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Novischi SYP, Karoly-Lakatos A, Chok K, Bonifer C, Becker-Baldus J, Glaubitz C. Probing the allosteric NBD-TMD crosstalk in the ABC transporter MsbA by solid-state NMR. Commun Biol 2024; 7:43. [PMID: 38182790 PMCID: PMC10770068 DOI: 10.1038/s42003-023-05617-0] [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: 06/11/2023] [Accepted: 11/21/2023] [Indexed: 01/07/2024] Open
Abstract
The ABC transporter MsbA plays a critical role in Gram-negative bacteria in the regulation of the outer membrane by translocating core-LPS across the inner membrane. Additionally, a broad substrate specificity for lipophilic drugs has been shown. The allosteric interplay between substrate binding in the transmembrane domains and ATP binding and turnover in the nucleotide-binding domains must be mediated via the NBD/TMD interface. Previous studies suggested the involvement of two intracellular loops called coupling helix 1 and 2 (CH1, CH2). Here, we demonstrate by solid-state NMR spectroscopy that substantial chemical shift changes within both CH1 and CH2 occur upon substrate binding, in the ATP hydrolysis transition state, and upon inhibitor binding. CH2 is domain-swapped within the MsbA structure, and it is noteworthy that substrate binding induces a larger response in CH2 compared to CH1. Our data demonstrate that CH1 and CH2 undergo structural changes as part of the TMD-NBD cross-talk.
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Affiliation(s)
- S Y Phoebe Novischi
- Institute for Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max von Laue Str. 9, 60438, Frankfurt, Germany
| | - Andrea Karoly-Lakatos
- Institute for Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max von Laue Str. 9, 60438, Frankfurt, Germany
| | - Kerby Chok
- Institute for Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max von Laue Str. 9, 60438, Frankfurt, Germany
| | - Christian Bonifer
- Institute for Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max von Laue Str. 9, 60438, Frankfurt, Germany
| | - Johanna Becker-Baldus
- Institute for Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max von Laue Str. 9, 60438, Frankfurt, Germany
| | - Clemens Glaubitz
- Institute for Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max von Laue Str. 9, 60438, Frankfurt, Germany.
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2
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Aranda-Caraballo J, Saenz RA, López-Zavala AA, Velazquez-Cruz B, Espinosa-Barrera L, Cárdenas-Conejo Y, Zárate-Romero A, Linares-Vergara O, Osuna-Castro JA, Bonales-Alatorre E, Centeno-Leija S, Serrano-Posada H. Binding Specificity of a Novel Cyclo/Maltodextrin-Binding Protein and Its Role in the Cyclodextrin ABC Importer System from Thermoanaerobacterales. Molecules 2023; 28:6080. [PMID: 37630332 PMCID: PMC10458862 DOI: 10.3390/molecules28166080] [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: 07/24/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 08/27/2023] Open
Abstract
Extracellular synthesis of functional cyclodextrins (CDs) as intermediates of starch assimilation is a convenient microbial adaptation to sequester substrates, increase the half-life of the carbon source, carry bioactive compounds, and alleviate chemical toxicity through the formation of CD-guest complexes. Bacteria encoding the four steps of the carbohydrate metabolism pathway via cyclodextrins (CM-CD) actively internalize CDs across the microbial membrane via a putative type I ATP-dependent ABC sugar importer system, MdxEFG-(X/MsmX). While the first step of the CM-CD pathway encompasses extracellular starch-active cyclomaltodextrin glucanotransferases (CGTases) to synthesize linear dextrins and CDs, it is the ABC importer system in the second step that is the critical factor in determining which molecules from the CGTase activity will be internalized by the cell. Here, structure-function relationship studies of the cyclo⁄maltodextrin-binding protein MdxE of the MdxEFG-MsmX importer system from Thermoanaerobacter mathranii subsp. mathranii A3 are presented. Calorimetric and fluorescence studies of recombinant MdxE using linear dextrins and CDs showed that although MdxE binds linear dextrins and CDs with high affinity, the open-to-closed conformational change is solely observed after α- and β-CD binding, suggesting that the CM-CD pathway from Thermoanaerobacterales is exclusive for cellular internalization of these molecules. Structural analysis of MdxE coupled with docking simulations showed an overall architecture typically found in sugar-binding proteins (SBPs) that comprised two N- and C-domains linked by three small hinge regions, including the conserved aromatic triad Tyr193/Trp269/Trp378 in the C-domain and Phe87 in the N-domain involved in CD recognition and stabilization. Structural bioinformatic analysis of the entire MdxFG-MsmX importer system provided further insights into the binding, internalization, and delivery mechanisms of CDs. Hence, while the MdxE-CD complex couples to the permease subunits MdxFG to deliver the CD into the transmembrane channel, the dimerization of the cytoplasmatic promiscuous ATPase MsmX triggers active transport into the cytoplasm. This research provides the first results on a novel thermofunctional SBP and its role in the internalization of CDs in extremely thermophilic bacteria.
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Affiliation(s)
- Jorge Aranda-Caraballo
- Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico; (J.A.-C.); (B.V.-C.); (L.E.-B.); (O.L.-V.)
| | - Roberto A. Saenz
- Facultad de Ciencias, Universidad de Colima, Bernal Díaz del Castillo 340, Colima 28045, Mexico;
| | - Alonso A. López-Zavala
- Departamento de Ciencias Químico-Biológicas, Universidad de Sonora, Hermosillo 83000, Mexico;
| | - Beatriz Velazquez-Cruz
- Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico; (J.A.-C.); (B.V.-C.); (L.E.-B.); (O.L.-V.)
| | - Laura Espinosa-Barrera
- Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico; (J.A.-C.); (B.V.-C.); (L.E.-B.); (O.L.-V.)
| | - Yair Cárdenas-Conejo
- Consejo Nacional de Humanidades, Ciencias y Tecnologías, Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico;
| | - Andrés Zárate-Romero
- Consejo Nacional de Humanidades, Ciencias y Tecnologías, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km 107 CarreteraTijuana-Ensenada, Ensenada 22860, Mexico;
| | - Oscar Linares-Vergara
- Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico; (J.A.-C.); (B.V.-C.); (L.E.-B.); (O.L.-V.)
| | - Juan A. Osuna-Castro
- Facultad de Ciencias Biológicas y Agropecuarias, Universidad de Colima, Autopista Colima-Manzanillo, Tecomán 28100, Mexico;
| | - Edgar Bonales-Alatorre
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Avenida 25 de julio 965, Colonia Villa de San Sebastián, Colima 28045, Mexico;
| | - Sara Centeno-Leija
- Consejo Nacional de Humanidades, Ciencias y Tecnologías, Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico;
| | - Hugo Serrano-Posada
- Consejo Nacional de Humanidades, Ciencias y Tecnologías, Laboratorio de Biología Sintética, Estructural y Molecular, Universidad de Colima, Carretera Los Limones-Loma de Juárez, Colima 28627, Mexico;
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3
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Plummer-Medeiros AM, Culbertson AT, Morales-Perez CL, Liao M. Activity and Structural Dynamics of Human ABCA1 in a Lipid Membrane. J Mol Biol 2023; 435:168038. [PMID: 36889459 DOI: 10.1016/j.jmb.2023.168038] [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: 01/19/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/08/2023]
Abstract
The human ATP-binding cassette (ABC) transporter ABCA1 plays a critical role in lipid homeostasis as it extracts sterols and phospholipids from the plasma membrane for excretion to the extracellular apolipoprotein A-I and subsequent formation of high-density lipoprotein (HDL) particles. Deleterious mutations of ABCA1 lead to sterol accumulation and are associated with atherosclerosis, poor cardiovascular outcomes, cancer, and Alzheimer's disease. The mechanism by which ABCA1 drives lipid movement is poorly understood, and a unified platform to produce active ABCA1 protein for both functional and structural studies has been missing. In this work, we established a stable expression system for both a human cell-based sterol export assay and protein purification for in vitro biochemical and structural studies. ABCA1 produced in this system was active in sterol export and displayed enhanced ATPase activity after reconstitution into a lipid bilayer. Our single-particle cryo-EM study of ABCA1 in nanodiscs showed protein induced membrane curvature, revealed multiple distinct conformations, and generated a structure of nanodisc-embedded ABCA1 at 4.0-Å resolution representing a previously unknown conformation. Comparison of different ABCA1 structures and molecular dynamics simulations demonstrates both concerted domain movements and conformational variations within each domain. Taken together, our platform for producing and characterizing ABCA1 in a lipid membrane enabled us to gain important mechanistic and structural insights and paves the way for investigating modulators that target the functions of ABCA1.
