1
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Gao J, Zhang YW. The Pathway of a Transmembrane Helix Insertion into the Membrane Assisted by Sec61α Channel. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:16454-16462. [PMID: 39046853 DOI: 10.1021/acs.langmuir.4c01776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
The significant inconsistency between the experimental and simulation results of the free energy for the translocon-assisted insertion of the transmembrane helix (TMH) has not been reasonably explained. Understanding the mechanism of TMH insertion through the translocon is the key to solving this problem. In this study, we performed a series of coarse-grained molecular dynamics simulations and calculated the potential mean forces (PMFs) for three insertion processes of a hydrophobic TMH. The simulations reveal the pathway of the TMH insertion assisted by a translocon. The results indicate that the TMH contacts the top of the lateral gate first and then inserts down the lateral gate, which agrees with the sliding model. The TMH begins to transfer laterally to the bilayer when it is blocked by the plug and reaches the exit of the lateral gate, where there is a free energy minimum point. We also found that the connecting section between TM2 and TM3 of Sec61α prevented TMH from leaving the lateral gate and directly transitioning to the surface-bound state. These findings provide insight into the mechanism of the insertion of TMH through the translocon.
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Affiliation(s)
- Jian Gao
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212100, People's Republic of China
- Jiangsu Provincial Engineering Research Center of Grain Bioprocessing, Zhenjiang 212100, People's Republic of China
| | - Ye-Wang Zhang
- School of Pharmacy, Jiangsu University, Zhenjiang 212013, People's Republic of China
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2
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Wenzell NA, Tuch BB, McMinn DL, Lyons MJ, Kirk CJ, Taunton J. Global signal peptide profiling reveals principles of selective Sec61 inhibition. Nat Chem Biol 2024:10.1038/s41589-024-01592-7. [PMID: 38519575 DOI: 10.1038/s41589-024-01592-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 02/26/2024] [Indexed: 03/25/2024]
Abstract
Cotransins target the Sec61 translocon and inhibit the biogenesis of an undefined subset of secretory and membrane proteins. Remarkably, cotransin inhibition depends on the unique signal peptide (SP) of each Sec61 client, which is required for cotranslational translocation into the endoplasmic reticulum. It remains unknown how an SP's amino acid sequence and biophysical properties confer sensitivity to structurally distinct cotransins. Here we describe a fluorescence-based, pooled-cell screening platform to interrogate nearly all human SPs in parallel. We profiled two cotransins with distinct effects on cancer cells and discovered a small subset of SPs, including the oncoprotein human epidermal growth factor receptor 3 (HER3), with increased sensitivity to the more selective cotransin, KZR-9873. By comparing divergent mouse and human orthologs, we unveiled a position-dependent effect of arginine on SP sensitivity. Our multiplexed profiling platform reveals how cotransins can exploit subtle sequence differences to achieve SP discrimination.
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Affiliation(s)
- Nicole A Wenzell
- Chemistry and Chemical Biology Program, University of California, San Francisco, San Francisco, CA, USA
| | - Brian B Tuch
- Kezar Life Sciences, South San Francisco, CA, USA
| | | | - Matthew J Lyons
- Chemistry and Chemical Biology Program, University of California, San Francisco, San Francisco, CA, USA
| | | | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA.
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3
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Dalisay DS, Tenebro CP, Sabido EM, Suarez AFL, Paderog MJV, Reyes-Salarda R, Saludes JP. Marine-Derived Anticancer Agents Targeting Apoptotic Pathways: Exploring the Depths for Novel Cancer Therapies. Mar Drugs 2024; 22:114. [PMID: 38535455 PMCID: PMC10972102 DOI: 10.3390/md22030114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/01/2024] [Accepted: 02/08/2024] [Indexed: 04/13/2024] Open
Abstract
Extensive research has been conducted on the isolation and study of bioactive compounds derived from marine sources. Several natural products have demonstrated potential as inducers of apoptosis and are currently under investigation in clinical trials. These marine-derived compounds selectively interact with extrinsic and intrinsic apoptotic pathways using a variety of molecular mechanisms, resulting in cell shrinkage, chromatin condensation, cytoplasmic blebs, apoptotic bodies, and phagocytosis by adjacent parenchymal cells, neoplastic cells, or macrophages. Numerous marine-derived compounds are currently undergoing rigorous examination for their potential application in cancer therapy. This review examines a total of 21 marine-derived compounds, along with their synthetic derivatives, sourced from marine organisms such as sponges, corals, tunicates, mollusks, ascidians, algae, cyanobacteria, fungi, and actinobacteria. These compounds are currently undergoing preclinical and clinical trials to evaluate their potential as apoptosis inducers for the treatment of different types of cancer. This review further examined the compound's properties and mode of action, preclinical investigations, clinical trial studies on single or combination therapy, and the prospective development of marine-derived anticancer therapies.
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Affiliation(s)
- Doralyn S. Dalisay
- Center for Chemical Biology and Biotechnology (C2B2), University of San Agustin, Iloilo City 5000, Philippines; (C.P.T.); (E.M.S.); (M.J.V.P.)
- Department of Biology, University of San Agustin, Iloilo City 5000, Philippines;
- Balik Scientist Program, Department of Science and Technology, Philippine Council for Health Research and Development (DOST-PCHRD), Taguig 1631, Philippines;
| | - Chuckcris P. Tenebro
- Center for Chemical Biology and Biotechnology (C2B2), University of San Agustin, Iloilo City 5000, Philippines; (C.P.T.); (E.M.S.); (M.J.V.P.)
| | - Edna M. Sabido
- Center for Chemical Biology and Biotechnology (C2B2), University of San Agustin, Iloilo City 5000, Philippines; (C.P.T.); (E.M.S.); (M.J.V.P.)
| | - Angelica Faith L. Suarez
- Center for Natural Drug Discovery and Development (CND3), University of San Agustin, Iloilo City 5000, Philippines;
| | - Melissa June V. Paderog
- Center for Chemical Biology and Biotechnology (C2B2), University of San Agustin, Iloilo City 5000, Philippines; (C.P.T.); (E.M.S.); (M.J.V.P.)
