1
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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 PMCID: PMC10305233 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)
| | | | | | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA; (S.A.B.); (U.H.I.); (E.K.)
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2
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Tran NNB, Bui ATA, Jaramillo-Martinez V, Weber J, Zhang Q, Urbatsch IL. Lipid environment determines the drug-stimulated ATPase activity of P-glycoprotein. Front Mol Biosci 2023; 10:1141081. [PMID: 36911528 PMCID: PMC9995911 DOI: 10.3389/fmolb.2023.1141081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
P-glycoprotein (Pgp) is a multidrug transporter that uses the energy from ATP binding and hydrolysis to export from cells a wide variety of hydrophobic compounds including anticancer drugs, and mediates the bioavailability and pharmacokinetics of many drugs. Lipids and cholesterol have been shown to modulate the substrate-stimulated ATPase activity of purified Pgp in detergent solution and the substrate transport activity after reconstitution into proteoliposomes. While lipid extracts from E. coli, liver or brain tissues generally support well Pgp's functionality, their ill-defined composition and high UV absorbance make them less suitable for optical biophysical assays. On the other hand, studies with defined synthetic lipids, usually the bilayer-forming phosphatidylcholine with or without cholesterol, are often plagued by low ATPase activity and low binding affinity of Pgp for drugs. Drawing from the lipid composition of mammalian plasma membranes, we here investigate how different head groups modulate the verapamil-stimulated ATPase activity of purified Pgp in detergent-lipid micelles and compare them with components of E. coli lipids. Our general approach was to assay modulation of verapamil-stimulation of ATPase activity by artificial lipid mixtures starting with the bilayer-forming palmitoyloyl-phosphatidylcholine (POPC) and -phosphatidylethanolamine (POPE). We show that POPC/POPE supplemented with sphingomyelin (SM), cardiolipin, or phosphatidic acid enhanced the verapamil-stimulated activity (Vmax) and decreased the concentration required for half-maximal activity (EC50). Cholesterol (Chol) and more so its soluble hemisuccinate derivative cholesteryl hemisuccinate substantially decreased EC50, perhaps by supporting the functional integrity of the drug binding sites. High concentrations of CHS (>15%) resulted in a significantly increased basal activity which could be due to binding of CHS to the drug binding site as transport substrate or as activator, maybe acting cooperatively with verapamil. Lastly, Pgp reconstituted into liposomes or nanodiscs displayed higher basal activity and sustained high levels of verapamil stimulated activity. The findings establish a stable source of artificial lipid mixtures containing either SM and cholesterol or CHS that restore Pgp functionality with activities and affinities similar to those in the natural plasma membrane environment and will pave the way for future functional and biophysical studies.
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Affiliation(s)
- Nghi N. B. Tran
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - A. T. A. Bui
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Valeria Jaramillo-Martinez
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Joachim Weber
- Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, United States
| | - Qinghai Zhang
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, United States
| | - Ina L. Urbatsch
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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3
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Inoue Y, Yamaguchi T, Otsuka T, Utsunomiya Y, Pan D, Ogawa H, Kato H. Structure-based alteration of tryptophan residues of the multidrug transporter CmABCB1 to assess substrate binding using fluorescence spectroscopy. Protein Sci 2022; 31:e4331. [PMID: 35634783 PMCID: PMC9123602 DOI: 10.1002/pro.4331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/01/2022] [Accepted: 04/06/2022] [Indexed: 09/17/2023]
Abstract
ABCB1, also known as P-glycoprotein, is an essential component of many physiological barriers and extrudes a variety of hydrophobic chemicals out of the cell. Structures of ABCB1 provided insights into the structural changes that occur upon ATP binding and the characteristic architecture of the substrate binding site. Yet, the structure-function relationship between substrate binding and transporting still remains largely obscured because there is no robust method for accurately measuring substrate binding constants. The methods currently used cannot identify whether the bound substrates are located in the inner chamber of the molecule in the transmembrane region or not because of the low spatial resolution. Here, we report a system for measuring the affinity of substrate binding to the Cyanidioschyzon merolae ABCB1 (CmABCB1) using site-specific tryptophan (Trp) fluorescence quenching. We designed a CmABCB1 mutant with an extrinsic Trp residue introduced into the inner chamber. Trp fluorescence was quenched by three substrates and one inhibitor, including rhodamine 6G, in a saturable fashion, allowing for accurate estimation of the dissociation constant (KD ) for each molecule. The KD for rhodamine 6G is similar to that determined using a reciprocal fluorescence quenching assay using rhodamine 6G fluorescence, suggesting that Trp fluorescence of the mutant was quenched by the interaction between the extrinsic Trp and substrates bound in the inner chamber. Structural comparison of the ABCB1 structures suggests that the system presented in this study could be ideal method of choice to determine the substrate binding affinities of compounds bound to the chamber of mammalian ABCB1.
