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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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Badiee SA, Isu UH, Khodadadi E, Moradi M. The Alternating Access Mechanism in Mammalian Multidrug Resistance Transporters and Their Bacterial Homologs. MEMBRANES 2023; 13:568. [PMID: 37367772 DOI: 10.3390/membranes13060568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 05/23/2023] [Accepted: 05/27/2023] [Indexed: 06/28/2023]
Abstract
Multidrug resistance (MDR) proteins belonging to the ATP-Binding Cassette (ABC) transporter group play a crucial role in the export of cytotoxic drugs across cell membranes. These proteins are particularly fascinating due to their ability to confer drug resistance, which subsequently leads to the failure of therapeutic interventions and hinders successful treatments. One key mechanism by which multidrug resistance (MDR) proteins carry out their transport function is through alternating access. This mechanism involves intricate conformational changes that enable the binding and transport of substrates across cellular membranes. In this extensive review, we provide an overview of ABC transporters, including their classifications and structural similarities. We focus specifically on well-known mammalian multidrug resistance proteins such as MRP1 and Pgp (MDR1), as well as bacterial counterparts such as Sav1866 and lipid flippase MsbA. By exploring the structural and functional features of these MDR proteins, we shed light on the roles of their nucleotide-binding domains (NBDs) and transmembrane domains (TMDs) in the transport process. Notably, while the structures of NBDs in prokaryotic ABC proteins, such as Sav1866, MsbA, and mammalian Pgp, are identical, MRP1 exhibits distinct characteristics in its NBDs. Our review also emphasizes the importance of two ATP molecules for the formation of an interface between the two binding sites of NBD domains across all these transporters. ATP hydrolysis occurs following substrate transport and is vital for recycling the transporters in subsequent cycles of substrate transportation. Specifically, among the studied transporters, only NBD2 in MRP1 possesses the ability to hydrolyze ATP, while both NBDs of Pgp, Sav1866, and MsbA are capable of carrying out this reaction. Furthermore, we highlight recent advancements in the study of MDR proteins and the alternating access mechanism. We discuss the experimental and computational approaches utilized to investigate the structure and dynamics of MDR proteins, providing valuable insights into their conformational changes and substrate transport. This review not only contributes to an enhanced understanding of multidrug resistance proteins but also holds immense potential for guiding future research and facilitating the development of effective strategies to overcome multidrug resistance, thus improving therapeutic interventions.
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Affiliation(s)
- Shadi A Badiee
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Ugochi H Isu
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Ehsaneh Khodadadi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
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3
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Oepen K, Mater V, Schneider D. Unfolding Individual Domains of BmrA, a Bacterial ABC Transporter Involved in Multidrug Resistance. Int J Mol Sci 2023; 24:ijms24065239. [PMID: 36982314 PMCID: PMC10049088 DOI: 10.3390/ijms24065239] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/01/2023] [Accepted: 03/06/2023] [Indexed: 03/30/2023] Open
Abstract
The folding and stability of proteins are often studied via unfolding (and refolding) a protein with urea. Yet, in the case of membrane integral protein domains, which are shielded by a membrane or a membrane mimetic, urea generally does not induce unfolding. However, the unfolding of α-helical membrane proteins may be induced by the addition of sodium dodecyl sulfate (SDS). When protein unfolding is followed via monitoring changes in Trp fluorescence characteristics, the contributions of individual Trp residues often cannot be disentangled, and, consequently, the folding and stability of the individual domains of a multi-domain membrane protein cannot be studied. In this study, the unfolding of the homodimeric bacterial ATP-binding cassette (ABC) transporter Bacillus multidrug resistance ATP (BmrA), which comprises a transmembrane domain and a cytosolic nucleotide-binding domain, was investigated. To study the stability of individual BmrA domains in the context of the full-length protein, the individual domains were silenced by mutating the existent Trps. The SDS-induced unfolding of the corresponding constructs was compared to the (un)folding characteristics of the wild-type (wt) protein and isolated domains. The full-length variants BmrAW413Y and BmrAW104YW164A were able to mirror the changes observed with the isolated domains; thus, these variants allowed for the study of the unfolding and thermodynamic stability of mutated domains in the context of full-length BmrA.
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Affiliation(s)
- Kristin Oepen
- Department of Chemistry-Biochemistry, Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany
| | - Veronika Mater
- Department of Chemistry-Biochemistry, Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany
| | - Dirk Schneider
- Department of Chemistry-Biochemistry, Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany
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4
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Bonito CA, Ferreira RJ, Ferreira MJU, Gillet JP, Cordeiro MNDS, Dos Santos DJVA. Long-range communication between transmembrane- and nucleotide-binding domains does not depend on drug binding to mutant P-glycoprotein. J Biomol Struct Dyn 2023; 41:14428-14437. [PMID: 36858814 DOI: 10.1080/07391102.2023.2181633] [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: 11/19/2022] [Accepted: 02/12/2023] [Indexed: 03/03/2023]
Abstract
In this study, the impact of four P-gp mutations (G185V, G830V, F978A and ΔF335) on drug-binding and efflux-related signal-transmission mechanism was comprehensively evaluated in the presence of ligands within the drug-binding pocket (DBP), experimentally related with changes in their drug efflux profiles. The severe repacking of the transmembrane helices (TMH), induced by mutations and exacerbated by the presence of ligands, indicates that P-gp is sensitive to perturbations in the transmembrane region. Alterations on drug-binding were also observed as a consequence of the TMH repacking, but were not always correlated with alterations on ligands binding mode and/or binding affinity. Finally, and although all P-gp variants holo systems showed considerable changes in the intracellular coupling helices/nucleotide-binding domain (ICH-NBD) interactions, they seem to be primarily induced by the mutation itself rather than by the presence of ligands within the DBP. The data further suggest that the changes in drug efflux experimentally reported are mostly related with changes on drug specificity rather than effects on signal-transmission mechanism. We also hypothesize that an increase in the drug-binding affinity may also be related with the decreased drug efflux, while minor changes in binding affinities are possibly related with the increased drug efflux observed in transfected cells.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Cátia A Bonito
- LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, Porto, Portugal
| | - Ricardo J Ferreira
- Red Glead Discovery AB, Medicon Village, Lund, Sweden
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Maria-José U Ferreira
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Jean-Pierre Gillet
- Laboratory of Molecular Cancer Biology, URPhyM, NARILIS, Faculty of Medicine, University of Namur, Namur, Belgium
| | - M Natália D S Cordeiro
- LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, Porto, Portugal
| | - Daniel J V A Dos Santos
- LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, Porto, Portugal
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- CBIOS-Research Center for Biosciences & Health Technologies, Universidade Lusófona de Humanidades e Tecnologias, Lisbon, Portugal
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Feyzizadeh M, Barfar A, Nouri Z, Sarfraz M, Zakeri-Milani P, Valizadeh H. Overcoming multidrug resistance through targeting ABC transporters: lessons for drug discovery. Expert Opin Drug Discov 2022; 17:1013-1027. [PMID: 35996765 DOI: 10.1080/17460441.2022.2112666] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION The argument around cancer therapy is an old one. Using chemotherapeutic drugs, as one of the most effective strategies in treatment of malignancies, is restricted by various issues that progress during therapy and avoid achieving clinical endpoints. Multidrug resistance (MDR), frequently mediated by ATP-binding cassette (ABC) transporters, is one of the most recognized obstacles in the success of pharmacological anticancer approaches. These transporters efflux diverse drugs to extracellular environment, causing MDR and responsiveness of tumor cells to chemotherapy diminishes. AREAS COVERED Several strategies have been used to overcome MDR phenomenon. Succession in this field requires complete knowledge about features and mechanism of ABC transporters. In this review, conventional synthetic and natural inhibitors are discussed first and then novel approaches including RNA, monoclonal antibodies, nanobiotechnology, and structural modification techniques are represented. EXPERT OPINION With increasing frequency of MDR in cancer cells, it is essential to develop new drugs to inhibit MDR. Using knowledge acquired about ABC transporter's structure, rational design of inhibitors is possible. Also, some herbal products have shown to be potential lead compounds in drug discovery for reversal of MDR.
