1
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Choi SH, Lee SS, Lee HY, Kim S, Kim JW, Jin MS. Cryo-EM structure of cadmium-bound human ABCB6. Commun Biol 2024; 7:672. [PMID: 38822018 PMCID: PMC11143254 DOI: 10.1038/s42003-024-06377-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 05/23/2024] [Indexed: 06/02/2024] Open
Abstract
ATP-binding cassette transporter B6 (ABCB6), a protein essential for heme biosynthesis in mitochondria, also functions as a heavy metal efflux pump. Here, we present cryo-electron microscopy structures of human ABCB6 bound to a cadmium Cd(II) ion in the presence of antioxidant thiol peptides glutathione (GSH) and phytochelatin 2 (PC2) at resolutions of 3.2 and 3.1 Å, respectively. The overall folding of the two structures resembles the inward-facing apo state but with less separation between the two halves of the transporter. Two GSH molecules are symmetrically bound to the Cd(II) ion in a bent conformation, with the central cysteine protruding towards the metal. The N-terminal glutamate and C-terminal glycine of GSH do not directly interact with Cd(II) but contribute to neutralizing positive charges of the binding cavity by forming hydrogen bonds and van der Waals interactions with nearby residues. In the presence of PC2, Cd(II) binding to ABCB6 is similar to that observed with GSH, except that two cysteine residues of each PC2 molecule participate in Cd(II) coordination to form a tetrathiolate. Structural comparison of human ABCB6 and its homologous Atm-type transporters indicate that their distinct substrate specificity might be attributed to variations in the capping residues situated at the top of the substrate-binding cavity.
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Affiliation(s)
- Seung Hun Choi
- School of Life Sciences, GIST, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea
| | - Sang Soo Lee
- School of Life Sciences, GIST, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea
| | - Hyeon You Lee
- School of Life Sciences, GIST, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea
| | - Subin Kim
- School of Life Sciences, GIST, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea
| | - Ji Won Kim
- Department of Life Sciences, POSTECH, 77 Cheongam-Ro, Nam-gu, Pohang, Republic of Korea
| | - Mi Sun Jin
- School of Life Sciences, GIST, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, Republic of Korea.
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2
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Dhanyamraju PK. Drug resistance mechanisms in cancers: Execution of pro-survival strategies. J Biomed Res 2024; 38:95-121. [PMID: 38413011 PMCID: PMC11001593 DOI: 10.7555/jbr.37.20230248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/21/2023] [Accepted: 12/07/2023] [Indexed: 02/29/2024] Open
Abstract
One of the quintessential challenges in cancer treatment is drug resistance. Several mechanisms of drug resistance have been described to date, and new modes of drug resistance continue to be discovered. The phenomenon of cancer drug resistance is now widespread, with approximately 90% of cancer-related deaths associated with drug resistance. Despite significant advances in the drug discovery process, the emergence of innate and acquired mechanisms of drug resistance has impeded the progress in cancer therapy. Therefore, understanding the mechanisms of drug resistance and the various pathways involved is integral to treatment modalities. In the present review, I discuss the different mechanisms of drug resistance in cancer cells, including DNA damage repair, epithelial to mesenchymal transition, inhibition of cell death, alteration of drug targets, inactivation of drugs, deregulation of cellular energetics, immune evasion, tumor-promoting inflammation, genome instability, and other contributing epigenetic factors. Furthermore, I highlight available treatment options and conclude with future directions.
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Affiliation(s)
- Pavan Kumar Dhanyamraju
- Fels Cancer Institute of Personalized Medicine, Lewis-Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
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3
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Fan W, Shao K, Luo M. Structural View of Cryo-Electron Microscopy-Determined ATP-Binding Cassette Transporters in Human Multidrug Resistance. Biomolecules 2024; 14:231. [PMID: 38397468 PMCID: PMC10886794 DOI: 10.3390/biom14020231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/01/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024] Open
Abstract
ATP-binding cassette (ABC) transporters, acting as cellular "pumps," facilitate solute translocation through membranes via ATP hydrolysis. Their overexpression is closely tied to multidrug resistance (MDR), a major obstacle in chemotherapy and neurological disorder treatment, hampering drug accumulation and delivery. Extensive research has delved into the intricate interplay between ABC transporter structure, function, and potential inhibition for MDR reversal. Cryo-electron microscopy has been instrumental in unveiling structural details of various MDR-causing ABC transporters, encompassing ABCB1, ABCC1, and ABCG2, as well as the recently revealed ABCC3 and ABCC4 structures. The newly obtained structural insight has deepened our understanding of substrate and drug binding, translocation mechanisms, and inhibitor interactions. Given the growing body of structural information available for human MDR transporters and their associated mechanisms, we believe it is timely to compile a comprehensive review of these transporters and compare their functional mechanisms in the context of multidrug resistance. Therefore, this review primarily focuses on the structural aspects of clinically significant human ABC transporters linked to MDR, with the aim of providing valuable insights to enhance the effectiveness of MDR reversal strategies in clinical therapies.
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Affiliation(s)
| | | | - Min Luo
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore; (W.F.); (K.S.)
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4
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Gerard L, Duvivier L, Fourrez M, Salazar P, Sprimont L, Xia D, Ambudkar SV, Gottesman MM, Gillet JP. Identification of two novel heterodimeric ABC transporters in melanoma: ABCB5β/B6 and ABCB5β/B9. J Biol Chem 2024; 300:105594. [PMID: 38145744 PMCID: PMC10828454 DOI: 10.1016/j.jbc.2023.105594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 11/18/2023] [Accepted: 12/15/2023] [Indexed: 12/27/2023] Open
Abstract
ABCB5 is a member of the ABC transporter superfamily composed of 48 transporters, which have been extensively studied for their role in cancer multidrug resistance and, more recently, in tumorigenesis. ABCB5 has been identified as a marker of skin progenitor cells, melanoma, and limbal stem cells. It has also been associated with multidrug resistance in several cancers. The unique feature of ABCB5 is that it exists as both a full transporter (ABCB5FL) and a half transporter (ABCB5β). Several studies have shown that the ABCB5β homodimer does not confer multidrug resistance, in contrast to ABCB5FL. In this study, using three complementary techniques, (1) nanoluciferase-based bioluminescence resonance energy transfer, (2) coimmunoprecipitation, and (3) proximity ligation assay, we identified two novel heterodimers in melanoma: ABCB5β/B6 and ABCB5β/B9. Both heterodimers could be expressed in High-Five insect cells and ATPase assays revealed that both functional nucleotide-binding domains of homodimers and heterodimers are required for their basal ATPase activity. These results are an important step toward elucidating the functional role of ABCB5β in melanocytes and melanoma.