- Department of Pharmacy, University of San Agustin, Iloilo City 5000, Philippines
| | - Rikka Reyes-Salarda
- Department of Biology, University of San Agustin, Iloilo City 5000, Philippines;
| | - Jonel P. Saludes
- Balik Scientist Program, Department of Science and Technology, Philippine Council for Health Research and Development (DOST-PCHRD), Taguig 1631, Philippines;
- Center for Natural Drug Discovery and Development (CND3), University of San Agustin, Iloilo City 5000, Philippines;
- Department of Chemistry, University of San Agustin, Iloilo City 5000, Philippines
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4
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Rehan S, Tranter D, Sharp PP, Craven GB, Lowe E, Anderl JL, Muchamuel T, Abrishami V, Kuivanen S, Wenzell NA, Jennings A, Kalyanaraman C, Strandin T, Javanainen M, Vapalahti O, Jacobson MP, McMinn D, Kirk CJ, Huiskonen JT, Taunton J, Paavilainen VO. Signal peptide mimicry primes Sec61 for client-selective inhibition. Nat Chem Biol 2023; 19:1054-1062. [PMID: 37169961 PMCID: PMC10449633 DOI: 10.1038/s41589-023-01326-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 04/06/2023] [Indexed: 05/13/2023]
Abstract
Preventing the biogenesis of disease-relevant proteins is an attractive therapeutic strategy, but attempts to target essential protein biogenesis factors have been hampered by excessive toxicity. Here we describe KZR-8445, a cyclic depsipeptide that targets the Sec61 translocon and selectively disrupts secretory and membrane protein biogenesis in a signal peptide-dependent manner. KZR-8445 potently inhibits the secretion of pro-inflammatory cytokines in primary immune cells and is highly efficacious in a mouse model of rheumatoid arthritis. A cryogenic electron microscopy structure reveals that KZR-8445 occupies the fully opened Se61 lateral gate and blocks access to the lumenal plug domain. KZR-8445 binding stabilizes the lateral gate helices in a manner that traps select signal peptides in the Sec61 channel and prevents their movement into the lipid bilayer. Our results establish a framework for the structure-guided discovery of novel therapeutics that selectively modulate Sec61-mediated protein biogenesis.
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Affiliation(s)
- Shahid Rehan
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Dale Tranter
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Phillip P Sharp
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | - Gregory B Craven
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | - Eric Lowe
- Kezar Life Sciences, South San Francisco, CA, USA
| | | | | | - Vahid Abrishami
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Suvi Kuivanen
- Institute of Virology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Nicole A Wenzell
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | | | - Chakrapani Kalyanaraman
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of California, San Francisco, CA, USA
| | - Tomas Strandin
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Matti Javanainen
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Olli Vapalahti
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Matthew P Jacobson
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of California, San Francisco, CA, USA
| | | | | | - Juha T Huiskonen
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA.
| | - Ville O Paavilainen
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland.
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5
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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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6
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Ricci D, Demangel C. From Bacterial Toxin to Therapeutic Agent: The Unexpected Fate of Mycolactone. Toxins (Basel) 2023; 15:369. [PMID: 37368670 DOI: 10.3390/toxins15060369] [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: 05/13/2023] [Revised: 05/27/2023] [Accepted: 05/28/2023] [Indexed: 06/29/2023] Open
Abstract
"Recognizing a surprising fact is the first step towards discovery." This famous quote from Louis Pasteur is particularly appropriate to describe what led us to study mycolactone, a lipid toxin produced by the human pathogen Mycobacterium ulcerans. M. ulcerans is the causative agent of Buruli ulcer, a neglected tropical disease manifesting as chronic, necrotic skin lesions with a "surprising" lack of inflammation and pain. Decades after its first description, mycolactone has become much more than a mycobacterial toxin. This uniquely potent inhibitor of the mammalian translocon (Sec61) helped reveal the central importance of Sec61 activity for immune cell functions, the spread of viral particles and, unexpectedly, the viability of certain cancer cells. We report in this review the main discoveries that marked our research into mycolactone, and the medical perspectives they opened up. The story of mycolactone is not over and the applications of Sec61 inhibition may go well beyond immunomodulation, viral infections, and oncology.
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Affiliation(s)
- Daniela Ricci
- Institut Pasteur, Université Paris Cité, Inserm U1224, Immunobiology and Therapy Unit, 75015 Paris, France
| | - Caroline Demangel
- Institut Pasteur, Université Paris Cité, Inserm U1224, Immunobiology and Therapy Unit, 75015 Paris, France
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7
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Pauwels E, Shewakramani NR, De Wijngaert B, Camps A, Provinciael B, Stroobants J, Kalies KU, Hartmann E, Maes P, Vermeire K, Das K. Structural insights into TRAP association with ribosome-Sec61 complex and translocon inhibition by a CADA derivative. SCIENCE ADVANCES 2023; 9:eadf0797. [PMID: 36867692 PMCID: PMC9984176 DOI: 10.1126/sciadv.adf0797] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 01/31/2023] [Indexed: 05/26/2023]
Abstract
During cotranslational translocation, the signal peptide of a nascent chain binds Sec61 translocon to initiate protein transport through the endoplasmic reticulum (ER) membrane. Our cryo-electron microscopy structure of ribosome-Sec61 shows binding of an ordered heterotetrameric translocon-associated protein (TRAP) complex, in which TRAP-γ is anchored at two adjacent positions of 28S ribosomal RNA and interacts with ribosomal protein L38 and Sec61α/γ. Four transmembrane helices (TMHs) of TRAP-γ cluster with one C-terminal helix of each α, β, and δ subunits. The seven TMH bundle helps position a crescent-shaped trimeric TRAP-α/β/δ core in the ER lumen, facing the Sec61 channel. Further, our in vitro assay establishes the cyclotriazadisulfonamide derivative CK147 as a translocon inhibitor. A structure of ribosome-Sec61-CK147 reveals CK147 binding the channel and interacting with the plug helix from the lumenal side. The CK147 resistance mutations surround the inhibitor. These structures help in understanding the TRAP functions and provide a new Sec61 site for designing translocon inhibitors.
