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Jaramillo-Martinez V, Sennoune SR, Tikhonova EB, Karamyshev AL, Ganapathy V, Urbatsch IL. Molecular phenotypes segregate missense mutations in SLC13A5 Epilepsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.23.594637. [PMID: 38826402 PMCID: PMC11142175 DOI: 10.1101/2024.05.23.594637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The sodium-coupled citrate transporter (NaCT, SLC13A5) mediates citrate uptake across the plasma membrane via an inward Na + gradient. Mutations in SLC13A5 cause early infantile epileptic encephalopathy type-25 (EIEE25, SLC13A5 Epilepsy) due to impaired citrate uptake in neurons. Despite clinical identification of disease-causing mutations, underlying mechanisms and cures remain elusive. We mechanistically classify the molecular phenotypes of six mutations. C50R, T142M, and T227M exhibit impaired citrate transport despite normal expression at the cell surface. G219R, S427L, and L488P are hampered by low protein expression, ER retention, and reduced transport. Mutants' mRNA levels resemble wildtype, suggesting post-translational defects. Class II mutations display immature core-glycosylation and shortened half-lives, indicating protein folding defects. These experiments provide a comprehensive understanding of the mutation's defects in SLC13A5 Epilepsy at the biochemical and molecular level and shed light into the trafficking pathway(s) of NaCT. The two classes of mutations will require fundamentally different treatment approaches to either restore transport function, or enable correction of protein folding defects. Summary Loss-of-function mutations in the SLC13A5 causes SLC13A5-Epilepsy, a devastating disease characterized by neonatal epilepsy. Currently no cure is available. We clarify the molecular-level defects to guide future developments for phenotype-specific treatment of disease-causing mutations.
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2
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Soya N, Xu H, Roldan A, Yang Z, Ye H, Jiang F, Premchandar A, Veit G, Cole SPC, Kappes J, Hegedüs T, Lukacs GL. Folding correctors can restore CFTR posttranslational folding landscape by allosteric domain-domain coupling. Nat Commun 2023; 14:6868. [PMID: 37891162 PMCID: PMC10611759 DOI: 10.1038/s41467-023-42586-8] [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: 11/16/2022] [Accepted: 10/16/2023] [Indexed: 10/29/2023] Open
Abstract
The folding/misfolding and pharmacological rescue of multidomain ATP-binding cassette (ABC) C-subfamily transporters, essential for organismal health, remain incompletely understood. The ABCC transporters core consists of two nucleotide binding domains (NBD1,2) and transmembrane domains (TMD1,2). Using molecular dynamic simulations, biochemical and hydrogen deuterium exchange approaches, we show that the mutational uncoupling or stabilization of NBD1-TMD1/2 interfaces can compromise or facilitate the CFTR(ABCC7)-, MRP1(ABCC1)-, and ABCC6-transporters posttranslational coupled domain-folding in the endoplasmic reticulum. Allosteric or orthosteric binding of VX-809 and/or VX-445 folding correctors to TMD1/2 can rescue kinetically trapped CFTR posttranslational folding intermediates of cystic fibrosis (CF) mutants of NBD1 or TMD1 by global rewiring inter-domain allosteric-networks. We propose that dynamic allosteric domain-domain communications not only regulate ABCC-transporters function but are indispensable to tune the folding landscape of their posttranslational intermediates. These allosteric networks can be compromised by CF-mutations, and reinstated by correctors, offering a framework for mechanistic understanding of ABCC-transporters (mis)folding.
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Affiliation(s)
- Naoto Soya
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada
| | - Haijin Xu
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada
| | - Ariel Roldan
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada
| | - Zhengrong Yang
- Heersink School of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - Haoxin Ye
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada
| | - Fan Jiang
- Heersink School of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - Aiswarya Premchandar
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada
| | - Guido Veit
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada
| | - Susan P C Cole
- Division of Cancer Biology and Genetics, Department of Pathology and Molecular Medicine, Queen's University Cancer Research Institute, Kingston, ON, Canada
| | - John Kappes
- Heersink School of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - Tamás Hegedüs
- Department of Biophysics and Radiation Biology, Semmelweis University, 1085, Budapest, Hungary
- ELKH-SE Biophysical Virology Research Group, Eötvös Loránd Research Network, Budapest, Hungary
| | - Gergely L Lukacs
- Department of Physiology and Biochemistry, McGill University, Montréal, QC, Canada.