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Affiliation(s)
- Louise Gerard
- Laboratory of Molecular Cancer Biology, URPhyM, NARILIS, University of Namur, Namur, Belgium
| | - Laurent Duvivier
- Laboratory of Molecular Cancer Biology, URPhyM, NARILIS, University of Namur, Namur, Belgium
| | - Marie Fourrez
- Laboratory of Molecular Cancer Biology, URPhyM, NARILIS, University of Namur, Namur, Belgium
| | - Paula Salazar
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Lindsay Sprimont
- Laboratory of Molecular Cancer Biology, URPhyM, NARILIS, University of Namur, Namur, Belgium
| | - Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Suresh V Ambudkar
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael M Gottesman
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jean-Pierre Gillet
- Laboratory of Molecular Cancer Biology, URPhyM, NARILIS, University of Namur, Namur, Belgium.
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5
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Lee SS, Park JG, Jang E, Choi SH, Kim S, Kim JW, Jin MS. W546 stacking disruption traps the human porphyrin transporter ABCB6 in an outward-facing transient state. Commun Biol 2023; 6:960. [PMID: 37735522 PMCID: PMC10514269 DOI: 10.1038/s42003-023-05339-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 09/11/2023] [Indexed: 09/23/2023] Open
Abstract
Human ATP-binding cassette transporter subfamily B6 (ABCB6) is a mitochondrial ATP-driven pump that translocates porphyrins from the cytoplasm into mitochondria for heme biosynthesis. Within the transport pathway, a conserved aromatic residue W546 located in each monomer plays a pivotal role in stabilizing the occluded conformation via π-stacking interactions. Herein, we employed cryo-electron microscopy to investigate the structural consequences of a single W546A mutation in ABCB6, both in detergent micelles and nanodiscs. The results demonstrate that the W546A mutation alters the conformational dynamics of detergent-purified ABCB6, leading to entrapment of the transporter in an outward-facing transient state. However, in the nanodisc system, we observed a direct interaction between the transporter and a phospholipid molecule that compensates for the absence of the W546 residue, thereby facilitating the normal conformational transition of the transporter toward the occluded state following ATP hydrolysis. The findings also reveal that adoption of the outward-facing conformation causes charge repulsion between ABCB6 and the bound substrate, and rearrangement of key interacting residues at the substrate-binding site. Consequently, the affinity for the substrate is significantly reduced, facilitating its release from the transporter.
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Affiliation(s)
- Sang Soo Lee
- School of Life Sciences, GIST, 123 Cheomdan-gwagiro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Jun Gyou Park
- School of Life Sciences, GIST, 123 Cheomdan-gwagiro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Eunhong Jang
- School of Life Sciences, GIST, 123 Cheomdan-gwagiro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Seung Hun Choi
- School of Life Sciences, GIST, 123 Cheomdan-gwagiro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Subin Kim
- School of Life Sciences, GIST, 123 Cheomdan-gwagiro, Buk-gu, Gwangju, 61005, Republic of Korea
| | - Ji Won Kim
- Department of Life Sciences, POSTECH, 77 Cheongam-Ro, Nam-gu, Pohang, 37673, Republic of Korea
| | - Mi Sun Jin
- School of Life Sciences, GIST, 123 Cheomdan-gwagiro, Buk-gu, Gwangju, 61005, Republic of Korea.
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6
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Kim S, Lee SS, Park JG, Kim JW, Ju S, Choi SH, Kim S, Kim NJ, Hong S, Kang JY, Jin MS. Structural Insights into Porphyrin Recognition by the Human ATP-Binding Cassette Transporter ABCB6. Mol Cells 2022; 45:575-587. [PMID: 35950458 PMCID: PMC9385563 DOI: 10.14348/molcells.2022.0040] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/07/2022] [Accepted: 04/07/2022] [Indexed: 11/27/2022] Open
Abstract
Human ABCB6 is an ATP-binding cassette transporter that regulates heme biosynthesis by translocating various porphyrins from the cytoplasm into the mitochondria. Here we report the cryo-electron microscopy (cryo-EM) structures of human ABCB6 with its substrates, coproporphyrin III (CPIII) and hemin, at 3.5 and 3.7 Å resolution, respectively. Metalfree porphyrin CPIII binds to ABCB6 within the central cavity, where its propionic acids form hydrogen bonds with the highly conserved Y550. The resulting structure has an overall fold similar to the inward-facing apo structure, but the two nucleotide-binding domains (NBDs) are slightly closer to each other. In contrast, when ABCB6 binds a metal-centered porphyrin hemin in complex with two glutathione molecules (1 hemin: 2 glutathione), the two NBDs end up much closer together, aligning them to bind and hydrolyze ATP more efficiently. In our structures, a glycine-rich and highly flexible "bulge" loop on TM helix 7 undergoes significant conformational changes associated with substrate binding. Our findings suggest that ABCB6 utilizes at least two distinct mechanisms to fine-tune substrate specificity and transport efficiency.
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Affiliation(s)
- Songwon Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Sang Soo Lee
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Jun Gyou Park
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Ji Won Kim
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Seulgi Ju
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Seung Hun Choi
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Subin Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Na Jin Kim
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Semi Hong
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
| | - Jin Young Kang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Mi Sun Jin
- School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea
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7
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She Q, Dong Y, Li D, An R, Zhou T, Nie X, Pan R, Deng Y. ABCB6 knockdown suppresses melanogenesis through the GSK3-β/β-catenin signaling axis in human melanoma and melanocyte cell lines. J Dermatol Sci 2022; 106:101-110. [DOI: 10.1016/j.jdermsci.2022.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/04/2022] [Accepted: 04/08/2022] [Indexed: 10/18/2022]
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8
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Bickers SC, Benlekbir S, Rubinstein JL, Kanelis V. Structure of Ycf1p reveals the transmembrane domain TMD0 and the regulatory region of ABCC transporters. Proc Natl Acad Sci U S A 2021; 118:e2025853118. [PMID: 34021087 PMCID: PMC8166025 DOI: 10.1073/pnas.2025853118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
ATP binding cassette (ABC) proteins typically function in active transport of solutes across membranes. The ABC core structure is composed of two transmembrane domains (TMD1 and TMD2) and two cytosolic nucleotide binding domains (NBD1 and NBD2). Some members of the C-subfamily of ABC (ABCC) proteins, including human multidrug resistance proteins (MRPs), also possess an N-terminal transmembrane domain (TMD0) that contains five transmembrane α-helices and is connected to the ABC core by the L0 linker. While TMD0 was resolved in SUR1, the atypical ABCC protein that is part of the hetero-octameric ATP-sensitive K+ channel, little is known about the structure of TMD0 in monomeric ABC transporters. Here, we present the structure of yeast cadmium factor 1 protein (Ycf1p), a homolog of human MRP1, determined by electron cryo-microscopy (cryo-EM). A comparison of Ycf1p, SUR1, and a structure of MRP1 that showed TMD0 at low resolution demonstrates that TMD0 can adopt different orientations relative to the ABC core, including a ∼145° rotation between Ycf1p and SUR1. The cryo-EM map also reveals that segments of the regulatory (R) region, which links NBD1 to TMD2 and was poorly resolved in earlier ABCC structures, interacts with the L0 linker, NBD1, and TMD2. These interactions, combined with fluorescence quenching experiments of isolated NBD1 with and without the R region, suggest how posttranslational modifications of the R region modulate ABC protein activity. Mapping known mutations from MRP2 and MRP6 onto the Ycf1p structure explains how mutations involving TMD0 and the R region of these proteins lead to disease.