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Affiliation(s)
- Eva Pauwels
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Neesha R. Shewakramani
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Brent De Wijngaert
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Anita Camps
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Becky Provinciael
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Joren Stroobants
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Kai-Uwe Kalies
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck 23562, Germany
| | - Enno Hartmann
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck 23562, Germany
| | - Piet Maes
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Clinical and Epidemiological Virology, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Kurt Vermeire
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
| | - Kalyan Das
- Department of Microbiology, Immunology, and Transplantation, KU Leuven, Leuven 3000, Belgium
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, KU Leuven, Leuven 3000, Belgium
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8
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Sec61 channel subunit Sbh1/Sec61β promotes ER translocation of proteins with suboptimal targeting sequences and is fine-tuned by phosphorylation. J Biol Chem 2023; 299:102895. [PMID: 36639027 PMCID: PMC9947333 DOI: 10.1016/j.jbc.2023.102895] [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: 07/05/2022] [Revised: 12/07/2022] [Accepted: 12/09/2022] [Indexed: 01/12/2023] Open
Abstract
The highly conserved endoplasmic reticulum (ER) protein translocation channel contains one nonessential subunit, Sec61β/Sbh1, whose function is poorly understood so far. Its intrinsically unstructured cytosolic domain makes transient contact with ER-targeting sequences in the cytosolic channel vestibule and contains multiple phosphorylation sites suggesting a potential for regulating ER protein import. In a microscopic screen, we show that 12% of a GFP-tagged secretory protein library depends on Sbh1 for translocation into the ER. Sbh1-dependent proteins had targeting sequences with less pronounced hydrophobicity and often no charge bias or an inverse charge bias which reduces their insertion efficiency into the Sec61 channel. We determined that mutating two N-terminal, proline-flanked phosphorylation sites in the Sbh1 cytosolic domain to alanine phenocopied the temperature-sensitivity of a yeast strain lacking SBH1 and its ortholog SBH2. The phosphorylation site mutations reduced translocation into the ER of a subset of Sbh1-dependent proteins, including enzymes whose concentration in the ER lumen is critical for ER proteostasis. In addition, we found that ER import of these proteins depended on the activity of the phospho-S/T-specific proline isomerase Ess1 (PIN1 in mammals). We conclude that Sbh1 promotes ER translocation of substrates with suboptimal targeting sequences and that its activity can be regulated by a conformational change induced by N-terminal phosphorylation.
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9
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Itskanov S, Park E. Mechanism of Protein Translocation by the Sec61 Translocon Complex. Cold Spring Harb Perspect Biol 2023; 15:a041250. [PMID: 35940906 PMCID: PMC9808579 DOI: 10.1101/cshperspect.a041250] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The endoplasmic reticulum (ER) is a major site for protein synthesis, folding, and maturation in eukaryotic cells, responsible for production of secretory proteins and most integral membrane proteins. The universally conserved protein-conducting channel Sec61 complex mediates core steps in these processes by translocating hydrophilic polypeptide segments of client proteins across the ER membrane and integrating hydrophobic transmembrane segments into the membrane. The Sec61 complex associates with several other molecular machines and enzymes to enable substrate engagement with the channel and coordination of protein translocation with translation, protein folding, and/or post-translational modifications. Recent cryo-electron microscopy and functional studies of these translocon complexes have greatly advanced our mechanistic understanding of Sec61-dependent protein biogenesis at the ER. Here, we will review the current models for how the Sec61 channel performs its functions in coordination with partner complexes.
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Affiliation(s)
- Samuel Itskanov
- Biophysics Graduate Program
- California Institute for Quantitative Biosciences
| | - Eunyong Park
- California Institute for Quantitative Biosciences
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
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10
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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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11
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Saha N, Tomar RS. Copper inhibits protein maturation in the secretory pathway by targeting the Sec61 translocon in Saccharomyces cerevisiae. J Biol Chem 2022; 298:102170. [PMID: 35738397 PMCID: PMC9304788 DOI: 10.1016/j.jbc.2022.102170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 06/03/2022] [Accepted: 06/09/2022] [Indexed: 11/16/2022] Open
Abstract
In Saccharomyces cerevisiae, proteins destined for secretion utilize the post-translational translocon machinery to gain entry into the endoplasmic reticulum. These proteins then mature by undergoing a number of post-translational modifications in different compartments of the secretory pathway. While these modifications have been well established for many proteins, to date only a few studies have been conducted regarding the conditions and factors affecting maturation of these proteins before entering into the endoplasmic reticulum. Here, using immunoblotting, microscopy, and spot test assays, we show that excess copper inhibits the Sec61 translocon function and causes accumulation of two well-known post-translationally translocated proteins, Gas1 (glycophospholipid-anchored surface protein) and CPY (carboxypeptidase Y), in the cytosol. We further show that the copper-sensitive phenotype of sec61-deficient yeast cells is ameliorated by restoring the levels of SEC61 through plasmid transformation. Furthermore, screening of translocation-defective Sec61 mutants revealed that sec61-22, bearing L80M, V134I, M248V, and L342S mutations, is resistant to copper, suggesting that copper might be inflicting toxicity through one of these residues. In conclusion, these findings imply that copper-mediated accumulation of post-translationally translocated proteins is due to the inhibition of Sec61.
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Affiliation(s)
- Nitu Saha
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, 462066, Madhya Pradesh, India
| | - Raghuvir Singh Tomar
- Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, 462066, Madhya Pradesh, India.
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12
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Domenger A, Choisy C, Baron L, Mayau V, Perthame E, Deriano L, Arnulf B, Bories JC, Dadaglio G, Demangel C. The Sec61 translocon is a therapeutic vulnerability in multiple myeloma. EMBO Mol Med 2022; 14:e14740. [PMID: 35014767 PMCID: PMC8899908 DOI: 10.15252/emmm.202114740] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 12/12/2022] Open
Abstract
Multiple myeloma (MM) is an incurable malignancy characterized by the uncontrolled expansion of plasma cells in the bone marrow. While proteasome inhibitors like bortezomib efficiently halt MM progression, drug resistance inevitably develop, and novel therapeutic approaches are needed. Here, we used a recently discovered Sec61 inhibitor, mycolactone, to assess the interest of disrupting MM proteostasis via protein translocation blockade. In human MM cell lines, mycolactone caused rapid defects in secretion of immunoglobulins and expression of pro‐survival interleukin (IL)‐6 receptor and CD40, whose activation stimulates IL‐6 production. Mycolactone also triggered pro‐apoptotic endoplasmic reticulum stress responses synergizing with bortezomib for induction of MM cell death and overriding acquired resistance to the proteasome inhibitor. Notably, the mycolactone–bortezomib combination rapidly killed patient‐derived MM cells ex vivo, but not normal mononuclear cells. In immunodeficient mice engrafted with MM cells, it demonstrated superior therapeutic efficacy over single drug treatments, without inducing toxic side effects. Collectively, these findings establish Sec61 blockers as novel anti‐MM agents and reveal the interest of targeting both the translocon and the proteasome in proteostasis‐addicted tumors.
