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Introini B, Cui W, Chu X, Zhang Y, Alves AC, Eckhardt-Strelau L, Golusik S, Tol M, Vogel H, Yuan S, Kudryashev M. Structure of tetrameric forms of the serotonin-gated 5-HT3 A receptor ion channel. EMBO J 2024:10.1038/s44318-024-00191-5. [PMID: 39232129 DOI: 10.1038/s44318-024-00191-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 06/16/2024] [Accepted: 07/15/2024] [Indexed: 09/06/2024] Open
Abstract
Multimeric membrane proteins are produced in the endoplasmic reticulum and transported to their target membranes which, for ion channels, is typically the plasma membrane. Despite the availability of many fully assembled channel structures, our understanding of assembly intermediates, multimer assembly mechanisms, and potential functions of non-standard assemblies is limited. We demonstrate that the pentameric ligand-gated serotonin 5-HT3A receptor (5-HT3AR) can assemble to tetrameric forms and report the structures of the tetramers in plasma membranes of cell-derived microvesicles and in membrane memetics using cryo-electron microscopy and tomography. The tetrameric structures have near-symmetric transmembrane domains, and asymmetric extracellular domains, and can bind serotonin molecules. Computer simulations, based on our cryo-EM structures, were used to decipher the assembly pathway of pentameric 5-HT3R and suggest a potential functional role for the tetrameric receptors.
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Affiliation(s)
- Bianca Introini
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt am Main, Frankfurt on Main, Germany
| | - Wenqiang Cui
- The Research Center for Computer-aided Drug Discovery, Institute of Biomedicine and Biotechnology, The Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaofeng Chu
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), In Situ Structural Biology, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Yingyi Zhang
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt am Main, Frankfurt on Main, Germany
| | - Ana Catarina Alves
- Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | | | - Sabrina Golusik
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), In Situ Structural Biology, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Menno Tol
- Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Horst Vogel
- The Research Center for Computer-aided Drug Discovery, Institute of Biomedicine and Biotechnology, The Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
- Institute of Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
- Faculty of Pharmaceutical Sciences, Shenzhen University of Advanced Technology (SUAT), Shenzhen, China.
| | - Shuguang Yuan
- The Research Center for Computer-aided Drug Discovery, Institute of Biomedicine and Biotechnology, The Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
- AlphaMol Science Ltd, Shenzhen, 518055, China.
| | - Mikhail Kudryashev
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt am Main, Frankfurt on Main, Germany.
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), In Situ Structural Biology, Robert-Rössle-Str. 10, 13125, Berlin, Germany.
- Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin, Berlin, Germany.
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2
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Tian L, Andrews C, Yan Q, Yang JJ. Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling. Chronic Dis Transl Med 2024; 10:167-194. [PMID: 39027195 PMCID: PMC11252437 DOI: 10.1002/cdt3.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 03/29/2024] [Accepted: 04/09/2024] [Indexed: 07/20/2024] Open
Abstract
Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.
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Affiliation(s)
- Li Tian
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Corey Andrews
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Qiuyun Yan
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Jenny J. Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
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3
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Mattos D, Neves WD, Kitamura T, Pradhan R, Wan X, da Hora CC, Tranter D, Kazemi S, Yu X, Tripathy N, Paavilainen VO, McPhail KL, Oishi S, Badr CE, Ishmael JE. Diastereomers of Coibamide A Show Altered Sec61 Client Selectivity and Ligand-Dependent Activity against Patient-Derived Glioma Stem-like Cells. ACS Pharmacol Transl Sci 2024; 7:1823-1838. [PMID: 38898945 PMCID: PMC11184607 DOI: 10.1021/acsptsci.4c00049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/23/2024] [Accepted: 04/29/2024] [Indexed: 06/21/2024]
Abstract
Coibamide A (CbA) is a cyanobacterial lariat depsipeptide that selectively inhibits multiple secreted and integral membrane proteins from entering the endoplasmic reticulum secretory pathway through binding the alpha subunit of the Sec61 translocon. As a complex peptide-based macrocycle with 13 stereogenic centers, CbA is presumed to adopt a conformationally restricted orientation in the ligand-bound state, resulting in potent antitumor and antiangiogenic bioactivity. A stereochemical structure-activity relationship for CbA was previously defined based on cytotoxicity against established cancer cell lines. However, the ability of synthetic isomers to inhibit the biosynthesis of specific Sec61 substrates was unknown. Here, we report that two less toxic diastereomers of CbA, [L-Hiv2]-CbA and [L-Hiv2, L-MeAla11]-CbA, are pharmacologically active Sec61 inhibitors. Both compounds inhibited the expression of a secreted reporter (Gaussia luciferase), VEGF-A, and a Type 1 membrane protein (VCAM1), while [L-Hiv2]-CbA also decreased the expression of ICAM1 and BiP/GRP78. Analysis of 43 different chemokines in the secretome of SF-268 glioblastoma cells revealed different inhibitory profiles for the two diastereomers. When the cytotoxic potential of CbA compounds was compared against a panel of patient-derived glioblastoma stem-like cells (GSCs), Sec61 inhibitors were remarkably toxic to five of the six GSCs tested. Each ligand showed a distinct cytotoxic potency and selectivity pattern for CbA-sensitive GSCs, with IC50 values ranging from subnanomolar to low micromolar concentrations. Together, these findings highlight the extreme sensitivity of GSCs to Sec61 modulation and the importance of ligand stereochemistry in determining the spectrum of inhibited Sec61 client proteins.