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Affiliation(s)
- Mohammad Feyzizadeh
- Student Research Committee and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Ashkan Barfar
- Student Research Committee and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zeinab Nouri
- Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Parvin Zakeri-Milani
- Liver and Gastrointestinal Diseases Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Hadi Valizadeh
- Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Science, Tabriz, Iran
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Xiao Q, Zhao W, Wu C, Wang X, Chen J, Shi X, Sha S, Li J, Liang X, Yang Y, Guo H, Wang Y, Fan J. Lemon-Derived Extracellular Vesicles Nanodrugs Enable to Efficiently Overcome Cancer Multidrug Resistance by Endocytosis-Triggered Energy Dissipation and Energy Production Reduction. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105274. [PMID: 35187842 PMCID: PMC9284146 DOI: 10.1002/advs.202105274] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Indexed: 05/20/2023]
Abstract
Multidrug resistance remains a great challenge for cancer chemotherapy. Herein, a biomimetic drug delivery system based on lemon-derived extracellular vesicles (EVs) nanodrugs (marked with heparin-cRGD-EVs-doxorubicin (HRED)) is demonstrated, achieving highly efficient overcoming cancer multidrug resistance. The HRED is fabricated by modifying functional heparin-cRGD (HR) onto the surface of EVs and then by loading with doxorubicin (DOX). The obtained HRED enable to effectively enter DOX-resistant cancer cells by caveolin-mediated endocytosis (main), macropinocytosis (secondary), and clathrin-mediated endocytosis (last), exhibiting excellent cellular uptake capacity. The diversified endocytosis capacity of HRED can efficiently dissipate intracellular energy and meanwhile trigger downstream production reduction of adenosine triphosphate (ATP), leading to a significant reduction of drug efflux. Consequently, they show excellent anti-proliferation capacities to DOX-resistant ovarian cancer, ensuring the efficiently overcoming ovarian cancer multidrug resistance in vivo. The authors believe this strategy provides a new strategy by endocytosis triggered-energy dissipation and ATP production reduction to design drug delivery system for overcoming cancer multidrug resistance.
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Affiliation(s)
- Qian Xiao
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Wei Zhao
- Division of Vascular and Interventional RadiologyDepartment of General Surgery, Nanfang HospitalSouthern Medical UniversityGuangzhouGuangdong510515P. R. China
| | - Chentian Wu
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Xuejiao Wang
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Jianping Chen
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Xiubo Shi
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Suinan Sha
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Jinheng Li
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Xiaomei Liang
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Yulu Yang
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Haoyan Guo
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Ying Wang
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
| | - Jun‐Bing Fan
- Cancer Research InstituteExperimental Education/Administration CenterSchool of Basic Medical SciencesSouthern Medical UniversityGuangzhou510515P. R. China
- Department of Hepatobiliary Surgery IIZhujiang HospitalSouthern Medical UniversityGuangzhou510515P. R. China
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Abstract
ATP-binding cassette (ABC) transporters constitute one of the largest and most ancient protein superfamilies found in all living organisms. They function as molecular machines by coupling ATP binding, hydrolysis, and phosphate release to translocation of diverse substrates across membranes. The substrates range from vitamins, steroids, lipids, and ions to peptides, proteins, polysaccharides, and xenobiotics. ABC transporters undergo substantial conformational changes during substrate translocation. A comprehensive understanding of their inner workings thus requires linking these structural rearrangements to the different functional state transitions. Recent advances in single-particle cryogenic electron microscopy have not only delivered crucial information on the architecture of several medically relevant ABC transporters and their supramolecular assemblies, including the ATP-sensitive potassium channel and the peptide-loading complex, but also made it possible to explore the entire conformational space of these nanomachines under turnover conditions and thereby gain detailed mechanistic insights into their mode of action.
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Affiliation(s)
- Christoph Thomas
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany; ,
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany; ,
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8
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Structural dynamics of ABC transporters: molecular simulation studies. Biochem Soc Trans 2021; 49:405-414. [PMID: 33634827 DOI: 10.1042/bst20200710] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/31/2022]
Abstract
The biological activities of living organisms involve various inputs and outputs. The ATP-driven substances (biomolecules) responsible for these kinds of activities through membrane (i.e. uptake and efflux of substrates) include ATP-binding cassette (ABC) transporters, some of which play important roles in multidrug resistance. The basic architecture of ABC transporters comprises transmembrane domains (TMDs) and nucleotide-binding domains (NBDs). The functional dynamics (substrate transport) of ABC transporters are realized by concerted motions, such as NBD dimerization, mechanical transmission via coupling helices (CHs), and the translocation of substrates through TMDs, which are induced by the binding and/or hydrolysis of ATP molecules and substrates. In this mini-review, we briefly discuss recent progresses in the structural dynamics as revealed by molecular simulation studies at all-atom (AA), coarse-grained (CG), and quantum mechanics/molecular mechanics (QM/MM) levels.
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9
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Singh A, Patel SK, Kumar P, Das KC, Verma D, Sharma R, Tripathi T, Giri R, Martins N, Garg N. Quercetin acts as a P-gp modulator via impeding signal transduction from nucleotide-binding domain to transmembrane domain. J Biomol Struct Dyn 2020; 40:4507-4515. [PMID: 33306006 DOI: 10.1080/07391102.2020.1858966] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The inherent ability of the cancer cells to resist chemotherapeutic agents is a major challenge in drug discovery. Chemotherapy is one of the most widely used treatment methods for cancer, but due to multidrug resistance (MDR) development in cancer cells, the healing procedure often fails. Various factors impart cancer resistance to cells; among them, P-glycoprotein (P-gp) overexpression is directly linked to MDR in cancer cells. P-gp leads to the efflux of drug molecules to the extracellular space. Several molecules have been reported to inhibit the P-gp activity. Among them, quercetin has revealed a great potential to modulate P-gp activity. However, the mechanistic understanding of quercetin induced modulation is not entirely elucidated. In the present work, we showed that quercetin binds in the interacting region between the transmembrane domain and nucleotide-binding domain out of the three plausible binding sites of P-gp and restrict the conformational change from inward- to outward-facing conformation of P-gp. Due to the absence of the inward-facing structure of human P-gp, we first modeled an inward-facing P-gp structure. Using molecular docking, the interacting residues of P-gp were identified, and the stability and interaction dynamics of the complex were studied using molecular dynamics simulation. Our work reveals the mechanistic understanding of quercetin induced modulation of P-gp and indicates its importance in cancer treatment.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Ashutosh Singh
- School of Basic Sciences and BioX Center, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, India
| | - Sandesh Kumar Patel
- School of Basic Sciences and BioX Center, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, India
| | - Prateek Kumar
- School of Basic Sciences and BioX Center, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, India
| | - Kanhu Charan Das
- Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, Meghalaya, India
| | - Deepanshu Verma
- School of Basic Sciences and BioX Center, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, India
| | - Rohit Sharma
- Department of Rasashastra and Bhaishajya Kalpana, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Timir Tripathi
- Department of Biochemistry, North-Eastern Hill University, Umshing, Shillong, Meghalaya, India
| | - Rajanish Giri
- School of Basic Sciences and BioX Center, Indian Institute of Technology Mandi, VPO Kamand, Mandi, Himachal Pradesh, India
| | - Natália Martins
- Faculty of Medicine, University of Porto, Porto, Portugal.,Institute for Research and Innovation in Health (i3S), University of Porto, Porto, Portugal
| | - Neha Garg
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