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Affiliation(s)
- Yoshiki Inoue
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Tomohiro Yamaguchi
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Tetsuo Otsuka
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Yuto Utsunomiya
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Dongqing Pan
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Haruo Ogawa
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
| | - Hiroaki Kato
- Department of Structural Biology, Graduate School of Pharmaceutical SciencesKyoto UniversityKyotoJapan
- Advanced Photon Technology DivisionRIKEN Harima Institute at SPring‐8Sayo‐gunHyogoJapan
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4
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Nicklisch SCT, Pouv AK, Rees SD, McGrath AP, Chang G, Hamdoun A. Transporter-interfering chemicals inhibit P-glycoprotein of yellowfin tuna (Thunnus albacares). Comp Biochem Physiol C Toxicol Pharmacol 2021; 248:109101. [PMID: 34116183 DOI: 10.1016/j.cbpc.2021.109101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 02/08/2023]
Abstract
Marine pollutants bioaccumulate at high trophic levels of marine food webs and are transferred to humans through consumption of apex species. Yellowfin tuna (Thunnus albacares) are marine predators, and one of largest commercial fisheries in the world. Previous studies have shown that yellowfin tuna can accumulate high levels of persistent organic pollutants, including Transporter Interfering Chemicals (TICs), which are chemicals shown to bind to mammalian xenobiotic transporters and interfere with their function. Here, we examined the extent to which these same compounds might interfere with the activity of the yellowfin tuna (Thunnus albacares) ortholog of this transporter. To accomplish this goal we identified, expressed, and functionally assayed tuna ABCB1. The results demonstrated a common mode of vertebrate ABCB1 interaction with TICs that predicts effects across these species, based on high conservation of specific interacting residues. Importantly several TICs showed potent inhibition of Ta-ABCB1, such as the organochlorine pesticides Endrin (EC50 = 1.2 ± 0.2 μM) and Mirex (EC50 = 2.3 ± 0.9 μM). However, unlike the effects observed on mouse ABCB1, low concentrations of the organochlorine pesticide TICs p,p'-DDT and its metabolite p,p'-DDD co-stimulated verapamil-induced Ta-ABCB1 ATPase activity possibly suggesting a low transport activity for these ligands in tuna. These results provide a mechanistic basis for understanding the potential vulnerability of tuna to these ubquitous pollutants.
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Affiliation(s)
- Sascha C T Nicklisch
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616, United States of America.
| | - Amara K Pouv
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616, United States of America.
| | - Steven D Rees
- Skaggs School of Pharmacy and Pharmaceutical Sciences, 9500 Gilman Drive #0754, University of California, San Diego, La Jolla, CA 92093, United States of America.
| | - Aaron P McGrath
- Skaggs School of Pharmacy and Pharmaceutical Sciences, 9500 Gilman Drive #0754, University of California, San Diego, La Jolla, CA 92093, United States of America
| | - Geoffrey Chang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, 9500 Gilman Drive #0754, University of California, San Diego, La Jolla, CA 92093, United States of America.
| | - Amro Hamdoun
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202, United States of America.