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3
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Soya N, Xu H, Roldan A, Yang Z, Ye H, Jiang F, Premchandar A, Veit G, Cole SPC, Kappes J, Hegedus T, Lukacs GL. Folding correctors can restore CFTR posttranslational folding landscape by allosteric domain-domain coupling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.19.563107. [PMID: 37905074 PMCID: PMC10614980 DOI: 10.1101/2023.10.19.563107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
The folding/misfolding and pharmacological rescue of multidomain ATP-binding cassette (ABC) C-subfamily transporters, essential for organismal health, remain incompletely understood. The ABCC transporters core consists of two nucleotide binding domains (NBD1,2) and transmembrane domains (TMD1,2). Using molecular dynamic simulations, biochemical and hydrogen deuterium exchange approaches, we show that the mutational uncoupling or stabilization of NBD1-TMD1/2 interfaces can compromise or facilitate the CFTR(ABCC7)-, MRP1(ABCC1)-, and ABCC6-transporters posttranslational coupled domain-folding in the endoplasmic reticulum. Allosteric or orthosteric binding of VX-809 and/or VX-445 folding correctors to TMD1/2 can rescue kinetically trapped CFTR post-translational folding intermediates of cystic fibrosis (CF) mutants of NBD1 or TMD1 by global rewiring inter-domain allosteric-networks. We propose that dynamic allosteric domain-domain communications not only regulate ABCC-transporters function but are indispensable to tune the folding landscape of their post-translational intermediates. These allosteric networks can be compromised by CF-mutations, and reinstated by correctors, offering a framework for mechanistic understanding of ABCC-transporters (mis)folding. One-Sentence Summary Allosteric interdomain communication and its modulation are critical determinants of ABCC-transporters post-translational conformational biogenesis, misfolding, and pharmacological rescue.
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4
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Jaramillo-Martinez V, Ganapathy V, Urbatsch IL. Peptide Tags and Domains for Expression and Detection of Mammalian Membrane Proteins at the Cell Surface. Methods Mol Biol 2022; 2507:337-358. [PMID: 35773591 DOI: 10.1007/978-1-0716-2368-8_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Normal functions of cell-surface proteins are dependent on their proper trafficking from the site of synthesis to the cell surface. Transport proteins mediating solute transfer across the plasma membrane constitute an important group of cell-surface proteins. There are several diseases resulting from mutations in these proteins that interfere with their transport function or trafficking, depending on the impact of the mutations on protein folding and structure. Recent advances in successful treatment of some of these diseases with small molecules which correct the mutations-induced folding and structural changes underline the need for detailed structural and biophysical characterization of membrane proteins. This requires methods to express and purify these proteins using heterologous expression systems. Here, using the solute carrier (SLC) transporter NaCT (Na+-coupled citrate transporter) as an example, we describe experimental strategies for this approach. We chose this example because several mutations in NaCT, distributed throughout the protein, cause a severe neurologic disease known as early infantile epileptic encephalopathy-25 (EIEE-25). NaCT was modified with various peptide tags, including a RGS-His10, a Twin-Strep, the SUMOstar domain, and an enhanced green fluorescent protein (EGFP), each alone or in various combinations. When transiently expressed in HEK293 cells, recombinant NaCT proteins underwent complex glycosylation, compartmentalized with the plasma membrane, and exhibited citrate transport activity similar to the nontagged protein. Surface NaCT expression was enhanced by the presence of SUMOstar on the N-terminus. The dual-purpose peptide epitopes RGS-His10 and Twin-Strep facilitated detection of NaCT by immunohistochemistry and western blot and may serve useful tags for affinity purification. This approach sets the stage for future analyses of mutant NaCT proteins that may alter protein folding and trafficking. It also demonstrates the capability of a transient mammalian cell expression system to produce human NaCT of sufficient quality and quantity to augment future biophysical and structural studies and drug discovery efforts.