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Goda K, Dönmez-Cakil Y, Tarapcsák S, Szalóki G, Szöllősi D, Parveen Z, Türk D, Szakács G, Chiba P, Stockner T. Human ABCB1 with an ABCB11-like degenerate nucleotide binding site maintains transport activity by avoiding nucleotide occlusion. PLoS Genet 2020; 16:e1009016. [PMID: 33031417 PMCID: PMC7544095 DOI: 10.1371/journal.pgen.1009016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 07/29/2020] [Indexed: 11/28/2022] Open
Abstract
Several ABC exporters carry a degenerate nucleotide binding site (NBS) that is unable to hydrolyze ATP at a rate sufficient for sustaining transport activity. A hallmark of a degenerate NBS is the lack of the catalytic glutamate in the Walker B motif in the nucleotide binding domain (NBD). The multidrug resistance transporter ABCB1 (P-glycoprotein) has two canonical NBSs, and mutation of the catalytic glutamate E556 in NBS1 renders ABCB1 transport-incompetent. In contrast, the closely related bile salt export pump ABCB11 (BSEP), which shares 49% sequence identity with ABCB1, naturally contains a methionine in place of the catalytic glutamate. The NBD-NBD interfaces of ABCB1 and ABCB11 differ only in four residues, all within NBS1. Mutation of the catalytic glutamate in ABCB1 results in the occlusion of ATP in NBS1, leading to the arrest of the transport cycle. Here we show that despite the catalytic glutamate mutation (E556M), ABCB1 regains its ATP-dependent transport activity, when three additional diverging residues are also replaced. Molecular dynamics simulations revealed that the rescue of ATPase activity is due to the modified geometry of NBS1, resulting in a weaker interaction with ATP, which allows the quadruple mutant to evade the conformationally locked pre-hydrolytic state to proceed to ATP-driven transport. In summary, we show that ABCB1 can be transformed into an active transporter with only one functional catalytic site by preventing the formation of the ATP-locked pre-hydrolytic state in the non-canonical site. ABC transporters are one of the largest membrane protein superfamilies, present in all organisms from archaea to humans. They transport a wide range of molecules including amino acids, sugars, vitamins, nucleotides, peptides, lipids, metabolites, antibiotics, and xenobiotics. ABC transporters energize substrate transport by hydrolyzing ATP in two symmetrically arranged nucleotide binding sites (NBSs). The human multidrug resistance transporter ABCB1 has two active NBSs, and it is generally believed that integrity and cooperation of both sites are needed for transport. Several human ABC transporters, such as the bile salt transporter ABCB11, have one degenerate NBS, which has significantly reduced ATPase activity. Interestingly, unilateral mutations affecting one of the two NBSs completely abolish the function of symmetrical ABC transporters. Here we engineered an ABCB1 variant with a degenerate, ABCB11-like NBS1, which can nevertheless transport substrates. Our results indicate that ABCB1 can mediate active transport with a single active site, questioning the validity of models assuming strictly alternating catalysis.
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Affiliation(s)
- Katalin Goda
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér, Debrecen, Hungary
| | - Yaprak Dönmez-Cakil
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse, Vienna, Austria
- Department of Histology and Embryology, Faculty of Medicine, Maltepe University, Maltepe, Istanbul, Turkey
| | - Szabolcs Tarapcsák
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér, Debrecen, Hungary
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, Egyetem tér, Debrecen, Hungary
| | - Gábor Szalóki
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem tér, Debrecen, Hungary
| | - Dániel Szöllősi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse, Vienna, Austria
| | - Zahida Parveen
- Institute of Medical Chemistry, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Waehringerstrasse, Vienna, Austria
- Department of Biochemistry, Abdul Wali Khan University Mardan, Khyber Pakhtunkhwa, Pakistan
| | - Dóra Türk
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja, Budapest, Hungary
| | - Gergely Szakács
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja, Budapest, Hungary
- Institute of Cancer Research, Medical University of Vienna, Borschkegasse, Vienna, Austria
| | - Peter Chiba
- Institute of Medical Chemistry, Center for Pathobiochemistry and Genetics, Medical University of Vienna, Waehringerstrasse, Vienna, Austria
- * E-mail: (PC); (TS)
| | - Thomas Stockner
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Waehringerstrasse, Vienna, Austria
- * E-mail: (PC); (TS)
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11
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Gupta SK, Singh P, Ali V, Verma M. Role of membrane-embedded drug efflux ABC transporters in the cancer chemotherapy. Oncol Rev 2020; 14:448. [PMID: 32676170 PMCID: PMC7358983 DOI: 10.4081/oncol.2020.448] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 03/20/2020] [Indexed: 12/12/2022] Open
Abstract
One of the major problems being faced by researchers and clinicians in leukemic treatment is the development of multidrug resistance (MDR) which restrict the action of several tyrosine kinase inhibitors (TKIs). MDR is a major obstacle to the success of cancer chemotherapy. The mechanism of MDR involves active drug efflux transport of ABC superfamily of proteins such as Pglycoprotein (P-gp/ABCB1), multidrug resistance-associated protein 2 (MRP2/ABCC2), and breast cancer resistance protein (BCRP/ABCG2) that weaken the effectiveness of chemotherapeutics and negative impact on the future of anticancer therapy. In this review, the authors aim to provide an overview of various multidrug resistance (MDR) mechanisms observed in cancer cells as well as the various strategies developed to overcome these MDR. Extensive studies have been carried out since last several years to enhance the efficacy of chemotherapy by defeating these MDR mechanisms with the use of novel anticancer drugs that could escape from the efflux reaction, MDR modulators or chemosensitizers, multifunctional nanotechnology, and RNA interference (RNAi) therapy.
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Affiliation(s)
- Sonu Kumar Gupta
- Department of Biochemistry, School of Basic & Applied Sciences, Central University of Punjab, Punjab, India
| | - Priyanka Singh
- Department of Biochemistry, School of Basic & Applied Sciences, Central University of Punjab, Punjab, India
| | - Villayat Ali
- Department of Biochemistry, School of Basic & Applied Sciences, Central University of Punjab, Punjab, India
| | - Malkhey Verma
- Department of Biochemistry, School of Basic & Applied Sciences, Central University of Punjab, Punjab, India
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12
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Mollazadeh S, Hadizadeh F, Ferreira RJ. Theoretical studies on 1,4-dihydropyridine derivatives as P-glycoprotein allosteric inhibitors: insights on symmetry and stereochemistry. J Biomol Struct Dyn 2020; 39:4752-4763. [DOI: 10.1080/07391102.2020.1780942] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Shirin Mollazadeh
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Farzin Hadizadeh
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Ricardo J. Ferreira
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
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13
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Bonito CA, Ferreira RJ, Ferreira MJU, Gillet JP, Cordeiro MNDS, Dos Santos DJVA. Theoretical insights on helix repacking as the origin of P-glycoprotein promiscuity. Sci Rep 2020; 10:9823. [PMID: 32555203 PMCID: PMC7300024 DOI: 10.1038/s41598-020-66587-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/27/2020] [Indexed: 12/14/2022] Open
Abstract
P-glycoprotein (P-gp, ABCB1) overexpression is, currently, one of the most important multidrug resistance (MDR) mechanisms in tumor cells. Thus, modulating drug efflux by P-gp has become one of the most promising approaches to overcome MDR in cancer. Yet, more insights on the molecular basis of drug specificity and efflux-related signal transmission mechanism between the transmembrane domains (TMDs) and the nucleotide binding domains (NBDs) are needed to develop molecules with higher selectivity and efficacy. Starting from a murine P-gp crystallographic structure at the inward-facing conformation (PDB ID: 4Q9H), we evaluated the structural quality of the herein generated human P-gp homology model. This initial human P-gp model, in the presence of the “linker” and inserted in a suitable lipid bilayer, was refined through molecular dynamics simulations and thoroughly validated. The best human P-gp model was further used to study the effect of four single-point mutations located at the TMDs, experimentally related with changes in substrate specificity and drug-stimulated ATPase activity. Remarkably, each P-gp mutation is able to induce transmembrane α-helices (TMHs) repacking, affecting the drug-binding pocket volume and the drug-binding sites properties (e.g. volume, shape and polarity) finally compromising drug binding at the substrate binding sites. Furthermore, intracellular coupling helices (ICH) also play an important role since changes in the TMHs rearrangement are shown to have an impact in residue interactions at the ICH-NBD interfaces, suggesting that identified TMHs repacking affect TMD-NBD contacts and interfere with signal transmission from the TMDs to the NBDs.