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5
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Zhang B, Kang Z, Zhang J, Kang Y, Liang L, Liu Y, Wang Q. Simultaneous binding mechanism of multiple substrates for multidrug resistance transporter P-glycoprotein. Phys Chem Chem Phys 2021; 23:4530-4543. [PMID: 33595579 DOI: 10.1039/d0cp05910b] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
P-glycoprotein (P-gp), a member of ATP-binding cassette (ABC) transporters, is a multidrug resistance pump. Its promiscuous nature is the main cause of multidrug resistance in cancer cells. P-gp can bind multiple drug molecules simultaneously; however, the binding mechanism is still not clear. Furthermore, the upper limit of the number of substrates that can be accommodated by the binding pocket is not fully understood. In this work, we explore the dynamic process of P-gp binding to multiple substrates by using molecular dynamics (MD) simulations. Our results show that P-gp possesses the ability for simultaneous binding, and that the number of substrates has an upper limit. The accommodating ability of P-gp relates to the size of the binding drugs, and conforms to induced fit theory. In the binding process, the residues 339PHE, 982MET and 986GLN are essential. The pocket of P-gp presents strong flexibility and adaptability features according to the mutation results in this work. Drug molecules tend to gather in the pocket during binding, and interactions between these molecules are beneficial to simultaneous binding. These findings provide new insights into the mechanism of the promiscuous nature of P-gp, and may give us a guideline for inhibiting the process of multidrug resistance.
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Affiliation(s)
- Bo Zhang
- Department of Chemistry and Soft Matter Research Center, Zhejiang University, Hangzhou 310027, People's Republic of China.
| | - Zhengzhong Kang
- Department of Chemistry and Soft Matter Research Center, Zhejiang University, Hangzhou 310027, People's Republic of China.
| | - Junqiao Zhang
- Department of Chemistry and Soft Matter Research Center, Zhejiang University, Hangzhou 310027, People's Republic of China.
| | - Yu Kang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
| | - Lijun Liang
- College of Life Information Science and Instrument Engineering, Hangzhou Dianzi University, Hangzhou, People's Republic of China
| | - Yingchun Liu
- Department of Chemistry and Soft Matter Research Center, Zhejiang University, Hangzhou 310027, People's Republic of China.
| | - Qi Wang
- Department of Chemistry and Soft Matter Research Center, Zhejiang University, Hangzhou 310027, People's Republic of China.
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6
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Nicklisch SC, Hamdoun A. Disruption of small molecule transporter systems by Transporter-Interfering Chemicals (TICs). FEBS Lett 2020; 594:4158-4185. [PMID: 33222203 PMCID: PMC8112642 DOI: 10.1002/1873-3468.14005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/25/2022]
Abstract
Small molecule transporters (SMTs) in the ABC and SLC families are important players in disposition of diverse endo- and xenobiotics. Interactions of environmental chemicals with these transporters were first postulated in the 1990s, and since validated in numerous in vitro and in vivo scenarios. Recent results on the co-crystal structure of ABCB1 with the flame-retardant BDE-100 demonstrate that a diverse range of man-made and natural toxic molecules, hereafter termed transporter-interfering chemicals (TICs), can directly bind to SMTs and interfere with their function. TIC-binding modes mimic those of substrates, inhibitors, modulators, inducers, and possibly stimulants through direct and allosteric mechanisms. Similarly, the effects could directly or indirectly agonize, antagonize or perhaps even prime the SMT system to alter transport function. Importantly, TICs are distinguished from drugs and pharmaceuticals that interact with transporters in that exposure is unintended and inherently variant. Here, we review the molecular mechanisms of environmental chemical interaction with SMTs, the methodological considerations for their evaluation, and the future directions for TIC discovery.