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Affiliation(s)
- Antoine Domenger
- Unité d'Immunobiologie de l'Infection, Institut Pasteur, INSERM U1224, Université de Paris, Paris, France.,Sorbonne Paris Cité, Université de Paris, Paris, France
| | - Caroline Choisy
- INSERM U976, Institut de Recherche Saint Louis, Université de Paris, Paris, France
| | - Ludivine Baron
- Unité d'Immunobiologie de l'Infection, Institut Pasteur, INSERM U1224, Université de Paris, Paris, France
| | - Véronique Mayau
- Unité d'Immunobiologie de l'Infection, Institut Pasteur, INSERM U1224, Université de Paris, Paris, France
| | - Emeline Perthame
- Bioinformatics and Biostatistics Hub, Institut Pasteur, Université de Paris, Paris, France
| | - Ludovic Deriano
- Unité d'Intégrité du Génome, Immunité et Cancer, Equipe Labellisée Ligue Contre Le Cancer, Institut Pasteur, INSERM U1223, Université de Paris, Paris, France
| | - Bertrand Arnulf
- INSERM U976, Institut de Recherche Saint Louis, Université de Paris, Paris, France.,APHP Department of Immuno-Hematology, Hôpital Saint Louis, Paris, France
| | | | - Gilles Dadaglio
- Unité d'Immunobiologie de l'Infection, Institut Pasteur, INSERM U1224, Université de Paris, Paris, France
| | - Caroline Demangel
- Unité d'Immunobiologie de l'Infection, Institut Pasteur, INSERM U1224, Université de Paris, Paris, France
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13
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Abstract
Mycobacterium ulcerans, the causative agent of Buruli ulcer disease, is unique among human pathogens in its capacity to produce mycolactone, a diffusible macrolide with immunosuppressive and cytotoxic properties. Recent studies have shown that mycolactone operates by inhibiting the host membrane translocation complex (Sec61), with an unprecedented potency compared to previously identified Sec61 blockers. Mycolactone binding to the pore-forming subunit of Sec61 inhibits its capacity to transport nascent secretory and membrane proteins into the endoplasmic reticulum, leading to their cytosolic degradation by the ubiquitin:proteasome system. In T lymphocytes, Sec61 blockade by mycolactone manifests as a sharp decrease in the cell's ability to express homing receptors and release cytokines following activation. Sustained exposure of human cells to mycolactone typically generates proteotoxic stress responses in their cytosol and endoplasmic reticulum (ER), ultimately inducing apoptosis. Here we describe cell-free systems for studying Sec61-mediated protein translocation that allow the impact of mycolactone on the biogenesis of secretory and membrane proteins to be probed. We also describe biological assays of mycolactone-driven inhibition of Sec61 providing rapid and sensitive means to quantitatively assess the presence of the toxin in biological samples.
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14
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Mycolactone enhances the Ca2+ leak from endoplasmic reticulum by trapping Sec61 translocons in a Ca2+ permeable state. Biochem J 2021; 478:4005-4024. [PMID: 34726690 PMCID: PMC8650850 DOI: 10.1042/bcj20210345] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 10/19/2021] [Accepted: 11/02/2021] [Indexed: 01/17/2023]
Abstract
The Mycobacterium ulcerans exotoxin, mycolactone, is an inhibitor of co-translational translocation via the Sec61 complex. Mycolactone has previously been shown to bind to, and alter the structure of the major translocon subunit Sec61α, and change its interaction with ribosome nascent chain complexes. In addition to its function in protein translocation into the ER, Sec61 also plays a key role in cellular Ca2+ homeostasis, acting as a leak channel between the endoplasmic reticulum (ER) and cytosol. Here, we have analysed the effect of mycolactone on cytosolic and ER Ca2+ levels using compartment-specific sensors. We also used molecular docking analysis to explore potential interaction sites for mycolactone on translocons in various states. These results show that mycolactone enhances the leak of Ca2+ ions via the Sec61 translocon, resulting in a slow but substantial depletion of ER Ca2+. This leak was dependent on mycolactone binding to Sec61α because resistance mutations in this protein completely ablated the increase. Molecular docking supports the existence of a mycolactone-binding transient inhibited state preceding translocation and suggests mycolactone may also bind Sec61α in its idle state. We propose that delayed ribosomal release after translation termination and/or translocon ‘breathing' during rapid transitions between the idle and intermediate-inhibited states allow for transient Ca2+ leak, and mycolactone's stabilisation of the latter underpins the phenotype observed.
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15
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Whitley P, Grau B, Gumbart JC, Martínez-Gil L, Mingarro I. Folding and Insertion of Transmembrane Helices at the ER. Int J Mol Sci 2021; 22:ijms222312778. [PMID: 34884581 PMCID: PMC8657811 DOI: 10.3390/ijms222312778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/16/2023] Open
Abstract
In eukaryotic cells, the endoplasmic reticulum (ER) is the entry point for newly synthesized proteins that are subsequently distributed to organelles of the endomembrane system. Some of these proteins are completely translocated into the lumen of the ER while others integrate stretches of amino acids into the greasy 30 Å wide interior of the ER membrane bilayer. It is generally accepted that to exist in this non-aqueous environment the majority of membrane integrated amino acids are primarily non-polar/hydrophobic and adopt an α-helical conformation. These stretches are typically around 20 amino acids long and are known as transmembrane (TM) helices. In this review, we will consider how transmembrane helices achieve membrane integration. We will address questions such as: Where do the stretches of amino acids fold into a helical conformation? What is/are the route/routes that these stretches take from synthesis at the ribosome to integration through the ER translocon? How do these stretches ‘know’ to integrate and in which orientation? How do marginally hydrophobic stretches of amino acids integrate and survive as transmembrane helices?
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Affiliation(s)
- Paul Whitley
- Department of Biology and Biochemistry, Centre for Regenerative Medicine, University of Bath, Bath BA2 7AY, UK;
| | - Brayan Grau
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
| | - James C. Gumbart
- School of Physics, School of Chemistry and Biochemistry, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Luis Martínez-Gil
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
| | - Ismael Mingarro
- Department of Biochemistry and Molecular Biology, Institute of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, E-46100 Burjassot, Spain; (B.G.); (L.M.-G.)