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Affiliation(s)
- Sarah C Bickers
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
- Department of Chemical and Physical Sciences, University of Toronto, Mississauga, ON L5L 1C6, Canada
| | - Samir Benlekbir
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - John L Rubinstein
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Voula Kanelis
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada;
- Department of Chemical and Physical Sciences, University of Toronto, Mississauga, ON L5L 1C6, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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9
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Le L, Sirés-Campos J, Raposo G, Delevoye C, Marks MS. Melanosome biogenesis in the pigmentation of mammalian skin. Integr Comp Biol 2021; 61:1517-1545. [PMID: 34021746 DOI: 10.1093/icb/icab078] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Melanins, the main pigments of the skin and hair in mammals, are synthesized within membrane-bound organelles of melanocytes called melanosomes. Melanosome structure and function are determined by a cohort of resident transmembrane proteins, many of which are expressed only in pigment cells, that localize specifically to melanosomes. Defects in the genes that encode melanosome-specific proteins or components of the machinery required for their transport in and out of melanosomes underlie various forms of ocular or oculocutaneous albinism, characterized by hypopigmentation of the hair, skin and eyes and by visual impairment. We review major components of melanosomes, including the enzymes that catalyze steps in melanin synthesis from tyrosine precursors, solute transporters that allow these enzymes to function, and structural proteins that underlie melanosome shape and melanin deposition. We then review the molecular mechanisms by which these components are biosynthetically delivered to newly forming melanosomes-many of which are shared by other cell types that generate cell type-specific lysosome-related organelles. We also highlight unanswered questions that need to be addressed by future investigation.
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Affiliation(s)
- Linh Le
- Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA USA.,Department of Pathology & Laboratory Medicine and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA.,Cell and Molecular Biology Graduate Group, University of Pennsylvania, Philadelphia, PA USA
| | - Julia Sirés-Campos
- Institut Curie, PSL Research University, CNRS, UMR 144, Structure and Membrane Compartments, Paris, 75005, France
| | - Graça Raposo
- Institut Curie, PSL Research University, CNRS, UMR 144, Structure and Membrane Compartments, Paris, 75005, France
| | - Cédric Delevoye
- Institut Curie, PSL Research University, CNRS, UMR 144, Structure and Membrane Compartments, Paris, 75005, France
| | - Michael S Marks
- Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA USA.,Department of Pathology & Laboratory Medicine and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA USA
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10
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Szakacs G, Abele R. An inventory of lysosomal ABC transporters. FEBS Lett 2020; 594:3965-3985. [DOI: 10.1002/1873-3468.13967] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/23/2020] [Accepted: 10/15/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Gergely Szakacs
- Institute of Enzymology Research Centre of Natural Sciences Eötvös Loránd Research Network Budapest Hungary
- Institute of Cancer Research Medical University of Vienna Vienna Austria
| | - Rupert Abele
- Institute of Biochemistry Goethe‐University Frankfurt am Main Frankfurt am Main Germany
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11
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Gyimesi G, Hediger MA. Sequence Features of Mitochondrial Transporter Protein Families. Biomolecules 2020; 10:E1611. [PMID: 33260588 PMCID: PMC7761412 DOI: 10.3390/biom10121611] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/20/2020] [Accepted: 11/22/2020] [Indexed: 02/08/2023] Open
Abstract
Mitochondrial carriers facilitate the transfer of small molecules across the inner mitochondrial membrane (IMM) to support mitochondrial function and core cellular processes. In addition to the classical SLC25 (solute carrier family 25) mitochondrial carriers, the past decade has led to the discovery of additional protein families with numerous members that exhibit IMM localization and transporter-like properties. These include mitochondrial pyruvate carriers, sideroflexins, and mitochondrial cation/H+ exchangers. These transport proteins were linked to vital physiological functions and disease. Their structures and transport mechanisms are, however, still largely unknown and understudied. Protein sequence analysis per se can often pinpoint hotspots that are of functional or structural importance. In this review, we summarize current knowledge about the sequence features of mitochondrial transporters with a special focus on the newly included SLC54, SLC55 and SLC56 families of the SLC solute carrier superfamily. Taking a step further, we combine sequence conservation analysis with transmembrane segment and secondary structure prediction methods to extract residue positions and sequence motifs that likely play a role in substrate binding, binding site gating or structural stability. We hope that our review will help guide future experimental efforts by the scientific community to unravel the transport mechanisms and structures of these novel mitochondrial carriers.
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Affiliation(s)
- Gergely Gyimesi
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, CH-3010 Bern, Switzerland;
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12
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Wang C, Cao C, Wang N, Wang X, Wang X, Zhang XC. Cryo-electron microscopy structure of human ABCB6 transporter. Protein Sci 2020; 29:2363-2374. [PMID: 33007128 DOI: 10.1002/pro.3960] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 01/12/2023]
Abstract
Human ATP-binding cassette transporter 6 of subfamily B (ABCB6) is an ABC transporter involved in the translocation toxic metals and anti-cancer drugs. Using cryo-electron microscopy, we determined the molecular structure of full-length ABCB6 in an apo state. The structure of ABCB6 unravels the architecture of a full-length ABCB transporter that harbors two N-terminal transmembrane domains which is indispensable for its ATPase activity in our in vitro assay. A slit-like substrate binding pocket of ABCB6 may accommodate the planar shape of porphyrins, and the existence of a secondary cavity near the mitochondrial intermembrane space side would further facilitate substrate release. Furthermore, the ATPase activity of ABCB6 stimulated with a variety of porphyrin substrates showed different profiles in the presence of glutathione (GSH), suggesting the action of a distinct substrate translocation mechanism depending on the use of GSH as a cofactor.