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Affiliation(s)
- Ashlee M Plummer-Medeiros
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Bryn Mawr College Chemistry Department, 101 N Merion Avenue, Bryn Mawr, PA 19010, USA
| | - Alan T Culbertson
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Roivant Sciences, Inc., 451 D Street, Boston, MA 02210, USA
| | - Claudio L Morales-Perez
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Generate Biomedicines, 4 Corporate Drive Andover, MA, 01810, USA
| | - Maofu Liao
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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4
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Ogden DS, Moradi M. Atomic-level characterization of the conformational transition pathways in SARS-CoV-1 and SARS-CoV-2 spike proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.11.29.518406. [PMID: 36482979 PMCID: PMC9727763 DOI: 10.1101/2022.11.29.518406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Severe acute respiratory syndrome (SARS) coronaviruses 1 and 2 (SARS-CoV-1 and SARS-CoV-2) derive transmissibility from spike protein activation in the receptor binding domain (RBD) and binding to the host cell angiotensin converting enzyme 2 (ACE2). However, the mechanistic details that describe the large-scale conformational changes associated with spike protein activation or deactivation are still somewhat unknown. Here, we have employed an extensive set of nonequilibrium all-atom molecular dynamics (MD) simulations, utilizing a novel protocol, for the SARS-CoV-1 (CoV-1) and SARS-CoV-2 (CoV-2) prefusion spike proteins in order to characterize the conformational pathways associated with the active-to-inactive transition. Our results indicate that both CoV-1 and CoV-2 spike proteins undergo conformational transitions along pathways unique to each protein. We have identified a number of key residues that form various inter-domain saltbridges, suggesting a multi-stage conformational change along the pathways. We have also constructed the free energy profiles along the transition pathways for both CoV-1 and CoV-2 spike proteins. The CoV-2 spike protein must overcome larger free energy barriers to undergo conformational changes towards protein activation or deactivation, when compared to CoV-1.
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5
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Abreu B, Cruz C, Oliveira ASF, Soares CM. ATP hydrolysis and nucleotide exit enhance maltose translocation in the MalFGK 2E importer. Sci Rep 2021; 11:10591. [PMID: 34012037 PMCID: PMC8134467 DOI: 10.1038/s41598-021-89556-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 04/27/2021] [Indexed: 02/03/2023] Open
Abstract
ATP binding cassette (ABC) transporters employ ATP hydrolysis to harness substrate translocation across membranes. The Escherichia coli MalFGK2E maltose importer is an example of a type I ABC importer and a model system for this class of ABC transporters. The MalFGK2E importer is responsible for the intake of malto-oligossacharides in E.coli. Despite being extensively studied, little is known about the effect of ATP hydrolysis and nucleotide exit on substrate transport. In this work, we studied this phenomenon using extensive molecular dynamics simulations (MD) along with potential of mean force calculations of maltose transport across the pore, in the pre-hydrolysis, post-hydrolysis and nucleotide-free states. We concluded that ATP hydrolysis and nucleotide exit trigger conformational changes that result in the decrease of energetic barriers to maltose translocation towards the cytoplasm, with a concomitant increase of the energy barrier in the periplasmic side of the pore, contributing for the irreversibility of the process. We also identified key residues that aid in positioning and orientation of maltose, as well as a novel binding pocket for maltose in MalG. Additionally, ATP hydrolysis leads to conformations similar to the nucleotide-free state. This study shows the contribution of ATP hydrolysis and nucleotide exit in the transport cycle, shedding light on ABC type I importer mechanisms.
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Affiliation(s)
- Bárbara Abreu
- grid.10772.330000000121511713ITQB NOVA, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Carlos Cruz
- grid.10772.330000000121511713ITQB NOVA, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - A. Sofia F. Oliveira
- grid.10772.330000000121511713ITQB NOVA, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal ,grid.5337.20000 0004 1936 7603School of Biochemistry and Centre for Computational Chemistry, University of Bristol, Bristol, UK
| | - Cláudio M. Soares
- grid.10772.330000000121511713ITQB NOVA, Instituto de Tecnologia Química E Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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6
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Rybenkov VV, Zgurskaya HI, Ganguly C, Leus IV, Zhang Z, Moniruzzaman M. The Whole Is Bigger than the Sum of Its Parts: Drug Transport in the Context of Two Membranes with Active Efflux. Chem Rev 2021; 121:5597-5631. [PMID: 33596653 PMCID: PMC8369882 DOI: 10.1021/acs.chemrev.0c01137] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cell envelope plays a dual role in the life of bacteria by simultaneously protecting it from a hostile environment and facilitating access to beneficial molecules. At the heart of this ability lie the restrictive properties of the cellular membrane augmented by efflux transporters, which preclude intracellular penetration of most molecules except with the help of specialized uptake mediators. Recently, kinetic properties of the cell envelope came into focus driven on one hand by the urgent need in new antibiotics and, on the other hand, by experimental and theoretical advances in studies of transmembrane transport. A notable result from these studies is the development of a kinetic formalism that integrates the Michaelis-Menten behavior of individual transporters with transmembrane diffusion and offers a quantitative basis for the analysis of intracellular penetration of bioactive compounds. This review surveys key experimental and computational approaches to the investigation of transport by individual translocators and in whole cells, summarizes key findings from these studies and outlines implications for antibiotic discovery. Special emphasis is placed on Gram-negative bacteria, whose envelope contains two separate membranes. This feature sets these organisms apart from Gram-positive bacteria and eukaryotic cells by providing them with full benefits of the synergy between slow transmembrane diffusion and active efflux.
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Affiliation(s)
- Valentin V Rybenkov
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Helen I Zgurskaya
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Chhandosee Ganguly
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Inga V Leus
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Zhen Zhang
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
| | - Mohammad Moniruzzaman
- Department of Chemistry and Biochemistry, Stephenson Life Sciences Research Center, University of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United States
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7
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Choi CC, Ford RC. ATP binding cassette importers in eukaryotic organisms. Biol Rev Camb Philos Soc 2021; 96:1318-1330. [PMID: 33655617 DOI: 10.1111/brv.12702] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 11/28/2022]
Abstract
ATP-binding cassette (ABC) transporters are ubiquitous across all realms of life. Dogma suggests that bacterial ABC transporters include both importers and exporters, whilst eukaryotic members of this family are solely exporters, implying that ABC import function was lost during evolution. This view is being challenged, for example energy-coupling factor (ECF)-type ABC importers appear to fulfil important roles in both algae and plants where they form the ABCI sub-family. Herein we discuss whether bacterial Type I and Type II ABC importers also made the transition into extant eukaryotes. Various studies suggest that Type I importers exist in algae and the liverwort family of primitive non-vascular plants, but not in higher plants. The existence of eukaryotic Type II importers is also supported: a transmembrane protein homologous to vitamin B12 import system transmembrane protein (BtuC), hemin transport system transmembrane protein (HmuU) and high-affinity zinc uptake system membrane protein (ZnuB) is present in the Cyanophora paradoxa genome. This protein has homologs within the genomes of red algae. Furthermore, its candidate nucleotide-binding domain (NBD) shows closest similarity to other bacterial Type II importer NBDs such as BtuD. Functional studies suggest that Type I importers have roles in maintaining sulphate levels in the chloroplast, whilst Type II importers probably act as importers of Mn2+ or Zn2+ , as inferred by comparisons with bacterial homologs. Possible explanations for the presence of these transporters in simple plants, but not in other eukaryotic organisms, are considered. In order to utilise the existing nomenclature for eukaryotic ABC proteins, we propose that eukaryotic Type I and II importers be classified as ABCJ and ABCK transporters, respectively.