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Affiliation(s)
- Daphne
R. Mattos
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Willian das Neves
- Department
of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, United States
| | - Takashi Kitamura
- Graduate
School of Pharmaceutical Sciences, Kyoto
University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Richa Pradhan
- Department
of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, United States
| | - Xuemei Wan
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Cintia Carla da Hora
- Department
of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, United States
| | - Dale Tranter
- Institute
of Biotechnology, University of Helsinki, Helsinki 00014, Finland
| | - Soheila Kazemi
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Xinhui Yu
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Nirmalya Tripathy
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | | | - Kerry L. McPhail
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Shinya Oishi
- Graduate
School of Pharmaceutical Sciences, Kyoto
University, Sakyo-ku, Kyoto 606-8501, Japan
- Laboratory
of Medicinal Chemistry, Kyoto Pharmaceutical
University, Yamashina-ku, Kyoto 607-8412, Japan
| | - Christian E. Badr
- Department
of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, United States
| | - Jane E. Ishmael
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
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4
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Chadha A, Yanai Y, Oide H, Wakana Y, Inoue H, Saha S, Tagaya M, Arasaki K, Mukherjee S. Legionella uses host Rab GTPases and BAP31 to create a unique ER niche. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593622. [PMID: 38765994 PMCID: PMC11100814 DOI: 10.1101/2024.05.10.593622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Upon entry into host cells, the facultative intracellular bacterium Legionella pneumophila ( L.p .) uses its type IV secretion system, Dot/Icm, to secrete ~330 bacterial effector proteins into the host cell. Some of these effectors hijack endoplasmic reticulum (ER)-derived vesicles to form the Legionella -containing vacuole (LCV). Despite extensive investigation over decades, the fundamental question persists: Is the LCV membrane distinct from or contiguous with the host ER network? Here, we employ advanced photobleaching techniques, revealing a temporal acquisition of both smooth and rough ER (sER and rER) markers on the LCV. In the early stages of infection, the sER intimately associates with the LCV. Remarkably, as the infection progresses, the LCV evolves into a distinct niche comprising an rER membrane that is independent of the host ER network. We discover that the L.p. effector LidA binds to and recruits two host proteins of the Rab superfamily, Rab10, and Rab4, that play significant roles in acquiring sER and rER membranes, respectively. Additionally, we identify the pivotal role of a host ER-resident protein, BAP31, in orchestrating the transition from sER to rER. While previously recognized for shuttling between sER and rER, we demonstrate BAP31's role as a Rab effector, mediating communication between these ER sub-compartments. Furthermore, using genomic deletion strains, we uncover a novel L.p. effector, Lpg1152, essential for recruiting BAP31 to the LCV and facilitating its transition from sER to rER. Depletion of BAP31 or infection with an isogenic L.p. strain lacking Lpg1152 results in a growth defect. Collectively, our findings illuminate the intricate interplay between molecular players from both host and pathogen, elucidating how L.p. orchestrates the transformation of its residing vacuole membrane from a host-associated sER to a distinct rER membrane that is not contiguous with the host ER network.
