ. The Borrelia afzelii outer membrane protein BAPKO_0422 binds human factor-H and is predicted to form a membrane-spanning β-barrel. Biosci Rep 2015; 35:e00240. [PMID: 26181365 PMCID: PMC4613713 DOI: 10.1042/bsr20150095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 06/23/2015] [Accepted: 07/06/2015] [Indexed: 12/11/2022] Open
Abstract
The deep evolutionary history of the Spirochetes places their branch point early in the evolution of the diderms, before the divergence of the present day Proteobacteria. As a spirochete, the morphology of the Borrelia cell envelope shares characteristics of both Gram-positive and Gram-negative bacteria. A thin layer of peptidoglycan, tightly associated with the cytoplasmic membrane, is surrounded by a more labile outer membrane (OM). This OM is rich in lipoproteins but with few known integral membrane proteins. The outer membrane protein A (OmpA) domain is an eight-stranded membrane-spanning β-barrel, highly conserved among the Proteobacteria but so far unknown in the Spirochetes. In the present work, we describe the identification of four novel OmpA-like β-barrels from Borrelia afzelii, the most common cause of erythema migrans (EM) rash in Europe. Structural characterization of one these proteins (BAPKO_0422) by SAXS and CD indicate a compact globular structure rich in β-strand consistent with a monomeric β-barrel. Ab initio molecular envelopes calculated from the scattering profile are consistent with homology models and demonstrate that BAPKO_0422 adopts a peanut shape with dimensions 25×45 Å (1 Å=0.1 nm). Deviations from the standard C-terminal signature sequence are apparent; in particular the C-terminal phenylalanine residue commonly found in Proteobacterial OM proteins is replaced by isoleucine/leucine or asparagine. BAPKO_0422 is demonstrated to bind human factor H (fH) and therefore may contribute to immune evasion by inhibition of the complement response. Encoded by chromosomal genes, these proteins are highly conserved between Borrelia subspecies and may be of diagnostic or therapeutic value.
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Affiliation(s)
- Adam Dyer
- Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Gemma Brown
- Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Lenka Stejskal
- Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Peter R Laity
- Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K. Present Address: Department of Materials Science and Engineering, Sir Robert Hadfield Building, Mappin Street, University of Sheffield, Sheffield S1 3JD, U.K
| | - Richard J Bingham
- Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.
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12
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Symmons MF, Marshall RL, Bavro VN. Architecture and roles of periplasmic adaptor proteins in tripartite efflux assemblies. Front Microbiol 2015; 6:513. [PMID: 26074901 PMCID: PMC4446572 DOI: 10.3389/fmicb.2015.00513] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/08/2015] [Indexed: 12/12/2022] Open
Abstract
Recent years have seen major advances in the structural understanding of the different components of tripartite efflux assemblies, which encompass the multidrug efflux (MDR) pumps and type I secretion systems. The majority of these investigations have focused on the role played by the inner membrane transporters and the outer membrane factor (OMF), leaving the third component of the system – the Periplasmic Adaptor Proteins (PAPs) – relatively understudied. Here we review the current state of knowledge of these versatile proteins which, far from being passive linkers between the OMF and the transporter, emerge as active architects of tripartite assemblies, and play diverse roles in the transport process. Recognition between the PAPs and OMFs is essential for pump assembly and function, and targeting this interaction may provide a novel avenue for combating multidrug resistance. With the recent advances elucidating the drug efflux and energetics of the tripartite assemblies, the understanding of the interaction between the OMFs and PAPs is the last piece remaining in the complete structure of the tripartite pump assembly puzzle.
