1
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Stackpole BJ, Fredericksen JM, Brasch NE. Exploring the potential of the vitamin B 12 derivative azidocobalamin to undergo Huisgen 1,3-dipolar azide-alkyne cycloaddition reactions. J Inorg Biochem 2024; 254:112504. [PMID: 38412777 DOI: 10.1016/j.jinorgbio.2024.112504] [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: 12/20/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/29/2024]
Abstract
There is considerable interest in using the metalloprotein cofactor vitamin B12 as a vehicle to deliver drugs and diagnostic agents into mammalian or bacterial cells by exploiting the B12-specific active uptake pathways. Conjugation of the cargo via the β-axial site or the 5'-OH of the ribose of the nucleotide are the most desirable sites, to maximise intracellular uptake. Herein we show the potential of conjugation at the beta-azido ligand of the vitamin B12 derivative azidocobalamin via a click-type azide-alkyne 1,3-dipolar cycloaddition (Huisgen cycloaddition) reaction. Reacting azidocobalamin with dimethyl acetylenedicarboxylate at 40 °C results in essentially stoichiometric conversion of azidocobalamin to the corresponding triazolato complex. The stability of the complex as a function of pH and in the presence of cyanide were investigated. The complex is stable in pD 7.0 phosphate buffer for 24 h. The rate of beta-axial ligand substitution was found to be one order of magnitude slower for the triazolatocobalamin complex compared with azidocobalamin.
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Affiliation(s)
- Ben J Stackpole
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand; The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand
| | - Jessica M Fredericksen
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand; The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand
| | - Nicola E Brasch
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand; The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand.
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2
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Nijland M, Lefebvre SN, Thangaratnarajah C, Slotboom DJ. Bidirectional ATP-driven transport of cobalamin by the mycobacterial ABC transporter BacA. Nat Commun 2024; 15:2626. [PMID: 38521790 PMCID: PMC10960864 DOI: 10.1038/s41467-024-46917-1] [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: 10/13/2023] [Accepted: 03/13/2024] [Indexed: 03/25/2024] Open
Abstract
BacA is a mycobacterial ATP-binding cassette (ABC) transporter involved in the translocation of water-soluble compounds across the lipid bilayer. Whole-cell-based assays have shown that BacA imports cobalamin as well as unrelated hydrophilic compounds such as the antibiotic bleomycin and the antimicrobial peptide Bac7 into the cytoplasm. Surprisingly, there are indications that BacA also mediates the export of different antibacterial compounds, which is difficult to reconcile with the notion that ABC transporters generally operate in a strictly unidirectional manner. Here we resolve this conundrum by developing a fluorescence-based transport assay to monitor the transport of cobalamin across liposomal membranes. We find that BacA transports cobalamin in both the import and export direction. This highly unusual bidirectionality suggests that BacA is mechanistically distinct from other ABC transporters and facilitates ATP-driven diffusion, a function that may be important for the evolvability of specific transporters, and may bring competitive advantages to microbial communities.
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Affiliation(s)
- Mark Nijland
- Faculty of Science and Engineering, Groningen, Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Solène N Lefebvre
- Faculty of Science and Engineering, Groningen, Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Chancievan Thangaratnarajah
- Faculty of Science and Engineering, Groningen, Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abington, Cambridge, CB21 6DG, UK
| | - 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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3
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Drew D, Boudker O. Ion and lipid orchestration of secondary active transport. Nature 2024; 626:963-974. [PMID: 38418916 DOI: 10.1038/s41586-024-07062-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 01/12/2024] [Indexed: 03/02/2024]
Abstract
Transporting small molecules across cell membranes is an essential process in cell physiology. Many structurally diverse, secondary active transporters harness transmembrane electrochemical gradients of ions to power the uptake or efflux of nutrients, signalling molecules, drugs and other ions across cell membranes. Transporters reside in lipid bilayers on the interface between two aqueous compartments, where they are energized and regulated by symported, antiported and allosteric ions on both sides of the membrane and the membrane bilayer itself. Here we outline the mechanisms by which transporters couple ion and solute fluxes and discuss how structural and mechanistic variations enable them to meet specific physiological needs and adapt to environmental conditions. We then consider how general bilayer properties and specific lipid binding modulate transporter activity. Together, ion gradients and lipid properties ensure the effective transport, regulation and distribution of small molecules across cell membranes.
