1
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Exapicheidou IA, Shams A, Ibrahim H, Tsarenko A, Backenköhler M, Hamed MM, Diamanti E, Volkamer A, Slotboom DJ, Hirsch AKH. Hit optimization by dynamic combinatorial chemistry on Streptococcus pneumoniae energy-coupling factor transporter ECF-PanT. Chem Commun (Camb) 2024; 60:870-873. [PMID: 38164786 DOI: 10.1039/d3cc04738e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Herein, we present the first application of target-directed dynamic combinatorial chemistry (tdDCC) to the whole complex of the highly dynamic transmembrane, energy-coupling factor (ECF) transporter ECF-PanT in Streptococcus pneumoniae. In addition, we successfully employed the tdDCC technique as a hit-identification and -optimization strategy that led to the identification of optimized ECF inhibitors with improved activity. We characterized the best compounds regarding cytotoxicity and performed computational modeling studies on the crystal structure of ECF-PanT to rationalize their binding mode. Notably, docking studies showed that the acylhydrazone linker is able to maintain the crucial interactions.
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Affiliation(s)
- Ioulia Antonia Exapicheidou
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123, Saarbrücken, Germany.
- Saarland University, Department of Pharmacy, Campus Building E8.1, 66123, Saarbrücken, Germany
| | - Atanaz Shams
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123, Saarbrücken, Germany.
- Saarland University, Department of Pharmacy, Campus Building E8.1, 66123, Saarbrücken, Germany
| | - Hamza Ibrahim
- Data Driven Drug Design Group, Center for Bioinformatics, Saarland Informatics Campus E2.1, Saarland University, Saarbrücken 66123, Germany
| | - Aleksei Tsarenko
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Michael Backenköhler
- Data Driven Drug Design Group, Center for Bioinformatics, Saarland Informatics Campus E2.1, Saarland University, Saarbrücken 66123, Germany
| | - Mostafa M Hamed
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123, Saarbrücken, Germany.
| | - Eleonora Diamanti
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123, Saarbrücken, Germany.
| | - Andrea Volkamer
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123, Saarbrücken, Germany.
- Data Driven Drug Design Group, Center for Bioinformatics, Saarland Informatics Campus E2.1, Saarland University, Saarbrücken 66123, Germany
| | - Dirk J Slotboom
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Anna K H Hirsch
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) - Helmholtz Centre for Infection Research (HZI), 66123, Saarbrücken, Germany.
- Saarland University, Department of Pharmacy, Campus Building E8.1, 66123, Saarbrücken, Germany
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2
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Diamanti E, Souza PCT, Setyawati I, Bousis S, Monjas L, Swier LJYM, Shams A, Tsarenko A, Stanek WK, Jäger M, Marrink SJ, Slotboom DJ, Hirsch AKH. Identification of inhibitors targeting the energy-coupling factor (ECF) transporters. Commun Biol 2023; 6:1182. [PMID: 37985798 PMCID: PMC10662466 DOI: 10.1038/s42003-023-05555-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 11/08/2023] [Indexed: 11/22/2023] Open
Abstract
The energy-coupling factor (ECF) transporters are a family of transmembrane proteins involved in the uptake of vitamins in a wide range of bacteria. Inhibition of the activity of these proteins could reduce the viability of pathogens that depend on vitamin uptake. The central role of vitamin transport in the metabolism of bacteria and absence from humans make the ECF transporters an attractive target for inhibition with selective chemical probes. Here, we report on the identification of a promising class of inhibitors of the ECF transporters. We used coarse-grained molecular dynamics simulations on Lactobacillus delbrueckii ECF-FolT2 and ECF-PanT to profile the binding mode and mechanism of inhibition of this novel chemotype. The results corroborate the postulated mechanism of transport and pave the way for further drug-discovery efforts.