- Correspondence: ; Tel.: +34-963543796
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16
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Jung SJ, Kim H. Emerging View on the Molecular Functions of Sec62 and Sec63 in Protein Translocation. Int J Mol Sci 2021; 22:ijms222312757. [PMID: 34884562 PMCID: PMC8657602 DOI: 10.3390/ijms222312757] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/23/2021] [Accepted: 11/23/2021] [Indexed: 12/18/2022] Open
Abstract
Most secreted and membrane proteins are targeted to and translocated across the endoplasmic reticulum (ER) membrane through the Sec61 protein-conducting channel. Evolutionarily conserved Sec62 and Sec63 associate with the Sec61 channel, forming the Sec complex and mediating translocation of a subset of proteins. For the last three decades, it has been thought that ER protein targeting and translocation occur via two distinct pathways: signal recognition particle (SRP)-dependent co-translational or SRP-independent, Sec62/Sec63 dependent post-translational translocation pathway. However, recent studies have suggested that ER protein targeting and translocation through the Sec translocon are more intricate than previously thought. This review summarizes the current understanding of the molecular functions of Sec62/Sec63 in ER protein translocation.
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Affiliation(s)
| | - Hyun Kim
- Correspondence: ; Tel.: +82-2-880-4440; Fax: +82-2-872-1993
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17
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Inhibitors of the Sec61 Complex and Novel High Throughput Screening Strategies to Target the Protein Translocation Pathway. Int J Mol Sci 2021; 22:ijms222112007. [PMID: 34769437 PMCID: PMC8585047 DOI: 10.3390/ijms222112007] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/25/2021] [Accepted: 10/29/2021] [Indexed: 02/08/2023] Open
Abstract
Proteins targeted to the secretory pathway start their intracellular journey by being transported across biological membranes such as the endoplasmic reticulum (ER). A central component in this protein translocation process across the ER is the Sec61 translocon complex, which is only intracellularly expressed and does not have any enzymatic activity. In addition, Sec61 translocon complexes are difficult to purify and to reconstitute. Screening for small molecule inhibitors impairing its function has thus been notoriously difficult. However, such translocation inhibitors may not only be valuable tools for cell biology, but may also represent novel anticancer drugs, given that cancer cells heavily depend on efficient protein translocation into the ER to support their fast growth. In this review, different inhibitors of protein translocation will be discussed, and their specific mode of action will be compared. In addition, recently published screening strategies for small molecule inhibitors targeting the whole SRP-Sec61 targeting/translocation pathway will be summarized. Of note, slightly modified assays may be used in the future to screen for substances affecting SecYEG, the bacterial ortholog of the Sec61 complex, in order to identify novel antibiotic drugs.
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18
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Pauwels E, Rutz C, Provinciael B, Stroobants J, Schols D, Hartmann E, Krause E, Stephanowitz H, Schülein R, Vermeire K. A Proteomic Study on the Membrane Protein Fraction of T Cells Confirms High Substrate Selectivity for the ER Translocation Inhibitor Cyclotriazadisulfonamide. Mol Cell Proteomics 2021; 20:100144. [PMID: 34481949 PMCID: PMC8477212 DOI: 10.1016/j.mcpro.2021.100144] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 08/09/2021] [Accepted: 08/30/2021] [Indexed: 11/15/2022] Open
Abstract
Cyclotriazadisulfonamide (CADA) inhibits the cotranslational translocation of type I integral membrane protein human CD4 (huCD4) across the endoplasmic reticulum in a signal peptide (SP)–dependent way. Previously, sortilin was identified as a secondary substrate for CADA but showed reduced CADA sensitivity as compared with huCD4. Here, we performed a quantitative proteomic study on the crude membrane fraction of human T-cells to analyze how many proteins are sensitive to CADA. To screen for these proteins, we employed stable isotope labeling by amino acids in cell culture technique in combination with quantitative MS on CADA-treated human T-lymphoid SUP-T1 cells expressing high levels of huCD4. In line with our previous reports, our current proteomic analysis (data available via ProteomeXchange with identifier PXD027712) demonstrated that only a very small subset of proteins is depleted by CADA. Our data also confirmed that cellular expression of both huCD4 and sortilin are affected by CADA treatment of SUP-T1 cells. Furthermore, three additional targets for CADA are identified, namely, endoplasmic reticulum lectin 1 (ERLEC1), inactive tyrosine-protein kinase 7 (PTK7), and DnaJ homolog subfamily C member 3 (DNAJC3). Western blot and flow cytometry analysis of ERLEC1, PTK7, and DNAJC3 protein expression validated susceptibility of these substrates to CADA, although with varying degrees of sensitivity. Additional cell-free in vitro translation/translocation data demonstrated that the new substrates for CADA carry cleavable SPs that are targets for the cotranslational translocation inhibition exerted by CADA. Thus, our quantitative proteomic analysis demonstrates that ERLEC1, PTK7, and DNAJC3 are validated additional substrates of CADA; however, huCD4 remains the most sensitive integral membrane protein for the endoplasmic reticulum translocation inhibitor CADA. Furthermore, to our knowledge, CADA is the first compound that specifically interferes with only a very small subset of SPs and does not affect signal anchor sequences. About 3007 proteins quantified in SILAC/MS study on CD4+ T-cells treated with CADA. Three new targets for CADA were identified: ERLEC1, PTK7, and DNAJC3. All CADA substrates carry cleavable signal peptides for translocation into ER. huCD4 remains the most sensitive substrate for the ER translocation inhibitor CADA.
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Affiliation(s)
- Eva Pauwels
- Laboratory of Virology and Chemotherapy, KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium
| | - Claudia Rutz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Becky Provinciael
- Laboratory of Virology and Chemotherapy, KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium
| | - Joren Stroobants
- Laboratory of Virology and Chemotherapy, KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium
| | - Dominique Schols
- Laboratory of Virology and Chemotherapy, KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium
| | - Enno Hartmann
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck, Germany
| | - Eberhard Krause
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Heike Stephanowitz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Ralf Schülein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Kurt Vermeire
- Laboratory of Virology and Chemotherapy, KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Leuven, Belgium.