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Affiliation(s)
- Cheri C Choi
- Faculty of Biology Medicine and Health, School of Biological Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.,Department of Biology, University of York, York, YO10 5DD, U.K
| | - Robert C Ford
- Faculty of Biology Medicine and Health, School of Biological Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL, U.K
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Serçinoğlu O, Senturk D, Altinisik Kaya FE, Avci FG, Frlan R, Tomašič T, Ozbek P, Orelle C, Jault JM, Sariyar Akbulut B. Identification of novel inhibitors of the ABC transporter BmrA. Bioorg Chem 2020; 105:104452. [PMID: 33212311 DOI: 10.1016/j.bioorg.2020.104452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 10/23/2020] [Accepted: 11/01/2020] [Indexed: 01/02/2023]
Abstract
The resistance of microbes to commonly used antibiotics has become a worldwide health problem. A major underlying mechanism of microbial antibiotic resistance is the export of drugs from bacterial cells. Drug efflux is mediated through the action of multidrug resistance efflux pumps located in the bacterial cell membranes. The critical role of bacterial efflux pumps in antibiotic resistance has directed research efforts to the identification of novel efflux pump inhibitors that can be used alongside antibiotics in clinical settings. Here, we aimed to find potential inhibitors of the archetypical ATP-binding cassette (ABC) efflux pump BmrA of Bacillus subtilis via virtual screening of the Mu.Ta.Lig. Chemotheca small molecule library. Molecular docking calculations targeting the nucleotide-binding domain of BmrA were performed using AutoDock Vina. Following a further drug-likeness filtering step based on Lipinski's Rule of Five, top 25 scorers were identified. These ligands were then clustered into separate groups based on their contact patterns with the BmrA nucleotide-binding domain. Six ligands with distinct contact patterns were used for further in vitro inhibition assays based on intracellular ethidium bromide accumulation. Using this methodology, we identified two novel inhibitors of BmrA from the Chemotheca small molecule library.
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Affiliation(s)
- Onur Serçinoğlu
- Department of Bioengineering, Recep Tayyip Erdogan University, Fener 53100, Rize, Turkey
| | - Duygu Senturk
- Department of Bioengineering, Marmara University, Kadikoy 34722, Istanbul, Turkey
| | | | - Fatma Gizem Avci
- Department of Bioengineering, Uskudar University, Uskudar 34662, Istanbul, Turkey
| | - Rok Frlan
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Tihomir Tomašič
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Pemra Ozbek
- Department of Bioengineering, Marmara University, Kadikoy 34722, Istanbul, Turkey
| | - Cédric Orelle
- University of Lyon, CNRS, UMR5086 "Molecular Microbiology and Structural Biochemistry", 7 passage du Vercors, 69367 Lyon Cedex 7, France
| | - Jean-Michel Jault
- University of Lyon, CNRS, UMR5086 "Molecular Microbiology and Structural Biochemistry", 7 passage du Vercors, 69367 Lyon Cedex 7, France
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9
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Pearson SA, Cowan JA. Evolution of the human mitochondrial ABCB7 [2Fe-2S](GS) 4 cluster exporter and the molecular mechanism of an E433K disease-causing mutation. Arch Biochem Biophys 2020; 697:108661. [PMID: 33157103 DOI: 10.1016/j.abb.2020.108661] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/08/2020] [Accepted: 10/29/2020] [Indexed: 11/18/2022]
Abstract
Iron-sulfur cluster proteins play key roles in a multitude of cellular processes. Iron-sulfur cofactors are assembled primarily in mitochondria and are then exported to the cytosol by use of an ABCB7 transporter. It has been shown that the yeast mitochondrial transporter Atm1 can export glutathione-coordinated iron-sulfur clusters, [2Fe-2S](SG)4, providing a source of cluster units for cytosolic iron-sulfur cluster assembly systems. This pathway is consistent with the endosymbiotic model of mitochondrial evolution where homologous bacterial heavy metal transporters, utilizing metal glutathione adducts, were adapted for use in eukaryotic mitochondria. Herein, the basis for endosymbiotic evolution of the human cluster export protein (ABCB7) is developed through a BLAST analysis of transporters from ancient proteobacteria. In addition, a functional comparison of native human protein, versus a disease-causing mutant, demonstrates a key role for residue E433 in promoting cluster transport. Dysfunction in mitochondrial export of Fe-S clusters is a likely cause of the disease condition X-linked sideroblastic anemia.
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Affiliation(s)
- Stephen A Pearson
- The Ohio State University Biophysics Program, The Ohio State University, 484 West 12thAvenue, Columbus, OH, 43210, United States
| | - J A Cowan
- The Ohio State University Biophysics Program, The Ohio State University, 484 West 12thAvenue, Columbus, OH, 43210, United States; Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH, 43210, United States. https://chemistry.osu.edu/people/cowan.2
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10
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Zhang H, Jing W, Zheng J, Jin Y, Wu D, Cao C, Dong Y, Shi X, Zhang W. The ATP-binding cassette transporter OsPDR1 regulates plant growth and pathogen resistance by affecting jasmonates biosynthesis in rice. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2020; 298:110582. [PMID: 32771142 DOI: 10.1016/j.plantsci.2020.110582] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
Jasmonates (JAs) are important regulators of plant growth, development, and defense. ATP-binding cassette (ABC) transporters participate in disease resistance by transporting JAs or antimicrobial secondary metabolites in dicotyledons. Here, we functionally characterized a JAs-inducible rice gene (OsPDR1) that encodes a member of the pleiotropic drug resistance (PDR) subfamily of ABC transporters. By affecting JAs biosynthesis, overexpression of OsPDR1 resulted in constitutive activation of defense-related genes and enhanced resistance to bacterial blight, whereas its mutation decreased pathogen resistance. In addition, overexpression and mutation of OsPDR1 resulted in decreased and increased plant growth at seedling stage, respectively, but eventually led to decreased grain yield. OsPDR1 encodes three splice isoforms, of which OsPDR1.2 and OsPDR1.3 contain a conserved glutamate residue in the "ENI-motif" of the first nucleotide-binding domain, while OsPDR1.1 does not. The three OsPDR1 transcripts are developmentally controlled and differentially regulated by JAs and pathogen infection. The OsPDR1.2- and OsPDR1.3-overexpressing plants exhibited higher JAs content and stronger growth inhibition and disease resistance than OsPDR1.1-overexpressing plants. These results indicated that alternative splicing affects the function of OsPDR1 gene in regulation of growth, development and disease resistance.
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Affiliation(s)
- Hongsheng Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Wen Jing
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
| | - Junming Zheng
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Yingying Jin
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Dan Wu
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Chengjuan Cao
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Yanmin Dong
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Xingyu Shi
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Wenhua Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
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11
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Abstract
Multidrug resistance (MDR) is a vital issue in cancer treatment. Drug resistance can be developed through a variety of mechanisms, including increased drug efflux, activation of detoxifying systems and DNA repair mechanisms, and escape of drug-induced apoptosis. Identifying the exact mechanism related in a particular case is a difficult task. Proteomics is the large-scale study of proteins, particularly their expression, structures and functions. In recent years, comparative proteomic methods have been performed to analyze MDR mechanisms in drug-selected model cancer cell lines. In this paper, we review the recent developments and progresses by comparative proteomic approaches to identify potential MDR mechanisms in drug-selected model cancer cell lines, which may help understand and design chemical sensitizers.
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12
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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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13
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Holland IB. Rise and rise of the ABC transporter families. Res Microbiol 2019; 170:304-320. [PMID: 31442613 DOI: 10.1016/j.resmic.2019.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/30/2019] [Accepted: 08/13/2019] [Indexed: 01/15/2023]
Abstract
This review will inevitably be influenced by my personal experience and personal view of the progression of this amazing family of proteins. This has generated a huge literature in over nearly five decades, some ideas have bloomed and faded while others have persisted, other contributions simply become redundant, overtaken by better techniques. At the outset, the pioneers had no idea of the magnitude of the topic they were working on, then a very rough idea of the significance emerged and, progressively, the picture becomes sharper and finally extraordinary. I have tried to produce at least an outline of that progression. My apologies for the also inevitable omissions, especially relating to the mass of biochemical and spectroscopy and genetical studies. I decided to prioritise structural biology because structures when successful are definitive and of course provide a 'visual' image. However, I tried to limit the structural aspects to the proteins that reflected the main advances.
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Affiliation(s)
- I Barry Holland
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Sud, Orsay, France.
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14
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Learning the ABCs one at a time: structure and mechanism of ABC transporters. Biochem Soc Trans 2019; 47:23-36. [PMID: 30626703 DOI: 10.1042/bst20180147] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/16/2018] [Accepted: 11/29/2018] [Indexed: 12/21/2022]
Abstract
ATP-binding cassette (ABC) transporters are essential proteins that are found across all kingdoms of life. ABC transporters harness the energy of ATP hydrolysis to drive the import of nutrients inside bacterial cells or the export of toxic compounds or essential lipids across bacteria and eukaryotic membranes. Typically, ABC transporters consist of transmembrane domains (TMDs) and nucleotide-binding domains (NBDs) to bind their substrate and ATP, respectively. The TMDs dictate what ligands can be recognised, whereas the NBDs are the power engine of the ABC transporter, carrying out ATP binding and hydrolysis. It has been proposed that they utilise the alternating access mechanism, inward- to outward-facing conformation, to transport their substrates. Here, we will review the recent progress on the structure determination of eukaryotic and bacterial ABC transporters as well as the novel mechanisms that have also been proposed, that fall out of the alternating access mechanism model.