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Affiliation(s)
- Eleonora Diamanti
- Helmholtz Institute for Pharmaceutical Research (HIPS) - Helmholtz Centre for Infection Research (HZI), Campus Building E 8.1, D-66123, Saarbrücken, Germany
| | - Paulo C T Souza
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS and University of Lyon, Lyon, France
- Laboratoire de Biologie et Modélisation de la Cellule (UMR 5239, Inserm, U1293) and Centre Blaise Pascal, École Normale Supérieure de Lyon, Université Claude Bernard Lyon 1 and CNRS, 46 Allée d'Italie, 69007, Lyon, France
| | - Inda Setyawati
- Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh 4, 9747AG, Groningen, The Netherlands
- Department of Biochemistry, Bogor Agricultural University, Dramaga, 16680, Bogor, Indonesia
| | - Spyridon Bousis
- Helmholtz Institute for Pharmaceutical Research (HIPS) - Helmholtz Centre for Infection Research (HZI), Campus Building E 8.1, D-66123, Saarbrücken, Germany
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123, Saarbrücken, Germany
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 7, NL-9747, AG Groningen, the Netherlands
| | - Leticia Monjas
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123, Saarbrücken, Germany
| | - Lotteke J Y M Swier
- Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Atanaz Shams
- Helmholtz Institute for Pharmaceutical Research (HIPS) - Helmholtz Centre for Infection Research (HZI), Campus Building E 8.1, D-66123, Saarbrücken, Germany
| | - Aleksei Tsarenko
- Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Weronika K Stanek
- Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Manuel Jäger
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 7, NL-9747, AG Groningen, the Netherlands
| | - Siewert J Marrink
- Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Dirk J Slotboom
- Biomolecular Sciences and Biotechnology Institute University of Groningen Nijenborgh 4, 9747AG, Groningen, The Netherlands
| | - Anna K H Hirsch
- Helmholtz Institute for Pharmaceutical Research (HIPS) - Helmholtz Centre for Infection Research (HZI), Campus Building E 8.1, D-66123, Saarbrücken, Germany.
- Department of Pharmacy, Saarland University, Campus Building E8.1, 66123, Saarbrücken, Germany.
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 7, NL-9747, AG Groningen, the Netherlands.
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3
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Thangaratnarajah C, Nijland M, Borges-Araújo L, Jeucken A, Rheinberger J, Marrink SJ, Souza PCT, Paulino C, Slotboom DJ. Expulsion mechanism of the substrate-translocating subunit in ECF transporters. Nat Commun 2023; 14:4484. [PMID: 37491368 PMCID: PMC10368641 DOI: 10.1038/s41467-023-40266-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 07/20/2023] [Indexed: 07/27/2023] Open
Abstract
Energy-coupling factor (ECF)-type transporters mediate the uptake of micronutrients in many bacteria. They consist of a substrate-translocating subunit (S-component) and an ATP-hydrolysing motor (ECF module) Previous data indicate that the S-component topples within the membrane to alternately expose the binding site to either side of the membrane. In many ECF transporters, the substrate-free S-component can be expelled from the ECF module. Here we study this enigmatic expulsion step by cryogenic electron microscopy and reveal that ATP induces a concave-to-convex shape change of two long helices in the motor, thereby destroying the S-component's docking site and allowing for its dissociation. We show that adaptation of the membrane morphology to the conformational state of the motor may favour expulsion of the substrate-free S-component when ATP is bound and docking of the substrate-loaded S-component after hydrolysis. Our work provides a picture of bilayer-assisted chemo-mechanical coupling in the transport cycle of ECF transporters.
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Affiliation(s)
- Chancievan Thangaratnarajah
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Mark Nijland
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Luís Borges-Araújo
- Molecular Microbiology and Structural Biochemistry, CNRS and University of Lyon, 69367, Lyon, France
| | - Aike Jeucken
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Jan Rheinberger
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Siewert J Marrink
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Molecular Dynamics Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Paulo C T Souza
- Molecular Microbiology and Structural Biochemistry, CNRS and University of Lyon, 69367, Lyon, France
| | - Cristina Paulino
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands.
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy Group, University of Groningen, 9747 AG, Groningen, The Netherlands.
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany.
| | - Dirk J Slotboom
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands.
