51
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Rosenberg MF, Oleschuk CJ, Wu P, Mao Q, Deeley RG, Cole SPC, Ford RC. Structure of a human multidrug transporter in an inward-facing conformation. J Struct Biol 2010; 170:540-7. [PMID: 20109555 DOI: 10.1016/j.jsb.2010.01.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 01/07/2010] [Accepted: 01/20/2010] [Indexed: 11/25/2022]
Abstract
Multidrug resistance protein 1 (ABCC1) is a member of the 'C' class of ATP-binding cassette transporters, which can give rise to resistance to chemotherapy via drug export from cells. It also acts as a leukotriene C4 transporter, and hence has a role in adaptive immune response. Most C-class members have an additional NH(2)-terminal transmembrane domain versus other ATP-binding cassette transporters, but little is known about the structure and role of this domain. Using electron cryomicroscopy of 2D crystals, data at 1/6per A(-1) resolution was generated for the full-length ABCC1 protein in the absence of ATP. Analysis using homologous structures from bacteria and mammals allowed the core transmembrane domains to be localised in the map. These display an inward-facing conformation and there is a noteworthy separation of the cytoplasmic nucleotide-binding domains. Examination of non-core features in the map suggests that the additional NH(2)-terminal domain has extensive contacts on one side of both core domains, and mirrors their inward-facing configuration in the absence of nucleotide.
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Affiliation(s)
- Mark F Rosenberg
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
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52
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Martelli C, Coronnello M, Dei S, Manetti D, Orlandi F, Scapecchi S, Novella Romanelli M, Salerno M, Mini E, Teodori E. Structure−Activity Relationships Studies in a Series of N,N-Bis(alkanol)amine Aryl Esters as P-Glycoprotein (Pgp) Dependent Multidrug Resistance (MDR) Inhibitors. J Med Chem 2010; 53:1755-62. [DOI: 10.1021/jm9016174] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Cecilia Martelli
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
| | - Marcella Coronnello
- Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy
| | - Silvia Dei
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
| | - Dina Manetti
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
| | - Francesca Orlandi
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
| | - Serena Scapecchi
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
| | - Maria Novella Romanelli
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
| | - Milena Salerno
- Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Universitè Paris 13, 74 rue Marcel Cachin, 93017 Bobigny, France
| | - Enrico Mini
- Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy
| | - Elisabetta Teodori
- Dipartimento di Scienze Farmaceutiche, Laboratorio di Progettazione Sintesi e Studio di Eterocicli Bioattivi (HeteroBioLab), Università di Firenze, via Ugo Schiff 6, 50019 Sesto Fiorentino (FI), Italy
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53
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Abstract
The constituents of the blood-brain barrier, including its efflux transporter system, can efficiently limit brain penetration of potential CNS therapeutics. Effective extrusion from the brain by transporters is a frequent reason for the pharmaceutical industry to exclude novel compounds from further development for CNS therapeutics. Moreover, high transporter expression levels that are present in individual patients or may be generally associated with the pathophysiology seem to be a major cause of therapeutic failure in a variety of CNS diseases including brain tumors, epilepsy, brain HIV infection, and psychiatric disorders. Increasing knowledge of the structure and function of the blood-brain barrier creates a basis for the development of strategies which aim to enhance brain uptake of beneficial pharmaceutical compounds. The different strategies discussed in this review aim to modulate blood-brain barrier function or to bypass constituents of the blood-brain barrier.
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54
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Kerr ID, Jones PM, George AM. Multidrug efflux pumps: the structures of prokaryotic ATP-binding cassette transporter efflux pumps and implications for our understanding of eukaryotic P-glycoproteins and homologues. FEBS J 2009; 277:550-63. [PMID: 19961540 DOI: 10.1111/j.1742-4658.2009.07486.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
One of the Holy Grails of ATP-binding cassette transporter research is a structural understanding of drug binding and transport in a eukaryotic multidrug resistance pump. These transporters are front-line mediators of drug resistance in cancers and represent an important therapeutic target in future chemotherapy. Although there has been intensive biochemical research into the human multidrug pumps, their 3D structure at atomic resolution remains unknown. The recent determination of the structure of a mouse P-glycoprotein at subatomic resolution is complemented by structures for a number of prokaryotic homologues. These structures have provided advances into our knowledge of the ATP-binding cassette exporter structure and mechanism, and have provided the template data for a number of homology modelling studies designed to reconcile biochemical data on these clinically important proteins.
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Affiliation(s)
- Ian D Kerr
- School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
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55
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Abstract
The role of the ATP-binding cassette ABCB1 in mediating the resistance to chemotherapy in many forms of cancer has been well established. The protein is also endogenously expressed in numerous barrier and excretory tissues, thereby regulating or impacting on drug pharmacokinetic profiles. Given these prominent roles in health and disease, a great deal of biochemical, structural and pharmacological research has been directed towards modulating its activity. Despite the effort, only a small handful of compounds have reached the later stages of clinical trials. What is responsible for this poor return on the heavy research investment? Perhaps the most significant factor is the lack of information on the location, physical features and chemical properties of the drug-binding site(s) in ABCB1. This minireview outlines the various strategies and outcomes of research efforts to pin-point the sites of interaction. The data may be assimilated into two working hypotheses to describe drug binding to ABCB1; (a) the central cavity and the (b) domain interface models.
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Affiliation(s)
- Emily Crowley
- Nuffield Department of Clinical Laboratory Sciences, University of Oxford, Oxford, UK
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56
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Abstract
The prominent role for the drug efflux pump ABCB1 (P-glycoprotein) in mediating resistance to chemotherapy was first suggested in 1976 and sparked an incredible drive to restore the efficacy of anticancer drugs. Achieving this goal seemed inevitable in 1982 when a series of calcium channel blockers were demonstrated to restore the efficacy of chemotherapy agents. A large number of other compounds have since been demonstrated to restore chemotherapeutic sensitivity in cancer cells or tissues. Where do we stand almost three decades since the first reports of ABCB1 inhibition? Unfortunately, in the aftermath of extensive fundamental and clinical research efforts the situation remains gloomy. Only a small handful of compounds have reached late stage clinical trials and none are in routine clinical usage to circumvent chemoresistance. Why has the translation process been so ineffective? One factor is the multifactorial nature of drug resistance inherent to cancer tissues; ABCB1 is not the sole factor. However, expression of ABCB1 remains a significant negative prognostic indicator and is closely associated with poor response to chemotherapy in many cancer types. The main difficulties with restoration of sensitivity to chemotherapy reside with poor properties of the ABCB1 inhibitors: (1) low selectivity to ABCB1, (2) poor potency to inhibit ABCB1, (3) inherent toxicity and/or (4) adverse pharmacokinetic interactions with anticancer drugs. Despite these difficulties, there is a clear requirement for effective inhibitors and to date the strategies for generating such compounds have involved serendipity or simple chemical syntheses. This chapter outlines more sophisticated approaches making use of bioinformatics, combinatorial chemistry and structure informed drug design. Generating a new arsenal of potent and selective ABCB1 inhibitors offers the promise of restoring the efficacy of a key weapon in cancer treatment--chemotherapy.
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57
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Kos V, Ford RC. The ATP-binding cassette family: a structural perspective. Cell Mol Life Sci 2009; 66:3111-26. [PMID: 19544044 PMCID: PMC11115812 DOI: 10.1007/s00018-009-0064-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 05/27/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
Abstract
The ATP-binding cassette family is one of the largest groupings of membrane proteins, moving allocrites across lipid membranes, using energy from ATP. In bacteria, they reside in the inner membrane and are involved in both uptake and export. In eukaryotes, these transporters reside in the cell's internal membranes as well as in the plasma membrane and are unidirectional-out of the cytoplasm. The range of substances that these proteins can transport is huge, which makes them interesting for structure-function studies. Moreover, their abundance in nature has made them targets for structural proteomics consortia. There are eight independent structures for ATP-binding cassette transporters, making this one of the best characterised membrane protein families. Our understanding of the mechanism of transport across membranes and membrane protein structure in general has been enhanced by recent developments for this family.