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Affiliation(s)
- Valeria Jaramillo-Martinez
- Departments of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Vadivel Ganapathy
- Cell Biology and Biochemistry, and the Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Ina L Urbatsch
- Cell Biology and Biochemistry, and the Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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5
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Differential Effects of Oleuropein and Hydroxytyrosol on Aggregation and Stability of CFTR NBD1-ΔF508 Domain. JOURNAL OF RESPIRATION 2021. [DOI: 10.3390/jor1030019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cystic Fibrosis (CF) is caused by loss of function mutations in the Cystic Fibrosis transmembrane conductance regulator (CFTR). The folding and assembly of CFTR is inefficient. Deletion of F508 in the first nucleotide binding domain (NBD1-ΔF508) further disrupts protein stability leading to endoplasmic reticulum retention and proteasomal degradation. Stabilization and prevention of NBD1-ΔF508 aggregation is critical to rescuing the folding and function of the entire CFTR channel. We report that the phenolic compounds Oleuropein and Hydroxytryosol reduce aggregation of NBD1-ΔF508. The NBD1-ΔF508 aggregate size was smaller in the presence of Hydroxytryosol as determined by dynamic light scattering. Neither phenolic compound increased the thermal stability of NBD1-ΔF508 as measured by differential scanning fluorimetry. Interestingly, Hydroxytyrosol inhibited the stabilizing effect of the indole compound BIA, a known stabilizer, on NBD1-ΔF508. Molecular docking studies predicted that Oleuropein preferred to bind in the F1-type core ATP-binding subdomain in NBD1. In contrast, Hydroxytyrosol preferred to bind in the α4/α5/α6 helical bundle of the ABCα subdomain of NBD1 next to the putative binding site for BIA. This result suggests that Hydroxytyrosol interferes with BIA binding, thus providing an explanation for the antagonistic effect on NBD1 stability upon incubation with both compounds. To our knowledge, these studies are the first to explore the effects of these two phenolic compounds on the aggregation and stability of NBD1-ΔF508 domain of CFTR.
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6
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Scholl D, Sigoillot M, Overtus M, Martinez RC, Martens C, Wang Y, Pardon E, Laeremans T, Garcia-Pino A, Steyaert J, Sheppard DN, Hendrix J, Govaerts C. A topological switch in CFTR modulates channel activity and sensitivity to unfolding. Nat Chem Biol 2021; 17:989-997. [PMID: 34341587 DOI: 10.1038/s41589-021-00844-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 06/28/2021] [Indexed: 12/25/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel is essential to maintain fluid homeostasis in key organs. Functional impairment of CFTR due to mutations in the cftr gene leads to cystic fibrosis. Here, we show that the first nucleotide-binding domain (NBD1) of CFTR can spontaneously adopt an alternate conformation that departs from the canonical NBD fold previously observed. Crystallography reveals that this conformation involves a topological reorganization of NBD1. Single-molecule fluorescence resonance energy transfer microscopy shows that the equilibrium between the conformations is regulated by adenosine triphosphate binding. However, under destabilizing conditions, such as the disease-causing mutation F508del, this conformational flexibility enables unfolding of the β-subdomain. Our data indicate that, in wild-type CFTR, this conformational transition of NBD1 regulates channel function, but, in the presence of the F508del mutation, it allows domain misfolding and subsequent protein degradation. Our work provides a framework to design conformation-specific therapeutics to prevent noxious transitions.
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Affiliation(s)
- Daniel Scholl
- SFMB, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Marie Overtus
- SFMB, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Chloé Martens
- SFMB, Université Libre de Bruxelles, Brussels, Belgium
| | - Yiting Wang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Els Pardon
- VIB-VUB center for Structural Biology, VIB, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Toon Laeremans
- VIB-VUB center for Structural Biology, VIB, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Abel Garcia-Pino
- Cellular and Molecular Microbiology, Université Libre de Bruxelles, Gosselies, Belgium
| | - Jan Steyaert
- VIB-VUB center for Structural Biology, VIB, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Jelle Hendrix
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium.,Molecular Imaging and Photonics, Chemistry Department, KU Leuven, Leuven, Belgium
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7
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Yang B, Lei C, Yang D, Tan Z, Guo T, Luo H. Whole-Exome Sequencing Identified CFTR Variants in Two Consanguineous Families in China. Front Genet 2021; 12:631221. [PMID: 34276759 PMCID: PMC8283821 DOI: 10.3389/fgene.2021.631221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 05/12/2021] [Indexed: 11/18/2022] Open
Abstract
Background Cystic fibrosis (CF) is an autosomal recessive disease caused by genetic variants of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. It is a common hereditary disease in Caucasians while rare in the Chinese. Until now, only 87 Chinese patients have been reported with molecular confirmations. The variant spectrum and clinical features of Chinese CF patients are obviously different from those of Caucasians. Materials and Methods Whole-exome sequencing was applied to analyze the exome of three individuals who have only the typical CF phenotype in the respiratory system from two consanguineous families. The protein domain and structure analysis were applied to predict the impact of the variants. Sanger sequencing was applied to validate the candidate variants. Results A previously reported homozygous variant in CFTR (NM_000492.4: c.1000C > T, p.R334W) was identified in proband I. A novel homozygous variant in a polymorphic position (NM_000492.4: c.1409T > A, p.V470E) was identified in two individuals in the family II. The novel CFTR variant predicted to be disease-causing is the first, to the best of our knowledge, to be reported in CFTR. However, in vitro validation is still needed. Conclusion Our finding expands the variant spectrum of CFTR, reveals clearer clinical phenotype distinction and variant spectrum distinction between Chinese and Caucasian CF patients, and contributes to a more rapid genetic diagnosis and future genetic counseling.