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Affiliation(s)
- Chunyu Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Can Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Nan Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Xiangxi Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Xianping Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Xuejun C Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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13
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Vesicular ATP-binding cassette transporters in human disease: relevant aspects of their organization for future drug development. FUTURE DRUG DISCOVERY 2020. [DOI: 10.4155/fdd-2020-0025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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14
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Kumar V, Santhosh Kumar TR, Kartha CC. Mitochondrial membrane transporters and metabolic switch in heart failure. Heart Fail Rev 2020; 24:255-267. [PMID: 30535838 DOI: 10.1007/s10741-018-9756-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mitochondrial dysfunction is widely recognized as a major factor for the progression of cardiac failure. Mitochondrial uptake of metabolic substrates and their utilization for ATP synthesis, electron transport chain activity, reactive oxygen species levels, ion homeostasis, mitochondrial biogenesis, and dynamics as well as levels of reactive oxygen species in the mitochondria are key factors which regulate mitochondrial function in the normal heart. Alterations in these functions contribute to adverse outcomes in heart failure. Iron imbalance and oxidative stress are also major factors for the evolution of cardiac hypertrophy, heart failure, and aging-associated pathological changes in the heart. Mitochondrial ATP-binding cassette (ABC) transporters have a key role in regulating iron metabolism and maintenance of redox status in cells. Deficiency of mitochondrial ABC transporters is associated with an impaired mitochondrial electron transport chain complex activity, iron overload, and increased levels of reactive oxygen species, all of which can result in mitochondrial dysfunction. In this review, we discuss the role of mitochondrial ABC transporters in mitochondrial metabolism and metabolic switch, alterations in the functioning of ABC transporters in heart failure, and mitochondrial ABC transporters as possible targets for therapeutic intervention in cardiac failure.
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Affiliation(s)
- Vikas Kumar
- Cardiovascular Diseases and Diabetes Biology group, Rajiv Gandhi Centre for Biotechnology (RGCB), Poojappura, Thycaud Post, Trivandrum, Kerala, 695014, India.,Graduate Studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - T R Santhosh Kumar
- Cardiovascular Diseases and Diabetes Biology group, Rajiv Gandhi Centre for Biotechnology (RGCB), Poojappura, Thycaud Post, Trivandrum, Kerala, 695014, India.,Graduate Studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India.,Cancer Research Program, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India
| | - C C Kartha
- Cardiovascular Diseases and Diabetes Biology group, Rajiv Gandhi Centre for Biotechnology (RGCB), Poojappura, Thycaud Post, Trivandrum, Kerala, 695014, India.
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15
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Linker Domains: Why ABC Transporters 'Live in Fragments no Longer'. Trends Biochem Sci 2019; 45:137-148. [PMID: 31839525 DOI: 10.1016/j.tibs.2019.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/30/2019] [Accepted: 11/13/2019] [Indexed: 11/20/2022]
Abstract
ATP-binding cassette (ABC) transporters are membrane proteins present in all kingdoms of life. We have considered the disordered region that connects the N- and C-terminal halves in many eukaryotic ABC transporters, allowing all four consensus functional domains to be linked. The recent availability of structures of ABC transporters containing linker regions has allowed us to identify the start and end points of the connectors as well as hinting at their localisation. We address questions such as: Where did the linker regions come from? Why do some ABC transporters have connectors and others not? What are the rules and roles of the linker regions? What are the consequences of mutations in these connector regions for disease in humans?
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16
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Rakvács Z, Kucsma N, Gera M, Igriczi B, Kiss K, Barna J, Kovács D, Vellai T, Bencs L, Reisecker JM, Szoboszlai N, Szakács G. The human ABCB6 protein is the functional homologue of HMT-1 proteins mediating cadmium detoxification. Cell Mol Life Sci 2019; 76:4131-4144. [PMID: 31053883 PMCID: PMC6785578 DOI: 10.1007/s00018-019-03105-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/31/2022]
Abstract
ABCB6 belongs to the family of ATP-binding cassette (ABC) transporters, which transport various molecules across extra- and intra-cellular membranes, bearing significant impact on human disease and pharmacology. Although mutations in the ABCB6 gene have been linked to a variety of pathophysiological conditions ranging from transfusion incompatibility to pigmentation defects, its precise cellular localization and function is not understood. In particular, the intracellular localization of ABCB6 has been a matter of debate, with conflicting reports suggesting mitochondrial or endolysosomal expression. ABCB6 shows significant sequence identity to HMT-1 (heavy metal tolerance factor 1) proteins, whose evolutionarily conserved role is to confer tolerance to heavy metals through the intracellular sequestration of metal complexes. Here, we show that the cadmium-sensitive phenotype of Schizosaccharomyces pombe and Caenorhabditis elegans strains defective for HMT-1 is rescued by the human ABCB6 protein. Overexpression of ABCB6 conferred tolerance to cadmium and As(III) (As2O3), but not to As(V) (Na2HAsO4), Sb(V), Hg(II), or Zn(II). Inactivating mutations of ABCB6 abolished vacuolar sequestration of cadmium, effectively suppressing the cadmium tolerance phenotype. Modulation of ABCB6 expression levels in human glioblastoma cells resulted in a concomitant change in cadmium sensitivity. Our findings reveal ABCB6 as a functional homologue of the HMT-1 proteins, linking endolysosomal ABCB6 to the highly conserved mechanism of intracellular cadmium detoxification.
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Affiliation(s)
- Zsófia Rakvács
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Nóra Kucsma
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Melinda Gera
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Barbara Igriczi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Katalin Kiss
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - János Barna
- Department of Genetics, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Dániel Kovács
- Department of Genetics, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Tibor Vellai
- Department of Genetics, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - László Bencs
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary
| | - Johannes M Reisecker
- Department of Medicine I, Comprehensive Cancer Center, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria
| | - Norbert Szoboszlai
- Department of Analytical Chemistry, Institute of Chemistry, Eötvös Loránd University, Budapest, Hungary
| | - Gergely Szakács
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
- Department of Medicine I, Comprehensive Cancer Center, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria.