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Affiliation(s)
- Veronica Kos
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of Guelph, Guelph, ON N1G 2W1 Canada
| | - Robert Curtis Ford
- Faculty of Life Sciences, Manchester Interdisplinary Biocentre, The University of Manchester, Manchester, M1 7DN UK
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58
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Eckford PDW, Sharom FJ. ABC efflux pump-based resistance to chemotherapy drugs. Chem Rev 2009; 109:2989-3011. [PMID: 19583429 DOI: 10.1021/cr9000226] [Citation(s) in RCA: 459] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Paul D W Eckford
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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59
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ABC transporters: a riddle wrapped in a mystery inside an enigma. Trends Biochem Sci 2009; 34:520-31. [PMID: 19748784 DOI: 10.1016/j.tibs.2009.06.004] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 06/22/2009] [Accepted: 06/24/2009] [Indexed: 12/13/2022]
Abstract
ATP-binding cassette (ABC) transporters form one of the largest and most ancient of protein families. ABC transporters couple hydrolysis of ATP to vectorial translocation of diverse substrates across cellular membranes. Many human ABC transporters are medically important in causing, for example, multidrug resistance to cytotoxic drugs. Seven complete prokaryotic structures and one eukaryotic structure have been solved for transporters from 2002 to date, and a wealth of research is being conducted on and around these structures to resolve the mechanistic conundrum of how these transporters couple ATP hydrolysis in cytosolic domains to substrate translocation through the transmembrane pore. Many questions remained unanswered about this mechanism, despite a plethora of data and a number of interesting and controversial models.
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60
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Crowley E, O'Mara ML, Reynolds C, Tieleman DP, Storm J, Kerr ID, Callaghan R. Transmembrane helix 12 modulates progression of the ATP catalytic cycle in ABCB1. Biochemistry 2009; 48:6249-58. [PMID: 19456124 DOI: 10.1021/bi900373x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multidrug efflux pumps, such as P-glycoprotein (ABCB1), present major barriers to the success of chemotherapy in a number of clinical settings. Molecular details of the multidrug efflux process by ABCB1 remain elusive, in particular, the interdomain communication associated with bioenergetic coupling. The present investigation has focused on the role of transmembrane helix 12 (TM12) in the multidrug efflux process of ABCB1. Cysteine residues were introduced at various positions within TM12, and their effect on ATPase activity, nucleotide binding, and drug interaction were assessed. Mutation of several residues within TM12 perturbed the maximal ATPase activity of ABCB1, and the underlying cause was a reduction in basal (i.e., drug-free) hydrolysis of the nucleotide. Two of the mutations (L976C and F978C) were found to reduce the binding of [gamma-(32)P]-azido-ATP to ABCB1. In contrast, the A980C mutation within TM12 enhanced the rate of ATP hydrolysis; once again, this was due to modified basal activity. Several residues also caused reductions in the potency of stimulation of ATP hydrolysis by nicardipine and vinblastine, although the effects were independent of changes in drug binding per se. Overall, the results indicate that TM12 plays a key role in the progression of the ATP hydrolytic cycle in ABCB1, even in the absence of the transported substrate.
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Affiliation(s)
- Emily Crowley
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, United Kingdom
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61
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Kodan A, Shibata H, Matsumoto T, Terakado K, Sakiyama K, Matsuo M, Ueda K, Kato H. Improved expression and purification of human multidrug resistance protein MDR1 from baculovirus-infected insect cells. Protein Expr Purif 2009; 66:7-14. [DOI: 10.1016/j.pep.2009.02.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 02/10/2009] [Accepted: 02/10/2009] [Indexed: 11/25/2022]
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62
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Zhang L, Aleksandrov LA, Zhao Z, Birtley JR, Riordan JR, Ford RC. Architecture of the cystic fibrosis transmembrane conductance regulator protein and structural changes associated with phosphorylation and nucleotide binding. J Struct Biol 2009; 167:242-51. [PMID: 19524678 DOI: 10.1016/j.jsb.2009.06.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 06/03/2009] [Accepted: 06/05/2009] [Indexed: 11/30/2022]
Abstract
We describe biochemical and structural studies of the isolated cystic fibrosis transmembrane conductance regulator (CFTR) protein. Using electron cryomicroscopy, low resolution three-dimensional structures have been obtained for the non-phosphorylated protein in the absence of nucleotide and for the phosphorylated protein with ATP. In the latter state, the cytosolic nucleotide-binding domains move closer together, forming a more compact packing arrangement. Associated with this is a reorganization within the cylindrical transmembrane domains, consistent with a shift from an inward-facing to outward-facing configuration. A region of density in the non-phosphorylated protein that extends from the bottom of the cytosolic regions up to the transmembrane domains is hypothesised to represent the unique regulatory region of CFTR. These data offer insights into the architecture of this ATP-binding cassette protein, and shed light on the global motions associated with nucleotide binding and priming of the chloride channel via phosphorylation of the regulatory region.
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Affiliation(s)
- Liang Zhang
- Faculty of Life Sciences, The University of Manchester, MIB, Manchester M1 7DN, UK
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63
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Affiliation(s)
- Stefan Balaz
- Department of Pharmaceutical Sciences, College of Pharmacy, North Dakota State University, Fargo, North Dakota 58105, USA.
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64
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Chan KF, Zhao Y, Chow T, Yan C, Ma D, Burkett B, Wong I, Chow L, Chan T. Flavonoid Dimers as Bivalent Modulators for P-Glycoprotein-Based Multidrug Resistance: Structure-Activity Relationships. ChemMedChem 2009; 4:594-614. [DOI: 10.1002/cmdc.200800413] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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65
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Aller SG, Yu J, Ward A, Weng Y, Chittaboina S, Zhuo R, Harrell PM, Trinh YT, Zhang Q, Urbatsch IL, Chang G. Structure of P-glycoprotein reveals a molecular basis for poly-specific drug binding. Science 2009; 323:1718-22. [PMID: 19325113 DOI: 10.1126/science.1168750] [Citation(s) in RCA: 1469] [Impact Index Per Article: 97.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
P-glycoprotein (P-gp) detoxifies cells by exporting hundreds of chemically unrelated toxins but has been implicated in multidrug resistance (MDR) in the treatment of cancers. Substrate promiscuity is a hallmark of P-gp activity, thus a structural description of poly-specific drug-binding is important for the rational design of anticancer drugs and MDR inhibitors. The x-ray structure of apo P-gp at 3.8 angstroms reveals an internal cavity of approximately 6000 angstroms cubed with a 30 angstrom separation of the two nucleotide-binding domains. Two additional P-gp structures with cyclic peptide inhibitors demonstrate distinct drug-binding sites in the internal cavity capable of stereoselectivity that is based on hydrophobic and aromatic interactions. Apo and drug-bound P-gp structures have portals open to the cytoplasm and the inner leaflet of the lipid bilayer for drug entry. The inward-facing conformation represents an initial stage of the transport cycle that is competent for drug binding.
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Affiliation(s)
- Stephen G Aller
- Department of Molecular Biology, Scripps Research Institute, 10550 North Torrey Pines Road, CB105, La Jolla, CA 92037, USA
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66
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McDevitt CA, Collins R, Kerr ID, Callaghan R. Purification and structural analyses of ABCG2. Adv Drug Deliv Rev 2009; 61:57-65. [PMID: 19124053 DOI: 10.1016/j.addr.2008.07.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 07/23/2008] [Indexed: 01/24/2023]
Abstract
ABCG2 is best known as a multidrug transporter capable of conferring resistance to cancer cells. However, the protein is also inherently expressed in numerous barrier tissues and intriguingly within hematopoietic stem cells. Unlike its partners ABCB1 and ABCC1, there is considerably less information available on the molecular mechanism of ABCG2. The transporter has a distinct topology and is presumed to function as a homodimer. However, a number of biochemical studies have presented data to suggest that the protein adopts higher order oligomers. This review focuses on this controversial issue with particular reference to findings from low resolution structural data. In addition, a number of molecular models of ABCG2 based on high resolution structures of bacterial ABC transporters have recently become available and are critically assessed. ABCG2 is a structurally distinct member of the triumvirate of human multidrug transporters and continues to evade description of a unifying molecular mechanism.