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Affiliation(s)
- Cátia A Bonito
- LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Ricardo J Ferreira
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, 75124, Uppsala, Sweden
| | - Maria-José U Ferreira
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal
| | - Jean-Pierre Gillet
- Laboratory of Molecular Cancer Biology, Molecular Physiology Research Unit-URPhyM, Namur Research Institute for Life Sciences (NARILIS), Faculty of Medicine, University of Namur, B-5000, Namur, Belgium
| | - M Natália D S Cordeiro
- LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal
| | - Daniel J V A Dos Santos
- LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007, Porto, Portugal. .,Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal.
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14
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Carey Hulyer AR, Briggs DA, O'Mara ML, Kerr ID, Harmer JR, Callaghan R. Cross-linking, DEER-spectroscopy and molecular dynamics confirm the inward facing state of P-glycoprotein in a lipid membrane. J Struct Biol 2020; 211:107513. [PMID: 32339763 DOI: 10.1016/j.jsb.2020.107513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/09/2020] [Accepted: 04/23/2020] [Indexed: 02/07/2023]
Abstract
The drug efflux pump P-glycoprotein (P-gp) displays a complex transport mechanism involving multiple drug binding sites and two centres for nucleotide hydrolysis. Elucidating the molecular mechanism of transport remains elusive and the availability of P-gp structures in distinct natural and ligand trapped conformations will accelerate our understanding. The present investigation sought to provide biochemical data to validate specific features of these structures; with particular focus on the transmembrane domain that provides the transport conduit. Hence our focus was on transmembrane helices six and twelve (TM6/TM12), which are believed to participate in drug binding, as they line the central transport conduit and provide a direct link to the catalytic centres. A series of P-gp mutants were generated with a single cysteine in both TM6 and TM12 to facilitate measurement of inter-helical distances using cross-linking and DEER strategies. Experimental results were compared to published structures per se and those refined by MD simulations. This analysis revealed that the refined inward-facing murine structure (4M1M) of P-gp provides a good representation of the proximity, topography and relative motions of TM6 and TM12 in reconstituted human P-gp.
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Affiliation(s)
- Alex R Carey Hulyer
- Research School of Biology, and the Medical School, Australian National University, Canberra, ACT 2601, Australia
| | - Deborah A Briggs
- Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - Megan L O'Mara
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Ian D Kerr
- Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - Jeffrey R Harmer
- The Centre for Advanced Imaging, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Richard Callaghan
- Research School of Biology, and the Medical School, Australian National University, Canberra, ACT 2601, Australia.
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15
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Szöllősi D, Chiba P, Szakacs G, Stockner T. Conversion of chemical to mechanical energy by the nucleotide binding domains of ABCB1. Sci Rep 2020; 10:2589. [PMID: 32054924 PMCID: PMC7018802 DOI: 10.1038/s41598-020-59403-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 01/27/2020] [Indexed: 01/13/2023] Open
Abstract
P-glycoprotein (ABCB1) is an important component of barrier tissues that extrudes a wide range of chemically unrelated compounds. ABCB1 consists of two transmembrane domains forming the substrate binding and translocation domain, and of two cytoplasmic nucleotide binding domains (NBDs) that provide the energy by binding and hydrolyzing ATP. We analyzed the mechanistic and energetic properties of the NBD dimer via molecular dynamics simulations. We find that MgATP stabilizes the NBD dimer through strong attractive forces by serving as an interaction hub. The irreversible ATP hydrolysis step converts the chemical energy stored in the phosphate bonds of ATP into potential energy. Following ATP hydrolysis, interactions between the NBDs and the ATP hydrolysis products MgADP + Pi remain strong, mainly because Mg2+ forms stabilizing interactions with ADP and Pi. Despite these stabilizing interactions MgADP + Pi are unable to hold the dimer together, which becomes separated by avid interactions of MgADP + Pi with water. ATP binding to the open NBDs and ATP hydrolysis in the closed NBD dimer represent two steps of energy input, each leading to the formation of a high energy state. Relaxation from these high energy states occurs through conformational changes that push ABCB1 through the transport cycle.
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Affiliation(s)
- Dániel Szöllősi
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstr. 13A, 1090, Vienna, Austria
| | - Peter Chiba
- Medical University of Vienna, Institute of Medical Chemistry, Center for Pathobiochemistry and Genetics, Waehringerstr. 10, 1090, Vienna, Austria
| | - Gergely Szakacs
- Medical University of Vienna, Institute of Cancer Research, Borschkegasse 8A, 1090, Vienna, Austria
| | - Thomas Stockner
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Waehringerstr. 13A, 1090, Vienna, Austria.
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16
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Residues contributing to drug transport by ABCG2 are localised to multiple drug-binding pockets. Biochem J 2018; 475:1553-1567. [PMID: 29661915 PMCID: PMC5934980 DOI: 10.1042/bcj20170923] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/28/2018] [Accepted: 04/16/2018] [Indexed: 01/09/2023]
Abstract
Multidrug binding and transport by the ATP-binding cassette transporter ABCG2 is a factor in the clinical resistance to chemotherapy in leukaemia, and a contributory factor to the pharmacokinetic profiles of many other prescribed drugs. Despite its importance, the structural basis of multidrug transport, i.e. the ability to transport multiple distinct chemicals, has remained elusive. Previous research has shown that at least two residues positioned towards the cytoplasmic end of transmembrane helix 3 (TM3) of the transporter play a role in drug transport. We hypothesised that other residues, either in the longitudinal span of TM3, or a perpendicular slice through the intracellular end of other TM helices would also contribute to drug binding and transport by ABCG2. Single-point mutant isoforms of ABCG2 were made at ∼30 positions and were analysed for effects on protein expression, localisation (western blotting, confocal microscopy) and function (flow cytometry) in a mammalian stable cell line expression system. Our data were interpreted in terms of recent structural data on the ABCG protein subfamily and enabled us to propose a surface-binding site for the drug mitoxantrone (MX) as well as a second, buried site for the same drug. Further mutational analysis of residues that spatially separate these two sites prompts us to suggest a molecular and structural pathway for MX transport by ABCG2.
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17
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Dail MB, Meek EC, Chambers HW, Chambers JE. In vitro P-glycoprotein activity does not completely explain in vivo efficacy of novel centrally effective oxime acetylcholinesterase reactivators. Drug Chem Toxicol 2018; 42:403-408. [PMID: 29722548 DOI: 10.1080/01480545.2018.1461902] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Novel-substituted phenoxyalkyl pyridinium oxime acetylcholinesterase (AChE) reactivators (US patent 9,227,937) that showed convincing evidence of penetration into the brains of intact rats were developed by our laboratories. The oximes separated into three groups based on their levels of brain AChE reactivation following exposure of rats to the sarin surrogate nitrophenyl isopropyl methylphosphonate (NIMP). P-glycoprotein (P-gp) is a major blood-brain barrier (BBB) transporter and requires ATP for efflux. To determine if P-gp affinity screening could be used to reduce animal use, we measured in vitro oxime-stimulated ATPase activity to see if the in vivo reactivation efficacies related to the oximes' functions as P-gp substrates. High efficacy oximes were expected to be poor P-gp substrates, thus remaining in the brain longer. The high efficacy oximes (24-35% brain AChE reactivation) were worse P-gp substrates than the low efficacy oximes (0-7% brain AChE reactivation). However, the oxime group with medium in vivo reactivation of 10-17% were even worse P-gp substrates than the high efficacy group so their reactivation ability was not reflected by P-gp export. The results suggest that in vitro P-gp ATPase activity can remove the low efficacy oximes from in vivo testing, but is not sufficient to differentiate between the top two tiers.