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Affiliation(s)
- David Drew
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
| | - Olga Boudker
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA.
- Howard Hughes Medical Institute, Weill Cornell Medicine, New York, NY, USA.
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4
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Raschka SL, Harris A, Luisi BF, Schmitt L. Flipping and other astonishing transporter dance moves in fungal drug resistance. Bioessays 2022; 44:e2200035. [PMID: 35451123 DOI: 10.1002/bies.202200035] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/07/2022] [Accepted: 04/12/2022] [Indexed: 11/09/2022]
Abstract
In all domains of life, transmembrane proteins from the ATP-binding cassette (ABC) transporter family drive the translocation of diverse substances across lipid bilayers. In pathogenic fungi, the ABC transporters of the pleiotropic drug resistance (PDR) subfamily confer antibiotic resistance and so are of interest as therapeutic targets. They also drive the quest for understanding how ABC transporters can generally accommodate such a wide range of substrates. The Pdr5 transporter from baker's yeast is representative of the PDR group and, ever since its discovery more than 30 years ago, has been the subject of extensive functional analyses. A new perspective of these studies has been recently provided in the framework of the first electron cryo-microscopy structures of Pdr5, as well as emergent applications of machine learning in the field. Taken together, the old and the new developments have been used to propose a mechanism for the transport process in PDR proteins. This mechanism involves a "flippase" step that moves the substrates from one leaflet of the bilayer to the other, as a central element of cellular efflux.
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Affiliation(s)
- Stefanie L Raschka
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Andrzej Harris
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University, Düsseldorf, Germany
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5
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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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6
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Ciftci D, Martens C, Ghani VG, Blanchard SC, Politis A, Huysmans GHM, Boudker O. Linking function to global and local dynamics in an elevator-type transporter. Proc Natl Acad Sci U S A 2021; 118:e2025520118. [PMID: 34873050 PMCID: PMC8670510 DOI: 10.1073/pnas.2025520118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2021] [Indexed: 11/24/2022] Open
Abstract
Transporters cycle through large structural changes to translocate molecules across biological membranes. The temporal relationships between these changes and function, and the molecular properties setting their rates, determine transport efficiency-yet remain mostly unknown. Using single-molecule fluorescence microscopy, we compare the timing of conformational transitions and substrate uptake in the elevator-type transporter GltPh We show that the elevator-like movements of the substrate-loaded transport domain across membranes and substrate release are kinetically heterogeneous, with rates varying by orders of magnitude between individual molecules. Mutations increasing the frequency of elevator transitions and reducing substrate affinity diminish transport rate heterogeneities and boost transport efficiency. Hydrogen deuterium exchange coupled to mass spectrometry reveals destabilization of secondary structure around the substrate-binding site, suggesting that increased local dynamics leads to faster rates of global conformational changes and confers gain-of-function properties that set transport rates.