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Affiliation(s)
- Christopher A McDevitt
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
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67
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Martelli C, Alderighi D, Coronnello M, Dei S, Frosini M, Le Bozec B, Manetti D, Neri A, Romanelli MN, Salerno M, Scapecchi S, Mini E, Sgaragli G, Teodori E. N,N-bis(Cyclohexanol)amine Aryl Esters: A New Class of Highly Potent Transporter-Dependent Multidrug Resistance Inhibitors. J Med Chem 2009; 52:807-17. [DOI: 10.1021/jm8012745] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Cecilia Martelli
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Daniela Alderighi
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Marcella Coronnello
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Silvia Dei
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Maria Frosini
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Bénédicte Le Bozec
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Dina Manetti
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Annalisa Neri
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Maria Novella Romanelli
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Milena Salerno
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Serena Scapecchi
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Enrico Mini
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Giampietro Sgaragli
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
| | - Elisabetta Teodori
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy, Dipartimento di Neuroscienze, Sezione di Farmacologia, Fisiologia e Tossicologia, Università di Siena, via A. Moro 2, 53100 Siena, Italy, Dipartimento di Farmacologia Preclinica e Clinica, Università di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy, Laboratoire de Biophysique Moléculaire, Cellulaire et Tissulaire (BioMoCeTi), UMR CNRS 7033, UMPC Université Paris 6 and Université Paris 13
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68
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Nucleotide dependent packing differences in helical crystals of the ABC transporter MsbA. J Struct Biol 2008; 165:169-75. [PMID: 19114108 DOI: 10.1016/j.jsb.2008.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 11/07/2008] [Accepted: 11/20/2008] [Indexed: 11/21/2022]
Abstract
Bacterial ATP binding cassette (ABC) exporters fulfill a wide variety of transmembrane transport roles and are homologous to the human multidrug resistance P-glycoprotein. Recent X-ray structures of the exporters MsbA and Sav1866 have begun to describe the conformational changes that accompany the ABC transport cycle. Here we present cryo-electron microscopy structures of MsbA reconstituted into a lipid bilayer. Using ATPase inhibitors, we captured three nucleotide transition states of the transporter that were subsequently reconstituted into helical arrays. The enzyme-substrate complex (trapped by ADP-aluminum fluoride or AMPPNP) crystallized in a different helical lattice than the enzyme-product complex (trapped by ADP-vanadate). Approximately 20A resolution maps were calculated for each state and revealed MsbA to be a dimer with a large channel between the membrane spanning domains, similar to the outward facing crystal structures of MsbA and Sav1866. This suggests that while there are likely structural differences between the nucleotide transition states, membrane embedded MsbA remains in an outward facing conformation while nucleotide is bound.
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69
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Zhou SF, Lecureur V, Guillouzo A. Structure, function and regulation of P-glycoprotein and its clinical relevance in drug disposition. Xenobiotica 2008; 38:802-32. [PMID: 18668431 DOI: 10.1080/00498250701867889] [Citation(s) in RCA: 372] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
1. P-glycoprotein (P-gp/MDR1), one of the most clinically important transmembrane transporters in humans, is encoded by the ABCB1/MDR1 gene. Recent insights into the structural features of P-gp/MDR1 enable a re-evaluation of the biochemical evidence on the binding and transport of drugs by P-gp/MDR1. 2. P-gp/MDR1 is found in various human tissues in addition to being expressed in tumours cells. It is located on the apical surface of intestinal epithelial cells, bile canaliculi, renal tubular cells, and placenta and the luminal surface of capillary endothelial cells in the brain and testes. 3. P-gp/MDR1 confers a multi-drug resistance (MDR) phenotype to cancer cells that have developed resistance to chemotherapy drugs. P-gp/MDR1 activity is also of great clinical importance in non-cancer-related drug therapy due to its wide-ranging effects on the absorption and excretion of a variety of drugs. 4. P-gp/MDR1 excretes xenobiotics such as cytotoxic compounds into the gastrointestinal tract, bile and urine. It also participates in the function of the blood-brain barrier. 5. One of the most interesting characteristics of P-gp/MDR1 is that its many substrates vary greatly in their structure and functionality, ranging from small molecules such as organic cations, carbohydrates, amino acids and some antibiotics to macromolecules such as polysaccharides and proteins. 6. Quite a number of single nucleotide polymorphisms have been found for the MDR1 gene. These single nucleotide polymorphisms are associated with altered oral bioavailability of P-gp/MDR1 substrates, drug resistance, and a susceptibility to some human diseases. 7. Altered P-gp/MDR1 activity due to induction and/or inhibition can cause drug-drug interactions with altered drug pharmacokinetics and response. 8. Further studies are warranted to explore the physiological function and pharmacological role of P-gp/MDR1.
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Affiliation(s)
- S-F Zhou
- Division of Chinese Medicine, School of Health Science, WHO Collaborating Centre for Traditional Medicine, RMIT University, Bundoora, Vic., Australia.
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70
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Koo JS, Choi WC, Rhee YH, Lee HJ, Lee EO, Ahn KS, Bae HS, Ahn KS, Kang JM, Choi SU, Kim MO, Lu J, Kim SH. Quinoline derivative KB3-1 potentiates paclitaxel induced cytotoxicity and cycle arrest via multidrug resistance reversal in MES-SA/DX5 cancer cells. Life Sci 2008; 83:700-8. [PMID: 18845169 DOI: 10.1016/j.lfs.2008.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 09/02/2008] [Indexed: 11/27/2022]
Abstract
AIMS The resistance to chemotherapeutic drugs is a major problem for successful cancer treatment. Multidrug resistance (MDR) phenotype is characterized by over-expression of P-glycoprotein (P-gp) on the cancer cell plasma membrane that extrudes drugs out of the cells. Therefore, novel MDR reversal agents are desirable for combination therapy to reduce MDR and enhance anti-tumor activity. Thus, the present study was aimed to evaluate the potent efficacy of novel quinoline derivative KB3-1 as a potent MDR-reversing agent for combined therapy with TAX. MAIN METHODS MDR reversing effect and TAX combined therapy were examined by Rhodamine accumulation and efflux assay and Confocal immunofluorescence microscopy, Western blotting, TUNEL assay, and cell cycle analysis. KEY FINDINGS The discovery of quinoline-3-carboxylic acid [4-(2-[benzyl-3[-(3,4-dimethoxy-phenyl)-propionyl]-amino]-ethyl)-phenyl]-amide (KB3-1) as a novel MDR-reversal agent. KB3-1 significantly enhanced the accumulation and retention of a P-gp substrate, rhodamine-123 in the P-gp-expressing MES-SA/DX5 uterine sarcoma cells but not in the P-gp-negative MES-SA cells at non-toxic concentrations of 1 microM and 3 microM. Similarly, fluorescence microscopy observation revealed that KB3-1 reduced the effluxed rhodamine-123 expression on the membrane of MES-SA/DX5 cells. Consistent with decreased P-gp pumping activity, confocal microscopic observation revealed that KB3-1 effectively diminished the expression of P-gp in paclitaxel (TAX)-treated MES-SA/DX-5 cells. Furthermore, Western blotting confirmed that KB3-1 reduced P-gp expression and enhanced cytochrome C release and Bax expression in TAX treated MES-SA/DX-5 cells. In addition, KB3-1 enhanced TAX-induced apoptotic bodies in MES-SA/DX5 cells by TdT-mediated-dUTP nick-end labeling (TUNEL) staining assay aswell as potentiated TAX- induced cytotoxicity, G2/M phase arrest and sub-G1 apoptosis in MES-SA/DX5 cells but not in MES-SA cells. Interestingly, KB3-1 at 3 microM had comparable MDR-reversal activity to 10 microM verapamil, a well-known MDR- reversal agent. SIGNIFICANCE KB3-1 can be a MDR-reversal drug candidate for combination chemotherapy with TAX.
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Affiliation(s)
- Jin-Suk Koo
- Oriental Medical College, Kyunghee University, 1 Hoegidong, Dongdaemungu, Seoul 130-701, South Korea
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71
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Lima SAC, Cordeiro-da-Silva A, de Castro B, Gameiro P. Benzodiazepine-mediated structural changes in the multidrug transporter P-glycoprotein: an intrinsic fluorescence quenching analysis. J Membr Biol 2008; 223:117-25. [PMID: 18791834 DOI: 10.1007/s00232-008-9117-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 06/10/2008] [Indexed: 11/28/2022]
Abstract
P-glycoprotein expressed in Pichia pastoris was used to study the drug binding sites of different benzodiazepines. The effect of bromazepam, chlordiazepoxide, diazepam and flurazepam on P-glycoprotein structure was investigated by measuring the intrinsic fluorescence of the transporter tryptophan residues. Purified mouse mdr1a transporter in mixed micelles of 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonic acid and 1,2-dimiristoyl-sn-glycerol-3-phosphocholine emitted fluorescence at 340 nm indicative of the fluorophores in a relatively apolar environment. Acrylamide and iodide ion were used as collisional quenchers toward distinct regions of the transporter, the protein and the interface protein-surface, respectively. Binding of ATP induced conformational changes at the protein surface level in accordance with the location of the nucleotide binding sites. Bromazepam interaction with the transporter was located at the protein-surface interface, diazepam at the membrane region and chlordiazepoxide at the protein surface. Only the flurazepam interaction site was not detected by the quenchers used. All benzodiazepines were able to elicit reorientation of the protein fluorophores on the P-glycoprotein-ATP complex.