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Affiliation(s)
- Mary Beth Dail
- a Center for Environmental Health Sciences, Department of Basic Sciences , College of Veterinary Medicine, Mississippi State University, Mississippi State , MS , USA
| | - Edward Caldwell Meek
- a Center for Environmental Health Sciences, Department of Basic Sciences , College of Veterinary Medicine, Mississippi State University, Mississippi State , MS , USA
| | - Howard Wayne Chambers
- b Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology , Entomology Unit, Mississippi State University, Mississippi State , MS , USA
| | - Janice Elaine Chambers
- a Center for Environmental Health Sciences, Department of Basic Sciences , College of Veterinary Medicine, Mississippi State University, Mississippi State , MS , USA
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18
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Spork M, Sohail MI, Schmid D, Ecker GF, Freissmuth M, Chiba P, Stockner T. Folding correction of ABC-transporter ABCB1 by pharmacological chaperones: a mechanistic concept. Pharmacol Res Perspect 2017; 5:e00325. [PMID: 28603639 PMCID: PMC5464349 DOI: 10.1002/prp2.325] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 03/21/2017] [Indexed: 12/20/2022] Open
Abstract
Point mutations of ATP‐binding cassette (ABC) proteins are a common cause of human diseases. Available crystal structures indicate a similarity in the architecture of several members of this protein family. Their molecular architecture makes these proteins vulnerable to mutation, when critical structural elements are affected. The latter preferentially involve the two transmembrane domain (TMD)/nucleotide‐binding domain (NBD) interfaces (transmission interfaces), formation of which requires engagement of coupling helices of intracellular loops with NBDs. Both, formation of the active sites and engagement of the coupling helices, are contingent on correct positioning of ICLs 2 and 4 and thus an important prerequisite for proper folding. Here, we show that active site compounds are capable of rescuing P‐glycoprotein (P‐gp) mutants ∆Y490 and ∆Y1133 in a concentration‐dependent manner. These trafficking deficient mutations are located at the transmission interface in pseudosymmetric position to each other. In addition, the ability of propafenone analogs to correct folding correlates with their ability to inhibit transport of model substrates. This finding indicates that folding correction and transport inhibition by propafenone analogs are brought about by binding to the active sites. Furthermore, this study demonstrates an asymmetry in folding correction with cis‐flupentixol, which reflects the asymmetric binding properties of this modulator to P‐gp. Our results suggest a mechanistic model for corrector action in a model ABC transporter based on insights into the molecular architecture of these transporters.
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Affiliation(s)
- Matthias Spork
- Institute of Medical Chemistry Center of Pathobiochemistry and Genetics Medical University of Vienna Waehringerstrasse 10 Vienna A-1090 Austria
| | - Muhammad Imran Sohail
- Institute of Medical Chemistry Center of Pathobiochemistry and Genetics Medical University of Vienna Waehringerstrasse 10 Vienna A-1090 Austria.,Department of Zoology Government College University Lahore Katchery Road Lahore 54000 Pakistan
| | - Diethart Schmid
- Institute of Physiology Center of Physiology und Pharmacology Medical University of Vienna Schwarzspanierstrasse 17 Vienna A -1090 Austria
| | - Gerhard F Ecker
- Department of Medicinal Chemistry University of Vienna Emerging Field Pharmacoinformatics Althanstrasse 14 Vienna A-1090 Austria (GFE)
| | - Michael Freissmuth
- Institute of Pharmacology Center of Physiology und Pharmacology Medical University of Vienna Waehringerstrasse 13a Vienna A-1090 Austria
| | - Peter Chiba
- Institute of Medical Chemistry Center of Pathobiochemistry and Genetics Medical University of Vienna Waehringerstrasse 10 Vienna A-1090 Austria
| | - Thomas Stockner
- Institute of Pharmacology Center of Physiology und Pharmacology Medical University of Vienna Waehringerstrasse 13a Vienna A-1090 Austria
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19
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Ferreira RJ, Bonito CA, Ferreira MJU, dos Santos DJ. About P-glycoprotein: a new drugable domain is emerging from structural data. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1316] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ricardo J. Ferreira
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy; Universidade de Lisboa; Lisboa Portugal
| | - Cátia A. Bonito
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy; Universidade de Lisboa; Lisboa Portugal
- LAQV@REQUIMTE/Department of Chemistry and Biochemistry, Faculty of Sciences; University of Porto; Porto Portugal
| | - Maria José U. Ferreira
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy; Universidade de Lisboa; Lisboa Portugal
| | - Daniel J.V.A. dos Santos
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy; Universidade de Lisboa; Lisboa Portugal
- LAQV@REQUIMTE/Department of Chemistry and Biochemistry, Faculty of Sciences; University of Porto; Porto Portugal
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20
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Bugde P, Biswas R, Merien F, Lu J, Liu DX, Chen M, Zhou S, Li Y. The therapeutic potential of targeting ABC transporters to combat multi-drug resistance. Expert Opin Ther Targets 2017; 21:511-530. [DOI: 10.1080/14728222.2017.1310841] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Piyush Bugde
- School of Science, Auckland University of Technology, Auckland, New Zealand
| | - Riya Biswas
- School of Science, Auckland University of Technology, Auckland, New Zealand
| | - Fabrice Merien
- School of Science, Auckland University of Technology, Auckland, New Zealand
- School of Science, AUT Roche Diagnostic Laboratory, Auckland University of Technology, Auckland, New Zealand
| | - Jun Lu
- School of Science, Auckland University of Technology, Auckland, New Zealand
- School of Interprofessional Health Studies, Auckland University of Technology, Auckland, New Zealand
| | - Dong-Xu Liu
- School of Science, Auckland University of Technology, Auckland, New Zealand
| | - Mingwei Chen
- Department of Respiratory Medicine, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Shufeng Zhou
- Department of Biotechnology and Bioengineering, College of Chemical Engineering, Huaqiao University, Xiamen, China
| | - Yan Li
- School of Science, Auckland University of Technology, Auckland, New Zealand
- School of Interprofessional Health Studies, Auckland University of Technology, Auckland, New Zealand
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21
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Loo TW, Clarke DM. Drugs Modulate Interactions between the First Nucleotide-Binding Domain and the Fourth Cytoplasmic Loop of Human P-Glycoprotein. Biochemistry 2016; 55:2817-20. [DOI: 10.1021/acs.biochem.6b00233] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tip W. Loo
- Departments
of Medicine and
Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - David M. Clarke
- Departments
of Medicine and
Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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22
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Loo TW, Clarke DM. P-glycoprotein ATPase activity requires lipids to activate a switch at the first transmission interface. Biochem Biophys Res Commun 2016; 472:379-83. [PMID: 26944019 DOI: 10.1016/j.bbrc.2016.02.124] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 02/29/2016] [Indexed: 01/31/2023]
Abstract
P-glycoprotein (P-gp) is an ABC (ATP-Binding Cassette) drug pump. A common feature of ABC proteins is that they are organized into two wings. Each wing contains a transmembrane domain (TMD) and a nucleotide-binding domain (NBD). Drug substrates and ATP bind at the interface between the TMDs and NBDs, respectively. Drug transport involves ATP-dependent conformational changes between inward- (open, NBDs far apart) and outward-facing (closed, NBDs close together) conformations. P-gps crystallized in the presence of detergent show an open structure. Human P-gp is inactive in detergent but basal ATPase activity is restored upon addition of lipids. The lipids might cause closure of the wings to bring the NBDs close together to allow ATP hydrolysis. We show however, that cross-linking the wings together did not activate ATPase activity when lipids were absent suggesting that lipids may induce other structural changes required for ATPase activity. We then tested the effect of lipids on disulfide cross-linking of mutants at the first transmission interface between intracellular loop 4 (TMD2) and NBD1. Mutants L443C/S909C and L443C/R905C but not G471C/S909C and V472C/S909C were cross-linked with oxidant when in membranes. The mutants were then purified and cross-linked with or without lipids. Mutants G471C/S909C and V472C/S909C cross-linked only in the absence of lipids whereas mutants L443C/S909C and L443C/R905C were cross-linked only in the presence of lipids. The results suggest that lipids activate a switch at the first transmission interface and that the structure of P-gp is different in detergents and lipids.