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Affiliation(s)
- Binyi Yang
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Hunan Diagnosis and Treatment Center of Respiratory Disease, Changsha, China
| | - Cheng Lei
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Hunan Diagnosis and Treatment Center of Respiratory Disease, Changsha, China
| | - Danhui Yang
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Hunan Diagnosis and Treatment Center of Respiratory Disease, Changsha, China
| | - Zhiping Tan
- Department of Cardiovascular Surgery, Clinical Center for Gene Diagnosis and Therapy, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Ting Guo
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Hunan Diagnosis and Treatment Center of Respiratory Disease, Changsha, China
| | - Hong Luo
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Hunan Diagnosis and Treatment Center of Respiratory Disease, Changsha, China
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8
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Bahia MS, Khazanov N, Zhou Q, Yang Z, Wang C, Hong JS, Rab A, Sorscher EJ, Brouillette CG, Hunt JF, Senderowitz H. Stability Prediction for Mutations in the Cytosolic Domains of Cystic Fibrosis Transmembrane Conductance Regulator. J Chem Inf Model 2021; 61:1762-1777. [PMID: 33720715 DOI: 10.1021/acs.jcim.0c01207] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cystic Fibrosis (CF) is caused by mutations to the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) chloride channel. CFTR is composed of two membrane spanning domains, two cytosolic nucleotide-binding domains (NBD1 and NBD2) and a largely unstructured R-domain. Multiple CF-causing mutations reside in the NBDs and some are known to compromise the stability of these domains. The ability to predict the effect of mutations on the stability of the cytosolic domains of CFTR and to shed light on the mechanisms by which they exert their effect is therefore important in CF research. With this in mind, we have predicted the effect on domain stability of 59 mutations in NBD1 and NBD2 using 15 different algorithms and evaluated their performances via comparison to experimental data using several metrics including the correct classification rate (CCR), and the squared Pearson correlation (R2) and Spearman's correlation (ρ) calculated between the experimental ΔTm values and the computationally predicted ΔΔG values. Overall, the best results were obtained with FoldX and Rosetta. For NBD1 (35 mutations), FoldX provided R2 and ρ values of 0.64 and -0.71, respectively, with an 86% correct classification rate (CCR). For NBD2 (24 mutations), FoldX R2, ρ, and CCR were 0.51, -0.73, and 75%, respectively. Application of the Rosetta high-resolution protocol (Rosetta_hrp) to NBD1 yielded R2, ρ, and CCR of 0.64, -0.75, and 69%, respectively, and for NBD2 yielded R2, ρ, and CCR of 0.29, -0.27, and 50%, respectively. The corresponding numbers for the Rosetta's low-resolution protocol (Rosetta_lrp) were R2 = 0.47, ρ = -0.69, and CCR = 69% for NBD1 and R2 = 0.27, ρ = -0.24, and CCR = 63% for NBD2. For NBD1, both algorithms suggest that destabilizing mutations suffer from destabilizing vdW clashes, whereas stabilizing mutations benefit from favorable H-bond interactions. Two triple consensus approaches based on FoldX, Rosetta_lpr, and Rosetta_hpr were attempted using either "majority-voting" or "all-voting". The all-voting consensus outperformed the individual predictors, albeit on a smaller data set. In summary, our results suggest that the effect of mutations on the stability of CFTR's NBDs could be largely predicted. Since NBDs are common to all ABC transporters, these results may find use in predicting the effect and mechanism of the action of multiple disease-causing mutations in other proteins.