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Affiliation(s)
- Sascha C.T. Nicklisch
- Department of Environmental Toxicology, University of California, Davis, Davis, CA 95616
| | - Amro Hamdoun
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0202
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7
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Replacing the eleven native tryptophans by directed evolution produces an active P-glycoprotein with site-specific, non-conservative substitutions. Sci Rep 2020; 10:3224. [PMID: 32081894 PMCID: PMC7035247 DOI: 10.1038/s41598-020-59802-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/28/2020] [Indexed: 11/09/2022] Open
Abstract
P-glycoprotein (Pgp) pumps an array of hydrophobic compounds out of cells, and has major roles in drug pharmacokinetics and cancer multidrug resistance. Yet, polyspecific drug binding and ATP hydrolysis-driven drug export in Pgp are poorly understood. Fluorescence spectroscopy using tryptophans (Trp) inserted at strategic positions is an important tool to study ligand binding. In Pgp, this method will require removal of 11 endogenous Trps, including highly conserved Trps that may be important for function, protein-lipid interactions, and/or protein stability. Here, we developed a directed evolutionary approach to first replace all eight transmembrane Trps and select for transport-active mutants in Saccharomyces cerevisiae. Surprisingly, many Trp positions contained non-conservative substitutions that supported in vivo activity, and were preferred over aromatic amino acids. The most active construct, W(3Cyto), served for directed evolution of the three cytoplasmic Trps, where two positions revealed strong functional bias towards tyrosine. W(3Cyto) and Trp-less Pgp retained wild-type-like protein expression, localization and transport function, and purified proteins retained drug stimulation of ATP hydrolysis and drug binding affinities. The data indicate preferred Trp substitutions specific to the local context, often dictated by protein structural requirements and/or membrane lipid interactions, and these new insights will offer guidance for membrane protein engineering.
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8
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Trexler AW, Knudsen GA, Nicklisch SCT, Birnbaum LS, Cannon RE. 2,4,6-Tribromophenol Exposure Decreases P-Glycoprotein Transport at the Blood-Brain Barrier. Toxicol Sci 2019; 171:463-472. [PMID: 31368499 PMCID: PMC6760274 DOI: 10.1093/toxsci/kfz155] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 06/12/2019] [Accepted: 07/09/2019] [Indexed: 01/24/2023] Open
Abstract
2,4,6-Tribromophenol (TBP, CAS No. 118-79-6) is a brominated chemical used in the production of flame-retardant epoxy resins and as a wood preservative. In marine environments, TBP is incorporated into shellfish and consumed by predatory fish. Food processing and water treatment facilities produce TBP as a byproduct. 2,4,6-Tribromophenol has been detected in human blood and breast milk. Biologically, TBP interferes with estrogen and thyroid hormone signaling, which regulate important transporters of the blood-brain barrier (BBB). The BBB is a selectively permeable barrier characterized by brain microvessels which are composed of endothelial cells mortared by tight-junction proteins. ATP-binding cassette (ABC) efflux transporters on the luminal membrane facilitate the removal of unwanted endobiotics and xenobiotics from the brain. In this study, we examined the in vivo and ex vivo effects of TBP on two important transporters of the BBB: P-glycoprotein (P-gp, ABCB1) and Multidrug Resistance-associated Protein 2 (MRP2, ABCC2), using male and female rats and mice. 2,4,6-Tribromophenol exposure ex vivo resulted in a time- (1-3 h) and dose- (1-100 nM) dependent decrease in P-gp transport activity. MRP2 transport activity was unchanged under identical conditions. Immunofluorescence and western blotting measured decreases in P-gp expression after TBP treatment. ATPase assays indicate that TBP is not a substrate and does not directly interact with P-gp. In vivo dosing with TBP (0.4 µmol/kg) produced decreases in P-gp transport. Co-treatment with selective protein kinase C (PKC) inhibitors prevented the TBP-mediated decreases in P-gp transport activity.