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15
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Predictive Structure and Topology of Peroxisomal ATP-Binding Cassette (ABC) Transporters. Int J Mol Sci 2017; 18:ijms18071593. [PMID: 28737695 PMCID: PMC5536080 DOI: 10.3390/ijms18071593] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 07/10/2017] [Accepted: 07/19/2017] [Indexed: 12/12/2022] Open
Abstract
The peroxisomal ATP-binding Cassette (ABC) transporters, which are called ABCD1, ABCD2 and ABCD3, are transmembrane proteins involved in the transport of various lipids that allow their degradation inside the organelle. Defective ABCD1 leads to the accumulation of very long-chain fatty acids and is associated with a complex and severe neurodegenerative disorder called X-linked adrenoleukodystrophy (X-ALD). Although the nucleotide-binding domain is highly conserved and characterized within the ABC transporters family, solid data are missing for the transmembrane domain (TMD) of ABCD proteins. The lack of a clear consensus on the secondary and tertiary structure of the TMDs weakens any structure-function hypothesis based on the very diverse ABCD1 mutations found in X-ALD patients. Therefore, we first reinvestigated thoroughly the structure-function data available and performed refined alignments of ABCD protein sequences. Based on the 2.85 Å resolution crystal structure of the mitochondrial ABC transporter ABCB10, here we propose a structural model of peroxisomal ABCD proteins that specifies the position of the transmembrane and coupling helices, and highlight functional motifs and putative important amino acid residues.
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16
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Weng J, Gu S, Gao X, Huang X, Wang W. Maltose-binding protein effectively stabilizes the partially closed conformation of the ATP-binding cassette transporter MalFGK2. Phys Chem Chem Phys 2017; 19:9366-9373. [DOI: 10.1039/c6cp07943a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Maltose transporter MalFGK2is a type-I importer in the ATP-binding cassette (ABC) transporter superfamily.
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Affiliation(s)
- Jingwei Weng
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Department of Chemistry, and Institutes of Biomedical Sciences
- Fudan University
- Shanghai
- P. R. China
| | - Shuo Gu
- Department of Chemistry
- Institute for Advance Study and School of Science
- The Hong Kong University of Science and Technology
- Kowloon
- China
| | - Xin Gao
- Computer, Electrical and Mathematical Sciences and Engineering Division
- King Abdullah University of Science and Technology
- Thuwal
- Saudi Arabia
| | - Xuhui Huang
- Department of Chemistry
- Institute for Advance Study and School of Science
- The Hong Kong University of Science and Technology
- Kowloon
- China
| | - Wenning Wang
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Department of Chemistry, and Institutes of Biomedical Sciences
- Fudan University
- Shanghai
- P. R. China
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17
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Pan C, Weng J, Wang W. Conformational Dynamics and Protein-Substrate Interaction of ABC Transporter BtuCD at the Occluded State Revealed by Molecular Dynamics Simulations. Biochemistry 2016; 55:6897-6907. [PMID: 27951660 DOI: 10.1021/acs.biochem.6b00386] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
ATP-binding cassette (ABC) transporters are ubiquitous in all three kingdoms of life and are implicated in many clinically relevant physiological processes. They couple the energy released by ATP hydrolysis to facilitate substrate translocation across cell membranes. The crystal structures of type II ABC importers have revealed their unique transmembrane domain architecture consisting of 10 transmembrane helices and their structurally conserved nucleotide-binding domains among all ABC transporters. However, molecular details of the interactions between the importers and their substrate remain largely elusive. Taking vitamin B12 importer BtuCD as an exemplar of type II importers, we investigated the dynamics of its occluded state and the detailed protein-substrate interactions using molecular dynamics simulation. Our trajectories show that the importer accommodates the substrate through a nonspecific binding mode as the substrate undergoes evident vertical and tilt motions inside the translocation cavity. Extensive hydrogen bond and hydrophobic interactions were observed between the substrate and the importer; however, most of these interactions are weak, with <38% occurrence. The presence of substrate leads to enlargement of the translocation cavity, especially at its cytoplasmic end, which may activate cytoplasmic regions and probably facilitate the transportation. The perturbations caused by periplasmic binding protein and nucleotides were also investigated. The study provides deeper insight into the translocation mechanism of BtuCD.
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Affiliation(s)
- Chao Pan
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, and Institutes of Biomedical Sciences, Fudan University , Shanghai, P. R. China
| | - Jingwei Weng
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, and Institutes of Biomedical Sciences, Fudan University , Shanghai, P. R. China
| | - Wenning Wang
- Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, and Institutes of Biomedical Sciences, Fudan University , Shanghai, P. R. China
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18
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Lv X, Liu H, Chen H, Gong H. Coupling between ATP hydrolysis and protein conformational change in maltose transporter. Proteins 2016; 85:207-220. [PMID: 27616441 DOI: 10.1002/prot.25160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/29/2016] [Accepted: 09/02/2016] [Indexed: 11/12/2022]
Abstract
As the intracellular part of maltose transporter, MalK dimer utilizes the energy of ATP hydrolysis to drive protein conformational change, which then facilitates substrate transport. Free energy evaluation of the complete conformational change before and after ATP hydrolysis is helpful to elucidate the mechanism of chemical-to-mechanical energy conversion in MalK dimer, but is lacking in previous studies. In this work, we used molecular dynamics simulations to investigate the structural transition of MalK dimer among closed, semi-open and open states. We observed spontaneous structural transition from closed to open state in the ADP-bound system and partial closure of MalK dimer from the semi-open state in the ATP-bound system. Subsequently, we calculated the reaction pathways connecting the closed and open states for the ATP- and ADP-bound systems and evaluated the free energy profiles along the paths. Our results suggested that the closed state is stable in the presence of ATP but is markedly destabilized when ATP is hydrolyzed to ADP, which thus explains the coupling between ATP hydrolysis and protein conformational change of MalK dimer in thermodynamics. Proteins 2017; 85:207-220. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Xiaoying Lv
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Hao Liu
- Department of Bioinformatics and Biostatistics, State Key Laboratory of Microbial metabolism, College of Life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Haifeng Chen
- Department of Bioinformatics and Biostatistics, State Key Laboratory of Microbial metabolism, College of Life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Haipeng Gong
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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19
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Lv D, Li C, Tan J, Zhang X, Wang C, Su J. Identification of functionally key residues in maltose transporter with an elastic network model-based thermodynamic method. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1234077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Dashuai Lv
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Chunhua Li
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Jianjun Tan
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Xiaoyi Zhang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Cunxin Wang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, China
| | - Jiguo Su
- College of Science, Yanshan University, Qinhuangdao, China
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20
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Prieß M, Schäfer LV. Release of Entropic Spring Reveals Conformational Coupling Mechanism in the ABC Transporter BtuCD-F. Biophys J 2016; 110:2407-2418. [PMID: 27276259 PMCID: PMC4906252 DOI: 10.1016/j.bpj.2016.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 03/30/2016] [Accepted: 04/20/2016] [Indexed: 01/14/2023] Open
Abstract
Substrate translocation by ATP-binding cassette (ABC) transporters involves coupling of ATP binding and hydrolysis in the nucleotide-binding domains (NBDs) to conformational changes in the transmembrane domains. We used molecular dynamics simulations to investigate the atomic-level mechanism of conformational coupling in the ABC transporter BtuCD-F, which imports vitamin B12 across the inner membrane of Escherichia coli. Our simulations show how an engineered disulfide bond across the NBD dimer interface reduces conformational fluctuations and hence configurational entropy. As a result, the disulfide bond is under substantial mechanical stress. Releasing this entropic spring, as is the case in the wild-type transporter, combined with analyzing the pairwise forces between individual residues, unravels the coupling mechanism. The identified pathways along which force is propagated from the NBDs via the coupling helix to the transmembrane domains are composed of highly conserved residues, underlining their functional relevance. This study not only reveals the details of conformational coupling in BtuCD-F, it also provides a promising approach to other long-range conformational couplings, e.g., in ABC exporters or other ATP-driven molecular machines.
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Affiliation(s)
- Marten Prieß
- Center for Theoretical Chemistry, Faculty of Chemistry and Biochemistry, Ruhr-University, Bochum, Germany
| | - Lars V Schäfer
- Center for Theoretical Chemistry, Faculty of Chemistry and Biochemistry, Ruhr-University, Bochum, Germany.