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Affiliation(s)
- Sofia A C Lima
- Rede de Química e Tecnologia (REQUIMTE), Departamento de Química, Faculdade Ciências, Universidade do Porto, Porto, Portugal
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72
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Development of predictive in silico model for cyclosporine- and aureobasidin-based P-glycoprotein inhibitors employing receptor surface analysis. J Mol Graph Model 2008; 27:439-51. [PMID: 18789739 DOI: 10.1016/j.jmgm.2008.07.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Revised: 07/28/2008] [Accepted: 07/29/2008] [Indexed: 11/21/2022]
Abstract
P-glycoprotein (Pgp) is implicated in multiple drug resistance (MDR) exhibited by several types of cancer against a multitude of anticancer chemotherapeutic agents. This problem prompted several research groups to search for effective P-gp inhibitors. Cyclosporine A (CsA), aureobasidin A (AbA) and related analogues were reported to possess potent inhibitory actions against Pgp. In this work we employed receptor surface analysis (RSA) to construct two satisfactory receptor surface models (RSMs) for cyclosporine- and aureobasidin-based Pgp inhibitors. These pseudoreceptors were combined to achieve satisfactory three-dimensional quantitative structure activity relationship (3D-QSAR) for 68 different cyclosporine and aureobasidin derivatives. Upon validation against an external set of 16 randomly selected Pgp inhibitors, the optimal 3D-QSAR was found to be self-consistent and predictive (r(LOO)(2)=0.673, r(PRESS)(2)=0.600). The resulting 3D-QSAR was employed to probe the structural factors that control the inhibitory activities of cyclosporine and aureobasidin analogues against Pgp.
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73
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McDevitt CA, Shintre CA, Grossmann JG, Pollock NL, Prince SM, Callaghan R, Ford RC. Structural insights into P-glycoprotein (ABCB1) by small angle X-ray scattering and electron crystallography. FEBS Lett 2008; 582:2950-6. [PMID: 18657537 DOI: 10.1016/j.febslet.2008.07.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 07/14/2008] [Indexed: 11/29/2022]
Abstract
P-glycoprotein (ABCB1) is an ATP-binding cassette protein that is associated with the acquisition of multi-drug resistance in cancer and the failure of chemotherapy in humans. Structural insights into this protein are described using a combination of small angle X-ray scattering data and cryo-electron crystallography data. We have compared the structures with bacterial homologues, and discuss the development of homology models for P-glycoprotein based on the bacterial Sav1866 structure.
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Affiliation(s)
- Christopher A McDevitt
- Nuffield Department of Clinical Laboratory Sciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
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74
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Sabatini S, Kaatz GW, Rossolini GM, Brandini D, Fravolini A. From phenothiazine to 3-phenyl-1,4-benzothiazine derivatives as inhibitors of the Staphylococcus aureus NorA multidrug efflux pump. J Med Chem 2008; 51:4321-30. [PMID: 18578473 DOI: 10.1021/jm701623q] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Overexpression of efflux pumps is an important mechanism by which bacteria evade effects of substrate antimicrobial agents and inhibition of such pumps is a promising strategy to circumvent this resistance mechanism. NorA is a Staphylococcus aureus multidrug efflux pump, the activity of which confers decreased susceptibility to many structurally unrelated agents, including fluoroquinolones, resulting in a multidrug resistant (MDR) phenotype. In this work, a series of 1,4-benzothiazine derivatives were designed and synthesized as a minimized structural template of phenothiazine MDR efflux pump inhibitors (EPIs) in an effort to identify more potent S. aureus NorA EPIs. Almost all derivatives evaluated showed good activity in combination with ciprofloxacin against S. aureus ATCC 25923; some were capable of completely restoring ciprofloxacin activity in a norA-overexpressing strain (SA-K2378). Compounds 6k and 7j displayed good activity against SA-1199B, a strain that also overexpresses norA, in an ethidium bromide (EtBr) efflux inhibition assay.
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Affiliation(s)
- Stefano Sabatini
- Dipartimento di Chimica e Tecnologia del Farmaco, Universita di Perugia, 06123 Perugia, Italy
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75
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Abstract
CLC-0 and cystic fibrosis transmembrane conductance regulator (CFTR) Cl−channels play important roles in Cl−transport across cell membranes. These two proteins belong to, respectively, the CLC and ABC transport protein families whose members encompass both ion channels and transporters. Defective function of members in these two protein families causes various hereditary human diseases. Ion channels and transporters were traditionally viewed as distinct entities in membrane transport physiology, but recent discoveries have blurred the line between these two classes of membrane transport proteins. CLC-0 and CFTR can be considered operationally as ligand-gated channels, though binding of the activating ligands appears to be coupled to an irreversible gating cycle driven by an input of free energy. High-resolution crystallographic structures of bacterial CLC proteins and ABC transporters have led us to a better understanding of the gating properties for CLC and CFTR Cl−channels. Furthermore, the joined force between structural and functional studies of these two protein families has offered a unique opportunity to peek into the evolutionary link between ion channels and transporters. A promising byproduct of this exercise is a deeper mechanistic insight into how different transport proteins work at a fundamental level.
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76
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Storm J, Modok S, O’Mara ML, Tieleman DP, Kerr ID, Callaghan R. Cytosolic Region of TM6 in P-Glycoprotein: Topographical Analysis and Functional Perturbation by Site Directed Labeling. Biochemistry 2008; 47:3615-24. [DOI: 10.1021/bi7023089] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Janet Storm
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, and Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, United Kingdom
| | - Szabolcs Modok
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, and Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, United Kingdom
| | - Megan L. O’Mara
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, and Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, United Kingdom
| | - D. Peter Tieleman
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, and Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, United Kingdom
| | - Ian D. Kerr
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, and Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, United Kingdom
| | - Richard Callaghan
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, United Kingdom, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada, and Centre for Biochemistry and Cell Biology, School of Biomedical Sciences, University of Nottingham, United Kingdom
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77
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Abstract
Since the late 1980s computational methods such as quantitative structure-activity relationship (QSAR) and pharmacophore approaches have become more widely applied to assess interactions between drug-like molecules and transporters, starting with P-glycoprotein (P-gp). Identifying molecules that interact with P-gp and other transporters is important for drug discovery, but it is normally ascertained using laborious in vitro and in vivo studies. Computational QSAR and pharmacophore models can be used to screen commercial databases of molecules rapidly and suggest those likely to bind as substrates or inhibitors for transporters. These predictions can then be readily verified in vitro, thus representing a more efficient route to screening. Recently, the application of this approach has seen the identification of new substrates and inhibitors for several transporters. The successful application of computational models and pharmacophore models in particular to predict transporter binding accurately represents a way to anticipate drug-drug interactions of novel molecules from molecular structure. These models may also see incorporation in future pharmacokinetic-pharmacodynamic models to improve predictions of in vivo drug effects in patients. The implications of early assessment of transporter activity, current advances in QSAR, and other computational methods for future development of these and systems-based approaches will be discussed.
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Affiliation(s)
- S Ekins
- Collaborations in Chemistry, Jenkintown, PA, USA.
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78
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Beck EJ, Yang Y, Yaemsiri S, Raghuram V. Conformational changes in a pore-lining helix coupled to cystic fibrosis transmembrane conductance regulator channel gating. J Biol Chem 2007; 283:4957-66. [PMID: 18056267 DOI: 10.1074/jbc.m702235200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR), the protein dysfunctional in cystic fibrosis, is unique among ATP-binding cassette transporters in that it functions as an ion channel. In CFTR, ATP binding opens the channel, and its subsequent hydrolysis causes channel closure. We studied the conformational changes in the pore-lining sixth transmembrane segment upon ATP binding by measuring state-dependent changes in accessibility of substituted cysteines to methanethiosulfonate reagents. Modification rates of three residues (resides 331, 333, and 335) near the extracellular side were 10-1000-fold slower in the open state than in the closed state. Introduction of a charged residue by chemical modification at two of these positions (resides 331 and 333) affected CFTR single-channel gating. In contrast, modifications of pore-lining residues 334 and 338 were not state-dependent. Our results suggest that ATP binding induces a modest conformational change in the sixth transmembrane segment, and this conformational change is coupled to the gating mechanism that regulates ion conduction. These results may establish a structural basis of gating involving the dynamic rearrangement of transmembrane domains necessary for vectorial transport of substrates in ATP-binding cassette transporters.