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Affiliation(s)
- Didar Ciftci
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065
- Tri-Institutional Training Program in Chemical Biology, New York, NY 10065
| | - Chloe Martens
- Department of Chemistry, King's College London, London SE1 1DB, United Kingdom
| | - Vishnu G Ghani
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065
| | - Scott C Blanchard
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105
| | - Argyris Politis
- Department of Chemistry, King's College London, London SE1 1DB, United Kingdom
| | - Gerard H M Huysmans
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065;
| | - Olga Boudker
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY 10065;
- Tri-Institutional Training Program in Chemical Biology, New York, NY 10065
- Howard Hughes Medical Institute, Weill Cornell Medicine, New York, NY 10065
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7
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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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8
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Sikkema HR, Poolman B. In silico method for selecting residue pairs for single-molecule microscopy and spectroscopy. Sci Rep 2021; 11:5756. [PMID: 33707507 PMCID: PMC7952708 DOI: 10.1038/s41598-021-85003-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
Obtaining (dynamic) structure related information on proteins is key for understanding their function. Methods as single-molecule Förster Resonance Energy Transfer (smFRET) and Electron Paramagnetic Resonance (EPR) that measure distances between labeled residues to obtain dynamic information rely on selection of suitable residue pairs for chemical modification. Selection of pairs of amino acids, that show sufficient distance changes upon activity of the protein, can be a tedious process. Here we present an in silico approach that makes use of two or more structures (or structure models) to filter suitable residue pairs for FRET or EPR from all possible pairs within the protein. We apply the method for the study of the conformational dynamics of the substrate-binding domain of the osmoregulatory ATP-Binding Cassette transporter OpuA. This method speeds up the process of designing mutants, and because of its systematic nature, the chances of missing promising candidates are reduced.
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Affiliation(s)
- Hendrik R Sikkema
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Bert Poolman
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
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9
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Tassis K, Vietrov R, de Koning M, de Boer M, Gouridis G, Cordes T. Single-molecule studies of conformational states and dynamics in the ABC importer OpuA. FEBS Lett 2021; 595:717-734. [PMID: 33314056 DOI: 10.1002/1873-3468.14026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 11/02/2020] [Accepted: 11/20/2020] [Indexed: 12/30/2022]
Abstract
The current model of active transport via ABC importers is mostly based on structural, biochemical and genetic data. We here establish single-molecule Förster resonance energy transfer (smFRET) assays to monitor the conformational states and heterogeneity of the osmoregulatory type I ABC importer OpuA from Lactococcus lactis. We present data probing both intradomain distances that elucidate conformational changes within the substrate-binding domain (SBD) OpuAC, and interdomain distances between SBDs or transmembrane domains. Using this methodology, we studied ligand-binding mechanisms, as well as ATP and glycine betaine dependences of conformational changes. Our work expands the scope of smFRET investigations towards a class of so far unstudied ABC importers, and paves the way for a full understanding of their transport cycle in the future.
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Affiliation(s)
- Konstantinos Tassis
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Ruslan Vietrov
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.,Department of Biochemistry, Groningen Biomolecular Science and Biotechnology Institute, Netherlands Proteomics Centre & Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Matthijs de Koning
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Marijn de Boer
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
| | - Giorgos Gouridis
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.,Laboratory of Molecular Bacteriology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, Belgium.,Structural Biology Division, Institute of Molecular Biology and Biotechnology (IMBB-FORTH), Heraklion-Crete, Greece
| | - Thorben Cordes
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.,Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians Universität München, Martinsried, Germany
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10
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Lewinson O, Orelle C, Seeger MA. Structures of ABC transporters: handle with care. FEBS Lett 2020; 594:3799-3814. [PMID: 33098660 PMCID: PMC7756565 DOI: 10.1002/1873-3468.13966] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/22/2020] [Accepted: 10/15/2020] [Indexed: 12/11/2022]
Abstract
In the past two decades, the ATP‐binding cassette (ABC) transporters' field has undergone a structural revolution. The importance of structural biology to the development of the field of ABC transporters cannot be overstated, as the ensemble of structures not only revealed the architecture of ABC transporters but also shaped our mechanistic view of these remarkable molecular machines. Nevertheless, we advocate that the mechanistic interpretation of the structures is not trivial and should be carried out with prudence. Herein, we bring several examples of structures of ABC transporters that merit re‐interpretation via careful comparison to experimental data. We propose that it is of the upmost importance to place new structures within the context of the available experimental data.