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17
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Kumar V, A AK, Sanawar R, Jaleel A, Santhosh Kumar TR, Kartha CC. Chronic Pressure Overload Results in Deficiency of Mitochondrial Membrane Transporter ABCB7 Which Contributes to Iron Overload, Mitochondrial Dysfunction, Metabolic Shift and Worsens Cardiac Function. Sci Rep 2019; 9:13170. [PMID: 31511561 PMCID: PMC6739357 DOI: 10.1038/s41598-019-49666-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 08/29/2019] [Indexed: 12/11/2022] Open
Abstract
We examined the hitherto unexplored role of mitochondrial transporters and iron metabolism in advancing metabolic and mitochondrial dysfunction in the heart during long term pressure overload. We also investigated the link between mitochondrial dysfunction and fluctuation in mitochondrial transporters associated with pressure overload cardiac hypertrophy. Left ventricular hypertrophy (LVH) was induced in 3-month-old male Wistar rats by constriction of the aorta using titanium clips. After sacrifice at the end of 6 and 15 months after constriction, tissues from the left ventricle (LV) from all animals were collected for histology, biochemical studies, proteomic and metabolic profiling, and gene and protein expression studies. LV tissues from rats with LVH had a significant decrease in the expression of ABCB7 and mitochondrial oxidative phosphorylation (mt-OXPHOS) enzymes, an increased level of lipid metabolites, decrease in the level of intermediate metabolites of pentose phosphate pathway and elevated levels of cytoplasmic and mitochondrial iron, reactive oxygen species (ROS) and autophagy-related proteins. Knockdown of ABCB7 in H9C2 cells and stimulation with angiotensin II resulted in increased ROS levels, ferritin, and transferrin receptor expression and iron overload in both mitochondria and cytoplasm. A decrease in mRNA and protein levels of mt-OXPHOS specific enzymes, mt-dynamics and autophagy clearance and activation of IGF-1 signaling were also seen in these cells. ABCB7 overexpression rescued all these changes. ABCB7 was found to interact with mitochondrial complexes IV and V. We conclude that in chronic pressure overload, ABCB7 deficiency results in iron overload and mitochondrial dysfunction, contributing to heart failure.
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Affiliation(s)
- Vikas Kumar
- Cardiovascular Diseases and Diabetes Biology, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India.,Graduate studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Aneesh Kumar A
- Cardiovascular Diseases and Diabetes Biology, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India.,Graduate studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Rahul Sanawar
- Cancer Research Program, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India.,Graduate studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Abdul Jaleel
- Cardiovascular Diseases and Diabetes Biology, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India.,Graduate studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - T R Santhosh Kumar
- Cardiovascular Diseases and Diabetes Biology, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India. .,Cancer Research Program, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India. .,Graduate studies, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India.
| | - C C Kartha
- Cardiovascular Diseases and Diabetes Biology, Rajiv Gandhi Centre for Biotechnology (RGCB), Trivandrum, Kerala, India.
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18
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Application of antihelix antibodies in protein structure determination. Proc Natl Acad Sci U S A 2019; 116:17786-17791. [PMID: 31371498 DOI: 10.1073/pnas.1910080116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Antibodies are indispensable tools in protein engineering and structural biology. Antibodies suitable for structural studies should recognize the 3-dimensional (3D) conformations of target proteins. Generating such antibodies and characterizing their complexes with antigens take a significant amount of time and effort. Here, we show that we can expand the application of well-characterized antibodies by "transplanting" the epitopes that they recognize to proteins with completely different structures and sequences. Previously, several antibodies have been shown to recognize the alpha-helical conformation of antigenic peptides. We demonstrate that these antibodies can be made to bind to a variety of unrelated "off-target" proteins by modifying amino acids in the preexisting alpha helices of such proteins. Using X-ray crystallography, we determined the structures of the engineered protein-antibody complexes. All of the antibodies bound to the epitope-transplanted proteins, forming accurately predictable structures. Furthermore, we showed that binding of these antihelix antibodies to the engineered target proteins can modulate their catalytic activities by trapping them in selected functional states. Our method is simple and efficient, and it will have applications in protein X-ray crystallography, electron microscopy, and nanotechnology.
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19
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Mares L, Vilchis F, Chávez B, Ramos L. Isolation and sex steroid effects on the expression of the ATP-binding cassette transporter ABCB6 in Harderian glands of hamster (Mesocricetus auratus). Comp Biochem Physiol A Mol Integr Physiol 2019; 232:40-46. [PMID: 30878759 DOI: 10.1016/j.cbpa.2019.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/25/2019] [Accepted: 03/08/2019] [Indexed: 10/27/2022]
Abstract
ATP-Binding Cassette, subfamily B, member 6 (ABCB6) is a transporter that is upregulated by elevated intracellular porphyrin concentrations. In the Harderian gland (HG), the synthesis of porphyrins appears to be under the influence of gonadal steroids and to exhibit a dimorphic pattern. To explore whether ABCB6 is also influenced by sex steroids, we isolated its specific cDNA sequence and investigated its mRNA levels in the HGs of hamsters. ABCB6's cDNA sequence presents an open reading frame (ORF) of 2529 bp that encodes a predicted 842-amino acid (aa) protein with a molecular weight of 93 kDa. Multiple sequence alignments showed that ABCB6's aa sequence is highly conserved and shares the highest homology (93%) with mouse ABCB6. RT-qPCR analysis indicated that ABCB6 is expressed in all the tissues examined, exhibiting high expression levels in the liver, adrenal glands, and testis. The mRNA concentrations of ABCB6 in HGs were very similar between males and in females; similarly, gonadectomy and treatment with sex steroids appear to scarcely affect ABCB6 mRNA levels. The intraglandular content of ABCB6 mRNA showed discrete, though non-significant, variations through the estrous cycle. The results provide evidence that gonadal steroids have a minimal physiological role on the regulation of ABCB6 expression and might indicate that this transporter has a small effect on porphyrin trafficking in the HGs of hamsters.
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Affiliation(s)
- L Mares
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México
| | - F Vilchis
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México
| | - B Chávez
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México
| | - L Ramos
- Department of Reproductive Biology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, México City, México.
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20
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Graab P, Bock C, Weiss K, Hirth A, Koller N, Braner M, Jung J, Loehr F, Tampé R, Behrends C, Abele R. Lysosomal targeting of the ABC transporter TAPL is determined by membrane-localized charged residues. J Biol Chem 2019; 294:7308-7323. [PMID: 30877195 DOI: 10.1074/jbc.ra118.007071] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/08/2019] [Indexed: 01/16/2023] Open
Abstract
The human lysosomal polypeptide ABC transporter TAPL (ABC subfamily B member 9, ABCB9) transports 6-59-amino-acid-long polypeptides from the cytosol into lysosomes. The subcellular localization of TAPL depends solely on its N-terminal transmembrane domain, TMD0, which lacks conventional targeting sequences. However, the intracellular route and the molecular mechanisms that control TAPL localization remain unclear. Here, we delineated the route of TAPL to lysosomes and investigated the determinants of single trafficking steps. By synchronizing trafficking events by a retention using selective hooks (RUSH) assay and visualizing individual intermediate steps through immunostaining and confocal microscopy, we demonstrate that TAPL takes the direct route to lysosomes. We further identified conserved charged residues within TMD0 transmembrane helices that are essential for individual steps of lysosomal targeting. Substitutions of these residues retained TAPL in the endoplasmic reticulum (ER) or Golgi. We also observed that for release from the ER, a salt bridge between Asp-17 and Arg-57 is essential. An interactome analysis revealed that Yip1-interacting factor homolog B membrane-trafficking protein (YIF1B) interacts with TAPL. We also found that YIF1B is involved in ER-to-Golgi trafficking and interacts with TMD0 of TAPL via its transmembrane domain and that this interaction strongly depends on the newly identified salt bridge within TMD0. These results expand our knowledge about lysosomal trafficking of TAPL and the general function of extra transmembrane domains of ABC transporters.