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Affiliation(s)
- Martyn F Symmons
- Department of Veterinary Medicine, University of Cambridge Cambridge, UK
| | - Robert L Marshall
- Institute of Microbiology and Infection, University of Birmingham Birmingham, UK
| | - Vassiliy N Bavro
- Institute of Microbiology and Infection, University of Birmingham Birmingham, UK
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13
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Zgurskaya HI, Weeks JW, Ntreh AT, Nickels LM, Wolloscheck D. Mechanism of coupling drug transport reactions located in two different membranes. Front Microbiol 2015; 6:100. [PMID: 25759685 PMCID: PMC4338810 DOI: 10.3389/fmicb.2015.00100] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 01/26/2015] [Indexed: 01/01/2023] Open
Abstract
Gram- negative bacteria utilize a diverse array of multidrug transporters to pump toxic compounds out of the cell. Some transporters, together with periplasmic membrane fusion proteins (MFPs) and outer membrane channels, assemble trans-envelope complexes that expel multiple antibiotics across outer membranes of Gram-negative bacteria and into the external medium. Others further potentiate this efflux by pumping drugs across the inner membrane into the periplasm. Together these transporters create a powerful network of efflux that protects bacteria against a broad range of antimicrobial agents. This review is focused on the mechanism of coupling transport reactions located in two different membranes of Gram-negative bacteria. Using a combination of biochemical, genetic and biophysical approaches we have reconstructed the sequence of events leading to the assembly of trans-envelope drug efflux complexes and characterized the roles of periplasmic and outer membrane proteins in this process. Our recent data suggest a critical step in the activation of intermembrane efflux pumps, which is controlled by MFPs. We propose that the reaction cycles of transporters are tightly coupled to the assembly of the trans-envelope complexes. Transporters and MFPs exist in the inner membrane as dormant complexes. The activation of complexes is triggered by MFP binding to the outer membrane channel, which leads to a conformational change in the membrane proximal domain of MFP needed for stimulation of transporters. The activated MFP-transporter complex engages the outer membrane channel to expel substrates across the outer membrane. The recruitment of the channel is likely triggered by binding of effectors (substrates) to MFP or MFP-transporter complexes. This model together with recent structural and functional advances in the field of drug efflux provides a fairly detailed understanding of the mechanism of drug efflux across the two membranes.
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Affiliation(s)
- Helen I Zgurskaya
- Department of Chemistry and Biochemistry, University of Oklahoma Norman, OK, USA
| | - Jon W Weeks
- Department of Chemistry and Biochemistry, University of Oklahoma Norman, OK, USA
| | - Abigail T Ntreh
- Department of Chemistry and Biochemistry, University of Oklahoma Norman, OK, USA
| | - Logan M Nickels
- Department of Chemistry and Biochemistry, University of Oklahoma Norman, OK, USA
| | - David Wolloscheck
- Department of Chemistry and Biochemistry, University of Oklahoma Norman, OK, USA
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Du D, van Veen HW, Luisi BF. Assembly and operation of bacterial tripartite multidrug efflux pumps. Trends Microbiol 2015; 23:311-9. [PMID: 25728476 DOI: 10.1016/j.tim.2015.01.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 01/13/2015] [Accepted: 01/22/2015] [Indexed: 01/21/2023]
Abstract
Microorganisms encode several classes of transmembrane pumps that can expel an enormous range of toxic substances, thereby improving their fitness in harsh environments and contributing to resistance against antimicrobial agents. In Gram-negative bacteria these pumps can take the form of tripartite assemblies that actively efflux drugs and other harmful compounds across the cell envelope. We describe recent structural and functional data that have provided insights into the transport mechanisms of these intricate molecular machines.
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Affiliation(s)
- Dijun Du
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
| | - Hendrik W van Veen
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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Hinchliffe P, Greene NP, Paterson NG, Crow A, Hughes C, Koronakis V. Structure of the periplasmic adaptor protein from a major facilitator superfamily (MFS) multidrug efflux pump. FEBS Lett 2014; 588:3147-53. [PMID: 24996185 PMCID: PMC4158417 DOI: 10.1016/j.febslet.2014.06.055] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 06/19/2014] [Accepted: 06/23/2014] [Indexed: 10/28/2022]
Abstract
Periplasmic adaptor proteins are key components of bacterial tripartite efflux pumps. The 2.85 Å resolution structure of an MFS (major facilitator superfamily) pump adaptor, Aquifex aeolicus EmrA, shows linearly arranged α-helical coiled-coil, lipoyl, and β-barrel domains, but lacks the fourth membrane-proximal domain shown in other pumps to interact with the inner membrane transporter. The adaptor α-hairpin, which binds outer membrane TolC, is exceptionally long at 127 Å, and the β-barrel contains a conserved disordered loop. The structure extends the view of adaptors as flexible, modular components that mediate diverse pump assembly, and suggests that in MFS tripartite pumps a hexamer of adaptors could provide a periplasmic seal.
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Affiliation(s)
- Philip Hinchliffe
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Nicholas P Greene
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Neil G Paterson
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Allister Crow
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Colin Hughes
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Vassilis Koronakis
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
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