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5
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Hamel L, Comeau M, Tardif R, Poirier‐Gravel F, Paré M, Lavoie P, Goulet M, Michaud D, D'Aoust M. Heterologous expression of influenza haemagglutinin leads to early and transient activation of the unfolded protein response in Nicotiana benthamiana. PLANT BIOTECHNOLOGY JOURNAL 2024; 22:1146-1163. [PMID: 38038125 PMCID: PMC11022800 DOI: 10.1111/pbi.14252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/06/2023] [Accepted: 11/16/2023] [Indexed: 12/02/2023]
Abstract
The unfolded protein response (UPR) allows cells to cope with endoplasmic reticulum (ER) stress induced by accumulation of misfolded proteins in the ER. Due to its sensitivity to Agrobacterium tumefaciens, the model plant Nicotiana benthamiana is widely employed for transient expression of recombinant proteins of biopharmaceutical interest, including antibodies and virus surface proteins used for vaccine production. As such, study of the plant UPR is of practical significance, since enforced expression of complex secreted proteins often results in ER stress. After 6 days of expression, we recently reported that influenza haemagglutinin H5 induces accumulation of UPR proteins. Since up-regulation of corresponding UPR genes was not detected at this time, accumulation of UPR proteins was hypothesized to be independent of transcriptional induction, or associated with early but transient UPR gene up-regulation. Using time course sampling, we here show that H5 expression does result in early and transient activation of the UPR, as inferred from unconventional splicing of NbbZIP60 transcripts and induction of UPR genes with varied functions. Transient nature of H5-induced UPR suggests that this response was sufficient to cope with ER stress provoked by expression of the secreted protein, as opposed to an antibody that triggered stronger and more sustained UPR activation. As up-regulation of defence genes responding to H5 expression was detected after the peak of UPR activation and correlated with high increase in H5 protein accumulation, we hypothesize that these immune responses, rather than the UPR, were responsible for onset of the necrotic symptoms on H5-expressing leaves.
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Affiliation(s)
| | | | | | | | | | | | - Marie‐Claire Goulet
- Centre de recherche et d'innovation sur les végétaux, Département de phytologieUniversité LavalQuébecQuebecCanada
| | - Dominique Michaud
- Centre de recherche et d'innovation sur les végétaux, Département de phytologieUniversité LavalQuébecQuebecCanada
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6
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Wu K, Itskanov S, Lynch DL, Chen Y, Turner A, Gumbart JC, Park E. Substrate recognition mechanism of the endoplasmic reticulum-associated ubiquitin ligase Doa10. Nat Commun 2024; 15:2182. [PMID: 38467638 PMCID: PMC10928120 DOI: 10.1038/s41467-024-46409-2] [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: 08/26/2023] [Accepted: 02/14/2024] [Indexed: 03/13/2024] Open
Abstract
Doa10 (MARCHF6 in metazoans) is a large polytopic membrane-embedded E3 ubiquitin ligase in the endoplasmic reticulum (ER) that plays an important role in quality control of cytosolic and ER proteins. Although Doa10 is highly conserved across eukaryotes, it is not understood how Doa10 recognizes its substrates. Here, we define the substrate recognition mechanism of Doa10 by structural and functional analyses on Saccharomyces cerevisiae Doa10 and its model substrates. Cryo-EM analysis shows that Doa10 has unusual architecture with a large lipid-filled central cavity, and its conserved middle domain forms an additional water-filled lateral tunnel open to the cytosol. Our biochemical data and molecular dynamics simulations suggest that the entrance of the substrate's degron peptide into the lateral tunnel is required for efficient polyubiquitination. The N- and C-terminal membrane domains of Doa10 seem to form fence-like features to restrict polyubiquitination to those proteins that can access the central cavity and lateral tunnel. Our study reveals how extended hydrophobic sequences at the termini of substrate proteins are recognized by Doa10 as a signal for quality control.
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Affiliation(s)
- Kevin Wu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - Samuel Itskanov
- Biophysics Graduate Program, University of California, Berkeley, CA, 94720, USA
| | - Diane L Lynch
- School of Physics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Yuanyuan Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - Aasha Turner
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA
| | - James C Gumbart
- School of Physics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Eunyong Park
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, 94720, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA.