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Affiliation(s)
- Edward J Beck
- Laboratory of Kidney and Electrolyte Metabolism, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA
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79
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Li G, Zhang QJ, Ji ZL, Wang YQ. Origin and evolution of vertebrate ABCA genes: A story from Amphioxus. Gene 2007; 405:88-95. [DOI: 10.1016/j.gene.2007.09.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2007] [Revised: 09/20/2007] [Accepted: 09/25/2007] [Indexed: 11/17/2022]
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80
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Lawson J, O'Mara ML, Kerr ID. Structure-based interpretation of the mutagenesis database for the nucleotide binding domains of P-glycoprotein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:376-91. [PMID: 18035039 DOI: 10.1016/j.bbamem.2007.10.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 10/12/2007] [Accepted: 10/25/2007] [Indexed: 12/15/2022]
Abstract
P-glycoprotein (P-gp) is the most intensively studied eukaryotic ATP binding cassette (ABC) transporter, due to its involvement in the multidrug resistance phenotype of a number of cancers. In common with most ABC transporters, P-gp is comprised of two transmembrane domains (TMDs) and two nucleotide binding domains (NBD), the latter coupling ATP hydrolysis with substrate transport (efflux in the case of P-gp). Biochemical investigations over the past twenty years have attempted to unlock mechanistic aspects of P-glycoprotein through scanning and site-directed mutagenesis of both the TMDs and the NBDs. Contemporaneously, crystallographers have elucidated the atomic structure of numerous ABC transporter NBDs, as well as the intact structure (i.e. NBDs and TMDs) of a distantly related ABC-exporter Sav1866. Significantly, the structure of P-gp remains unknown, and only low resolution electron microscopy data exists. Within the current manuscript we employ crystallographic data for homologous proteins, and a molecular model for P-gp, to perform a structural interpretation of the existing "mutagenesis database" for P-gp NBDs. Consequently, this will enable testable predictions to be made that will result in further in-roads into our understanding of this clinically important drug pump.
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Affiliation(s)
- J Lawson
- School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK
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81
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Ravna AW, Sylte I, Sager G. Molecular model of the outward facing state of the human P-glycoprotein (ABCB1), and comparison to a model of the human MRP5 (ABCC5). Theor Biol Med Model 2007; 4:33. [PMID: 17803828 PMCID: PMC2211457 DOI: 10.1186/1742-4682-4-33] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Accepted: 09/06/2007] [Indexed: 01/24/2023] Open
Abstract
Background Multidrug resistance is a particular limitation to cancer chemotherapy, antibiotic treatment and HIV medication. The ABC (ATP binding cassette) transporters human P-glycoprotein (ABCB1) and the human MRP5 (ABCC5) are involved in multidrug resistance. Results In order to elucidate structural and molecular concepts of multidrug resistance, we have constructed a molecular model of the ATP-bound outward facing conformation of the human multidrug resistance protein ABCB1 using the Sav1866 crystal structure as a template, and compared the ABCB1 model with a previous ABCC5 model. The electrostatic potential surface (EPS) of the ABCB1 substrate translocation chamber, which transports cationic amphiphilic and lipophilic substrates, was neutral with negative and weakly positive areas. In contrast, EPS of the ABCC5 substrate translocation chamber, which transports organic anions, was generally positive. Positive-negative ratios of amino acids in the TMDs of ABCB1 and ABCC5 were also analyzed, and the positive-negative ratio of charged amino acids was higher in the ABCC5 TMDs than in the ABCB1 TMDs. In the ABCB1 model residues Leu65 (transmembrane helix 1 (TMH1)), Ile306 (TMH5), Ile340 (TMH6) and Phe343 (TMH6) may form a binding site, and this is in accordance with previous site directed mutagenesis studies. Conclusion The Sav1866 X-ray structure may serve as a suitable template for the ABCB1 model, as it did with ABCC5. The EPS in the substrate translocation chambers and the positive-negative ratio of charged amino acids were in accordance with the transport of cationic amphiphilic and lipophilic substrates by ABCB1, and the transport of organic anions by ABCC5.
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Affiliation(s)
- Aina W Ravna
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway
| | - Ingebrigt Sylte
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway
| | - Georg Sager
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway
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82
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Storm J, O'Mara ML, Crowley EH, Peall J, Tieleman DP, Kerr ID, Callaghan R. Residue G346 in transmembrane segment six is involved in inter-domain communication in P-glycoprotein. Biochemistry 2007; 46:9899-910. [PMID: 17696319 DOI: 10.1021/bi700447p] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multidrug transporters such as P-glycoprotein require considerable inter-domain communication to couple energy utilization with substrate translocation. Elucidation of the regions or residues involved in these communication pathways is a key step in the eventual molecular description of multidrug transport. We used cysteine-scanning mutagenesis to probe the functional involvement of residues along the cytoplasmic half of transmembrane segment 6 (TM6) and its extension toward the nucleotide binding domain. The mutation of one residue (G346C) in this segment adversely affected drug transport in cells. Further investigation using purified protein revealed that the underlying biochemical effect was a reduction in basal ATP hydrolysis. This G346C mutation also affected the stimulation of ATPase activity in a drug dependent manner but had no effect on drug binding, ATP binding, or ADP release. Homology modeling of P-glycoprotein indicated that the G346C mutation caused a steric interaction between TM5 and TM6, thereby precluding a helical movement required to support ATP hydrolysis.
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Affiliation(s)
- Janet Storm
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, United Kingdom
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83
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O'Mara ML, Tieleman DP. P-glycoprotein models of the apo and ATP-bound states based on homology with Sav1866 and MalK. FEBS Lett 2007; 581:4217-22. [PMID: 17706648 DOI: 10.1016/j.febslet.2007.07.069] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 06/25/2007] [Accepted: 07/25/2007] [Indexed: 11/17/2022]
Abstract
We exploit the biochemical and sequence similarity between Staphylococcus aureus Sav1866 and P-glycoprotein to develop a homology model of P-glycoprotein representing an ATP-bound state, which captures the major features of the low-resolution EM structure and is consistent with cysteine mutagenesis studies. Using insights from the MalK crystal structures and BtuCD simulations, we model two nucleotide-free conformations. Conformational changes are characterized by pincering rigid-body rotations of the nucleotide-binding domains, inducing transmembrane domain reorganizations which correspond to the two lowest frequency normal modes of the protein. These conformations (see supplementary material) may characterize some of the major steps in the nucleotide catalytic cycle.
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Affiliation(s)
- Megan L O'Mara
- Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada
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84
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Loo TW, Bartlett MC, Clarke DM. Nucleotide binding, ATP hydrolysis, and mutation of the catalytic carboxylates of human P-glycoprotein cause distinct conformational changes in the transmembrane segments. Biochemistry 2007; 46:9328-36. [PMID: 17636884 DOI: 10.1021/bi700837y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
P-Glycoprotein (P-gp, ABCB1) transports a variety of structurally unrelated cytotoxic compounds out of the cell. Each homologous half of P-gp has a transmembrane (TM) domain containing six TM segments and a nucleotide-binding domain (NBD) and is joined by a linker region. It has been postulated that binding of two ATP molecules at the NBD interface to form a "nucleotide sandwich" induces drug efflux by altering packing of the TM segments that make up the drug-binding pocket. To test if ATP binding alone could alter packing of the TM segments, we introduced catalytic carboxylate mutations (E556Q in NBD1 and E1201Q in NBD2) into double-cysteine mutants that exhibited ATP-dependent cross-linking so that the mutants could bind but not hydrolyze ATP. It was found that ATP binding alone could alter disulfide cross-linking between the TM segments. For example, ATP inhibited cross-linking of mutant L339C(TM6)/V982C(TM12)/E556Q(NBD1)/E1201Q(NBD2) but promoted cross-linking of mutant F343C(TM6)/V982C(TM12)/E556Q(NBD1)/E1201Q(NBD2). Cross-linking of some mutants, however, appeared to require ATP hydrolysis as introduction of the catalytic carboxylate mutations into mutant L332C(TM6)/L975C(TM12) inhibited ATP-dependent cross-linking. Cross-linking between cysteines in the TM segments also could be altered via introduction of a single catalytic carboxylate mutation into mutant L332C(TM6)/L975C(TM12) or by using the nonhydrolyzable ATP analogue, AMP.PNP. The results show that the TM segments are quite sensitive to changes within the ATP-binding sites because different conformations could be detected in the presence of ATP, AMP.PNP, during ATP hydrolysis or through mutation of the catalytic carboxylates.