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4
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Rivera-Lugo R, Huang S, Lee F, Méheust R, Iavarone AT, Sidebottom AM, Oldfield E, Portnoy DA, Light SH. Distinct Energy-Coupling Factor Transporter Subunits Enable Flavin Acquisition and Extracytosolic Trafficking for Extracellular Electron Transfer in Listeria monocytogenes. mBio 2023; 14:e0308522. [PMID: 36744898 PMCID: PMC9973259 DOI: 10.1128/mbio.03085-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/05/2023] [Indexed: 02/07/2023] Open
Abstract
A variety of electron transfer mechanisms link bacterial cytosolic electron pools with functionally diverse redox activities in the cell envelope and extracellular space. In Listeria monocytogenes, the ApbE-like enzyme FmnB catalyzes extracytosolic protein flavinylation, covalently linking a flavin cofactor to proteins that transfer electrons to extracellular acceptors. L. monocytogenes uses an energy-coupling factor (ECF) transporter complex that contains distinct substrate-binding, transmembrane, ATPase A, and ATPase A' subunits (RibU, EcfT, EcfA, and EcfA') to import environmental flavins, but the basis of extracytosolic flavin trafficking for FmnB flavinylation remains poorly defined. In this study, we show that the EetB and FmnA proteins are related to ECF transporter substrate-binding and transmembrane subunits, respectively, and are essential for exporting flavins from the cytosol for flavinylation. Comparisons of the flavin import versus export capabilities of L. monocytogenes strains lacking different ECF transporter subunits demonstrate a strict directionality of substrate-binding subunit transport but partial functional redundancy of transmembrane and ATPase subunits. Based on these results, we propose that ECF transporter complexes with different subunit compositions execute directional flavin import/export through a broadly conserved mechanism. Finally, we present genomic context analyses that show that related ECF exporter genes are distributed across members of the phylum Firmicutes and frequently colocalize with genes encoding flavinylated extracytosolic proteins. These findings clarify the basis of ECF transporter export and extracytosolic flavin cofactor trafficking in Firmicutes. IMPORTANCE Bacteria import vitamins and other essential compounds from their surroundings but also traffic related compounds from the cytosol to the cell envelope where they serve various functions. Studying the foodborne pathogen Listeria monocytogenes, we find that the modular use of subunits from a prominent class of bacterial transporters enables the import of environmental vitamin B2 cofactors and the extracytosolic trafficking of a vitamin B2-derived cofactor that facilitates redox reactions in the cell envelope. These studies clarify the basis of bidirectional small-molecule transport across the cytoplasmic membrane and the assembly of redox-active proteins within the cell envelope and extracellular space.
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Affiliation(s)
- Rafael Rivera-Lugo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Shuo Huang
- Duchossois Family Institute, University of Chicago, Chicago, Illinois, USA
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Frank Lee
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Raphaël Méheust
- Génomique Métabolique, CEA, Genoscope, Institut François Jacob, Université d’Évry, Université Paris-Saclay, CNRS, Evry, France
| | - Anthony T. Iavarone
- QB3/Chemistry Mass Spectrometry Facility, University of California, Berkeley, Berkeley, California, USA
| | | | - Eric Oldfield
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Daniel A. Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Samuel H. Light
- Duchossois Family Institute, University of Chicago, Chicago, Illinois, USA
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
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5
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Host-dependent resistance of Group A Streptococcus to sulfamethoxazole mediated by a horizontally-acquired reduced folate transporter. Nat Commun 2022; 13:6557. [PMID: 36450721 PMCID: PMC9712650 DOI: 10.1038/s41467-022-34243-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 10/19/2022] [Indexed: 12/03/2022] Open
Abstract
Described antimicrobial resistance mechanisms enable bacteria to avoid the direct effects of antibiotics and can be monitored by in vitro susceptibility testing and genetic methods. Here we describe a mechanism of sulfamethoxazole resistance that requires a host metabolite for activity. Using a combination of in vitro evolution and metabolic rescue experiments, we identify an energy-coupling factor (ECF) transporter S component gene (thfT) that enables Group A Streptococcus to acquire extracellular reduced folate compounds. ThfT likely expands the substrate specificity of an endogenous ECF transporter to acquire reduced folate compounds directly from the host, thereby bypassing the inhibition of folate biosynthesis by sulfamethoxazole. As such, ThfT is a functional equivalent of eukaryotic folate uptake pathways that confers very high levels of resistance to sulfamethoxazole, yet remains undetectable when Group A Streptococcus is grown in the absence of reduced folates. Our study highlights the need to understand how antibiotic susceptibility of pathogens might function during infections to identify additional mechanisms of resistance and reduce ineffective antibiotic use and treatment failures, which in turn further contribute to the spread of antimicrobial resistance genes amongst bacterial pathogens.