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7
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Wu K, Itskanov S, Lynch DL, Chen Y, Turner A, Gumbart JC, Park E. Substrate recognition mechanism of the endoplasmic reticulum-associated ubiquitin ligase Doa10. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.09.574907. [PMID: 38260251 PMCID: PMC10802466 DOI: 10.1101/2024.01.09.574907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Doa10 (MARCH6 in metazoans) is a large polytopic membrane-embedded E3 ubiquitin ligase in the endoplasmic reticulum (ER) that plays an important role in quality control of cytosolic and ER proteins. Although Doa10 is highly conserved across eukaryotes, it is not understood how Doa10 recognizes its substrates. Here, we defined the substrate recognition mechanism of Doa10 by structural and functional analyses on Saccharomyces cerevisiae Doa10 and its well-defined degron Deg1. Cryo-EM analysis shows that Doa10 has unusual architecture with a large lipid-filled central cavity, and its conserved middle domain forms an additional water-filled lateral tunnel open to the cytosol. Our biochemical data and molecular dynamics simulations suggest that the entrance of the substrate's degron peptide into the lateral tunnel is required for efficient polyubiquitination. The N- and C-terminal membrane domains of Doa10 seem to form fence-like features to restrict polyubiquitination to those proteins that can access the central cavity and lateral tunnel.
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Affiliation(s)
- Kevin Wu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
| | - Samuel Itskanov
- Biophysics Graduate Program, University of California, Berkeley, CA 94720, USA
| | - Diane L. Lynch
- School of Physics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Yuanyuan Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
| | - Aasha Turner
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - James C. Gumbart
- School of Physics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Eunyong Park
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
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8
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Kleizen B, de Mattos E, Papaioannou O, Monti M, Tartaglia GG, van der Sluijs P, Braakman I. Transmembrane Helices 7 and 8 Confer Aggregation Sensitivity to the Cystic Fibrosis Transmembrane Conductance Regulator. Int J Mol Sci 2023; 24:15741. [PMID: 37958724 PMCID: PMC10648718 DOI: 10.3390/ijms242115741] [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: 09/04/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 11/15/2023] Open
Abstract
The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a large multi-spanning membrane protein that is susceptible to misfolding and aggregation. We have identified here the region responsible for this instability. Temperature-induced aggregation of C-terminally truncated versions of CFTR demonstrated that all truncations up to the second transmembrane domain (TMD2), including the R region, largely resisted aggregation. Limited proteolysis identified a folded structure that was prone to aggregation and consisted of TMD2 and at least part of the Regulatory Region R. Only when both TM7 (TransMembrane helix 7) and TM8 were present, TMD2 fragments became as aggregation-sensitive as wild-type CFTR, in line with increased thermo-instability of late CFTR nascent chains and in silico prediction of aggregation propensity. In accord, isolated TMD2 was degraded faster in cells than isolated TMD1. We conclude that TMD2 extended at its N-terminus with part of the R region forms a protease-resistant structure that induces heat instability in CFTR and may be responsible for its limited intracellular stability.
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Affiliation(s)
- Bertrand Kleizen
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Eduardo de Mattos
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Olga Papaioannou
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Michele Monti
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy; (M.M.); (G.G.T.)
- Centre for Human Technologies (CHT), Istituto Italiano di Tecnologia (IIT), 16152 Genoa, Italy
| | - Gian Gaetano Tartaglia
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy; (M.M.); (G.G.T.)
- Centre for Human Technologies (CHT), Istituto Italiano di Tecnologia (IIT), 16152 Genoa, Italy
| | - Peter van der Sluijs
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
| | - Ineke Braakman
- Cellular Protein Chemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, 3584 CH Utrecht, The Netherlands; (B.K.); (E.d.M.); (O.P.); (P.v.d.S.)