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21
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Carlson ML, Bao H, Duong F. Formation of a Chloride-conducting State in the Maltose ATP-binding Cassette (ABC) Transporter. J Biol Chem 2016; 291:12119-25. [PMID: 27059961 DOI: 10.1074/jbc.m115.711622] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Indexed: 11/06/2022] Open
Abstract
ATP-binding cassette transporters use an alternating access mechanism to move substrates across cellular membranes. This mode of transport ensures the selective passage of molecules while preserving membrane impermeability. The crystal structures of MalFGK2, inward- and outward-facing, show that the transporter is sealed against ions and small molecules. It has yet to be determined whether membrane impermeability is maintained when MalFGK2 cycles between these two conformations. Through the use of a mutant that resides in intermediate conformations close to the transition state, we demonstrate that not only is chloride conductance occurring, but also to a degree large enough to compromise cell viability. Introduction of mutations in the periplasmic gate lead to the formation of a channel that is quasi-permanently open. MalFGK2 must therefore stay away from these ion-conducting conformations to preserve the membrane barrier; otherwise, a few mutations that increase access to the ion-conducting states are enough to convert an ATP-binding cassette transporter into a channel.
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Affiliation(s)
- Michael L Carlson
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Huan Bao
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Franck Duong
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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22
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Liu H, Li D, Li Y, Hou T. Atomistic molecular dynamics simulations of ATP-binding cassette transporters. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2016. [DOI: 10.1002/wcms.1247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Hui Liu
- College of Pharmaceutical Sciences; Zhejiang University; Hangzhou China
| | - Dan Li
- College of Pharmaceutical Sciences; Zhejiang University; Hangzhou China
| | - Youyong Li
- Institute of Functional Nano & Soft Materials (FUNSOM); Soochow University; Suzhou China
| | - Tingjun Hou
- College of Pharmaceutical Sciences; Zhejiang University; Hangzhou China
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23
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Gu RX, Corradi V, Singh G, Choudhury HG, Beis K, Tieleman DP. Conformational Changes of the Antibacterial Peptide ATP Binding Cassette Transporter McjD Revealed by Molecular Dynamics Simulations. Biochemistry 2015; 54:5989-98. [PMID: 26334959 DOI: 10.1021/acs.biochem.5b00753] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ATP binding cassette (ABC) transporters form one of the largest protein superfamilies. They use the energy of ATP hydrolysis to transport chemically diverse ligands across membranes. An alternating access mechanism in which the transporter switches between inward- and outward-facing conformations has been proposed to describe the translocation process. One of the main open questions in this process is the degree of opening of the transporter at different stages of the transport cycle, as crystal structures and biochemical data have suggested a wide range of distances between nucleotide binding domains. Recently, the crystal structure of McjD, an antibacterial peptide ABC transporter from Escherichia coli, revealed a new occluded intermediate state of the transport cycle. The transmembrane domain is closed on both sides of the membrane, forming a cavity that can accommodate its ligand, MccJ25, a lasso peptide of 21 amino acids. In this work, we investigate the degree of opening of the transmembrane cavity required for ligand translocation. By means of steered molecular dynamics simulations, the ligand was pulled from the internal cavity to the extracellular side. This resulted in an outward-facing state. Comparison with existing outward-facing crystal structures shows a smaller degree of opening in the simulations, suggesting that the large conformational changes in some crystal structures may not be necessary even for a large substrate like MccJ25.
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Affiliation(s)
- Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary , 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary , 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Gurpreet Singh
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary , 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Hassanul G Choudhury
- Department of Life Sciences, Imperial College London , South Kensington, London SW7 2AZ, United Kingdom.,Membrane Protein Lab, Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, OX11 0DE, United Kingdom.,Rutherford Appleton Laboratory , Research Complex at Harwell, Oxfordshire OX11 0DE, United Kingdom
| | - Konstantinos Beis
- Department of Life Sciences, Imperial College London , South Kensington, London SW7 2AZ, United Kingdom.,Membrane Protein Lab, Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire, OX11 0DE, United Kingdom.,Rutherford Appleton Laboratory , Research Complex at Harwell, Oxfordshire OX11 0DE, United Kingdom
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary , 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
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24
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Wang JH, Xue XH, Zhou J, Fan CY, Xie QQ, Wang P. Cloning and Iron Transportation of Nucleotide Binding Domain of Cryptosporidium andersoni ATP-Binding Cassette (CaABC) Gene. THE KOREAN JOURNAL OF PARASITOLOGY 2015; 53:335-9. [PMID: 26174828 PMCID: PMC4510675 DOI: 10.3347/kjp.2015.53.3.335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 03/30/2015] [Accepted: 04/10/2015] [Indexed: 12/03/2022]
Abstract
Cryptosporidium andersoni ATP-binding cassette (CaABC) is an important membrane protein involved in substrate transport across the membrane. In this research, the nucleotide binding domain (NBD) of CaABC gene was amplified by PCR, and the eukaryotic expression vector of pEGFP-C1-CaNBD was reconstructed. Then, the recombinant plasmid of pEGFP-C1-CaNBD was transformed into the mouse intestinal epithelial cells (IECs) to study the iron transportation function of CaABC. The results indicated that NBD region of CaABC gene can significantly elevate the transport efficiency of Ca2+, Mg2+, K+, and HCO3- in IECs (P<0.05). The significance of this study is to find the ATPase inhibitors for NBD region of CaABC gene and to inhibit ATP binding and nutrient transport of CaABC transporter. Thus, C. andersoni will be killed by inhibition of nutrient uptake. This will open up a new way for treatment of cryptosporidiosis.
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Affiliation(s)
- Ju-Hua Wang
- College of Animal Science and Technology, Anhui Agriculture University, Hefei, Anhui, 230036, China
| | - Xiu-Heng Xue
- College of Tea & Food Technology, Anhui Agriculture University, Hefei, Anhui, 230036, China
| | - Jie Zhou
- College of Animal Science and Technology, Anhui Agriculture University, Hefei, Anhui, 230036, China
| | - Cai-Yun Fan
- College of Animal Science and Technology, Anhui Agriculture University, Hefei, Anhui, 230036, China
| | - Qian-Qian Xie
- College of Animal Science and Technology, Anhui Agriculture University, Hefei, Anhui, 230036, China
| | - Pan Wang
- College of Animal Science and Technology, Anhui Agriculture University, Hefei, Anhui, 230036, China
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25
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Su JG, Han XM, Zhang X, Hou YX, Zhu JZ, Wu YD. Analysis of conformational motions and related key residue interactions responsible for a specific function of proteins with elastic network model. J Biomol Struct Dyn 2015; 34:560-71. [DOI: 10.1080/07391102.2015.1044910] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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26
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Prajapati R, Sangamwar AT. Translocation mechanism of P-glycoprotein and conformational changes occurring at drug-binding site: Insights from multi-targeted molecular dynamics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2882-98. [DOI: 10.1016/j.bbamem.2014.07.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 07/03/2014] [Accepted: 07/08/2014] [Indexed: 11/29/2022]
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27
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Chang SY, Liu FF, Dong XY, Sun Y. Molecular insight into conformational transmission of human P-glycoprotein. J Chem Phys 2014; 139:225102. [PMID: 24329094 DOI: 10.1063/1.4832740] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
P-glycoprotein (P-gp), a kind of ATP-binding cassette transporter, can export candidates through a channel at the two transmembrane domains (TMDs) across the cell membranes using the energy released from ATP hydrolysis at the two nucleotide-binding domains (NBDs). Considerable evidence has indicated that human P-gp undergoes large-scale conformational changes to export a wide variety of anti-cancer drugs out of the cancer cells. However, molecular mechanism of the conformational transmission of human P-gp from the NBDs to the TMDs is still unclear. Herein, targeted molecular dynamics simulations were performed to explore the atomic detail of the conformational transmission of human P-gp. It is confirmed that the conformational transition from the inward- to outward-facing is initiated by the movement of the NBDs. It is found that the two NBDs move both on the two directions (x and y). The movement on the x direction leads to the closure of the NBDs, while the movement on the y direction adjusts the conformations of the NBDs to form the correct ATP binding pockets. Six key segments (KSs) protruding from the TMDs to interact with the NBDs are identified. The relative movement of the KSs along the y axis driven by the NBDs can be transmitted through α-helices to the rest of the TMDs, rendering the TMDs to open towards periplasm in the outward-facing conformation. Twenty eight key residue pairs are identified to participate in the interaction network that contributes to the conformational transmission from the NBDs to the TMDs of human P-gp. In addition, 9 key residues in each NBD are also identified. The studies have thus provided clear insight into the conformational transmission from the NBDs to the TMDs in human P-gp.