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Affiliation(s)
- Tip W Loo
- Department of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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85
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Gangjee A, Yu J, Copper JE, Smith CD. Discovery of novel antitumor antimitotic agents that also reverse tumor resistance. J Med Chem 2007; 50:3290-301. [PMID: 17567121 PMCID: PMC3858178 DOI: 10.1021/jm070194u] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We have discovered a novel series of 7-benzyl-4-methyl-5-[(2-substituted phenyl)ethyl]-7H-pyrrolo[2,3-d]pyrimidin-2-amines, which possess antimitotic and antitumor activities against antimitotic-sensitive as well as resistant tumor cells. These agents bind to a site on tubulin that is distinct from the colchicine, vinca alkaloid, and paclitaxel binding sites and some, in addition to their antitumor activity, remarkably also reverse tumor resistance to antimitotic agents mediated via the P-glycoprotein efflux pump. The compounds were synthesized from N-(7-benzyl-5-ethynyl-4-methyl-7H-pyrrolo[2,3-d]pyrimidin-2-yl)-2,2-dimethylpropanamide 11 or the corresponding 5-iodo analog 14 via Sonogashira couplings with appropriate iodobenzenes or phenylacetylene followed by reduction and deprotection to afford the target analogs. Sodium and liquid NH3 afforded the debenzylated analogs. The most potent analog 1 was one to three digit nanomolar against the growth of both sensitive and resistant tumor cells in culture. Compounds of this series are promising novel antimitotic agents that have the potential for treating both sensitive and resistant tumors.
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Affiliation(s)
- Aleem Gangjee
- Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282, USA.
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86
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Abstract
The acquisition of multidrug resistance is a serious impediment to improved healthcare. Multidrug resistance is most frequently due to active transporters that pump a broad spectrum of chemically distinct, cytotoxic molecules out of cells, including antibiotics, antimalarials, herbicides and cancer chemotherapeutics in humans. The paradigm multidrug transporter, mammalian P-glycoprotein, was identified 30 years ago. Nonetheless, success in overcoming or circumventing multidrug resistance in a clinical setting has been modest. Recent structural and biochemical data for several multidrug transporters now provide mechanistic insights into how they work. Organisms have evolved several elegant solutions to ridding the cell of such cytotoxic compounds. Answers are emerging to questions such as how multispecificity for different drugs is achieved, why multidrug resistance arises so readily, and what chance there is of devising a clinical solution.
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Affiliation(s)
- Christopher F Higgins
- MRC Clinical Sciences Centre, Imperial College, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
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87
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Sharom FJ. Shedding light on drug transport: structure and function of the P-glycoprotein multidrug transporter (ABCB1). Biochem Cell Biol 2007; 84:979-92. [PMID: 17215884 DOI: 10.1139/o06-199] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
P-glycoprotein (Pgp; ABCB1), a member of the ATP-binding cassette (ABC) superfamily, exports structurally diverse hydrophobic compounds from the cell, driven by ATP hydrolysis. Pgp expression has been linked to the efflux of chemotherapeutic drugs in human cancers, leading to multidrug resistance (MDR). The protein also plays an important physiological role in limiting drug uptake in the gut and entry into the brain. Substrates partition into the lipid bilayer before interacting with Pgp, which has been proposed to function as a hydrophobic vacuum cleaner. Low- and medium-resolution structural models of Pgp suggest that the 2 nucleotide-binding domains are closely associated to form a nucleotide sandwich dimer. Pgp is an outwardly directed flippase for fluorescent phospholipid and glycosphingolipid derivatives, which suggests that it may also translocate drug molecules from the inner to the outer membrane leaflet. The ATPase catalytic cycle of the protein is thought to proceed via an alternating site mechanism, although the details are not understood. The lipid bilayer plays an important role in Pgp function, and may regulate both the binding and transport of drugs. This review focuses on the structure and function of Pgp, and highlights the importance of fluorescence spectroscopic techniques in exploring the molecular details of this enigmatic transporter.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B
- ATP Binding Cassette Transporter, Subfamily B, Member 1/chemistry
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology
- ATP-Binding Cassette Transporters/metabolism
- Adenosine Triphosphate/metabolism
- Animals
- Awards and Prizes
- Biological Transport/drug effects
- Drug Resistance, Multiple
- Humans
- Models, Biological
- Models, Molecular
- Organic Anion Transporters/metabolism
- Spectrometry, Fluorescence
- Structure-Activity Relationship
- Substrate Specificity
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Affiliation(s)
- Frances J Sharom
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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88
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Siarheyeva A, Lopez JJ, Lehner I, Hellmich UA, van Veen HW, Glaubitz C. Probing the Molecular Dynamics of the ABC Multidrug Transporter LmrA by Deuterium Solid-State Nuclear Magnetic Resonance†. Biochemistry 2007; 46:3075-83. [PMID: 17302438 DOI: 10.1021/bi062109a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The molecular dynamics of the 64 kDa ABC multidrug efflux pump LmrA from Lactococcus lactis within lipid membranes has been investigated by deuterium solid-state NMR. Deuteriomethyl-labeled alanine has been used to probe global protein backbone dynamics. A comparison of static deuterium NMR spectra of full-length LmrA in the resting state and its isolated transmembrane domain revealed a high mobility for the nucleotide binding domains. Their motional freedom is restricted upon ATP binding as seen for LmrA in complex with AMP-PNP, a nonhydrolyzable ATP analogue. LmrA returns to full motional flexibility in the posthydrolysis, vanadate-trapped state. These experiments provide insight into the molecular dynamics of a full-length ABC transporter during the catalytic cycle. Data are discussed in the context of known biochemical data and structural models of ABC transporters.
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Affiliation(s)
- Alena Siarheyeva
- Institute for Biophysical Chemistry and Centre for Biomolecular Magnetic Resonance, J. W. Goethe Universität, Frankfurt am Main, Germany
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89
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Li G, Shi P, Wang Y. Evolutionary dynamics of the ABCA chromosome 17q24 cluster genes in vertebrates. Genomics 2007; 89:385-91. [PMID: 17188459 DOI: 10.1016/j.ygeno.2006.07.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Revised: 07/28/2006] [Accepted: 07/29/2006] [Indexed: 10/23/2022]
Abstract
ABCA is a subfamily of ATP-binding-cassette (ABC) transporter genes. In this subfamily, it was found that five ABCA genes cluster in a head-to-tail pattern in the human and mouse genomes, but only one was found in fish. To understand better the evolution of this cluster of genes, we screened 11 vertebrate genome sequences and newly identified 28 ABCA cluster genes. Comparative genomic analysis reveals that the ABCA5 gene is relatively evolutionarily conserved. In contrast, the repertoires of the other ABCA genes in this cluster diverge tremendously among species, which is due mainly to postspeciation duplications. In addition, maximum likelihood analysis reveals that positive selection is acting on the paralogous genes ABCA6 and Abca8a, suggesting that these two genes have possibly acquired new functions after duplication. Because most eukaryotic ABC proteins integrate into the cytoplasmic membrane and transport a wide range of substrates across it, we conjecture that newly duplicated ABCA cluster genes are under diversifying selection for the ability to recognize a diverse array of substrates.
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Affiliation(s)
- Guang Li
- Key Laboratory of Ministry of Education for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen, Fujian 361005, China
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90
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McDevitt CA, Callaghan R. How can we best use structural information on P-glycoprotein to design inhibitors? Pharmacol Ther 2007; 113:429-41. [PMID: 17208306 DOI: 10.1016/j.pharmthera.2006.10.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Accepted: 10/13/2006] [Indexed: 10/23/2022]
Abstract
This year marks the 30th anniversary of the discovery of the multidrug resistance (MDR) ATP-binding cassette (ABC) transporter P-glycoprotein (P-gp). Since then a considerable research effort has attempted to provide a greater understanding of the biological enigma of "multidrug" efflux. Moreover, the growing correlation between P-gp expression and a negative prognosis or poor outcome for chemotherapy has sparked significant interest in the generation of inhibitors. How close are we to overcoming the unwanted actions of P-gp in resistant cancer following 30 years of research? The initial inhibitors were pre-existing clinically used compounds and exploited the broad specificity of P-gp. Unfortunately, the concentrations required to inhibit P-gp meant that these compounds generated considerable toxicity. Pharmacological investigations progressed to rational design using the 1st generation compounds as a template structure. Inherent toxicity of the drugs was reduced; however, pharmacokinetic interactions with the anticancer drugs were unsustainable. Generation of the most recent of inhibitors employed combinatorial chemistry to produce a handful of potent and selective P-gp inhibitors. Some of these drugs have progressed to clinical trials with poor results or in some cases, undisclosed progress. There remains a clear need for the generation of P-gp inhibitors and this review describes the potential for a structure-based design to facilitate this undertaking. In particular, the plethora of functional data can provide important regions on the protein that could conceivably be exploited as inhibitor targets.