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Affiliation(s)
| | | | | | | | | | | | - Jennifer Jung
- the Institute of Biochemistry II, Medical School, Goethe University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany, and
| | - Frank Loehr
- the Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Strasse 9, 60438 Frankfurt am Main, Germany
| | - Robert Tampé
- From the Institute of Biochemistry, Biocenter, and
| | - Christian Behrends
- the Institute of Biochemistry II, Medical School, Goethe University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany, and.,the Munich Cluster for Systems Neurology, Ludwig Maximilians University Munich, Feodor-Lynen-Strasse 17, 81377 Munich, Germany
| | - Rupert Abele
- From the Institute of Biochemistry, Biocenter, and
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21
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Pharmacological targeting of mitochondria in cancer stem cells: An ancient organelle at the crossroad of novel anti-cancer therapies. Pharmacol Res 2019; 139:298-313. [DOI: 10.1016/j.phrs.2018.11.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/13/2018] [Accepted: 11/13/2018] [Indexed: 02/07/2023]
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22
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Bock C, Löhr F, Tumulka F, Reichel K, Würz J, Hummer G, Schäfer L, Tampé R, Joseph B, Bernhard F, Dötsch V, Abele R. Structural and functional insights into the interaction and targeting hub TMD0 of the polypeptide transporter TAPL. Sci Rep 2018; 8:15662. [PMID: 30353140 PMCID: PMC6199259 DOI: 10.1038/s41598-018-33841-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 10/04/2018] [Indexed: 11/09/2022] Open
Abstract
The ATP-binding cassette transporter TAPL translocates polypeptides from the cytosol into the lysosomal lumen. TAPL can be divided into two functional units: coreTAPL, active in ATP-dependent peptide translocation, and the N-terminal membrane spanning domain, TMD0, responsible for cellular localization and interaction with the lysosomal associated membrane proteins LAMP-1 and LAMP-2. Although the structure and function of ABC transporters were intensively analyzed in the past, the knowledge about accessory membrane embedded domains is limited. Therefore, we expressed the TMD0 of TAPL via a cell-free expression system and confirmed its correct folding by NMR and interaction studies. In cell as well as cell-free expressed TMD0 forms oligomers, which were assigned as dimers by PELDOR spectroscopy and static light scattering. By NMR spectroscopy of uniformly and selectively isotope labeled TMD0 we performed a complete backbone and partial side chain assignment. Accordingly, TMD0 has a four transmembrane helix topology with a short helical segment in a lysosomal loop. The topology of TMD0 was confirmed by paramagnetic relaxation enhancement with paramagnetic stearic acid as well as by nuclear Overhauser effects with c6-DHPC and cross-peaks with water.
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Affiliation(s)
- Christoph Bock
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Frank Löhr
- Institute of Biophysical Chemistry & Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Franz Tumulka
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Katrin Reichel
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Julia Würz
- Institute of Biophysical Chemistry & Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
| | - Lars Schäfer
- Lehrstuhl für Theoretische Chemie, Ruhr-University Bochum, 4780, Bochum, Germany
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Benesh Joseph
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Frank Bernhard
- Institute of Biophysical Chemistry & Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry & Center for Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Rupert Abele
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany.
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23
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Kim S, Sharma AK, Vatamaniuk OK. N-Terminal Extension and C-Terminal Domains Are Required for ABCB6/HMT-1 Protein Interactions, Function in Cadmium Detoxification, and Localization to the Endosomal-Recycling System in Caenorhabditis elegans. Front Physiol 2018; 9:885. [PMID: 30104978 PMCID: PMC6077975 DOI: 10.3389/fphys.2018.00885] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/19/2018] [Indexed: 01/30/2023] Open
Abstract
The chronic exposure of humans to toxic metals such as cadmium from food and air causes dysfunction of vital organs, neurodegenerative conditions, and cancer. In this regard, members of the ABCB sub-family of the ATP-binding cassette (ABC) transporter superfamily, ABCB6/HMT-1, are acutely required for the detoxification of heavy metals and are present in genomes of many organisms including the nematode worm, Caenorhabditis elegans and humans. We showed previously that C. elegans ABCB6/HMT-1 detoxifies cadmium, copper, and arsenic, and is expressed in liver-like cells, the coelomocytes, head neurons and intestinal cells, which are the cell types that are affected by heavy metal poisoning in humans. The subcellular localization of ABCB6/HMT-1 proteins is unclear. ABCB6/HMT-1 proteins have a distinguishing topology: in addition to one transmembrane domain and one nucleotide-binding domain, they possess a hydrophobic N-terminal extension (NTE) domain encompassing five to six transmembrane spans. The role of the NTE domain in the function of ABCB6/HMT-1 in the native organism remains to be investigated. We used a versatile, multicellular model system, C. elegans, to establish the subcellular localization of ABCB6/HMT-1 and refine its structure-function studies in the native organism. We show that ABCB6/HMT-1 localizes mainly to the apical recycling endosomes and, in part, to early and late endosomes of intestinal cells. We also show that ABCB6/HMT-1 lacking the NTE domain is mistargeted to the plasma membrane and is unable to confer cadmium resistance. Although the NTE domain is essential for ABCB6/HMT-1 interaction with itself, the absence of NTE does not fully prevent this interaction. As a result, ABCB6/HMT-1 lacking the NTE domain, and expressed in wild-type worms or co-expressed with the full-length polypeptide, inactivates and mistargets the full-length ABCB6/HMT-1. We also show that the 43 amino acid residue stretch at the COOH-terminus is required for the ABCB6/HMT-1 interaction with itself and cadmium detoxification function. These results suggest that both NTE and COOH-terminus must be present to allow the protein to interact with itself and confer cadmium resistance. Considering that ABCB6/HMT-1 proteins are highly conserved, this study advances our understanding of how these proteins function in cadmium resistance in different species. Furthermore, these studies uncover the role of the endosomal-recycling system in cadmium detoxification.