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Affiliation(s)
- Shan-Yan Chang
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Fu-Feng Liu
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Xiao-Yan Dong
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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28
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Li CH, Yang YX, Su JG, Liu B, Tan JJ, Zhang XY, Wang CX. Allosteric transitions of the maltose transporter studied by an elastic network model. Biopolymers 2014; 101:758-68. [DOI: 10.1002/bip.22455] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 12/02/2013] [Accepted: 12/09/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Chun Hua Li
- College of Life Science and Bioengineering; Beijing University of Technology; Beijing 100124 China
| | - Yong Xiao Yang
- College of Life Science and Bioengineering; Beijing University of Technology; Beijing 100124 China
| | - Ji Guo Su
- College of Science; Yanshan University; Qinhuangdao 066004 China
| | - Bin Liu
- College of Life Science and Bioengineering; Beijing University of Technology; Beijing 100124 China
| | - Jian Jun Tan
- College of Life Science and Bioengineering; Beijing University of Technology; Beijing 100124 China
| | - Xiao Yi Zhang
- College of Life Science and Bioengineering; Beijing University of Technology; Beijing 100124 China
| | - Cun Xin Wang
- College of Life Science and Bioengineering; Beijing University of Technology; Beijing 100124 China
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Structure and mechanism of ATP-dependent phospholipid transporters. Biochim Biophys Acta Gen Subj 2014; 1850:461-75. [PMID: 24746984 DOI: 10.1016/j.bbagen.2014.04.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. SCOPE OF REVIEW This review aims to identify common mechanistic features in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. MAJOR CONCLUSIONS Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit. Further, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic molecules have also been found embedded in P-type ATPase crystal structures. Taken together, in two diverse groups of pumps, nature appears to have evolved quite similar ways of flipping phospholipids. GENERAL SIGNIFICANCE Our understanding of the structural basis for phospholipid flipping is still limited but it seems plausible that a general mechanism for phospholipid flipping exists in nature. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
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Bao H, Duong F. Nucleotide-free MalK drives the transition of the maltose transporter to the inward-facing conformation. J Biol Chem 2014; 289:9844-51. [PMID: 24526688 DOI: 10.1074/jbc.m113.545525] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The complex MalFGK2 hydrolyzes ATP and alternates between inward- and outward-facing conformations during maltose transport. It has been shown that ATP promotes closure of MalK2 and opening of MalFG toward the periplasm. Yet, why the transporter rests in a conformation facing the cytosol in the absence of nucleotide and how it returns to this state after hydrolysis of ATP is unknown. The membrane domain MalFG may be naturally stable in the inward-facing conformation, or the ABC domain may catalyze the transition. We address this question by analyzing the conformation of MalFG in nanodiscs and in proteoliposomes. We find that MalFG alone exists in an intermediate state until MalK binds and converts the membrane domain to the inward-facing state. We also find that MalK, if overly-bound to MalFG, blocks the transition of the transporter, whereas suppressor mutations that weaken this association restore transport. MalK therefore exploits hydrolysis of ATP to reverse the conformation of MalFG to the inward-facing conformation, a step essential for release of maltose in the cytosol.
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Affiliation(s)
- Huan Bao
- From the Department of Biochemistry and Molecular Biology, Life Sciences Institute, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia V6T1Z3, Canada
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31
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The Maltose ABC Transporter: Where Structure Meets Function. SPRINGER SERIES IN BIOPHYSICS 2014. [DOI: 10.1007/978-3-642-53839-1_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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32
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A Microscopic View of the Mechanisms of Active Transport Across the Cellular Membrane. ANNUAL REPORTS IN COMPUTATIONAL CHEMISTRY 2014. [DOI: 10.1016/b978-0-444-63378-1.00004-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Mechanistic picture for conformational transition of a membrane transporter at atomic resolution. Proc Natl Acad Sci U S A 2013; 110:18916-21. [PMID: 24191018 DOI: 10.1073/pnas.1313202110] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During their transport cycle, ATP-binding cassette (ABC) transporters undergo large-scale conformational changes between inward- and outward-facing states. Using an approach based on designing system-specific reaction coordinates and using nonequilibrium work relations, we have performed extensive all-atom molecular dynamics simulations in the presence of explicit membrane/solvent to sample a large number of mechanistically distinct pathways for the conformational transition of MsbA, a bacterial ABC exporter whose structure has been solved in multiple functional states. The computational approach developed here is based on (i) extensive exploration of system-specific biasing protocols (e.g., using collective variables designed based on available low-resolution crystal structures) and (ii) using nonequilibrium work relations for comparing the relevance of the transition pathways. The most relevant transition pathway identified using this approach involves several distinct stages reflecting the complex nature of the structural changes associated with the function of the protein. The opening of the cytoplasmic gate during the outward- to inward-facing transition of apo MsbA is found to be disfavored when the periplasmic gate is open and facilitated by a twisting motion of the nucleotide-binding domains that involves a dramatic change in their relative orientation. These results highlight the cooperativity between the transmembrane and the nucleotide-binding domains in the conformational transition of ABC exporters. The approach introduced here provides a framework to study large-scale conformational changes of other membrane transporters whose computational investigation at an atomic resolution may not be currently feasible using conventional methods.
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34
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Ma J, Biggin PC. Substrate versus inhibitor dynamics of P-glycoprotein. Proteins 2013; 81:1653-68. [PMID: 23670856 DOI: 10.1002/prot.24324] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 03/24/2013] [Accepted: 04/19/2013] [Indexed: 12/20/2022]
Abstract
By far the most studied multidrug resistance protein is P-glycoprotein. Despite recent structural data, key questions about its function remain. P-glycoprotein (P-gp) is flexible and undergoes large conformational changes as part of its function and in this respect, details not only of the export cycle, but also the recognition stage are currently lacking. Given the flexibility, molecular dynamics (MD) simulations provide an ideal tool to examine this aspect in detail. We have performed MD simulations to examine the behaviour of P-gp. In agreement with previous reports, we found that P-gp undergoes large conformational changes which tended to result in the nucleotide-binding domains coming closer together. In all simulations, the approach of the NBDs was asymmetrical in agreement with previous observations for other ABC transporter proteins. To validate the simulations, we make extensive comparison to previous cross-linking data. Our results show very good agreement with the available data. We then went on to compare the influence of inhibitor compounds bound with simulations of a substrate (daunorubicin) bound. Our results suggest that inhibitors may work by keeping the NBDs apart, thus preventing ATP-hydrolysis. On the other hand, repeat simulations of daunorubicin (substrate) in one particular binding pose suggest that the approach of the NBDs is not impaired and that the structure would be still be competent to perform ATP hydrolysis, thus providing a model for inhibition or substrate transport. Finally we compare the latter to earlier QSAR data to provide a model for the first part of substrate transport within P-gp.
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Affiliation(s)
- Jerome Ma
- Department of Biochemistry, Structural Bioinformatics and Computational Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
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35
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Wen PC, Verhalen B, Wilkens S, Mchaourab HS, Tajkhorshid E. On the origin of large flexibility of P-glycoprotein in the inward-facing state. J Biol Chem 2013; 288:19211-20. [PMID: 23658020 PMCID: PMC3696692 DOI: 10.1074/jbc.m113.450114] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
P-glycoprotein (Pgp) is one of the most biomedically relevant transporters in the ATP binding
cassette (ABC) superfamily due to its involvement in developing multidrug resistance in cancer
cells. Employing molecular dynamics simulations and double electron-electron resonance spectroscopy,
we have investigated the structural dynamics of membrane-bound Pgp in the inward-facing state and
found that Pgp adopts an unexpectedly wide range of conformations, highlighted by the degree of
separation between the two nucleotide-binding domains (NBDs). The distance between the two NBDs in
the equilibrium simulations covers a range of at least 20 Å, including, both, more open and
more closed NBD configurations than the crystal structure. The double electron-electron resonance
measurements on spin-labeled Pgp mutants also show wide distributions covering both longer and
shorter distances than those observed in the crystal structure. Based on structural and sequence
analyses, we propose that the transmembrane domains of Pgp might be more flexible than other
structurally known ABC exporters. The structural flexibility of Pgp demonstrated here is not only in
close agreement with, but also helps rationalize, the reported high NBD fluctuations in several ABC
exporters and possibly represents a fundamental difference in the transport mechanism between ABC
exporters and ABC importers. In addition, during the simulations we have captured partial entrance
of a lipid molecule from the bilayer into the lumen of Pgp, reaching the putative drug binding site.