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Affiliation(s)
- Tip W Loo
- Department of Medicine and Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - David M Clarke
- Department of Medicine and Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.
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23
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Loo TW, Clarke DM. Mapping the Binding Site of the Inhibitor Tariquidar That Stabilizes the First Transmembrane Domain of P-glycoprotein. J Biol Chem 2015; 290:29389-401. [PMID: 26507655 PMCID: PMC4705942 DOI: 10.1074/jbc.m115.695171] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Indexed: 11/26/2022] Open
Abstract
ABC (ATP-binding cassette) transporters are clinically important because drug pumps like P-glycoprotein (P-gp, ABCB1) confer multidrug resistance and mutant ABC proteins are responsible for many protein-folding diseases such as cystic fibrosis. Identification of the tariquidar-binding site has been the subject of intensive molecular modeling studies because it is the most potent inhibitor and corrector of P-gp. Tariquidar is a unique P-gp inhibitor because it locks the pump in a conformation that blocks drug efflux but activates ATPase activity. In silico docking studies have identified several potential tariquidar-binding sites. Here, we show through cross-linking studies that tariquidar most likely binds to sites within the transmembrane (TM) segments located in one wing or at the interface between the two wings (12 TM segments form 2 divergent wings). We then introduced arginine residues at all positions in the 12 TM segments (223 mutants) of P-gp. The rationale was that a charged residue in the drug-binding pocket would disrupt hydrophobic interaction with tariquidar and inhibit its ability to rescue processing mutants or stimulate ATPase activity. Arginines introduced at 30 positions significantly inhibited tariquidar rescue of a processing mutant and activation of ATPase activity. The results suggest that tariquidar binds to a site within the drug-binding pocket at the interface between the TM segments of both structural wings. Tariquidar differed from other drug substrates, however, as it stabilized the first TM domain. Stabilization of the first TM domain appears to be a key mechanism for high efficiency rescue of ABC processing mutants that cause disease.
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Affiliation(s)
- Tip W Loo
- From the Departments of Medicine and Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - David M Clarke
- From the Departments of Medicine and Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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24
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Mammalian drug efflux transporters of the ATP binding cassette (ABC) family in multidrug resistance: A review of the past decade. Cancer Lett 2015; 370:153-64. [PMID: 26499806 DOI: 10.1016/j.canlet.2015.10.010] [Citation(s) in RCA: 504] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/09/2015] [Accepted: 10/10/2015] [Indexed: 12/21/2022]
Abstract
Multidrug resistance (MDR) is a serious phenomenon employed by cancer cells which hampers the success of cancer pharmacotherapy. One of the common mechanisms of MDR is the overexpression of ATP-binding cassette (ABC) efflux transporters in cancer cells such as P-glycoprotein (P-gp/ABCB1), multidrug resistance-associated protein 2 (MRP2/ABCC2), and breast cancer resistance protein (BCRP/ABCG2) that limits the prolonged and effective use of chemotherapeutic drugs. Researchers have found that developing inhibitors of ABC efflux transporters as chemosensitizers could overcome MDR. But the clinical trials have shown that most of these chemosensitizers are merely toxic and only show limited or no benefits to cancer patients, thus new inhibitors are being explored. Recent findings also suggest that efflux pumps of the ABC transporter family are subject to epigenetic gene regulation. In this review, we summarize recent findings of the role of ABC efflux transporters in MDR.
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25
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Mutational Analysis of Intracellular Loops Identify Cross Talk with Nucleotide Binding Domains of Yeast ABC Transporter Cdr1p. Sci Rep 2015; 5:11211. [PMID: 26053667 PMCID: PMC4459223 DOI: 10.1038/srep11211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 05/07/2015] [Indexed: 02/06/2023] Open
Abstract
The ABC transporter Cdr1 protein (Cdr1p) of Candida albicans, which plays a major role in antifungal resistance, has two transmembrane domains (TMDs) and two nucleotide binding domains (NBDs) that are interconnected by extracellular (ECLs) and intracellular (ICLs) loops. To examine the communication interface between the NBDs and ICLs of Cdr1p, we subjected all four ICLs to alanine scanning mutagenesis, replacing each of the 85 residues with an alanine. The resulting ICL mutant library was analyzed by biochemical and phenotypic mapping. Only 18% of the mutants from this library displayed enhanced drug susceptibility. Most of the drug-susceptible mutants displayed uncoupling between ATP hydrolysis and drug transport. The two drug-susceptible ICL1 mutants (I574A and S593A) that lay within or close to the predicted coupling helix yielded two chromosomal suppressor mutations that fall near the Q-loop of NBD2 (R935) and in the Walker A motif (G190) of NBD1. Based on a 3D homology model and kinetic analysis of drug transport, our data suggest that large distances between ICL residues and their respective chromosomal suppressor mutations rule out a direct interaction between them. However, they impact the transport cycle by restoring the coupling interface via indirect downstream signaling.
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26
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Shah AH, Banerjee A, Rawal MK, Saxena AK, Mondal AK, Prasad R. ABC transporter Cdr1p harbors charged residues in the intracellular loop and nucleotide-binding domain critical for protein trafficking and drug resistance. FEMS Yeast Res 2015; 15:fov036. [DOI: 10.1093/femsyr/fov036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2015] [Indexed: 12/26/2022] Open
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27
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Loo TW, Clarke DM. The Transmission Interfaces Contribute Asymmetrically to the Assembly and Activity of Human P-glycoprotein. J Biol Chem 2015; 290:16954-63. [PMID: 25987565 PMCID: PMC4505440 DOI: 10.1074/jbc.m115.652602] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Indexed: 11/21/2022] Open
Abstract
P-glycoprotein (P-gp; ABCB1) is an ABC drug pump that protects us from toxic compounds. It is clinically important because it confers multidrug resistance. The homologous halves of P-gp each contain a transmembrane (TM) domain (TMD) with 6 TM segments followed by a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the interface between the TMDs and NBDs, respectively. Each NBD is connected to the TMDs by a transmission interface involving a pair of intracellular loops (ICLs) that form ball-and-socket joints. P-gp is different from CFTR (ABCC7) in that deleting NBD2 causes misprocessing of only P-gp. Therefore, NBD2 might be critical for stabilizing ICLs 2 and 3 that form a tetrahelix bundle at the NBD2 interface. Here we report that the NBD1 and NBD2 transmission interfaces in P-gp are asymmetric. Point mutations to 25 of 60 ICL2/ICL3 residues at the NBD2 transmission interface severely reduced P-gp assembly while changes to the equivalent residues in ICL1/ICL4 at the NBD1 interface had little effect. The hydrophobic nature at the transmission interfaces was also different. Mutation of Phe-1086 or Tyr-1087 to arginine at the NBD2 socket blocked activity or assembly while the equivalent mutations at the NBD1 socket had only modest effects. The results suggest that the NBD transmission interfaces are asymmetric. In contrast to the ICL2/3-NBD2 interface, the ICL1/4-NBD1 transmission interface is more hydrophilic and insensitive to mutations. Therefore the ICL2/3-NBD2 transmission interface forms a precise hydrophobic connection that acts as a linchpin for assembly and trafficking of P-gp.