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19
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CRISPR-based screens uncover determinants of immunotherapy response in multiple myeloma. Blood Adv 2021; 4:2899-2911. [PMID: 32589729 DOI: 10.1182/bloodadvances.2019001346] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 05/11/2020] [Indexed: 02/01/2023] Open
Abstract
Cancer cells commonly develop resistance to immunotherapy by loss of antigen expression. Combinatorial treatments that increase levels of the target antigen on the surface of cancer cells have the potential to restore efficacy to immunotherapy. Here, we use our CRISPR interference- and CRISPR activation-based functional genomics platform to systematically identify pathways controlling cell surface expression of the multiple myeloma immunotherapy antigen B-cell maturation antigen (BCMA). We discovered that pharmacologic inhibition of HDAC7 and the Sec61 complex increased cell surface BCMA, including in primary patient cells. Pharmacologic Sec61 inhibition enhanced the antimyeloma efficacy of a BCMA-targeted antibody-drug conjugate. A CRISPR interference chimeric antigen receptor T cells (CAR-T cells) coculture screen enabled us to identify both antigen-dependent and antigen-independent mechanisms controlling response of myeloma cells to BCMA-targeted CAR-T cells. Thus, our study shows the potential of CRISPR screens to uncover mechanisms controlling response of cancer cells to immunotherapy and to suggest potential combination therapies.
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20
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Sicking M, Lang S, Bochen F, Roos A, Drenth JPH, Zakaria M, Zimmermann R, Linxweiler M. Complexity and Specificity of Sec61-Channelopathies: Human Diseases Affecting Gating of the Sec61 Complex. Cells 2021; 10:1036. [PMID: 33925740 PMCID: PMC8147068 DOI: 10.3390/cells10051036] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/15/2021] [Accepted: 04/17/2021] [Indexed: 12/14/2022] Open
Abstract
The rough endoplasmic reticulum (ER) of nucleated human cells has crucial functions in protein biogenesis, calcium (Ca2+) homeostasis, and signal transduction. Among the roughly one hundred components, which are involved in protein import and protein folding or assembly, two components stand out: The Sec61 complex and BiP. The Sec61 complex in the ER membrane represents the major entry point for precursor polypeptides into the membrane or lumen of the ER and provides a conduit for Ca2+ ions from the ER lumen to the cytosol. The second component, the Hsp70-type molecular chaperone immunoglobulin heavy chain binding protein, short BiP, plays central roles in protein folding and assembly (hence its name), protein import, cellular Ca2+ homeostasis, and various intracellular signal transduction pathways. For the purpose of this review, we focus on these two components, their relevant allosteric effectors and on the question of how their respective functional cycles are linked in order to reconcile the apparently contradictory features of the ER membrane, selective permeability for precursor polypeptides, and impermeability for Ca2+. The key issues are that the Sec61 complex exists in two conformations: An open and a closed state that are in a dynamic equilibrium with each other, and that BiP contributes to its gating in both directions in cooperation with different co-chaperones. While the open Sec61 complex forms an aqueous polypeptide-conducting- and transiently Ca2+-permeable channel, the closed complex is impermeable even to Ca2+. Therefore, we discuss the human hereditary and tumor diseases that are linked to Sec61 channel gating, termed Sec61-channelopathies, as disturbances of selective polypeptide-impermeability and/or aberrant Ca2+-permeability.
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Affiliation(s)
- Mark Sicking
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Sven Lang
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Florian Bochen
- Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, D-66421 Homburg, Germany; (F.B.); (M.L.)
| | - Andreas Roos
- Department of Neuropediatrics, Essen University Hospital, D-45147 Essen, Germany;
| | - Joost P. H. Drenth
- Department of Molecular Gastroenterology and Hepatology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Muhammad Zakaria
- Department of Genetics, Hazara University, Mansehra 21300, Pakistan;
| | - Richard Zimmermann
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Maximilian Linxweiler
- Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, D-66421 Homburg, Germany; (F.B.); (M.L.)
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21
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Targeting of HER/ErbB family proteins using broad spectrum Sec61 inhibitors coibamide A and apratoxin A. Biochem Pharmacol 2020; 183:114317. [PMID: 33152346 DOI: 10.1016/j.bcp.2020.114317] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 01/17/2023]
Abstract
Coibamide A is a potent cancer cell toxin and one of a select group of natural products that inhibit protein entry into the secretory pathway via a direct inhibition of the Sec61 protein translocon. Many Sec61 client proteins are clinically relevant drug targets once trafficked to their final destination in or outside the cell, however the use of Sec61 inhibitors to block early biosynthesis of specific proteins is at a pre-clinical stage. In the present study we evaluated the action of coibamide A against human epidermal growth factor receptor (HER, ErbB) proteins in representative breast and lung cancer cell types. HERs were selected for this study as they represent a family of Sec61 clients that is frequently dysregulated in human cancers, including coibamide-sensitive cell types. Although coibamide A inhibits biogenesis of a broad range of Sec61 substrate proteins in a presumed substrate-nonselective manner, endogenous HER3 (ErbB-3) and EGFR (ErbB-1) proteins were more sensitive to coibamide A, and the related Sec61 inhibitor apratoxin A, than HER2 (ErbB-2). Despite this rank order of sensitivity (HER3 > EGFR > HER2), Sec61-dependent inhibition by coibamide A was sufficient to decrease cell surface expression of HER2. We report that coibamide A- or apratoxin A-mediated block of HER3 entry into the secretory pathway is unlikely to be mediated by the HER3 signal peptide alone. HER3 (G11L/S15L), that is fully resistant to the highly substrate-selective cotransin analogue CT8, was more resistant than wild-type HER3 but only at low coibamide A (3 nM) concentrations; HER3 (G11L/S15L) expression was inhibited by higher concentrations of either natural product. Time- and concentration-dependent decreases in HER protein expression induced a commensurate reduction in AKT/MAPK signaling in breast and lung cancer cell types and loss in cell viability. Coibamide A potentiated the cytotoxic efficacy of small molecule kinase inhibitors lapatinib and erlotinib in breast and lung cancer cell types, respectively. These data indicate that natural product modulators of Sec61 function have value as chemical probes to interrogate HER/ErbB signaling in treatment-resistant human cancers.