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Affiliation(s)
- Sungjin Kim
- Section of Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
| | - Anuj K. Sharma
- Section of Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
| | - Olena K. Vatamaniuk
- Section of Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
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24
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Bergam P, Reisecker JM, Rakvács Z, Kucsma N, Raposo G, Szakacs G, van Niel G. ABCB6 Resides in Melanosomes and Regulates Early Steps of Melanogenesis Required for PMEL Amyloid Matrix Formation. J Mol Biol 2018; 430:3802-3818. [PMID: 29940187 DOI: 10.1016/j.jmb.2018.06.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/11/2018] [Accepted: 06/15/2018] [Indexed: 01/08/2023]
Abstract
Genetically inheritable pigmentation defects provide a unique opportunity to reveal the function of proteins contributing to melanogenesis. Dyschromatosis universalis hereditaria (DUH) is a rare pigmentary genodermatosis associated with mutations in the ABCB6 gene. Here we use optical and electron microscopy imaging combined with biochemical tools to investigate the localization and function of ABCB6 in pigment cells. We show that ABCB6 localizes to the membrane of early melanosomes and lysosomes of the human melanocytic cell line MNT-1. Depletion of ABCB6 by siRNA impaired PMEL amyloidogenesis in early melanosomes and induced aberrant accumulation of multilamellar aggregates in pigmented melanosomes. PMEL fibril formation and normal maturation of pigmented melanosomes could be restored by the overexpression of wild-type ABCB6 but not by variants containing an inactivating catalytic mutation (K629M) or the G579E DUH mutation. In line with the impairment of PMEL matrix formation in the absence of ABCB6, morphological analysis of the retinal pigment epithelium of ABCB6 knockout mice revealed a significant decrease of melanosome numbers. Our study extends the localization of ABCB6 to melanosomes, suggesting a potential link between the function of ABCB6 and the etiology of DUH to amyloid formation in pigment cells.
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Affiliation(s)
- Ptissam Bergam
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'Ulm, 75231 Paris, France; Centre National de la Recherche Scientifique, UMR144, Paris F-75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris, France
| | | | - Zsófia Rakvács
- Institute of Enzymology, Research Centre for National Sciences, HAS, Budapest 1117, Hungary
| | - Nóra Kucsma
- Institute of Enzymology, Research Centre for National Sciences, HAS, Budapest 1117, Hungary
| | - Graça Raposo
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'Ulm, 75231 Paris, France; Centre National de la Recherche Scientifique, UMR144, Paris F-75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris, France
| | - Gergely Szakacs
- Institute of Cancer Research, Medical University Vienna, Vienna, Austria; Institute of Enzymology, Research Centre for National Sciences, HAS, Budapest 1117, Hungary.
| | - Guillaume van Niel
- Institut Curie, PSL Research University, UMR144, Centre de Recherche, 26 rue d'Ulm, 75231 Paris, France; Centre National de la Recherche Scientifique, UMR144, Paris F-75248, France; Cell and Tissue Imaging Core Facility PICT-IBiSA, Institut Curie, Paris, France; Center for Psychiatry and Neuroscience, Hopital Saint-Anne, Université Descartes, INSERM U894, Paris, France.
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25
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Boswell-Casteel RC, Fukuda Y, Schuetz JD. ABCB6, an ABC Transporter Impacting Drug Response and Disease. AAPS JOURNAL 2017; 20:8. [PMID: 29192381 DOI: 10.1208/s12248-017-0165-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 10/16/2017] [Indexed: 12/11/2022]
Abstract
Recent findings have discovered how insufficiency of ATP-binding cassette (ABC) transporter, ABCB6, can negatively impact human health. These advances were made possible by, first, finding that ABCB6 deficiency was the genetic basis for some severe transfusion reactions and by, second, determining that functionally impaired ABCB6 variants enhanced the severity of porphyria, i.e., diseases associated with defects in heme synthesis. ABCB6 is a broad-spectrum porphyrin transporter that is capable of both exporting and importing heme and its precursors across the plasma membrane and outer mitochondrial membrane, respectively. Biochemical studies have demonstrated that while ABCB6 influences the antioxidant system by reducing the levels of reactive oxygen species, the exact mechanism is currently unknown, though effects on heme synthesis are likely. Furthermore, it is unknown what biochemical or cellular signals determine where ABCB6 localizes in the cell. This review highlights the major recent findings on ABCB6 and focuses on details of its structure, mechanism, transport, contributions to cellular stress, and current clinical implications.
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Affiliation(s)
- Rebba C Boswell-Casteel
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee, 38105-2794, USA
| | - Yu Fukuda
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee, 38105-2794, USA
| | - John D Schuetz
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee, 38105-2794, USA.
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26
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Maniero MÁ, Guerrero-Gimenez ME, Fanelli MA, Wuilloud RG. Inorganic mercury in mammary cells: viability, metal uptake but efflux? Biometals 2017; 31:69-80. [DOI: 10.1007/s10534-017-0068-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 11/20/2017] [Indexed: 11/28/2022]
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27
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Subcellular Trafficking of Mammalian Lysosomal Proteins: An Extended View. Int J Mol Sci 2016; 18:ijms18010047. [PMID: 28036022 PMCID: PMC5297682 DOI: 10.3390/ijms18010047] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 12/15/2016] [Accepted: 12/18/2016] [Indexed: 01/02/2023] Open
Abstract
Lysosomes clear macromolecules, maintain nutrient and cholesterol homeostasis, participate in tissue repair, and in many other cellular functions. To assume these tasks, lysosomes rely on their large arsenal of acid hydrolases, transmembrane proteins and membrane-associated proteins. It is therefore imperative that, post-synthesis, these proteins are specifically recognized as lysosomal components and are correctly sorted to this organelle through the endosomes. Lysosomal transmembrane proteins contain consensus motifs in their cytosolic regions (tyrosine- or dileucine-based) that serve as sorting signals to the endosomes, whereas most lysosomal acid hydrolases acquire mannose 6-phosphate (Man-6-P) moieties that mediate binding to two membrane receptors with endosomal sorting motifs in their cytosolic tails. These tyrosine- and dileucine-based motifs are tickets for boarding in clathrin-coated carriers that transport their cargo from the trans-Golgi network and plasma membrane to the endosomes. However, increasing evidence points to additional mechanisms participating in the biogenesis of lysosomes. In some cell types, for example, there are alternatives to the Man-6-P receptors for the transport of some acid hydrolases. In addition, several “non-consensus” sorting motifs have been identified, and atypical transport routes to endolysosomes have been brought to light. These “unconventional” or “less known” transport mechanisms are the focus of this review.
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Abstract
A small number of physiologically important ATP-binding cassette (ABC) transporters are found in mitochondria. Most are half transporters of the B group forming homodimers and their topology suggests they function as exporters. The results of mutant studies point towards involvement in iron cofactor biosynthesis. In particular, ABC subfamily B member 7 (ABCB7) and its homologues in yeast and plants are required for iron-sulfur (Fe-S) cluster biosynthesis outside of the mitochondria, whereas ABCB10 is involved in haem biosynthesis. They also play a role in preventing oxidative stress. Mutations in ABCB6 and ABCB7 have been linked to human disease. Recent crystal structures of yeast Atm1 and human ABCB10 have been key to identifying substrate-binding sites and transport mechanisms. Combined with in vitro and in vivo studies, progress is being made to find the physiological substrates of the different mitochondrial ABC transporters.