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Affiliation(s)
- Tip W Loo
- From the Departments of Medicine and Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - David M Clarke
- From the Departments of Medicine and Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Tome ME, Schaefer CP, Jacobs LM, Zhang Y, Herndon JM, Matty FO, Davis TP. Identification of P-glycoprotein co-fractionating proteins and specific binding partners in rat brain microvessels. J Neurochem 2015; 134:200-10. [PMID: 25832806 DOI: 10.1111/jnc.13106] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/26/2015] [Accepted: 03/23/2015] [Indexed: 11/27/2022]
Abstract
Drug delivery to the brain for the treatment of pathologies with a CNS component is a significant clinical challenge. P-glycoprotein (PgP), a drug efflux pump in the endothelial cell membrane, is a major factor in preventing therapeutics from crossing the blood-brain barrier (BBB). Identifying PgP regulatory mechanisms is key to developing agents to modulate PgP activity. Previously, we found that PgP trafficking was altered concomitant with increased PgP activity and disassembly of high molecular weight PgP-containing complexes during acute peripheral inflammatory pain. These data suggest that PgP activity is post-translationally regulated at the BBB. The goal of the current study was to identify proteins that co-localize with PgP in rat brain microvessel endothelial cell membrane microdomains and use the data to suggest potential regulatory mechanisms. Using new density gradients of microvessel homogenates, we identified two unique pools (1,2) of PgP in membrane fractions. Caveolar constituents, caveolin1, cavin1, and cavin2, co-localized with PgP in these fractions indicating the two pools contained caveolae. A chaperone (Hsc71), protein disulfide isomerase and endosomal/lysosomal sorting proteins (Rab5, Rab11a) also co-fractionated with PgP in the gradients. These data suggest signaling pathways with a potential role in post-translational regulation of PgP activity at the BBB.
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Affiliation(s)
- Margaret E Tome
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
| | - Charles P Schaefer
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
| | - Leigh M Jacobs
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
| | - Yifeng Zhang
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
| | - Joseph M Herndon
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
| | - Fabian O Matty
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
| | - Thomas P Davis
- Department of Medical Pharmacology, University of Arizona, Tucson, Arizona, USA
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Szewczyk P, Tao H, McGrath AP, Villaluz M, Rees SD, Lee SC, Doshi R, Urbatsch IL, Zhang Q, Chang G. Snapshots of ligand entry, malleable binding and induced helical movement in P-glycoprotein. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:732-41. [PMID: 25760620 PMCID: PMC4356375 DOI: 10.1107/s1399004715000978] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 01/16/2015] [Indexed: 01/17/2023]
Abstract
P-glycoprotein (P-gp) is a transporter of great clinical and pharmacological significance. Several structural studies of P-gp and its homologs have provided insights into its transport cycle, but questions remain regarding how P-gp recognizes diverse substrates and how substrate binding is coupled to ATP hydrolysis. Here, four new P-gp co-crystal structures with a series of rationally designed ligands are presented. It is observed that the binding of certain ligands, including an ATP-hydrolysis stimulator, produces a large conformational change in the fourth transmembrane helix, which is positioned to potentially transmit a signal to the nucleotide-binding domains. A new ligand-binding site on the surface of P-gp facing the inner leaflet of the membrane is also described, providing vital insights regarding the entry mechanism of hydrophobic drugs and lipids into P-gp. These results represent significant advances in the understanding of how P-gp and related transporters bind and export a plethora of metabolites, antibiotics and clinically approved and pipeline drugs.
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Affiliation(s)
- Paul Szewczyk
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92023, USA
| | - Houchao Tao
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Aaron P. McGrath
- Skaggs School of Pharmacy and Pharmaceutical Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Mark Villaluz
- Skaggs School of Pharmacy and Pharmaceutical Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Steven D. Rees
- Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California, La Jolla, CA 92023, USA
| | - Sung Chang Lee
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Rupak Doshi
- Skaggs School of Pharmacy and Pharmaceutical Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ina L. Urbatsch
- Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Qinghai Zhang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Geoffrey Chang
- Department of Pharmacology, School of Medicine, University of California at San Diego, La Jolla, CA 92093, USA
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30
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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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P-glycoprotein trafficking as a therapeutic target to optimize CNS drug delivery. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 71:25-44. [PMID: 25307213 DOI: 10.1016/bs.apha.2014.06.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The primary function of the blood-brain barrier (BBB)/neurovascular unit is to protect the central nervous system (CNS) from potentially harmful xenobiotic substances and maintain CNS homeostasis. Restricted access to the CNS is maintained via a combination of tight junction proteins as well as a variety of efflux and influx transporters that limits the transcellular and paracellular movement of solutes. Of the transporters identified at the BBB, P-glycoprotein (P-gp) has emerged as the transporter that is the greatest obstacle to effective CNS drug delivery. In this chapter, we provide data to support intracellular protein trafficking of P-gp within cerebral capillary microvessels as a potential target for improved drug delivery. We show that pain-induced changes in P-gp trafficking are associated with changes in P-gp's association with caveolin-1, a key scaffolding/trafficking protein that colocalizes with P-gp at the luminal membrane of brain microvessels. Changes in colocalization with the phosphorylated and nonphosphorylated forms of caveolin-1, by pain, are accompanied by dynamic changes in the distribution, relocalization, and activation of P-gp "pools" between microvascular endothelial cell subcellular compartments. Since redox-sensitive processes may be involved in signaling disassembly of higher-order structures of P-gp, we feel that manipulating redox signaling, via specific protein targeting at the BBB, may protect disulfide bond integrity of P-gp reservoirs and control trafficking to the membrane surface, providing improved CNS drug delivery. The advantage of therapeutic drug "relocalization" of a protein is that the physiological impact can be modified, temporarily or long term, despite pathology-induced changes in gene transcription.
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Furuta T, Yamaguchi T, Kato H, Sakurai M. Analysis of the structural and functional roles of coupling helices in the ATP-binding cassette transporter MsbA through enzyme assays and molecular dynamics simulations. Biochemistry 2014; 53:4261-72. [PMID: 24937232 DOI: 10.1021/bi500255j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
ATP-binding cassette (ABC) transporters are constructed from some common structural units: the highly conserved nucleotide-binding domains (NBDs), which work as a nucleotide-dependent engine for driving substrate transport, the diverse transmembrane domains (TMDs), which create the translocation pathway, and the coupling helices (CHs), which are located at the NBD-TMD interface. Although the CHs are believed to be essential for NBD-TMD communication, their roles remain unclear. In this study, we performed enzyme assays and molecular dynamics (MD) simulations of the ABC transporter MsbA and two MsbA mutants in which the amino acid residues of one of the CHs were mutated to alanines: (i) wild type (Wt), (ii) CH1 mutant (Mt1), and (iii) CH2 mutant (Mt2). The experiments show that the CH2 mutation decreases the ATPase activity (kcat) compared with that of the Wt (a decrease of 32%), and a nearly equal degree of decrease in the ATP binding affinity (Km) was observed for both Mt1 and Mt2. The MD simulations successfully accounted for several structural and dynamical origins for these experimental observations. In addition, on the basis of collective motion and morphing analyses, we propose that the reverse-rotational motions and noddinglike motions between the NBDs and TMDs are indispensable for the conformational transition between the inward- and outward-facing conformations. In particular, CH2 is significantly important for the occurrence of the noddinglike motion. These findings provide important insights into the structure-function relationship of ABC transporters.