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Affiliation(s)
| | - Netaly Khazanov
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Qingxian Zhou
- School of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Zhengrong Yang
- School of Medicine, Division of Hematology & Oncology, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Chi Wang
- 702 Fairchild Center, MC3423, Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Jeong S Hong
- Department of Paediatrics, Emory University School of Medicine, Atlanta, Georgia 30303, United States
| | - Andras Rab
- Department of Paediatrics, Emory University School of Medicine, Atlanta, Georgia 30303, United States
| | - Eric J Sorscher
- Department of Paediatrics, Emory University School of Medicine, Atlanta, Georgia 30303, United States
| | - Christie G Brouillette
- Department of Biochemistry & Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - John F Hunt
- 702 Fairchild Center, MC3423, Department of Biological Sciences, Columbia University, New York, New York 10027, United States
| | - Hanoch Senderowitz
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel
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9
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Meng X, Clews J, Ciuta AD, Martin ER, Ford RC. CFTR structure, stability, function and regulation. Biol Chem 2020; 400:1359-1370. [PMID: 30738013 DOI: 10.1515/hsz-2018-0470] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/30/2019] [Indexed: 12/15/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is a unique member of the ATP-binding cassette family of proteins because it has evolved into a channel. Mutations in CFTR cause cystic fibrosis, the most common genetic disease in people of European origin. The F508del mutation is found in about 90% of patients and here we present data that suggest its main effect is on CFTR stability rather than on the three-dimensional (3D) folded state. A survey of recent cryo-electron microscopy studies was carried out and this highlighted differences in terms of CFTR conformation despite similarities in experimental conditions. We further studied CFTR structure under various phosphorylation states and with the CFTR-interacting protein NHERF1. The coexistence of outward-facing and inward-facing conformations under a range of experimental conditions was suggested from these data. These results are discussed in terms of structural models for channel gating, and favour the model where the mostly disordered regulatory-region of the protein acts as a channel plug.
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Affiliation(s)
- Xin Meng
- School of Biological Sciences, Faculty of Biology Medicine and Health, Michael Smith Building, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Jack Clews
- School of Biological Sciences, Faculty of Biology Medicine and Health, Michael Smith Building, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Anca D Ciuta
- School of Biological Sciences, Faculty of Biology Medicine and Health, Michael Smith Building, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Eleanor R Martin
- School of Biological Sciences, Faculty of Biology Medicine and Health, Michael Smith Building, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Robert C Ford
- School of Biological Sciences, Faculty of Biology Medicine and Health, Michael Smith Building, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
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10
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Towards next generation therapies for cystic fibrosis: Folding, function and pharmacology of CFTR. J Cyst Fibros 2020; 19 Suppl 1:S25-S32. [PMID: 31902693 PMCID: PMC7052731 DOI: 10.1016/j.jcf.2019.12.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 12/19/2022]
Abstract
The treatment of cystic fibrosis (CF) has been transformed by orally-bioavailable small molecule modulators of the cystic fibrosis transmembrane conductance regulator (CFTR), which restore function to CF mutants. However, CFTR modulators are not available to all people with CF and better modulators are required to prevent disease progression. Here, we review selectively recent advances in CFTR folding, function and pharmacology. We highlight ensemble and single-molecule studies of CFTR folding, which provide new insight into CFTR assembly, its perturbation by CF mutations and rescue by CFTR modulators. We discuss species-dependent differences in the action of the F508del-CFTR mutation on CFTR expression, stability and function, which might influence pharmacological studies of CFTR modulators in CF animal models. Finally, we illuminate the identification of combinations of two CFTR potentiators (termed co-potentiators), which restore therapeutically-relevant levels of CFTR activity to rare CF mutations. Thus, mechanistic studies of CFTR folding, function and pharmacology inform the development of highly effective CFTR modulators.
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11
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Sigoillot M, Overtus M, Grodecka M, Scholl D, Garcia-Pino A, Laeremans T, He L, Pardon E, Hildebrandt E, Urbatsch I, Steyaert J, Riordan JR, Govaerts C. Domain-interface dynamics of CFTR revealed by stabilizing nanobodies. Nat Commun 2019; 10:2636. [PMID: 31201318 PMCID: PMC6572788 DOI: 10.1038/s41467-019-10714-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 05/21/2019] [Indexed: 01/17/2023] Open
Abstract
The leading cause of cystic fibrosis (CF) is the deletion of phenylalanine 508 (F508del) in the first nucleotide-binding domain (NBD1) of the cystic fibrosis transmembrane conductance regulator (CFTR). The mutation affects the thermodynamic stability of the domain and the integrity of the interface between NBD1 and the transmembrane domain leading to its clearance by the quality control system. Here, we develop nanobodies targeting NBD1 of human CFTR and demonstrate their ability to stabilize both isolated NBD1 and full-length protein. Crystal structures of NBD1-nanobody complexes provide an atomic description of the epitopes and reveal the molecular basis for stabilization. Furthermore, our data uncover a conformation of CFTR, involving detachment of NBD1 from the transmembrane domain, which contrast with the compact assembly observed in cryo-EM structures. This unexpected interface rearrangement is likely to have major relevance for CF pathogenesis but also for the normal function of CFTR and other ABC proteins.