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Affiliation(s)
- Oded Lewinson
- Department of Molecular Microbiology and the Rappaport Institute for Medical Sciences, Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel
| | - Cédric Orelle
- CNRS, Molecular Microbiology and Structural Biochemistry (MMSB, UMR 5086), University of Lyon, Lyon, France
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
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11
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Bacic L, Sabantsev A, Deindl S. Recent advances in single-molecule fluorescence microscopy render structural biology dynamic. Curr Opin Struct Biol 2020; 65:61-68. [PMID: 32634693 DOI: 10.1016/j.sbi.2020.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/21/2020] [Accepted: 05/21/2020] [Indexed: 01/30/2023]
Abstract
Single-molecule fluorescence microscopy has long been appreciated as a powerful tool to study the structural dynamics that enable biological function of macromolecules. Recent years have witnessed the development of more complex single-molecule fluorescence techniques as well as powerful combinations with structural approaches to obtain mechanistic insights into the workings of various molecular machines and protein complexes. In this review, we highlight these developments that together bring us one step closer to a dynamic understanding of biological processes in atomic details.
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Affiliation(s)
- Luka Bacic
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Anton Sabantsev
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
| | - Sebastian Deindl
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
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12
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Acar B, Rose J, Aykac Fas B, Ben-Tal N, Lewinson O, Haliloglu T. Distinct Allosteric Networks Underlie Mechanistic Speciation of ABC Transporters. Structure 2020; 28:651-663.e5. [DOI: 10.1016/j.str.2020.03.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/20/2020] [Accepted: 03/27/2020] [Indexed: 02/08/2023]
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13
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Wang L, Johnson ZL, Wasserman MR, Levring J, Chen J, Liu S. Characterization of the kinetic cycle of an ABC transporter by single-molecule and cryo-EM analyses. eLife 2020; 9:56451. [PMID: 32458799 PMCID: PMC7253176 DOI: 10.7554/elife.56451] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/15/2020] [Indexed: 01/21/2023] Open
Abstract
ATP-binding cassette (ABC) transporters are molecular pumps ubiquitous across all kingdoms of life. While their structures have been widely reported, the kinetics governing their transport cycles remain largely unexplored. Multidrug resistance protein 1 (MRP1) is an ABC exporter that extrudes a variety of chemotherapeutic agents and native substrates. Previously, the structures of MRP1 were determined in an inward-facing (IF) or outward-facing (OF) conformation. Here, we used single-molecule fluorescence spectroscopy to track the conformational changes of bovine MRP1 (bMRP1) in real time. We also determined the structure of bMRP1 under active turnover conditions. Our results show that substrate stimulates ATP hydrolysis by accelerating the IF-to-OF transition. The rate-limiting step of the transport cycle is the dissociation of the nucleotide-binding-domain dimer, while ATP hydrolysis per se does not reset MRP1 to the resting state. The combination of structural and kinetic data illustrates how different conformations of MRP1 are temporally linked and how substrate and ATP alter protein dynamics to achieve active transport.
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Affiliation(s)
- Ling Wang
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, United States
| | - Zachary Lee Johnson
- Laboratory of Membrane Biology and Biophysics, The Rockefeller University, New York, United States
| | - Michael R Wasserman
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, United States
| | - Jesper Levring
- Laboratory of Membrane Biology and Biophysics, The Rockefeller University, New York, United States
| | - Jue Chen
- Laboratory of Membrane Biology and Biophysics, The Rockefeller University, New York, United States.,Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, United States
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14
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Endicott N, Rivera GSM, Yang J, Wencewicz TA. Emergence of Ferrichelatase Activity in a Siderophore-Binding Protein Supports an Iron Shuttle in Bacteria. ACS CENTRAL SCIENCE 2020; 6:493-506. [PMID: 32341999 PMCID: PMC7181320 DOI: 10.1021/acscentsci.9b01257] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Indexed: 05/08/2023]
Abstract
Siderophores are small-molecule high-affinity multidentate chelators selective for ferric iron that are produced by pathogenic microbes to aid in nutrient sequestration and enhance virulence. In Gram-positive bacteria, the currently accepted paradigm in siderophore-mediated iron acquisition is that effluxed metal-free siderophores extract ferric iron from biological sources and the resulting ferric siderophore complex undergoes diffusion-controlled association with a surface-displayed siderophore-binding protein (SBP) followed by ABC permease-mediated translocation across the cell envelope powered by ATP hydrolysis. Here we show that a more efficient paradigm is possible in Gram-positive bacteria where extracellular metal-free siderophores associate directly with apo-SBPs on the cell surface and serve as non-covalent cofactors that enable the holo-SBPs to non-reductively extract ferric iron directly from host metalloproteins with so-called "ferrichelatase" activity. The resulting SBP-bound ferric siderophore complex is ready for import through an associated membrane permease and enzymatic turnover is achieved through cofactor replacement from the readily available pool of extracellular siderophores. This new "iron shuttle" model closes a major knowledge gap in microbial iron acquisition and defines new roles of the siderophore and SBP as cofactor and enzyme, respectively, in addition to the classically accepted roles as a transport substrate and receptor pair. We propose the formal name "siderophore-dependent ferrichelatases" for this new class of catalytic SBPs.