The location of the protruding lipid suggests a putative pathway for direct drug recruitment from
the membrane.
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Affiliation(s)
- Po-Chao Wen
- Center for Biophysics and Computational Biology, Department of Biochemistry, College of Medicine, and The Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illnois 61801, USA
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36
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In silico model for P-glycoprotein substrate prediction: insights from molecular dynamics and in vitro studies. J Comput Aided Mol Des 2013; 27:347-63. [DOI: 10.1007/s10822-013-9650-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 04/16/2013] [Indexed: 11/25/2022]
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37
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Transient formation of water-conducting states in membrane transporters. Proc Natl Acad Sci U S A 2013; 110:7696-701. [PMID: 23610412 DOI: 10.1073/pnas.1218986110] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Membrane transporters rely on highly coordinated structural transitions between major conformational states for their function, to prevent simultaneous access of the substrate binding site to both sides of the membrane--a mode of operation known as the alternating access model. Although this mechanism successfully accounts for the efficient exchange of the primary substrate across the membrane, accruing evidence on significant water transport and even uncoupled ion transport mediated by transporters has challenged the concept of perfect mechanical coupling and coordination of the gating mechanism in transporters, which might be expected from the alternating access model. Here, we present a large set of extended equilibrium molecular dynamics simulations performed on several classes of membrane transporters in different conformational states, to test the presence of the phenomenon in diverse transporter classes and to investigate the underlying molecular mechanism of water transport through membrane transporters. The simulations reveal spontaneous formation of transient water-conducting (channel-like) states allowing passive water diffusion through the lumen of the transporters. These channel-like states are permeable to water but occluded to substrate, thereby not hindering the uphill transport of the primary substrate, i.e., the alternating access model remains applicable to the substrate. The rise of such water-conducting states during the large-scale structural transitions of the transporter protein is indicative of imperfections in the coordinated closing and opening motions of the cytoplasmic and extracellular gates. We propose that the observed water-conducting states likely represent a universal phenomenon in membrane transporters, which is consistent with their reliance on large-scale motion for function.
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38
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Shaikh S, Li J, Enkavi G, Wen PC, Huang Z, Tajkhorshid E. Visualizing functional motions of membrane transporters with molecular dynamics simulations. Biochemistry 2013; 52:569-87. [PMID: 23298176 PMCID: PMC3560430 DOI: 10.1021/bi301086x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 12/21/2012] [Indexed: 01/08/2023]
Abstract
Computational modeling and molecular simulation techniques have become an integral part of modern molecular research. Various areas of molecular sciences continue to benefit from, indeed rely on, the unparalleled spatial and temporal resolutions offered by these technologies, to provide a more complete picture of the molecular problems at hand. Because of the continuous development of more efficient algorithms harvesting ever-expanding computational resources, and the emergence of more advanced and novel theories and methodologies, the scope of computational studies has expanded significantly over the past decade, now including much larger molecular systems and far more complex molecular phenomena. Among the various computer modeling techniques, the application of molecular dynamics (MD) simulation and related techniques has particularly drawn attention in biomolecular research, because of the ability of the method to describe the dynamical nature of the molecular systems and thereby to provide a more realistic representation, which is often needed for understanding fundamental molecular properties. The method has proven to be remarkably successful in capturing molecular events and structural transitions highly relevant to the function and/or physicochemical properties of biomolecular systems. Herein, after a brief introduction to the method of MD, we use a number of membrane transport proteins studied in our laboratory as examples to showcase the scope and applicability of the method and its power in characterizing molecular motions of various magnitudes and time scales that are involved in the function of this important class of membrane proteins.
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Affiliation(s)
- Saher
A. Shaikh
- Department of Biochemistry, Beckman Institute for Advanced
Science and Technology, and Center for Biophysics and Computational
Biology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - Jing Li
- Department of Biochemistry, Beckman Institute for Advanced
Science and Technology, and Center for Biophysics and Computational
Biology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - Giray Enkavi
- Department of Biochemistry, Beckman Institute for Advanced
Science and Technology, and Center for Biophysics and Computational
Biology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - Po-Chao Wen
- Department of Biochemistry, Beckman Institute for Advanced
Science and Technology, and Center for Biophysics and Computational
Biology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - Zhijian Huang
- Department of Biochemistry, Beckman Institute for Advanced
Science and Technology, and Center for Biophysics and Computational
Biology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Department of Biochemistry, Beckman Institute for Advanced
Science and Technology, and Center for Biophysics and Computational
Biology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States
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39
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Enkavi G, Li J, Mahinthichaichan P, Wen PC, Huang Z, Shaikh SA, Tajkhorshid E. Simulation studies of the mechanism of membrane transporters. Methods Mol Biol 2013; 924:361-405. [PMID: 23034756 DOI: 10.1007/978-1-62703-017-5_14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Membrane transporters facilitate active transport of their specific substrates, often against their electrochemical gradients across the membrane, through coupling the process to various sources of cellular energy, for example, ATP binding and hydrolysis in primary transporters, and pre-established electrochemical gradient of molecular species other than the substrate in the case of secondary transporters. In order to provide efficient energy-coupling mechanisms, membrane transporters have evolved into molecular machines in which stepwise binding, translocation, and transformation of various molecular species are closely coupled to protein conformational changes that take the transporter from one functional state to another during the transport cycle. Furthermore, in order to prevent the formation of leaky states and to be able to pump the substrate against its electrochemical gradient, all membrane transporters use the widely-accepted "alternating access mechanism," which ensures that the substrate is only accessible from one side of the membrane at a given time, but relies on complex and usually global protein conformational changes that differ for each family of membrane transporters. Describing the protein conformational changes of different natures and magnitudes is therefore at the heart of mechanistic studies of membrane transporters. Here, using a number of membrane transporters from diverse families, we present common protocols used in setting up and performing molecular dynamics simulations of membrane transporters and in analyzing the results, in order to characterize relevant motions of the system. The emphasis will be on highlighting how optimal design of molecular dynamics simulations combined with mechanistically oriented analysis can shed light onto key functionally relevant protein conformational changes in this family of membrane proteins.
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Affiliation(s)
- Giray Enkavi
- Department of Biochemistry, Center for Biophysics and Computational Biology, College of Medicine, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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40
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Biswas-Fiss EE, Affet S, Ha M, Biswas SB. Retinoid binding properties of nucleotide binding domain 1 of the Stargardt disease-associated ATP binding cassette (ABC) transporter, ABCA4. J Biol Chem 2012; 287:44097-107. [PMID: 23144455 DOI: 10.1074/jbc.m112.409623] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The retina-specific ATP binding cassette transporter, ABCA4 protein, is associated with a broad range of inherited macular degenerations, including Stargardt disease, autosomal recessive cone rod dystrophy, and fundus flavimaculatus. In order to understand its role in retinal transport in rod out segment discs, we have investigated the interactions of the soluble domains of ABCA4 with both 11-cis- and all-trans-retinal. Using fluorescence anisotropy-based binding analysis and recombinant polypeptides derived from the amino acid sequences of the four soluble domains of ABCA4, we demonstrated that the nucleotide binding domain 1 (NBD1) specifically bound 11-cis-retinal. Its affinity for all-trans-retinal was markedly reduced. Stargardt disease-associated mutations in this domain resulted in attenuation of 11-cis-retinal binding. Significant differences in 11-cis-retinal binding affinities were observed between NBD1 and other cytoplasmic and lumenal domains of ABCA4. The results suggest a possible role of ABCA4 and, in particular, the NBD1 domain in 11-cis-retinal binding. These results also correlate well with a recent report on the in vivo role of ABCA4 in 11-cis-retinal transport.
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Affiliation(s)
- Esther E Biswas-Fiss
- Department of Bioscience Technologies, Program in Biotechnology, Jefferson School of Health Professions, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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41
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Jones PM, George AM. Mechanism of the ABC transporter ATPase domains: catalytic models and the biochemical and biophysical record. Crit Rev Biochem Mol Biol 2012; 48:39-50. [PMID: 23131203 DOI: 10.3109/10409238.2012.735644] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
ABC transporters comprise a large, diverse, and ubiquitous superfamily of membrane active transporters. Their core architecture is a dimer of dimers, comprising two transmembrane domains that bind substrate and form the channel, and two ATP-binding cassettes, which bind and hydrolyze ATP to energize the translocase function. The prevailing paradigm for the ABC transport mechanism is the Switch Model, in which the nucleotide binding domains are proposed to dimerise upon binding of two ATP molecules, and thence dissociate upon sequential hydrolysis of the ATP. This idea appears consistent with crystal structures of both isolated subunits and whole transporters, as well as with a significant body of biochemical data. Nonetheless, an alternative Constant Contact Model has been proposed, in which the nucleotide binding domains do not fully dissociate, and ATP hydrolysis occurs alternately at each of the two active sites. Here, we review the biochemical and biophysical data relating to the ABC catalytic mechanism, to show how they may be construed as consistent with a Constant Contact Model, and to assess to what extent they support the Switch Model.