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Affiliation(s)
- Andrew W Trexler
- NCI Laboratory of Toxicology and Toxicokinetics, Research Triangl Park, North Carolina, 27709
| | - Gabriel A Knudsen
- NCI Laboratory of Toxicology and Toxicokinetics, Research Triangl Park, North Carolina, 27709
| | - Sascha C T Nicklisch
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla 92093, California
- Department of Environmental Toxicology, University of California Davis 95616, Davis, California
| | - Linda S Birnbaum
- NCI Laboratory of Toxicology and Toxicokinetics, Research Triangl Park, North Carolina, 27709
| | - Ronald E Cannon
- NCI Laboratory of Toxicology and Toxicokinetics, Research Triangl Park, North Carolina, 27709
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9
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Gibbs ME, Wilt LA, Ledwitch KV, Roberts AG. A Conformationally Gated Model of Methadone and Loperamide Transport by P-Glycoprotein. J Pharm Sci 2018; 107:1937-1947. [PMID: 29499278 DOI: 10.1016/j.xphs.2018.02.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/18/2018] [Accepted: 02/21/2018] [Indexed: 01/16/2023]
Abstract
P-glycoprotein (Pgp) is a multidrug resistance transporter that limits the penetration of a wide range of neurotherapeutics into the brain including opioids. The diphenylpropylamine opioids methadone and loperamide are structurally similar, but loperamide has about a 4-fold higher Pgp-mediated transport rate. In addition to these differences, they showed significant differences in their effects on Pgp-mediated adenosine triphosphate (ATP) hydrolysis. The activation of Pgp-mediated ATP hydrolysis by methadone was monophasic, whereas loperamide activation of ATP hydrolysis was biphasic implying methadone has a single binding site and loperamide has 2 binding sites on Pgp. Quenching of tryptophan fluorescence with these drugs and digoxin showed competition between the opioids and that loperamide does not compete for the digoxin-binding site. Acrylamide quenching of tryptophan fluorescence to probe Pgp conformational changes revealed that methadone- and loperamide-induced conformational changes were distinct. These results were used to develop a model for Pgp-mediated transport of methadone and loperamide where opioid binding and conformational changes are used to explain the differences in the opioid transport rates between methadone and loperamide.
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Affiliation(s)
- Morgan E Gibbs
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602
| | - Laura A Wilt
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602
| | - Kaitlyn V Ledwitch
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235
| | - Arthur G Roberts
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602.
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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: 1.4] [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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11
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Wilt LA, Nguyen D, Roberts AG. Insights Into the Molecular Mechanism of Triptan Transport by P-glycoprotein. J Pharm Sci 2017; 106:1670-1679. [PMID: 28283434 DOI: 10.1016/j.xphs.2017.02.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 02/28/2017] [Accepted: 02/28/2017] [Indexed: 01/16/2023]
Abstract
The P-glycoprotein (Pgp) transporter reduces the penetration of a chemically diverse range of neurotherapeutics at the blood-brain barrier, but the molecular features of drugs and drug-Pgp interactions that drive transport remain to be clarified. In particular, the triptan neurotherapeutics, eletriptan (ETT) and sumatriptan (STT), were identified to have a >10-fold difference in transport rates despite being from the same drug class. Consistent with these transport differences, ETT activated Pgp-mediated ATP hydrolysis ∼2-fold, whereas STT slightly inhibited Pgp-mediated ATP hydrolysis by ∼10%. The interactions between them were also noncompetitive, suggesting that they occupy different binding sites on the transporter. Despite these differences, protein fluorescence spectroscopy revealed that the drugs have similar affinity to the transporter. NMR with Pgp and the drugs showed that they have distinct interactions with the transporter. Tertiary conformational changes probed by acrylamide quenching of Pgp tryptophan fluorescence with the drugs and a nonhydrolyzable ATP analog implied that the STT-bound Pgp must undergo larger conformational changes to hydrolyze ATP than ETT-bound Pgp. These results and previous transport studies were used to build a conformationally driven model for triptan transport with Pgp where STT presents a higher conformational barrier for ATP hydrolysis and transport than ETT.