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Affiliation(s)
- Christopher A McDevitt
- Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
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91
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Teodori E, Martelli C, Salerno M, Darghal N, Dei S, Garnier-Suillerot A, Gualtieri F, Manetti D, Scapecchi S, Romanelli MN. Isomeric N,N-Bis(cyclohexanol)amine Aryl Esters: The Discovery of a New Class of Highly Potent P-Glycoprotein (Pgp)-dependent Multidrug Resistance (MDR) Inhibitors. J Med Chem 2007; 50:599-602. [PMID: 17256837 DOI: 10.1021/jm0614432] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A new series of P-glycoprotein (Pgp)-dependent multidrug resistance (MDR) inhibitors having a N,N-bis(cyclohexanol)amine scaffold have been designed, following the frozen analog approach. With respect to the parent flexible molecules, the new compounds show improved potency and efficacy. Among them, compound 1d, on anthracycline-resistant erythroleukemia K562 cells, is able to completely reverse Pgp-dependent MDR at low nanomolar concentration.
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Affiliation(s)
- Elisabetta Teodori
- Dipartimento di Scienze Farmaceutiche, Università di Firenze, via U. Schiff 6, 50019 Sesto Fiorentino (FI), Italy
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92
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Wong ILK, Chan KF, Burkett BA, Zhao Y, Chai Y, Sun H, Chan TH, Chow LMC. Flavonoid dimers as bivalent modulators for pentamidine and sodium stiboglucanate resistance in leishmania. Antimicrob Agents Chemother 2006; 51:930-40. [PMID: 17194831 PMCID: PMC1803137 DOI: 10.1128/aac.00998-06] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Drug resistance by overexpression of ATP-binding cassette (ABC) transporters is an impediment in the treatment of leishmaniasis. Flavonoids are known to reverse multidrug resistance (MDR) in Leishmania and mammalian cancers by inhibiting ABC transporters. Here, we found that synthetic flavonoid dimers with three (compound 9c) or four (compound 9d) ethylene glycol units exhibited a significantly higher reversing activity than other shorter or longer ethylene glycol-ligated dimers, with approximately 3-fold sensitization of pentamidine and sodium stibogluconate (SSG) resistance in Leishmania, respectively. This modulatory effect was dosage dependent and not observed in apigenin monomers with the linker, suggesting that the modulatory effect is due to its bivalent nature. The mechanism of reversal activity was due to increased intracellular accumulation of pentamidine and total antimony in Leishmania. Compared to other MDR modulators such as verapamil, reserpine, quinine, quinacrine, and quinidine, compounds 9c and 9d were the only agents that can reverse SSG resistance. In terms of reversing pentamidine resistance, 9c and 9d have activities comparable to those of reserpine and quinacrine. Modulators 9c and 9d exhibited reversal activity on pentamidine resistance among LeMDR1(-/-), LeMDR1(+/+), and LeMDR1-overexpressed mutants, suggesting that these modulators are specific to a non-LeMDR1 pentamidine transporter. The LeMDR1 copy number is inversely related to pentamidine resistance, suggesting that it might be involved in importing pentamidine into the mitochondria. In summary, bivalency could be a useful strategy for the development of more potent ABC transporter modulators and flavonoid dimers represent a promising reversal agent for overcoming pentamidine and SSG resistance in parasite Leishmania.
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Affiliation(s)
- Iris L K Wong
- Department of Applied Biology and Chemical Technology and Central Laboratory of the Institute of Molecular Technology for Drug Discovery and Synthesis, The Hong Kong Polytechnic University, Hong Kong, People's Republic of China
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93
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Acharya P, Tran TT, Polli JW, Ayrton A, Ellens H, Bentz J. P-Glycoprotein (P-gp) expressed in a confluent monolayer of hMDR1-MDCKII cells has more than one efflux pathway with cooperative binding sites. Biochemistry 2006; 45:15505-19. [PMID: 17176072 DOI: 10.1021/bi060593b] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The multidrug resistance transporter P-glycoprotein (P-gp) effluxes a wide range of substrates and can be affected by a wide range of inhibitors or modulators. Many studies have presented classifications for these binding interactions, within either the context of equilibrium binding or the Michaelis-Menten enzyme analysis of the ATPase activity of P-gp. Our approach is to study P-gp transport and its inhibition using a physiologically relevant confluent monolayer of hMDR1-MDCKII cells. We measure the elementary rate constants for P-gp efflux of substrates and study inhibition using pairwise combinations with a different unlabeled substrate acting as the inhibitor. Our current kinetic model for P-gp has only a single binding site, because a previous study proved that the mass-action kinetics of efflux of a single substrate were not sensitive to whether there are one or more substrate-binding and efflux sites. In this study, using this one-site model, we found that, with "high" concentrations of either a substrate or an inhibitor, the elementary rate constants fitted independently for each of the substrates alone quantitatively predicted the efflux curves, simply applying the assumption that binding at the "one site" was competitive. On the other hand, at "low" concentrations of both the substrate and inhibitor, we found no inhibition of the substrate efflux, despite the fact that both the substrate and inhibitor were being well-effluxed. This was not an effect of excess "empty" P-gp molecules, because the competitive efflux model takes site occupancy into account. Rather, it is quantitative evidence that the substrate and inhibitor are being effluxed by multiple pathways within P-gp. Remarkably, increasing the substrate concentration above the "low" concentration, caused the inhibition to become competitive; i.e., the inhibitor became effective. These data and their analysis show that the binding of these substrates must be cooperative, either positive or negative.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology
- Animals
- Binding, Competitive/genetics
- Biological Transport, Active/drug effects
- Biological Transport, Active/genetics
- Carbamates/antagonists & inhibitors
- Carbamates/metabolism
- Cell Line
- Cell Membrane Permeability/genetics
- Dogs
- Furans
- Humans
- Loperamide/antagonists & inhibitors
- Loperamide/metabolism
- Protein Binding/genetics
- Quinidine/pharmacology
- Signal Transduction/genetics
- Substrate Specificity/drug effects
- Substrate Specificity/genetics
- Sulfonamides/antagonists & inhibitors
- Sulfonamides/metabolism
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Affiliation(s)
- Poulomi Acharya
- Department of Bioscience and Biotechnology, Drexel University, Philadelphia, Pennsylvania 19104, USA
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94
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Sarkadi B, Homolya L, Szakács G, Váradi A. Human multidrug resistance ABCB and ABCG transporters: participation in a chemoimmunity defense system. Physiol Rev 2006; 86:1179-236. [PMID: 17015488 DOI: 10.1152/physrev.00037.2005] [Citation(s) in RCA: 536] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In this review we give an overview of the physiological functions of a group of ATP binding cassette (ABC) transporter proteins, which were discovered, and still referred to, as multidrug resistance (MDR) transporters. Although they indeed play an important role in cancer drug resistance, their major physiological function is to provide general protection against hydrophobic xenobiotics. With a highly conserved structure, membrane topology, and mechanism of action, these essential transporters are preserved throughout all living systems, from bacteria to human. We describe the general structural and mechanistic features of the human MDR-ABC transporters and introduce some of the basic methods that can be applied for the analysis of their expression, function, regulation, and modulation. We treat in detail the biochemistry, cell biology, and physiology of the ABCB1 (MDR1/P-glycoprotein) and the ABCG2 (MXR/BCRP) proteins and describe emerging information related to additional ABCB- and ABCG-type transporters with a potential role in drug and xenobiotic resistance. Throughout this review we demonstrate and emphasize the general network characteristics of the MDR-ABC transporters, functioning at the cellular and physiological tissue barriers. In addition, we suggest that multidrug transporters are essential parts of an innate defense system, the "chemoimmunity" network, which has a number of features reminiscent of classical immunology.
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Affiliation(s)
- Balázs Sarkadi
- National Medical Center, Institute of Hematology and Immunology, Membrane Research Group, Budapest, Hungary.
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95
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Chan KF, Zhao Y, Burkett BA, Wong ILK, Chow LMC, Chan TH. Flavonoid Dimers as Bivalent Modulators for P-Glycoprotein-Based Multidrug Resistance: Synthetic Apigenin Homodimers Linked with Defined-Length Poly(ethylene glycol) Spacers Increase Drug Retention and Enhance Chemosensitivity in Resistant Cancer Cells. J Med Chem 2006; 49:6742-59. [PMID: 17154505 DOI: 10.1021/jm060593+] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Much effort has been spent on searching for better P-glycoprotein- (P-gp-) based multidrug resistance (MDR) modulators. Our approach was to target the binding sites of P-gp using dimers of dietary flavonoids. A series of apigenin-based flavonoid dimers, linked by poly(ethylene glycol) chains of various lengths, have been synthesized. These flavonoid dimers modulate drug chemosensitivity and retention in breast and leukemic MDR cells with the optimal number of ethylene glycol units equal to 2-4. Compound 9d bearing four ethylene glycol units increased drug accumulation in drug-resistant cells and enhanced cytotoxicity of paclitaxel, doxorubicin, daunomycin, vincristine, and vinblastine in drug-resistant breast cancer and leukemia cells in vitro, resulting in reduction of IC50 by 5-50 times. This compound also stimulated P-gp's ATPase activity by 3.3-fold. Its modulating activity was presumably by binding to the substrate binding sites of P-gp and disrupting drug efflux.