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6
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Tordai H, Suhajda E, Sillitoe I, Nair S, Varadi M, Hegedus T. Comprehensive Collection and Prediction of ABC Transmembrane Protein Structures in the AI Era of Structural Biology. Int J Mol Sci 2022; 23:ijms23168877. [PMID: 36012140 PMCID: PMC9408558 DOI: 10.3390/ijms23168877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/05/2022] [Accepted: 08/07/2022] [Indexed: 02/06/2023] Open
Abstract
The number of unique transmembrane (TM) protein structures doubled in the last four years, which can be attributed to the revolution of cryo-electron microscopy. In addition, AlphaFold2 (AF2) also provided a large number of predicted structures with high quality. However, if a specific protein family is the subject of a study, collecting the structures of the family members is highly challenging in spite of existing general and protein domain-specific databases. Here, we demonstrate this and assess the applicability and usability of automatic collection and presentation of protein structures via the ABC protein superfamily. Our pipeline identifies and classifies transmembrane ABC protein structures using the PFAM search and also aims to determine their conformational states based on special geometric measures, conftors. Since the AlphaFold database contains structure predictions only for single polypeptide chains, we performed AF2-Multimer predictions for human ABC half transporters functioning as dimers. Our AF2 predictions warn of possibly ambiguous interpretation of some biochemical data regarding interaction partners and call for further experiments and experimental structure determination. We made our predicted ABC protein structures available through a web application, and we joined the 3D-Beacons Network to reach the broader scientific community through platforms such as PDBe-KB.
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Affiliation(s)
- Hedvig Tordai
- Department of Biophysics and Radiation Biology, Semmelweis University, 1085 Budapest, Hungary
| | - Erzsebet Suhajda
- Department of Biophysics and Radiation Biology, Semmelweis University, 1085 Budapest, Hungary
- Faculty of Electrical Engineering and Informatics, Budapest University of Technology and Economics, 1111 Budapest, Hungary
- Wigner Research Centre for Physics, 1121 Budapest, Hungary
| | - Ian Sillitoe
- Department of Structural and Molecular Biology, University College London, London WC1E 6BT, UK
| | - Sreenath Nair
- European Bioinformatics Institute, European Molecular Biology Laboratory, Hinxton CB10 1SD, UK
| | - Mihaly Varadi
- European Bioinformatics Institute, European Molecular Biology Laboratory, Hinxton CB10 1SD, UK
| | - Tamas Hegedus
- Department of Biophysics and Radiation Biology, Semmelweis University, 1085 Budapest, Hungary
- ELKH-SE Biophysical Virology Research Group, Eötvös Loránd Research Network, 1052 Budapest, Hungary
- Correspondence:
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7
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Galluccio M, Mazza T, Scalise M, Sarubbi MC, Indiveri C. Bacterial over-expression of functionally active human CT2 (SLC22A16) carnitine transporter. Mol Biol Rep 2022; 49:8185-8193. [PMID: 35608746 DOI: 10.1007/s11033-022-07491-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 04/20/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND Escherichia coli is a widely used tool for the over-expression of human proteins for studying structure and function. The toxicity of human proteins for E. coli often hampers the expression. This study aims to find conditions for the expression of a membrane transporter known as the carnitine transporter CT2. The knowledge on this transporter is scarce, thus obtaining the recombinant protein is very important for further studies. METHODS AND RESULTS The cDNAs coding for human CT2 (hCT2) was cloned in the pH6EX3 vector and different transformed E. coli strains were cultured in absence or in presence of glucose. hCT2 expression was obtained. The protein was purified and reconstituted into proteoliposomes in a functionally active state. CONCLUSIONS Using the appropriate IPTG concentration, together with the addition of glucose, hCT2 has been expressed in E. coli. The protein is active and shows capacity to transport carnitine in proteoliposomes. The results have a great interest in basic biochemistry of membrane transporters and applications to human health since hCT2 is involved in human pathology.
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Affiliation(s)
- Michele Galluccio
- Department DiBEST Biologia, Ecologia, Scienze Della Terra Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci cubo 4C, 87036, Arcavacata di Rende, Italy
| | - Tiziano Mazza
- Department DiBEST Biologia, Ecologia, Scienze Della Terra Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci cubo 4C, 87036, Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST Biologia, Ecologia, Scienze Della Terra Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci cubo 4C, 87036, Arcavacata di Rende, Italy
| | - Maria Chiara Sarubbi
- Department DiBEST Biologia, Ecologia, Scienze Della Terra Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci cubo 4C, 87036, Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST Biologia, Ecologia, Scienze Della Terra Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci cubo 4C, 87036, Arcavacata di Rende, Italy. .,CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology IBIOM, via Amendola 122/O, 70126, Bari, Italy.