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Affiliation(s)
- Laura A Wilt
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602
| | - Diana Nguyen
- Department of Biomanufacturing and Bioprocessing, University of Georgia, Athens, Georgia 30602
| | - Arthur G Roberts
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, Georgia 30602.
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12
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Fendley GA, Urbatsch IL, Sutton RB, Zoghbi ME, Altenberg GA. Nucleotide dependence of the dimerization of ATP binding cassette nucleotide binding domains. Biochem Biophys Res Commun 2016; 480:268-272. [PMID: 27765627 DOI: 10.1016/j.bbrc.2016.10.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 10/16/2016] [Indexed: 10/20/2022]
Abstract
ATP-binding cassette proteins are ubiquitously present throughout all known genomes. Their basic functional unit possesses two transmembrane domains and two nucleotide-binding domains. The nucleotide-binding domains are responsible for ATP binding and hydrolysis, and their 3-dimensional structure is conserved across ATP-binding cassette proteins. Binding of ATP produces nucleotide-binding domain dimerization, a step necessary for hydrolysis. However, the possibility that nucleotide-binding domains bind and/or hydrolyze nucleotide triphosphates different from ATP has not been explored in detail. Here, we studied that possibility using M. jannaschii MJ0796, a prototypical ATP-binding cassette nucleotide-binding domain. We found that nucleotide-binding domain dimerization occurs as a result of binding to the natural nucleotide triphosphates ATP, GTP, CTP and UTP, and also to the analog ATP-γ-S. All the natural nucleotide triphosphates are hydrolyzed at similar rates, whereas ATP-γ-S is not hydrolyzed. We also found that the non-hydrolyzable ATP analog AMP-PNP, frequently assumed to produce the nucleotide-bound conformation, failed to elicit nucleotide-binding domain dimerization. Our results raise the possibility that not all the nucleotide binding sites of nucleotide-binding domains are occupied by ATP under physiological conditions, and that ATP is not always the nucleotide hydrolyzed to dissociate the nucleotide-binding domain dimers.
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Affiliation(s)
- Gregory A Fendley
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA
| | - Ina L Urbatsch
- Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA; Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA
| | - Roger B Sutton
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA; Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA
| | - Maria E Zoghbi
- School of Natural Sciences, University of California, Merced, 4225 N. Hospital Road, Atwater, CA 95301, USA
| | - Guillermo A Altenberg
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA; Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA.
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13
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Yang Z, Zhou Q, Mok L, Singh A, Swartz DJ, Urbatsch IL, Brouillette CG. Interactions and cooperativity between P-glycoprotein structural domains determined by thermal unfolding provides insights into its solution structure and function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:48-60. [PMID: 27783926 DOI: 10.1016/j.bbamem.2016.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/19/2016] [Accepted: 10/21/2016] [Indexed: 12/16/2022]
Abstract
Structural changes in mouse P-glycoprotein (Pgp) induced by thermal unfolding were studied by differential scanning calorimetry (DSC), circular dichroism and fluorescence spectroscopy to gain insight into the solution conformation(s) of this ABC transporter that may not be apparent from current crystal structures. DSC of reconstituted Pgp showed two thermal unfolding transitions in the absence of MgATP, suggesting that each transition involved the cooperative unfolding of two or more interacting structural domains. A low calorimetric unfolding enthalpy and minimal structural changes were observed, which are hallmarks of the thermal unfolding of α-helical membrane proteins, because generally only the extramembranous regions undergo significant unfolding. Nucleotide binding increased the unfolding temperature of both transitions to the same extent, suggesting that one nucleotide binding domain (NBD) unfolds with each transition. Combined with the results from the two isolated NBDs, we propose that each DSC transition represents the cooperative unfolding of one NBD and the two contacting intracellular loops. Further, the presence of two transitions in both apo and MgATP bound wild-type Pgp suggests the NBD-dimeric conformation is transient, and that Pgp resides predominantly in the crystallographically observed inward-facing conformation with NBDs separated, even under conditions supporting continuous MgATP hydrolysis. In contrast, DSC of the vanadate-trapped MgADP·Pgp complex and the MgATP-bound catalytically inactive mutant, E552A/E1197A, show an additional transition at much higher temperature, corresponding to the unfolding of the nucleotide-trapped NBD-dimeric outward-facing conformation. The collective results indicate a strong preference for an NBD dissociated, inward-facing conformation of Pgp.