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22
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Tranter D, Paatero AO, Kawaguchi S, Kazemi S, Serrill JD, Kellosalo J, Vogel WK, Richter U, Mattos DR, Wan X, Thornburg CC, Oishi S, McPhail KL, Ishmael JE, Paavilainen VO. Coibamide A Targets Sec61 to Prevent Biogenesis of Secretory and Membrane Proteins. ACS Chem Biol 2020; 15:2125-2136. [PMID: 32608972 PMCID: PMC7497630 DOI: 10.1021/acschembio.0c00325] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/01/2020] [Indexed: 01/19/2023]
Abstract
Coibamide A (CbA) is a marine natural product with potent antiproliferative activity against human cancer cells and a unique selectivity profile. Despite promising antitumor activity, the mechanism of cytotoxicity and specific cellular target of CbA remain unknown. Here, we develop an optimized synthetic CbA photoaffinity probe (photo-CbA) and use it to demonstrate that CbA directly targets the Sec61α subunit of the Sec61 protein translocon. CbA binding to Sec61 results in broad substrate-nonselective inhibition of ER protein import and potent cytotoxicity against specific cancer cell lines. CbA targets a lumenal cavity of Sec61 that is partially shared with known Sec61 inhibitors, yet profiling against resistance conferring Sec61α mutations identified from human HCT116 cells suggests a distinct binding mode for CbA. Specifically, despite conferring strong resistance to all previously known Sec61 inhibitors, the Sec61α mutant R66I remains sensitive to CbA. A further unbiased screen for Sec61α resistance mutations identified the CbA-resistant mutation S71P, which confirms nonidentical binding sites for CbA and apratoxin A and supports the susceptibility of the Sec61 plug region for channel inhibition. Remarkably, CbA, apratoxin A, and ipomoeassin F do not display comparable patterns of potency and selectivity in the NCI60 panel of human cancer cell lines. Our work connecting CbA activity with selective prevention of secretory and membrane protein biogenesis by inhibition of Sec61 opens up possibilities for developing new Sec61 inhibitors with improved drug-like properties that are based on the coibamide pharmacophore.
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Affiliation(s)
- Dale Tranter
- Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - Anja O. Paatero
- Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - Shinsaku Kawaguchi
- Graduate
School of Pharmaceutical Sciences, Kyoto
University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Soheila Kazemi
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Jeffrey D. Serrill
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Juho Kellosalo
- Institute of Biotechnology, University of Helsinki, Helsinki, 00014, Finland
| | - Walter K. Vogel
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Uwe Richter
- Molecular
and Integrative Biosciences Research Programme, Faculty of Biological
and Environmental Sciences, University of
Helsinki, Helsinki, 00014, Finland
| | - Daphne R. Mattos
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Xuemei Wan
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Christopher C. Thornburg
- Frederick
National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland 21702, United States
| | - Shinya Oishi
- Graduate
School of Pharmaceutical Sciences, Kyoto
University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kerry L. McPhail
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
| | - Jane E. Ishmael
- Department
of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, United States
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23
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Structure of the Inhibited State of the Sec Translocon. Mol Cell 2020; 79:406-415.e7. [PMID: 32692975 PMCID: PMC7427319 DOI: 10.1016/j.molcel.2020.06.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/30/2020] [Accepted: 06/05/2020] [Indexed: 02/06/2023]
Abstract
Protein secretion in eukaryotes and prokaryotes involves a universally conserved protein translocation channel formed by the Sec61 complex. Unrelated small-molecule natural products and synthetic compounds inhibit Sec61 with differential effects for different substrates or for Sec61 from different organisms, making this a promising target for therapeutic intervention. To understand the mode of inhibition and provide insight into the molecular mechanism of this dynamic translocon, we determined the structure of mammalian Sec61 inhibited by the Mycobacterium ulcerans exotoxin mycolactone via electron cryo-microscopy. Unexpectedly, the conformation of inhibited Sec61 is optimal for substrate engagement, with mycolactone wedging open the cytosolic side of the lateral gate. The inability of mycolactone-inhibited Sec61 to effectively transport substrate proteins implies that signal peptides and transmembrane domains pass through the site occupied by mycolactone. This provides a foundation for understanding the molecular mechanism of Sec61 inhibitors and reveals novel features of translocon function and dynamics. The inhibited Sec translocon adopts a conformation optimal for substrate engagement The inhibitor mycolactone wedges open the lateral gate of Sec61α Mycolactone blocks the path taken by the signal peptide during engagement Resistance mutations are likely to operate by modulating translocon dynamics
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24
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Crossing the Vacuolar Rubicon: Structural Insights into Effector Protein Trafficking in Apicomplexan Parasites. Microorganisms 2020; 8:microorganisms8060865. [PMID: 32521667 PMCID: PMC7355975 DOI: 10.3390/microorganisms8060865] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/01/2020] [Accepted: 06/05/2020] [Indexed: 12/13/2022] Open
Abstract
Apicomplexans form a large phylum of parasitic protozoa, including the genera Plasmodium, Toxoplasma, and Cryptosporidium, the causative agents of malaria, toxoplasmosis, and cryptosporidiosis, respectively. They cause diseases not only in humans but also in animals, with dramatic consequences in agriculture. Most apicomplexans are vacuole-dwelling and obligate intracellular parasites; as they invade the host cell, they become encased in a parasitophorous vacuole (PV) derived from the host cellular membrane. This creates a parasite-host interface that acts as a protective barrier but also constitutes an obstacle through which the pathogen must import nutrients, eliminate wastes, and eventually break free upon egress. Completion of the parasitic life cycle requires intense remodeling of the infected host cell. Host cell subversion is mediated by a subset of essential effector parasitic proteins and virulence factors actively trafficked across the PV membrane. In the malaria parasite Plasmodium, a unique and highly specialized ATP-driven vacuolar secretion system, the Plasmodium translocon of exported proteins (PTEX), transports effector proteins across the vacuolar membrane. Its core is composed of the three essential proteins EXP2, PTEX150, and HSP101, and is supplemented by the two auxiliary proteins TRX2 and PTEX88. Many but not all secreted malarial effector proteins contain a vacuolar trafficking signal or Plasmodium export element (PEXEL) that requires processing by an endoplasmic reticulum protease, plasmepsin V, for proper export. Because vacuolar parasitic protein export is essential to parasite survival and virulence, this pathway is a promising target for the development of novel antimalarial therapeutics. This review summarizes the current state of structural and mechanistic knowledge on the Plasmodium parasitic vacuolar secretion and effector trafficking pathway, describing its most salient features and discussing the existing differences and commonalities with the vacuolar effector translocation MYR machinery recently described in Toxoplasma and other apicomplexans of significance to medical and veterinary sciences.