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9
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Itskanov S, Wang L, Junne T, Sherriff R, Xiao L, Blanchard N, Shi WQ, Forsyth C, Hoepfner D, Spiess M, Park E. A common mechanism of Sec61 translocon inhibition by small molecules. Nat Chem Biol 2023; 19:1063-1071. [PMID: 37169959 DOI: 10.1038/s41589-023-01337-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 04/12/2023] [Indexed: 05/13/2023]
Abstract
The Sec61 complex forms a protein-conducting channel in the endoplasmic reticulum membrane that is required for secretion of soluble proteins and production of many membrane proteins. Several natural and synthetic small molecules specifically inhibit Sec61, generating cellular effects that are useful for therapeutic purposes, but their inhibitory mechanisms remain unclear. Here we present near-atomic-resolution structures of human Sec61 inhibited by a comprehensive panel of structurally distinct small molecules-cotransin, decatransin, apratoxin, ipomoeassin, mycolactone, cyclotriazadisulfonamide and eeyarestatin. All inhibitors bind to a common lipid-exposed pocket formed by the partially open lateral gate and plug domain of Sec61. Mutations conferring resistance to the inhibitors are clustered at this binding pocket. The structures indicate that Sec61 inhibitors stabilize the plug domain in a closed state, thereby preventing the protein-translocation pore from opening. Our study provides the atomic details of Sec61-inhibitor interactions and the structural framework for further pharmacological studies and drug design.
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Affiliation(s)
- Samuel Itskanov
- Biophysics Graduate Program, University of California, Berkeley, Berkeley, CA, USA
| | - Laurie Wang
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Tina Junne
- Biozentrum, University of Basel, Basel, Switzerland
| | - Rumi Sherriff
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Li Xiao
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Nicolas Blanchard
- Université de Haute-Alsace, Université de Strasbourg, CNRS, LIMA, UMR 7042, Mulhouse, France
| | - Wei Q Shi
- Department of Chemistry, Ball State University, Muncie, IN, USA
| | - Craig Forsyth
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Dominic Hoepfner
- Novartis Institutes for BioMedical Research, Novartis Pharma AG, Forum 1 Novartis Campus, Basel, Switzerland
| | | | - Eunyong Park
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA.
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10
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Wu H, Hegde RS. Mechanism of signal-anchor triage during early steps of membrane protein insertion. Mol Cell 2023; 83:961-973.e7. [PMID: 36764302 PMCID: PMC10155758 DOI: 10.1016/j.molcel.2023.01.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/08/2022] [Accepted: 01/18/2023] [Indexed: 02/11/2023]
Abstract
Most membrane proteins use their first transmembrane domain, known as a signal anchor (SA), for co-translational targeting to the endoplasmic reticulum (ER) via the signal recognition particle (SRP). The SA then inserts into the membrane using either the Sec61 translocation channel or the ER membrane protein complex (EMC) insertase. How EMC and Sec61 collaborate to ensure SA insertion in the correct topology is not understood. Using site-specific crosslinking, we detect a pre-insertion SA intermediate adjacent to EMC. This intermediate forms after SA release from SRP but before ribosome transfer to Sec61. The polypeptide's N-terminal tail samples a cytosolic vestibule bordered by EMC3, from where it can translocate across the membrane concomitant with SA insertion. The ribosome then docks on Sec61, which has an opportunity to insert those SAs skipped by EMC. These results suggest that EMC acts between SRP and Sec61 to triage SAs for insertion during membrane protein biogenesis.
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Affiliation(s)
- Haoxi Wu
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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Sun J, Qin F, Sun F, He P, Wei E, Wang R, Zhu F, Wang Q, Tang X, Zhang Y, Shen Z. Identification and subcellular colocalization of protein transport protein Sec61α and Sec61γ in Nosema bombycis. Gene X 2023; 851:146971. [DOI: 10.1016/j.gene.2022.146971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/27/2022] [Accepted: 10/11/2022] [Indexed: 11/07/2022] Open
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Abstract
More than 30% of eukaryotic proteins contain domains that must translocate across or integrate into the endoplasmic reticulum (ER) membrane. With few exceptions, protein translocation and transmembrane domain integration at the ER require the conserved Sec61 translocon. Decades of studies have established a clear mechanistic model for how the Sec61 translocon functions. The biosynthesis of distinct subsets of proteins at the ER also involves accessory factors that interact with the Sec61 translocon and translocating nascent proteins. However, assigning specific functions to many translocon accessory factors has been a persistent challenge in the field. This Perspective discusses recent insights into mechanisms that promote protein biosynthesis at the ER through accessory factors that directly regulate the Sec61 translocon or chaperone nascent proteins within the ER membrane. These translocon accessory factor functions, and more still to be discovered, are essential for producing a diverse and high-fidelity proteome at the ER.
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Affiliation(s)
- Sichen Shao
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115,*Address correspondence to: Sichen Shao ()
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