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Affiliation(s)
- Zhengrong Yang
- Center for Structural Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Qingxian Zhou
- Center for Structural Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Leo Mok
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Anukriti Singh
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Douglas J Swartz
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Ina L Urbatsch
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
| | - Christie G Brouillette
- Center for Structural Biology, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA.
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14
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Nicklisch SCT, Rees SD, McGrath AP, Gökirmak T, Bonito LT, Vermeer LM, Cregger C, Loewen G, Sandin S, Chang G, Hamdoun A. Global marine pollutants inhibit P-glycoprotein: Environmental levels, inhibitory effects, and cocrystal structure. SCIENCE ADVANCES 2016; 2:e1600001. [PMID: 27152359 PMCID: PMC4846432 DOI: 10.1126/sciadv.1600001] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 03/21/2016] [Indexed: 05/05/2023]
Abstract
The world's oceans are a global reservoir of persistent organic pollutants to which humans and other animals are exposed. Although it is well known that these pollutants are potentially hazardous to human and environmental health, their impacts remain incompletely understood. We examined how persistent organic pollutants interact with the drug efflux transporter P-glycoprotein (P-gp), an evolutionarily conserved defense protein that is essential for protection against environmental toxicants. We identified specific congeners of organochlorine pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers that inhibit mouse and human P-gp, and determined their environmental levels in yellowfin tuna from the Gulf of Mexico. In addition, we solved the cocrystal structure of P-gp bound to one of these inhibitory pollutants, PBDE (polybrominated diphenyl ether)-100, providing the first view of pollutant binding to a drug transporter. The results demonstrate the potential for specific binding and inhibition of mammalian P-gp by ubiquitous congeners of persistent organic pollutants present in fish and other foods, and argue for further consideration of transporter inhibition in the assessment of the risk of exposure to these chemicals.
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Affiliation(s)
- Sascha C. T. Nicklisch
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093–0202, USA
| | - Steven D. Rees
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093–0657, USA
| | - Aaron P. McGrath
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093–0657, USA
| | - Tufan Gökirmak
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093–0202, USA
| | - Lindsay T. Bonito
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093–0202, USA
| | - Lydia M. Vermeer
- Sekisui XenoTech, LLC, 1101 West Cambridge Circle Drive, Kansas City, KS 66103, USA
| | - Cristina Cregger
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093–0657, USA
| | - Greg Loewen
- Sekisui XenoTech, LLC, 1101 West Cambridge Circle Drive, Kansas City, KS 66103, USA
| | - Stuart Sandin
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093–0202, USA
| | - Geoffrey Chang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093–0657, USA
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA 92093–0657, USA
| | - Amro Hamdoun
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093–0202, USA
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15
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Swartz D, Mok L, Botta S, Singh A, Altenberg G, Urbatsch I. Directed evolution of P-glycoprotein cysteines reveals site-specific, non-conservative substitutions that preserve multidrug resistance. Biosci Rep 2014; 34:e00116. [PMID: 24825346 PMCID: PMC4069687 DOI: 10.1042/bsr20140062] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/05/2014] [Accepted: 05/06/2014] [Indexed: 11/21/2022] Open
Abstract
Pgp (P-glycoprotein) is a prototype ABC (ATP-binding-cassette) transporter involved in multidrug resistance of cancer. We used directed evolution to replace six cytoplasmic Cys (cysteine) residues in Pgp with all 20 standard amino acids and selected for active mutants. From a pool of 75000 transformants for each block of three Cys, we identified multiple mutants that preserved drug resistance and yeast mating activity. The most frequent substitutions were glycine and serine for Cys427 (24 and 20%, respectively) and Cys1070 (37 and 25%) of the Walker A motifs in the NBDs (nucleotide-binding domains), Cys1223 in NBD2 (25 and 8%) and Cys638 in the linker region (24 and 16%), whereas close-by Cys669 tolerated glycine (16%) and alanine (14%), but not serine (absent). Cys1121 in NBD2 showed a clear preference for positively charged arginine (38%) suggesting a salt bridge with Glu269 in the ICL2 (intracellular loop 2) may stabilize domain interactions. In contrast, three Cys residues in transmembrane α-helices could be successfully replaced by alanine. The resulting CL (Cys-less) Pgp was fully active in yeast cells, and purified proteins displayed drug-stimulated ATPase activities indistinguishable from WT (wild-type) Pgp. Overall, directed evolution identified site-specific, non-conservative Cys substitutions that allowed building of a robust CL Pgp, an invaluable new tool for future functional and structural studies, and that may guide the construction of other CL proteins where alanine and serine have proven unsuccessful.