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Affiliation(s)
- Maud Sigoillot
- SFMB, Université Libre de Bruxelles (ULB), CP206/02, Boulevard du Triomphe, building BC, B-1050, Brussels, Belgium
| | - Marie Overtus
- SFMB, Université Libre de Bruxelles (ULB), CP206/02, Boulevard du Triomphe, building BC, B-1050, Brussels, Belgium
| | - Magdalena Grodecka
- SFMB, Université Libre de Bruxelles (ULB), CP206/02, Boulevard du Triomphe, building BC, B-1050, Brussels, Belgium
| | - Daniel Scholl
- SFMB, Université Libre de Bruxelles (ULB), CP206/02, Boulevard du Triomphe, building BC, B-1050, Brussels, Belgium
| | - Abel Garcia-Pino
- Laboratoire de Microbiologie Moléculaire et Cellulaire, ULB CP300, rue des Professeurs Jeener et Brachet 12, B-6041, Charleroi, Belgium
| | - Toon Laeremans
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050, Brussels, Belgium.,VIB-VUB center for Structural Biology, VIB, Pleinlaan 2, B-1050, Brussels, Belgium
| | - Lihua He
- Department of Biochemistry and Biophysics and Cystic Fibrosis Center, University of North Carolina-Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050, Brussels, Belgium.,VIB-VUB center for Structural Biology, VIB, Pleinlaan 2, B-1050, Brussels, Belgium
| | - Ellen Hildebrandt
- Department of Cell Biology and Biochemistry and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX, 79430, USA
| | - Ina Urbatsch
- Department of Cell Biology and Biochemistry and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX, 79430, USA
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050, Brussels, Belgium.,VIB-VUB center for Structural Biology, VIB, Pleinlaan 2, B-1050, Brussels, Belgium
| | - John R Riordan
- Department of Biochemistry and Biophysics and Cystic Fibrosis Center, University of North Carolina-Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Cedric Govaerts
- SFMB, Université Libre de Bruxelles (ULB), CP206/02, Boulevard du Triomphe, building BC, B-1050, Brussels, Belgium.
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Fay JF, Aleksandrov LA, Jensen TJ, Cui LL, Kousouros JN, He L, Aleksandrov AA, Gingerich DS, Riordan JR, Chen JZ. Cryo-EM Visualization of an Active High Open Probability CFTR Anion Channel. Biochemistry 2018; 57:6234-6246. [PMID: 30281975 DOI: 10.1021/acs.biochem.8b00763] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, crucial to epithelial salt and water homeostasis, and defective due to mutations in its gene in patients with cystic fibrosis, is a unique member of the large family of ATP-binding cassette transport proteins. Regulation of CFTR channel activity is stringently controlled by phosphorylation and nucleotide binding. Structural changes that underlie transitions between active and inactive functional states are not yet fully understood. Indeed the first 3D structures of dephosphorylated, ATP-free, and phosphorylated ATP-bound states were only recently reported. Here we have determined the structure of inactive and active states of a thermally stabilized CFTR, the latter with a very high channel open probability, confirmed after reconstitution into proteoliposomes. These structures, obtained at nominal resolution of 4.3 and 6.6 Å, reveal a unique repositioning of the transmembrane helices and regulatory domain density that provide insights into the structural transition between active and inactive functional states of CFTR. Moreover, we observe an extracellular vestibule that may provide anion access to the pore due to the conformation of transmembrane helices 7 and 8 that differs from the previous orthologue CFTR structures. In conclusion, our work contributes detailed structural information on an active, open state of the CFTR anion channel.
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Affiliation(s)
- Jonathan F Fay
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Luba A Aleksandrov
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Timothy J Jensen
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Liying L Cui
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Joseph N Kousouros
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Lihua He
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Andrei A Aleksandrov
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Drew S Gingerich
- Oregon Health & Science University , Portland , Oregon 97239 , United States
| | - John R Riordan
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - James Z Chen
- Oregon Health & Science University , Portland , Oregon 97239 , United States
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