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Affiliation(s)
- Peter M Jones
- School of Medical and Molecular Biosciences, University of Technology Sydney, Broadway, NSW, Australia
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42
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George AM, Jones PM. Perspectives on the structure-function of ABC transporters: the Switch and Constant Contact models. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 109:95-107. [PMID: 22765920 DOI: 10.1016/j.pbiomolbio.2012.06.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 06/14/2012] [Indexed: 12/20/2022]
Abstract
ABC transporters constitute one of the largest protein families across the kingdoms of archaea, eubacteria and eukarya. They couple ATP hydrolysis to vectorial translocation of diverse substrates across membranes. The ABC transporter architecture comprises two transmembrane domains and two cytosolic ATP-binding cassettes. During 2002-2012, nine prokaryotic ABC transporter structures and two eukaryotic structures have been solved to medium resolution. Despite a wealth of biochemical, biophysical, and structural data, fundamental questions remain regarding the coupling of ATP hydrolysis to unidirectional substrate translocation, and the mechanistic suite of steps involved. The mechanics of the ATP cassette dimer is defined most popularly by the 'Switch Model', which proposes that hydrolysis in each protomer is sequential, and that as the sites are freed of nucleotide, the protomers lose contact across a large solvent-filled gap of 20-30 Å; as captured in several X-ray solved structures. Our 'Constant Contact' model for the operational mechanics of ATP binding and hydrolysis in the ATP-binding cassettes is derived from the 'alternating sites' model, proposed in 1995, and which requires an intrinsic asymmetry in the ATP sites, but does not require the partner protomers to lose contact. Thus one of the most debated issues regarding the function of ABC transporters is whether the cooperative mechanics of ATP hydrolysis requires the ATP cassettes to separate or remain in constant contact and this dilemma is discussed at length in this review.
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Affiliation(s)
- Anthony M George
- School of Medical and Molecular Biosciences, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia.
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Jones PM, George AM. Role of the D-loops in allosteric control of ATP hydrolysis in an ABC transporter. J Phys Chem A 2012; 116:3004-13. [PMID: 22369471 DOI: 10.1021/jp211139s] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
ABC transporters couple ATP hydrolysis to movement of substrates across cell membranes. They comprise two transmembrane domains and two cytosolic nucleotide-binding domains forming two active sites that hydrolyze ATP cooperatively. The mechanism of ATP hydrolysis is controversial and the structural dynamic basis of its allosteric control unknown. Here we report molecular dynamics simulations of the ATP/apo and ATP/ADP states of the bacterial ABC exporter Sav1866, in which the cytoplasmic region of the protein was simulated in explicit water for 150 ns. In the simulation of the ATP/apo state, we observed, for the first time, conformers of the active site with the canonical geometry for an in-line nucleophilic attack on the ATP γ-phosphate. The conserved glutamate immediately downstream of the Walker B motif is the catalytic base, forming a dyad with the H-loop histidine, whereas the Q-loop glutamine has an organizing role. Each D-loop provides a coordinating residue of the attacking water, and comparison with the simulation of the ATP/ADP state suggests that via their flexibility, the D-loops modulate formation of the hydrolysis-competent state. A global switch involving a coupling helix delineates the signal transmission route by which allosteric control of ATP hydrolysis in ABC transporters is mediated.
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Affiliation(s)
- Peter M Jones
- School of Medical and Molecular Biosciences, and iThree Institute, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia.
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Neubauer O, Reiffler C, Behrendt L, Eitinger T. Interactions among the A and T units of an ECF-type biotin transporter analyzed by site-specific crosslinking. PLoS One 2011; 6:e29087. [PMID: 22216173 PMCID: PMC3246461 DOI: 10.1371/journal.pone.0029087] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 11/18/2011] [Indexed: 12/18/2022] Open
Abstract
Energy-coupling factor (ECF) transporters are a huge group of micronutrient importers in prokaryotes. They are composed of a substrate-specific transmembrane protein (S component) and a module consisting of a moderately conserved transmembrane protein (T component) and two ABC ATPase domains (A components). Modules of A and T units may be dedicated to a specific S component or shared by many different S units in an organism. The mode of subunit interactions in ECF transporters is largely unknown. BioMNY, the focus of the present study, is a biotin transporter with a dedicated AT module. It consists of the S unit BioY, the A unit BioM and the T unit BioN. Like all T units, BioN contains two three-amino-acid signatures with a central Arg residue in a cytoplasmic helical region. Our previous work had demonstrated a central role of the two motifs in T units for stability and function of BioMNY and other ECF transporters. Here we show by site-specific crosslinking of pairs of mono-cysteine variants that the Ala-Arg-Ser and Ala-Arg-Gly signatures in BioN are coupling sites to the BioM ATPases. Analysis of 64 BioN-BioM pairs uncovered interactions of both signatures predominantly with a segment of ∼13 amino acid residues C-terminal of the Q loop of BioM. Our results further demonstrate that portions of all BioN variants with single Cys residues in the two signatures are crosslinked to homodimers. This finding may point to a dimeric architecture of the T unit in BioMNY complexes.
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Affiliation(s)
- Olivia Neubauer
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
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Vergauwen B, Van der Meeren R, Dansercoer A, Savvides SN. Delineation of the Pasteurellaceae-specific GbpA-family of glutathione-binding proteins. BMC BIOCHEMISTRY 2011; 12:59. [PMID: 22087650 PMCID: PMC3295651 DOI: 10.1186/1471-2091-12-59] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/16/2011] [Indexed: 01/27/2023]
Abstract
BACKGROUND The Gram-negative bacterium Haemophilus influenzae is a glutathione auxotroph and acquires the redox-active tripeptide by import. The dedicated glutathione transporter belongs to the ATP-binding cassette (ABC)-transporter superfamily and displays more than 60% overall sequence identity with the well-studied dipeptide (Dpp) permease of Escherichia coli. The solute binding protein (SBP) that mediates glutathione transport in H. influenzae is a lipoprotein termed GbpA and is 54% identical to E. coli DppA, a well-studied member of family 5 SBP's. The discovery linking GbpA to glutathione import came rather unexpectedly as this import-priming SBP was previously annotated as a heme-binding protein (HbpA), and was thought to mediate heme acquisition. Nonetheless, although many SBP's have been implicated in more than one function, a prominent physiological role for GbpA and its partner permease in heme acquisition appears to be very unlikely. Here, we sought to characterize five representative GbpA homologs in an effort to delineate the novel GbpA-family of glutathione-specific family 5 SBPs and to further clarify their functional role in terms of ligand preferences. RESULTS Lipoprotein and non-lipoprotein GbpA homologs were expressed in soluble form and substrate specificity was evaluated via a number of ligand binding assays. A physiologically insignificant affinity for hemin was observed for all five GbpA homologous test proteins. Three out of five test proteins were found to bind glutathione and some of its physiologically relevant derivatives with low- or submicromolar affinity. None of the tested SBP family 5 allocrites interacted with the remaining two GbpA test proteins. Structure-based sequence alignments and phylogenetic analysis show that the two binding-inert GbpA homologs clearly form a separate phylogenetic cluster. To elucidate a structure-function rationale for this phylogenetic differentiation, we determined the crystal structure of one of the GbpA family outliers from H. parasuis. Comparisons thereof with the previously determined structure of GbpA in complex with oxidized glutathione reveals the structural basis for the lack of allocrite binding capacity, thereby explaining the outlier behavior. CONCLUSIONS Taken together, our studies provide for the first time a collective functional look on a novel, Pasteurellaceae-specific, SBP subfamily of glutathione binding proteins, which we now term GbpA proteins. Our studies strongly implicate GbpA family SBPs in the priming step of ABC-transporter-mediated translocation of useful forms of glutathione across the inner membrane, and rule out a general role for GbpA proteins in heme acquisition.
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Affiliation(s)
- Bjorn Vergauwen
- Unit for Structural Biology, Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University, 9000 Ghent, Belgium.
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