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8
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Nijland M, Martínez Felices JM, Slotboom DJ, Thangaratnarajah C. Membrane transport of cobalamin. VITAMINS AND HORMONES 2022; 119:121-148. [PMID: 35337617 DOI: 10.1016/bs.vh.2022.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A wide variety of organisms encode cobalamin-dependent enzymes catalyzing essential metabolic reactions, but the cofactor cobalamin (vitamin B12) is only synthesized by a subset of bacteria and archaea. The biosynthesis of cobalamin is complex and energetically costly, making cobalamin variants and precursors metabolically valuable. Auxotrophs for these molecules have evolved uptake mechanisms to compensate for the lack of a synthesis pathway. Bacterial transport of cobalamin involves the passage over one or two lipidic membranes in Gram-positive and -negative bacteria, respectively. In higher eukaryotes, a complex system of carriers, receptors and transporters facilitates the delivery of the essential molecule to the tissues. Biochemical and genetic approaches have identified different transporter families involved in cobalamin transport. The majority of the characterized cobalamin transporters are active transport systems that belong to the ATP-binding cassette (ABC) superfamily of transporters. In this chapter, we describe the different cobalamin transport systems characterized to date that are present in bacteria and humans, as well as yet-to-be-identified transporters.
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Affiliation(s)
- Mark Nijland
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, Groningen, Netherlands
| | - Jose M Martínez Felices
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, Groningen, Netherlands
| | - Dirk J Slotboom
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, Groningen, Netherlands.
| | - Chancievan Thangaratnarajah
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, Groningen, Netherlands
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9
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Younus I, Kochkina S, Choi CC, Sun W, Ford RC. ATP-Binding Cassette Transporters: Snap-on Complexes? Subcell Biochem 2022; 99:35-82. [PMID: 36151373 DOI: 10.1007/978-3-031-00793-4_2] [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] [Indexed: 06/16/2023]
Abstract
ATP-binding cassette (ABC) transporters are one of the largest families of membrane proteins in prokaryotic organisms. Much is now understood about the structure of these transporters and many reviews have been written on that subject. In contrast, less has been written on the assembly of ABC transporter complexes and this will be a major focus of this book chapter. The complexes are formed from two cytoplasmic subunits that are highly conserved (in terms of their primary and three-dimensional structures) across the whole family. These ATP-binding subunits give rise to the name of the family. They must assemble with two transmembrane subunits that will typically form the permease component of the transporter. The transmembrane subunits have been found to be surprisingly diverse in structure when the whole family is examined, with seven distinct folds identified so far. Hence nucleotide-binding subunits appear to have been bolted on to a variety of transmembrane platforms during evolution, leading to a greater variety in function. Furthermore, many importers within the family utilise a further external substrate-binding component to trap scarce substrates and deliver them to the correct permease components. In this chapter, we will discuss whether assembly of the various ABC transporter subunits occurs with high fidelity within the crowded cellular environment and whether promiscuity in assembly of transmembrane and cytoplasmic components can occur. We also discuss the new AlphaFold protein structure prediction tool which predicts a new type of transmembrane domain fold within the ABC transporters that is associated with cation exporters of bacteria and plants.
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Affiliation(s)
- Iqra Younus
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Sofia Kochkina
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Cheri C Choi
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Wenjuan Sun
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Robert C Ford
- Faculty of Biology, Medicine and Health, School of Biological Sciences, The University of Manchester, Manchester, UK.
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10
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Abstract
Membrane proteins (MPs) play essential roles in numerous cellular processes. Because around 70% of the currently marketed drugs target MPs, a detailed understanding of their structure, binding properties, and functional dynamics in a physiologically relevant environment is crucial for a more detailed understanding of this important protein class. We here summarize the benefits of using lipid nanodiscs for NMR structural investigations and provide a detailed overview of the currently used lipid nanodisc systems as well as their applications in solution-state NMR. Despite the increasing use of other structural methods for the structure determination of MPs in lipid nanodiscs, solution NMR turns out to be a versatile tool to probe a wide range of MP features, ranging from the structure determination of small to medium-sized MPs to probing ligand and partner protein binding as well as functionally relevant dynamical signatures in a lipid nanodisc setting. We will expand on these topics by discussing recent NMR studies with lipid nanodiscs and work out a key workflow for optimizing the nanodisc incorporation of an MP for subsequent NMR investigations. With this, we hope to provide a comprehensive background to enable an informed assessment of the applicability of lipid nanodiscs for NMR studies of a particular MP of interest.