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15
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Mazal H, Haran G. Single-molecule FRET methods to study the dynamics of proteins at work. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2019; 12:8-17. [PMID: 31989063 PMCID: PMC6984960 DOI: 10.1016/j.cobme.2019.08.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Feynman commented that "Everything that living things do can be understood in terms of the jiggling and wiggling of atoms". Proteins can jiggle and wiggle large structural elements such as domains and subunits as part of their functional cycles. Single-molecule fluorescence resonance energy transfer (smFRET) is an excellent tool to study conformational dynamics and decipher coordinated large-scale motions within proteins. smFRET methods introduced in recent years are geared toward understanding the time scales and amplitudes of function-related motions. This review discusses the methodology for obtaining and analyzing smFRET temporal trajectories that provide direct dynamic information on transitions between conformational states. It also introduces correlation methods that are useful for characterizing intramolecular motions. This arsenal of techniques has been used to study multiple molecular systems, from membrane proteins through molecular chaperones, and we examine some of these studies here. Recent exciting methodological novelties permit revealing very fast, submillisecond dynamics, whose relevance to protein function is yet to be fully grasped.
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Affiliation(s)
- Hisham Mazal
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Gilad Haran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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16
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Mächtel R, Narducci A, Griffith DA, Cordes T, Orelle C. An integrated transport mechanism of the maltose ABC importer. Res Microbiol 2019; 170:321-337. [PMID: 31560984 PMCID: PMC6906923 DOI: 10.1016/j.resmic.2019.09.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 09/10/2019] [Accepted: 09/13/2019] [Indexed: 12/27/2022]
Abstract
ATP-binding cassette (ABC) transporters use the energy of ATP hydrolysis to transport a large diversity of molecules actively across biological membranes. A combination of biochemical, biophysical, and structural studies has established the maltose transporter MalFGK2 as one of the best characterized proteins of the ABC family. MalF and MalG are the transmembrane domains, and two MalKs form a homodimer of nucleotide-binding domains. A periplasmic maltose-binding protein (MalE) delivers maltose and other maltodextrins to the transporter, and triggers its ATPase activity. Substrate import occurs in a unidirectional manner by ATP-driven conformational changes in MalK2 that allow alternating access of the substrate-binding site in MalF to each side of the membrane. In this review, we present an integrated molecular mechanism of the transport process considering all currently available information. Furthermore, we summarize remaining inconsistencies and outline possible future routes to decipher the full mechanistic details of transport by MalEFGK2 complex and that of related importer systems.
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Affiliation(s)
- Rebecca Mächtel
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Großhadernerstr. 2-4, 82152 Planegg-Martinsried, Germany
| | - Alessandra Narducci
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Großhadernerstr. 2-4, 82152 Planegg-Martinsried, Germany
| | - Douglas A Griffith
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Großhadernerstr. 2-4, 82152 Planegg-Martinsried, Germany
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Großhadernerstr. 2-4, 82152 Planegg-Martinsried, Germany.
| | - Cédric Orelle
- Université de Lyon, CNRS, UMR5086 "Molecular Microbiology and Structural Biochemistry", IBCP, 7 passage du Vercors, 69367 Lyon, France.