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Affiliation(s)
- Kin-Fai Chan
- Department of Applied Biology and Chemical Technology and the Institute of Molecular Technology for Drug Discovery and Synthesis, The Hong Kong Polytechnic University, Hong Kong SAR
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96
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Goda K, Fenyvesi F, Bacsó Z, Nagy H, Márián T, Megyeri A, Krasznai Z, Juhász I, Vecsernyés M, Szabó G. Complete Inhibition of P-glycoprotein by Simultaneous Treatment with a Distinct Class of Modulators and the UIC2 Monoclonal Antibody. J Pharmacol Exp Ther 2006; 320:81-8. [PMID: 17050779 DOI: 10.1124/jpet.106.110155] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
P-glycoprotein (Pgp) is one of the active efflux pumps that are able to extrude a large variety of chemotherapeutic drugs from the cells, causing multidrug resistance. The conformation-sensitive UIC2 monoclonal antibody potentially inhibits Pgp-mediated substrate transport. However, this inhibition is usually partial, and its extent is variable because UIC2 binds only to 10 to 40% Pgp present in the cell membrane. The rest of the Pgp molecules become recognized by this antibody only in the presence of certain substrates or modulators, including vinblastine, cyclosporine A (CsA), and SDZ PSC 833 (valspodar). Simultaneous application of any of these modulators and UIC2, followed by the removal of the modulator, results in a completely restored steady-state accumulation of various Pgp substrates (calcein-AM, daunorubicin, and 99mTc-hexakis-2-methoxybutylisonitrile), indicating near 100% inhibition of pump activity. Remarkably, the inhibitory binding of the antibody is brought about by coincubation with concentrations of CsA or SDZ PSC 833 approximately 20 times lower than what is necessary for Pgp inhibition when the modulators are applied alone. The feasibility of such a combinative treatment for in vivo multidrug resistance reversal was substantiated by the dramatic increase of daunorubicin accumulation in xenotransplanted Pgp+ tumors in response to a combined treatment with UIC2 and CsA, both administered at doses ineffective when applied alone. These observations establish the combined application of a class of modulators used at low concentrations and of the UIC2 antibody as a novel, specific, and effective way of blocking Pgp function in vivo.
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Affiliation(s)
- Katalin Goda
- Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary
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97
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Mahadevan D. Will MDR-1/P-gp modulators provide clinical benefit in hematologic malignancies? Leuk Res 2006; 30:1077-8. [PMID: 16678260 DOI: 10.1016/j.leukres.2006.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 03/20/2006] [Accepted: 03/21/2006] [Indexed: 11/22/2022]
MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- Animals
- Antibiotics, Antineoplastic/pharmacology
- Antineoplastic Combined Chemotherapy Protocols/pharmacology
- Antineoplastic Combined Chemotherapy Protocols/therapeutic use
- Blast Crisis/drug therapy
- Blast Crisis/pathology
- Carbazoles/pharmacology
- Carbazoles/therapeutic use
- Cell Line, Tumor
- Daunorubicin/pharmacology
- Drug Resistance, Neoplasm/drug effects
- Drug Screening Assays, Antitumor
- Enzyme Inhibitors/pharmacology
- Enzyme Inhibitors/therapeutic use
- Humans
- Indoles/pharmacology
- Indoles/therapeutic use
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Mice
- Mice, Inbred BALB C
- Mice, Transgenic
- Multiple Myeloma/drug therapy
- Multiple Myeloma/pathology
- Pyrroles/pharmacology
- Pyrroles/therapeutic use
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98
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Linton KJ, Higgins CF. Structure and function of ABC transporters: the ATP switch provides flexible control. Pflugers Arch 2006; 453:555-67. [PMID: 16937116 DOI: 10.1007/s00424-006-0126-x] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 06/15/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
ATP-binding cassette (ABC) transporters are ubiquitous integral membrane proteins that facilitate the transbilayer movement of ligands. They comprise, minimally, two transmembrane domains, which impart ligand specificity, and two nucleotide-binding domains (NBDs), which power the transport cycle. Almost 25 years of biochemistry is reviewed in light of the recent structure analyses resulting in the ATP-switch model for function in which the NBDs switch between a dimeric conformation, closed around two molecules of ATP, and a nucleotide-free, dimeric 'open' conformation. The flexibility of this switching mechanism has evolved to provide different kinetic control for different transporters and has also been co-opted to diverse functions other than transmembrane transport.
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Affiliation(s)
- Kenneth J Linton
- MRC Clinical Sciences Centre, Imperial College Hammersmith Hospital Campus, London, UK.
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99
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Tombline G, Donnelly DJ, Holt JJ, You Y, Ye M, Gannon MK, Nygren CL, Detty MR. Stimulation of P-glycoprotein ATPase by analogues of tetramethylrosamine: coupling of drug binding at the "R" site to the ATP hydrolysis transition state. Biochemistry 2006; 45:8034-47. [PMID: 16800628 DOI: 10.1021/bi0603470] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The multidrug resistance efflux pump P-glycoprotein (Pgp) couples drug export to ATP binding and hydrolysis. Details regarding drug trajectory, as well as the molecular basis for coupling, remain unknown. Nearly all drugs exported by Pgp have been assayed for competitive behavior with rhodamine123 transport at a canonical "R" drug binding site. Tetramethylrosamine (TMR) displays a relatively high affinity for Pgp when compared to other rhodamines. Here, we present the construction and characterization of a library of compounds based upon the TMR scaffold and use this set to assess the determinants of drug binding to the "R" site of Pgp. This set contained modifications in (1) the number, location, and conformational mobility of hydrogen-bond acceptors; (2) the heteroatom in the xanthylium core; and (3) the size of the substituent in the 9-position of the xanthylium core. Relative specificity for coupling to the distal ATP catalytic site was assessed by ATPase stimulation. We found marked ( approximately 1000-fold) variation in the ATPase specificity constant within the library of TMR analogues. Using established methods involving ADP-Vi trapping by wild-type Pgp and ATP binding by catalytic carboxylate mutant Pgp, these effects can be extended to ATP hydrolysis transition-state stabilization and ATP occlusion at a single site. These data support the idea that drugs trigger the engagement of ATP catalytic site residues necessary for hydrolysis. Further, the nature of the drug binding site and coupling mechanism may be dissected by variation of a drug-like scaffold. These studies may facilitate development of novel competitive inhibitors at the "R" drug site.
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Affiliation(s)
- Gregory Tombline
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, USA.
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Deeley RG, Westlake C, Cole SPC. Transmembrane transport of endo- and xenobiotics by mammalian ATP-binding cassette multidrug resistance proteins. Physiol Rev 2006; 86:849-99. [PMID: 16816140 DOI: 10.1152/physrev.00035.2005] [Citation(s) in RCA: 533] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Multidrug Resistance Proteins (MRPs), together with the cystic fibrosis conductance regulator (CFTR/ABCC7) and the sulfonylurea receptors (SUR1/ABCC8 and SUR2/ABCC9) comprise the 13 members of the human "C" branch of the ATP binding cassette (ABC) superfamily. All C branch proteins share conserved structural features in their nucleotide binding domains (NBDs) that distinguish them from other ABC proteins. The MRPs can be further divided into two subfamilies "long" (MRP1, -2, -3, -6, and -7) and "short" (MRP4, -5, -8, -9, and -10). The short MRPs have a typical ABC transporter structure with two polytropic membrane spanning domains (MSDs) and two NBDs, while the long MRPs have an additional NH2-terminal MSD. In vitro, the MRPs can collectively confer resistance to natural product drugs and their conjugated metabolites, platinum compounds, folate antimetabolites, nucleoside and nucleotide analogs, arsenical and antimonial oxyanions, peptide-based agents, and, under certain circumstances, alkylating agents. The MRPs are also primary active transporters of other structurally diverse compounds, including glutathione, glucuronide, and sulfate conjugates of a large number of xeno- and endobiotics. In vivo, several MRPs are major contributors to the distribution and elimination of a wide range of both anticancer and non-anticancer drugs and metabolites. In this review, we describe what is known of the structure of the MRPs and the mechanisms by which they recognize and transport their diverse substrates. We also summarize knowledge of their possible physiological functions and evidence that they may be involved in the clinical drug resistance of various forms of cancer.
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Affiliation(s)
- Roger G Deeley
- Division of Cancer Biology and Genetics, Cancer Research Institute and Department of Biochemistry, Queen's University Kingdom, Ontario, Canada.
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