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Affiliation(s)
- Umut Günsel
- Bavarian NMR Center (BNMRZ) at the Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany
| | - Franz Hagn
- Bavarian NMR Center (BNMRZ) at the Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
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11
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Insights into the bilayer-mediated toppling mechanism of a folate-specific ECF transporter by cryo-EM. Proc Natl Acad Sci U S A 2021; 118:2105014118. [PMID: 34408021 DOI: 10.1073/pnas.2105014118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Energy-coupling factor (ECF)-type transporters are small, asymmetric membrane protein complexes (∼115 kDa) that consist of a membrane-embedded, substrate-binding protein (S component) and a tripartite ATP-hydrolyzing module (ECF module). They import micronutrients into bacterial cells and have been proposed to use a highly unusual transport mechanism, in which the substrate is dragged across the membrane by a toppling motion of the S component. However, it remains unclear how the lipid bilayer could accommodate such a movement. Here, we used cryogenic electron microscopy at 200 kV to determine structures of a folate-specific ECF transporter in lipid nanodiscs and detergent micelles at 2.7- and 3.4-Å resolution, respectively. The structures reveal an irregularly shaped bilayer environment around the membrane-embedded complex and suggest that toppling of the S component is facilitated by protein-induced membrane deformations. In this way, structural remodeling of the lipid bilayer environment is exploited to guide the transport process.
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Elucidating the Mechanism Behind Sodium-Coupled Neurotransmitter Transporters by Reconstitution. Neurochem Res 2021; 47:127-137. [PMID: 34347265 DOI: 10.1007/s11064-021-03413-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/01/2021] [Accepted: 07/27/2021] [Indexed: 10/20/2022]
Abstract
Sodium-coupled neurotransmitter transporters play a fundamental role in the termination of synaptic neurotransmission, which makes them a major drug target. The reconstitution of these secondary active transporters into liposomes has shed light on their molecular transport mechanisms. From the earliest days of the reconstitution technique up to today's single-molecule studies, insights from live functioning transporters have been indispensable for our understanding of their physiological impact. The two classes of sodium-coupled neurotransmitter transporters, the neurotransmitter: sodium symporters and the excitatory amino acid transporters, have vastly different molecular structures, but complementary proteoliposome studies have sought to unravel their ion-dependence and transport kinetics. Furthermore, reconstitution experiments have been used on both protein classes to investigate the role of e.g. the lipid environment, of posttranslational modifications, and of specific amino acid residues in transport. Techniques that allow the detection of transport at a single-vesicle resolution have been developed, and single-molecule studies have started to reveal single transporter kinetics, which will expand our understanding of how transport across the membrane is facilitated at protein level. Here, we review a selection of the results and applications where the reconstitution of the two classes of neurotransmitter transporters has been instrumental.
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Identification and characterization of metal uptake ABC transporters in Mycobacterium tuberculosis unveil their ligand specificity. Int J Biol Macromol 2021; 185:324-337. [PMID: 34171249 DOI: 10.1016/j.ijbiomac.2021.06.126] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 01/09/2023]
Abstract
Mycobacterium tuberculosis, one of the major threats to mankind, requires micronutrients like metal ions for their survival and pathogenicity inside the host system. Intracellular pathogens such as M. tuberculosis have co-evolved to combat the nutritional immunity developed by the host. It has developed eminent mechanisms to sequester essential metal ions from the host system. One such prominent mechanism to scavenge metal ions to thrive in the host cell involves ATP-binding cassette (ABC) transporters, which transport metal ions (in free and/or complex forms) across the cell membrane. This study employs a high-throughput data mining analysis to identify open reading frames (ORFs) encoding metal uptake ABC transporters in M. tuberculosis H37Rv. In total, 19 ORFs resulting in seven ABC transport systems and two P-type ATPases were identified, which are potentially involved in the uptake of different metal ions. The results also suggest the existence of a subunit sharing mechanism in M. tuberculosis where the transmembrane and nucleotide binding domains are shared among different ABC transport systems indicating the import of multiple substrates via a single ABC transporter. Thus, this study reflects an overview of the repertoire of metal-specific ABC transport systems in M. tuberculosis H37Rv, providing potential therapeutic targets for the future.
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