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17
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Bacterial ABC transporters of iron containing compounds. Res Microbiol 2019; 170:345-357. [DOI: 10.1016/j.resmic.2019.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/15/2019] [Accepted: 10/15/2019] [Indexed: 11/20/2022]
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18
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Agrawal P, DeVico AL, Foulke JS, Lewis GK, Pazgier M, Ray K. Stoichiometric Analyses of Soluble CD4 to Native-like HIV-1 Envelope by Single-Molecule Fluorescence Spectroscopy. Cell Rep 2019; 29:176-186.e4. [PMID: 31577947 PMCID: PMC6897359 DOI: 10.1016/j.celrep.2019.08.074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 06/17/2019] [Accepted: 08/23/2019] [Indexed: 01/14/2023] Open
Abstract
Analyses of HIV-1 envelope (Env) binding to CD4, and the conformational changes the interactions induce, inform the molecular mechanisms and factors governing HIV-1 infection. To address these questions, we used a single-molecule detection (SMD) approach to study the nature of reactions between soluble CD4 (sCD4) and soluble HIV-1 trimers. SMD of these reactions distinguished a mixture of one, two, or three CD4-bound trimer species. Single-ligand trimers were favored at early reaction times and ligand-saturated trimers later. Furthermore, some trimers occupied by one sCD4 molecule did not bind additional ligands, whereas the majority of two ligand-bound species rapidly transitioned to the saturated state. Quantification of liganded trimers observed in reactions with various sCD4 concentrations reflected an overall negative cooperativity in ligand binding. Collectively, our results highlight the general utility of SMD in studying protein interactions and provide critical insights on the nature of sCD4-HIV-1 Env interactions.
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Affiliation(s)
- Parul Agrawal
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Anthony L DeVico
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA; Department of Medicine, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - James S Foulke
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - George K Lewis
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA; Department of Microbiology and Immunology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Marzena Pazgier
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Krishanu Ray
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
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19
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Fiorentino F, Bolla JR, Mehmood S, Robinson CV. The Different Effects of Substrates and Nucleotides on the Complex Formation of ABC Transporters. Structure 2019; 27:651-659.e3. [PMID: 30799075 PMCID: PMC6453779 DOI: 10.1016/j.str.2019.01.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/17/2018] [Accepted: 01/18/2019] [Indexed: 11/27/2022]
Abstract
The molybdate importer (ModBC-A of Archaeoglobus fulgidus) and the vitamin B12 importer (BtuCD-F of Escherichia coli) are members of the type I and type II ABC importer families. Here we study the influence of substrate and nucleotide binding on complex formation and stability. Using native mass spectrometry we show that the interaction between the periplasmic substrate-binding protein (SBP) ModA and the transporter ModBC is dependent upon binding of molybdate. By contrast, vitamin B12 disrupts interactions between the transporter BtuCD and the SBP BtuF. Moreover, while ATP binds cooperatively to BtuCD-F, and acts synergistically with vitamin B12 to destabilize the BtuCD-F complex, no effect is observed for ATP binding on the stability of ModBC-A. These observations not only highlight the ability of mass spectrometry to capture these importer-SBP complexes but allow us to add molecular detail to proposed transport mechanisms.