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Affiliation(s)
- Tadaomi Furuta
- Center for Biological Resources and Informatics, Tokyo Institute of Technology , B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
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33
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Antibody repertoire deep sequencing reveals antigen-independent selection in maturing B cells. Proc Natl Acad Sci U S A 2014; 111:E2622-9. [PMID: 24927543 DOI: 10.1073/pnas.1403278111] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antibody repertoires are known to be shaped by selection for antigen binding. Unexpectedly, we now show that selection also acts on a non-antigen-binding antibody region: the heavy-chain variable (VH)-encoded "elbow" between variable and constant domains. By sequencing 2.8 million recombined heavy-chain genes from immature and mature B-cell subsets in mice, we demonstrate a striking gradient in VH gene use as pre-B cells mature into follicular and then into marginal zone B cells. Cells whose antibodies use VH genes that encode a more flexible elbow are more likely to mature. This effect is distinct from, and exceeds in magnitude, previously described maturation-associated changes in heavy-chain complementarity determining region 3, a key antigen-binding region, which arise from junctional diversity rather than differential VH gene use. Thus, deep sequencing reveals a previously unidentified mode of B-cell selection.
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34
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Mishra S, Verhalen B, Stein RA, Wen PC, Tajkhorshid E, Mchaourab HS. Conformational dynamics of the nucleotide binding domains and the power stroke of a heterodimeric ABC transporter. eLife 2014; 3:e02740. [PMID: 24837547 PMCID: PMC4046567 DOI: 10.7554/elife.02740] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Multidrug ATP binding cassette (ABC) exporters are ubiquitous ABC transporters that extrude cytotoxic molecules across cell membranes. Despite recent progress in structure determination of these transporters, the conformational motion that transduces the energy of ATP hydrolysis to the work of substrate translocation remains undefined. Here, we have investigated the conformational cycle of BmrCD, a representative of the heterodimer family of ABC exporters that have an intrinsically impaired nucleotide binding site. We measured distances between pairs of spin labels monitoring the movement of the nucleotide binding (NBD) and transmembrane domains (TMD). The results expose previously unobserved structural intermediates of the NBDs arising from asymmetric configuration of catalytically inequivalent nucleotide binding sites. The two-state transition of the TMD, from an inward- to an outward-facing conformation, is driven exclusively by ATP hydrolysis. These findings provide direct evidence of divergence in the mechanism of ABC exporters.DOI: http://dx.doi.org/10.7554/eLife.02740.001.
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Affiliation(s)
- Smriti Mishra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Brandy Verhalen
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
| | - Po-Chao Wen
- Department of Biochemistry, College of Medicine, University of Illinois, Urbana, United States Center for Biophysics and Computational Biology, University of Illinois, Urbana, United States The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Unites States
| | - Emad Tajkhorshid
- Department of Biochemistry, College of Medicine, University of Illinois, Urbana, United States Center for Biophysics and Computational Biology, University of Illinois, Urbana, United States The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Unites States
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
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35
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Loo TW, Clarke DM. Identification of the distance between the homologous halves of P-glycoprotein that triggers the high/low ATPase activity switch. J Biol Chem 2014; 289:8484-92. [PMID: 24523403 DOI: 10.1074/jbc.m114.552075] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
P-glycoprotein (P-gp, ABCB1) is an ATP-binding cassette drug pump that protects us from toxic compounds and confers multidrug resistance. Each homologous half contains a transmembrane domain with six transmembrane segments followed by a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the interface between the transmembrane domain and NBDs, respectively. Drug binding activates ATPase activity by an unknown mechanism. There is no high resolution structure of human P-gp, but homology models based on the crystal structures of bacterial, mouse, and Caenorhabditis elegans ATP-binding cassette drug pumps yield both open (NBDs apart) and closed (NBDs together) conformations. Molecular dynamics simulations predict that the NBDs can be separated over a range of distances (over 20 Å). To determine the distance that show high or low ATPase activity, we cross-linked reporter cysteines L175C (N-half) and N820C (C-half) with cross-linkers of various lengths that separated the halves between 6 and 30 Å (α-carbons). We observed that ATPase activity increased over 10-fold when the cysteines were cross-linked at distances between 6 and 19 Å, although cross-linking at distances greater than 20 Å yielded basal levels of activity. The results suggest that the ATPase activation switch appears to be turned on or off when L175C/N820 are clamped at distances less than or greater than 20 Å, respectively. We predict that the high/low ATPase activity switch may occur at a distance where the NBDs are predicted in molecular dynamic simulations to undergo pronounced twisting as they approach each other (Wise, J. G. (2012) Biochemistry 51, 5125-5141).
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Affiliation(s)
- Tip W Loo
- From the Departments of Medicine and Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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36
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The cystic fibrosis V232D mutation inhibits CFTR maturation by disrupting a hydrophobic pocket rather than formation of aberrant interhelical hydrogen bonds. Biochem Pharmacol 2014; 88:46-57. [PMID: 24412276 DOI: 10.1016/j.bcp.2013.12.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/30/2013] [Accepted: 12/31/2013] [Indexed: 11/21/2022]
Abstract
Processing mutations that inhibit folding and trafficking of CFTR are the main cause of cystic fibrosis. Repair of CFTR mutants requires an understanding of the mechanisms of misfolding caused by processing mutations. Previous studies on helix-loop-helix fragments of the V232D processing mutation suggested that its mechanism was to lock transmembrane (TM) segments 3 and 4 together by a non-native hydrogen bond (Asp232(TM4)/Gln207(TM3)). Here, we performed mutational analysis to test for Asp232/Gln207 interactions in full-length CFTR. The rationale was that a V232N mutation should mimic V232D and a V232D/Q207A mutant should mature if the processing defect was caused by hydrogen bonds. We report that only Val232 mutations to charged amino acids severely blocked CFTR maturation. The V232N mutation did not mimic V232D as V232N showed 40% maturation compared to 2% for V232D. Mutation of Val232 to large nonpolar residues (Leu, Phe) had little effect. The Q207L mutation did not rescue V232D because Q207L showed about 50% maturation in the presence of corrector VX-809 while V232D/Q207A could no longer be rescued. These results suggest that V232D inhibits maturation by disrupting a hydrophobic pocket between TM segments rather than forming a non-native hydrogen bond. Disulfide cross-linking analysis of cysteines W356C(TM6) and W1145C(TM12) suggest that the V232D mutation inhibits maturation by trapping CFTR as a partially folded intermediate. Since correctors can efficiently rescue V232D CFTR, the results suggest that hydrophilic processing mutations facing a hydrophobic pocket are good candidates for rescue with pharmacological chaperones.
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Loo TW, Clarke DM. Locking intracellular helices 2 and 3 together inactivates human P-glycoprotein. J Biol Chem 2013; 289:229-36. [PMID: 24275649 DOI: 10.1074/jbc.m113.527804] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The P-glycoprotein (P-gp) drug pump (ABCB1) has two transmembrane domains and two nucleotide-binding domains (NBDs). Coupling of the drug-binding sites in the transmembrane domains to the NBDs occurs through interaction of the intracellular helices (IHs) with residues in the NBDs (IH1/IH4/NBD1 and IH2/IH3/NBD2). We showed previously that cross-linking of cysteines in IH3 and IH1 with a short cross-linker mimicked drug binding as it activated P-gp ATPase activity. Here we show that residue A259C(IH2) could be directly cross-linked to W803C(IH3). Cross-linking was inhibited by the presence of ATP and adenosine 5'-(β,γ-imino)triphosphate but not by ADP. Cross-linking of mutant A259C/W803C inhibited its verapamil-stimulated ATPase activity mutant, but activity was restored after addition of dithiothreitol. Because these residues are close to the ball-and-socket joint A266C(IH2)/Phe(1086)(NBD2), we mutated the adjacent Tyr(1087)(NBD2) close to IH3. Mutants Y1087A and Y1087L, but not Y1087F, were misprocessed, and all inhibited ATPase activity. Mutation of hydrophobic residues (F793A, L797A, L814A, and L818A) flanking IH3 also inhibited maturation. The results suggest that these residues, together with Trp(803) and Phe(804), form a large hydrophobic pocket. The results show that there is an important hydrophobic network at the IH2/IH3/NBD2 transmission interface that is critical for folding and activity of P-gp.
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Affiliation(s)
- Tip W Loo
- From the Departments of Medicine and Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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