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Translocation of the ABC transporter ABCD4 from the endoplasmic reticulum to lysosomes requires the escort protein LMBD1. Sci Rep 2016; 6:30183. [PMID: 27456980 PMCID: PMC4960490 DOI: 10.1038/srep30183] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 06/30/2016] [Indexed: 11/29/2022] Open
Abstract
We previously demonstrated that ABCD4 does not localize to peroxisomes but rather, the endoplasmic reticulum (ER), because it lacks the NH2-terminal hydrophilic region required for peroxisomal targeting. It was recently reported that mutations in ABCD4 result in a failure to release vitamin B12 from lysosomes. A similar phenotype is caused by mutations in LMBRD1, which encodes the lysosomal membrane protein LMBD1. These findings suggested to us that ABCD4 translocated from the ER to lysosomes in association with LMBD1. In this report, it is demonstrated that ABCD4 interacts with LMBD1 and then localizes to lysosomes, and this translocation depends on the lysosomal targeting ability of LMBD1. Furthermore, endogenous ABCD4 was localized to both lysosomes and the ER, and its lysosomal localization was disturbed by knockout of LMBRD1. To the best of our knowledge, this is the first report demonstrating that the subcellular localization of the ABC transporter is determined by its association with an adaptor protein.
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Grebowski J, Studzian M, Bartosz G, Pulaski L. Leishmania tarentolae as a host for heterologous expression of functional human ABCB6 transporter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2617-2624. [PMID: 27349731 DOI: 10.1016/j.bbamem.2016.06.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 06/13/2016] [Accepted: 06/22/2016] [Indexed: 11/18/2022]
Abstract
The need for large amounts of reproducibly produced and isolated protein arises not only in structural studies, but even more so in biochemical ones, and with regard to ABC transporters it is especially pressing when faced with the prospect of enzymatic/transport activity studies, substrate screening etc. Thus, reliable heterologous expression systems/model organisms for large and complex proteins are at a premium. We have verified the applicability of the recently established novel eukaryotic expression system, using Leishmania tarentolae as a host, for human ABC protein overexpression. We succeeded in overexpressing human ABCB6, a protein with controversial subcellular localization and multiple proposed cellular functions. We were able to demonstrate its efficient expression in the expected subcellular locations as well as biochemical activity of the overexpressed protein (ATPase activity and porphyrin-like substrate transport). This activity was absent in cells overexpressing the catalytically inactive variant of ABCB6 (K629M). We demonstrate the possibility of applying a cost-effective expression system to study the activity of membrane transporters from the ABC superfamily.
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Affiliation(s)
- Jacek Grebowski
- Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 12/16 Banacha St., 90-237 Lodz, Poland
| | - Maciej Studzian
- Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 12/16 Banacha St., 90-237 Lodz, Poland
| | - Grzegorz Bartosz
- Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 12/16 Banacha St., 90-237 Lodz, Poland
| | - Lukasz Pulaski
- Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 12/16 Banacha St., 90-237 Lodz, Poland.
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Martínez-García M, Campos-Salinas J, Cabello-Donayre M, Pineda-Molina E, Gálvez FJ, Orrego LM, Sánchez-Cañete MP, Malagarie-Cazenave S, Koeller DM, Pérez-Victoria JM. LmABCB3, an atypical mitochondrial ABC transporter essential for Leishmania major virulence, acts in heme and cytosolic iron/sulfur clusters biogenesis. Parasit Vectors 2016; 9:7. [PMID: 26728034 PMCID: PMC4700571 DOI: 10.1186/s13071-015-1284-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/23/2015] [Indexed: 11/24/2022] Open
Abstract
Background Mitochondria play essential biological functions including the synthesis and trafficking of porphyrins and iron/sulfur clusters (ISC), processes that in mammals involve the mitochondrial ATP-Binding Cassette (ABC) transporters ABCB6 and ABCB7, respectively. The mitochondrion of pathogenic protozoan parasites such as Leishmania is a promising goal for new therapeutic approaches. Leishmania infects human macrophages producing the neglected tropical disease known as leishmaniasis. Like most trypanosomatid parasites, Leishmania is auxotrophous for heme and must acquire porphyrins from the host. Methods LmABCB3, a new Leishmania major protein with significant sequence similarity to human ABCB6/ABCB7, was identified and characterized using bioinformatic tools. Fluorescent microscopy was used to determine its cellular localization, and its level of expression was modulated by molecular genetic techniques. Intracellular in vitro assays were used to demonstrate its role in amastigotes replication, and an in vivo mouse model was used to analyze its role in virulence. Functional characterization of LmABCB3 was carried out in Leishmania promastigotes and Saccharomyces cerevisiae. Structural analysis of LmABCB3 was performed using molecular modeling software. Results LmABCB3 is an atypical ABC half-transporter that has a unique N-terminal extension not found in any other known ABC protein. This extension is required to target LmABCB3 to the mitochondrion and includes a potential metal-binding domain. We have shown that LmABCB3 interacts with porphyrins and is required for the mitochondrial synthesis of heme from a host precursor. We also present data supporting a role for LmABCB3 in the biogenesis of cytosolic ISC, essential cofactors for cell viability in all three kingdoms of life. LmABCB3 fully complemented the severe growth defect shown in yeast lacking ATM1, an orthologue of human ABCB7 involved in exporting from the mitochondria a gluthatione-containing compound required for the generation of cytosolic ISC. Indeed, docking analyzes performed with a LmABCB3 structural model using trypanothione, the main thiol in this parasite, as a ligand showed how both, LmABCB3 and yeast ATM1, contain a similar thiol-binding pocket. Additionally, we show solid evidence suggesting that LmABCB3 is an essential gene as dominant negative inhibition of LmABCB3 is lethal for the parasite. Moreover, the abrogation of only one allele of the gene did not impede promastigote growth in axenic culture but prevented the replication of intracellular amastigotes and the virulence of the parasites in a mouse model of cutaneous leishmaniasis. Conclusions Altogether our results present the previously undescribed LmABCB3 as an unusual mitochondrial ABC transporter essential for Leishmania survival through its role in the generation of heme and cytosolic ISC. Hence, LmABCB3 could represent a novel target to combat leishmaniasis. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-1284-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marta Martínez-García
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | - Jenny Campos-Salinas
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | - María Cabello-Donayre
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | - Estela Pineda-Molina
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | - Francisco J Gálvez
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | - Lina M Orrego
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | - María P Sánchez-Cañete
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
| | | | - David M Koeller
- Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, OR, USA.
| | - José M Pérez-Victoria
- Instituto de Parasitología y Biomedicina "López-Neyra" (IPBLN), CSIC, PTS Granada, Granada, Spain.
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