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Affiliation(s)
- Francesco Fiorentino
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Jani Reddy Bolla
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Shahid Mehmood
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
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20
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Husada F, Bountra K, Tassis K, de Boer M, Romano M, Rebuffat S, Beis K, Cordes T. Conformational dynamics of the ABC transporter McjD seen by single-molecule FRET. EMBO J 2018; 37:e100056. [PMID: 30237313 PMCID: PMC6213277 DOI: 10.15252/embj.2018100056] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/04/2018] [Accepted: 09/05/2018] [Indexed: 12/16/2022] Open
Abstract
ABC transporters utilize ATP for export processes to provide cellular resistance against toxins, antibiotics, and harmful metabolites in eukaryotes and prokaryotes. Based on static structure snapshots, it is believed that they use an alternating access mechanism, which couples conformational changes to ATP binding (outward-open conformation) and hydrolysis (inward-open) for unidirectional transport driven by ATP Here, we analyzed the conformational states and dynamics of the antibacterial peptide exporter McjD from Escherichia coli using single-molecule Förster resonance energy transfer (smFRET). For the first time, we established smFRET for an ABC exporter in a native-like lipid environment and directly monitor conformational dynamics in both the transmembrane- (TMD) and nucleotide-binding domains (NBD). With this, we unravel the ligand dependences that drive conformational changes in both domains. Furthermore, we observe intrinsic conformational dynamics in the absence of ATP and ligand in the NBDs. ATP binding and hydrolysis on the other hand can be observed via NBD conformational dynamics. We believe that the progress made here in combination with future studies will facilitate full understanding of ABC transport cycles.
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Affiliation(s)
- Florence Husada
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Kiran Bountra
- Department of Life Sciences, Imperial College London, London, UK
- Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, UK
| | - Konstantinos Tassis
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Marijn de Boer
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Maria Romano
- Department of Life Sciences, Imperial College London, London, UK
- Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, UK
| | - Sylvie Rebuffat
- Communication Molecules and Adaptation of Microorganisms Laboratory, (MCAM, UMR 7245 CNRS-MNHN), Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités, Paris, France
| | - Konstantinos Beis
- Department of Life Sciences, Imperial College London, London, UK
- Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, UK
| | - Thorben Cordes
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
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21
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Noncanonical role for the binding protein in substrate uptake by the MetNI methionine ATP Binding Cassette (ABC) transporter. Proc Natl Acad Sci U S A 2018; 115:E10596-E10604. [PMID: 30352853 PMCID: PMC6233128 DOI: 10.1073/pnas.1811003115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The high-affinity methionine importer MetNI belongs to the ATP Binding Cassette (ABC) family of transporters that carry out the ATP-dependent uptake of substrates into cells. As with other ABC importers, MetNI requires a soluble binding protein (MetQ) that in the canonical mechanistic model delivers substrates to the transporter. We made the unexpected observation that a MetQ variant with significantly impaired ligand-binding properties supports d-selenomethionine uptake at a higher rate than wild-type MetQ. A crystal structure of MetNIQ in the outward-facing conformation reveals access channels through the binding protein to the transmembrane translocation pathway. These studies support a noncanonical role for the binding protein in facilitating the uptake of certain substrates directly through the transporter–binding protein complex. The Escherichia coli methionine ABC transporter MetNI exhibits both high-affinity transport toward l-methionine and broad specificity toward methionine derivatives, including d-methionine. In this work, we characterize the transport of d-methionine derivatives by the MetNI transporter. Unexpectedly, the N229A substrate-binding deficient variant of the cognate binding protein MetQ was found to support high MetNI transport activity toward d-selenomethionine. We determined the crystal structure at 2.95 Å resolution of the ATPγS-bound MetNIQ complex in the outward-facing conformation with the N229A apo MetQ variant. This structure revealed conformational changes in MetQ providing substrate access through the binding protein to the transmembrane translocation pathway. MetQ likely mediates uptake of methionine derivatives through two mechanisms: in the methionine-bound form delivering substrate from the periplasm to the transporter (the canonical mechanism) and in the apo form by facilitating ligand binding when complexed to the transporter (the noncanonical mechanism). This dual role for substrate-binding proteins is proposed to provide a kinetic strategy for ABC transporters to transport both high- and low-affinity substrates present in a physiological concentration range.