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Key Words
- abc transporter
- multidrug transporter
- non-conservative cysteine substitutions
- protein evolution site-saturation mutagenesis
- yeast drug resistance
- abc, atp-binding-cassette
- cftr, cystic fibrosis transmembrane conductance regulator
- cl, cys-less
- cp-mts, 7-diethylamino-3-(4′-maleimidylphenyl)-4-methylcoumarin
- ddm, n-dodecyl-β-d-maltopyranoside
- icl, intracellular loop
- nbd, nucleotide-binding domain
- pgp, p-glycoprotein
- sec, size exclusion chromatography
- tmd, transmembrane domain
- wt, wild-type
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Affiliation(s)
- Douglas J. Swartz
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Leo Mok
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Sri K. Botta
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Anukriti Singh
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Guillermo A. Altenberg
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- ‡Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
| | - Ina L. Urbatsch
- *Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
- †Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas, U.S.A
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16
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Dönmez Cakil Y, Khunweeraphong N, Parveen Z, Schmid D, Artaker M, Ecker GF, Sitte HH, Pusch O, Stockner T, Chiba P. Pore-exposed tyrosine residues of P-glycoprotein are important hydrogen-bonding partners for drugs. Mol Pharmacol 2013; 85:420-8. [PMID: 24366667 DOI: 10.1124/mol.113.088526] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The multispecific efflux transporter, P-glycoprotein, plays an important role in drug disposition. Substrate translocation occurs along the interface of its transmembrane domains. The rotational C2 symmetry of ATP-binding cassette transporters implies the existence of two symmetry-related sets of substrate-interacting amino acids. These sets are identical in homodimeric transporters, and remain evolutionary related in full transporters, such as P-glycoprotein, in which substrates bind preferentially, but nonexclusively, to one of two binding sites. We explored the role of pore-exposed tyrosines for hydrogen-bonding interactions with propafenone type ligands in their preferred binding site 2. Tyrosine 953 is shown to form hydrogen bonds not only with propafenone analogs, but also with the preferred site 1 substrate rhodamine123. Furthermore, an accessory role of tyrosine 950 for binding of selected propafenone analogs is demonstrated. The present study demonstrates the importance of domain interface tyrosine residues for interaction of small molecules with P-glycoprotein.
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Affiliation(s)
- Yaprak Dönmez Cakil
- Institutes of Medical Chemistry (Y.D.C., N.K., Z.P., P.C.), Pharmacology (Y.D.C., H.H.S., T.S.), and Physiology (D.S.), Department of Medical Biochemistry, Max F. Perutz Laboratories (M.A.), and Department of Cell and Developmental Biology (O.P.), Medical University of Vienna, Vienna, Austria; Department of Biochemistry, Abdul Wali Khan University Mardan, Pakistan (Z.P.); and Emerging Field Pharmacoinformatics, Department of Medicinal Chemistry, University of Vienna, Vienna, Austria (G.F.E.)
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