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22
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Tang JD, Caliari SR, Lampe KJ. Temperature-Dependent Complex Coacervation of Engineered Elastin-like Polypeptide and Hyaluronic Acid Polyelectrolytes. Biomacromolecules 2018; 19:3925-3935. [DOI: 10.1021/acs.biomac.8b00837] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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23
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Yang M, Livnat Levanon N, Acar B, Aykac Fas B, Masrati G, Rose J, Ben-Tal N, Haliloglu T, Zhao Y, Lewinson O. Single-molecule probing of the conformational homogeneity of the ABC transporter BtuCD. Nat Chem Biol 2018; 14:715-722. [PMID: 29915236 DOI: 10.1038/s41589-018-0088-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/15/2018] [Indexed: 02/07/2023]
Abstract
ATP-binding cassette (ABC) transporters use the energy of ATP hydrolysis to move molecules through cellular membranes. They are directly linked to human diseases, cancer multidrug resistance, and bacterial virulence. Very little is known of the conformational dynamics of ABC transporters, especially at the single-molecule level. Here, we combine single-molecule spectroscopy and a novel molecular simulation approach to investigate the conformational dynamics of the ABC transporter BtuCD. We observe a single dominant population of molecules in each step of the transport cycle and tight coupling between conformational transitions and ligand binding. We uncover transient conformational changes that allow substrate to enter the transporter. This is followed by a 'squeezing' motion propagating from the extracellular to the intracellular side of the translocation cavity. This coordinated sequence of events provides a mechanism for the unidirectional transport of vitamin B12 by BtuCD.
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Affiliation(s)
- Min Yang
- National Laboratory of Macromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Nurit Livnat Levanon
- Department of Biochemistry and the Rappaport Institute for Medical Sciences, Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel
| | - Burçin Acar
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, Istanbul, Turkey
| | - Burcu Aykac Fas
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, Istanbul, Turkey
| | - Gal Masrati
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Jessica Rose
- Department of Biochemistry and the Rappaport Institute for Medical Sciences, Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel
| | - Nir Ben-Tal
- Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
| | - Turkan Haliloglu
- Department of Chemical Engineering and Polymer Research Center, Bogazici University, Istanbul, Turkey.
| | - Yongfang Zhao
- National Laboratory of Macromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Oded Lewinson
- Department of Biochemistry and the Rappaport Institute for Medical Sciences, Faculty of Medicine, The Technion-Israel Institute of Technology, Haifa, Israel.
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24
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Santos JA, Rempel S, Mous ST, Pereira CT, Ter Beek J, de Gier JW, Guskov A, Slotboom DJ. Functional and structural characterization of an ECF-type ABC transporter for vitamin B12. eLife 2018; 7:35828. [PMID: 29809140 PMCID: PMC5997447 DOI: 10.7554/elife.35828] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 05/26/2018] [Indexed: 01/01/2023] Open
Abstract
Vitamin B12 (cobalamin) is the most complex B-type vitamin and is synthetized exclusively in a limited number of prokaryotes. Its biologically active variants contain rare organometallic bonds, which are used by enzymes in a variety of central metabolic pathways such as L-methionine synthesis and ribonucleotide reduction. Although its biosynthesis and role as co-factor are well understood, knowledge about uptake of cobalamin by prokaryotic auxotrophs is scarce. Here, we characterize a cobalamin-specific ECF-type ABC transporter from Lactobacillus delbrueckii, ECF-CbrT, and demonstrate that it mediates the specific, ATP-dependent uptake of cobalamin. We solved the crystal structure of ECF-CbrT in an apo conformation to 3.4 Å resolution. Comparison with the ECF transporter for folate (ECF-FolT2) from the same organism, reveals how the identical ECF module adjusts to interact with the different substrate binding proteins FolT2 and CbrT. ECF-CbrT is unrelated to the well-characterized B12 transporter BtuCDF, but their biochemical features indicate functional convergence.
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Affiliation(s)
- Joana A Santos
- Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | - Stephan Rempel
- Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | - Sandra Tm Mous
- Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | | | - Josy Ter Beek
- Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | - Jan-Willem de Gier
- Department of Biochemistry and Biophysics, Center for Biomembrane Research, Stockholm University, Stockholm, Sweden
| | - Albert Guskov
- Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands
| | - Dirk J Slotboom
- Groningen Biomolecular and Biotechnology Institute (GBB), University of Groningen, Groningen, The Netherlands.,Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
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