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25
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Lumangtad LA, Bell TW. The signal peptide as a new target for drug design. Bioorg Med Chem Lett 2020; 30:127115. [PMID: 32209293 PMCID: PMC7138182 DOI: 10.1016/j.bmcl.2020.127115] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 03/06/2020] [Accepted: 03/15/2020] [Indexed: 01/16/2023]
Abstract
Many current and potential drug targets are membrane-bound or secreted proteins that are expressed and transported via the Sec61 secretory pathway. They are targeted to translocon channels across the membrane of the endoplasmic reticulum (ER) by signal peptides (SPs), which are temporary structures on the N-termini of their nascent chains. During translation, such proteins enter the lumen and membrane of the ER by a process known as co-translational translocation. Small molecules have been found that interfere with this process, decreasing protein expression by recognizing the unique structures of the SPs of particular proteins. The SP may thus become a validated target for designing drugs for numerous disorders, including certain hereditary diseases.
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Affiliation(s)
| | - Thomas W Bell
- Department of Chemistry, University of Nevada, Reno, NV 89557-0216, USA.
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26
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Luesch H, Paavilainen VO. Natural products as modulators of eukaryotic protein secretion. Nat Prod Rep 2020; 37:717-736. [PMID: 32067014 DOI: 10.1039/c9np00066f] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Covering: up to the end of 2019Diverse natural product small molecules have allowed critical insights into processes that govern eukaryotic cells' ability to secrete cytosolically synthesized secretory proteins into their surroundings or to insert newly synthesized integral membrane proteins into the lipid bilayer of the endoplasmic reticulum. In addition, many components of the endoplasmic reticulum, required for protein homeostasis or other processes such as lipid metabolism or maintenance of calcium homeostasis, are being investigated for their potential in modulating human disease conditions such as cancer, neurodegenerative conditions and diabetes. In this review, we cover recent findings up to the end of 2019 on natural products that influence protein secretion or impact ER protein homeostasis, and serve as powerful chemical tools to understand protein flux through the mammalian secretory pathway and as leads for the discovery of new therapeutics.
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Affiliation(s)
- Hendrik Luesch
- Department of Medicinal Chemistry, Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, P.O. Box 100485, Gainesville, Florida 32610, USA.
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Ito K, Shimokawa-Chiba N, Chiba S. Sec translocon has an insertase-like function in addition to polypeptide conduction through the channel. F1000Res 2020; 8. [PMID: 32025287 PMCID: PMC6971846 DOI: 10.12688/f1000research.21065.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/17/2019] [Indexed: 11/20/2022] Open
Abstract
The Sec translocon provides a polypeptide-conducting channel, which is insulated from the hydrophobic lipidic environment of the membrane, for translocation of hydrophilic passenger polypeptides. Its lateral gate allows a downstream hydrophobic segment (stop-transfer sequence) to exit the channel laterally for integration into the lipid phase. We note that this channel model only partly accounts for the translocon function. The other essential role of translocon is to facilitate de novo insertion of the N-terminal topogenic segment of a substrate polypeptide into the membrane. Recent structural studies suggest that de novo insertion does not use the polypeptide-conducting channel; instead, it takes place directly at the lateral gate, which is prone to opening. We propose that the de novo insertion process, in concept, is similar to that of insertases (such as YidC in bacteria and EMC3 in eukaryotes), in which an intramembrane surface of the machinery provides the halfway point of insertion.
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Affiliation(s)
- Koreaki Ito
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, Japan
| | - Naomi Shimokawa-Chiba
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, Japan
| | - Shinobu Chiba
- Faculty of Life Sciences and Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto, Japan
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28
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Van Puyenbroeck V, Pauwels E, Provinciael B, Bell TW, Schols D, Kalies KU, Hartmann E, Vermeire K. Preprotein signature for full susceptibility to the co-translational translocation inhibitor cyclotriazadisulfonamide. Traffic 2019; 21:250-264. [PMID: 31675144 DOI: 10.1111/tra.12713] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/24/2019] [Accepted: 10/26/2019] [Indexed: 01/13/2023]
Abstract
Cyclotriazadisulfonamide (CADA) inhibits the co-translational translocation of human CD4 (huCD4) into the endoplasmic reticulum lumen in a signal peptide (SP)-dependent way. We propose that CADA binds the nascent huCD4 SP in a folded conformation within the translocon resembling a normally transitory state during translocation. Here, we used alanine scanning on the huCD4 SP to identify the signature for full susceptibility to CADA. In accordance with our previous work, we demonstrate that residues in the vicinity of the hydrophobic h-region are critical for sensitivity to CADA. In particular, exchanging Gln-15, Val-17 or Pro-20 in the huCD4 SP for Ala resulted in a resistant phenotype. Together with positively charged residues at the N-terminal portion of the mature protein, these residues mediate full susceptibility to the co-translational translocation inhibitory activity of CADA towards huCD4. In addition, sensitivity to CADA is inversely related to hydrophobicity in the huCD4 SP. In vitro translocation experiments confirmed that the general hydrophobicity of the h-domain and positive charges in the mature protein are key elements that affect both the translocation efficiency of huCD4 and the sensitivity towards CADA. Besides these two general SP parameters that determine the functionality of the signal sequence, unique amino acid pairs (L14/Q15 and L19/P20) in the SP hydrophobic core add specificity to the sensitivity signature for a co-translational translocation inhibitor.
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Affiliation(s)
- Victor Van Puyenbroeck
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Eva Pauwels
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Becky Provinciael
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Thomas W Bell
- Department of Chemistry, University of Nevada, Reno, Nevada
| | - Dominique Schols
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Kai-Uwe Kalies
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck, Germany
| | - Enno Hartmann
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck, Germany
| | - Kurt Vermeire
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
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Abstract
One-fourth of eukaryotic genes code for integral membrane proteins, nearly all of which are inserted and assembled at the endoplasmic reticulum (ER). The defining feature of membrane proteins is one or more transmembrane domains (TMDs). During membrane protein biogenesis, TMDs are selectively recognized, shielded, and chaperoned into the lipid bilayer, where they often assemble with other TMDs. If maturation fails, exposed TMDs serve as a cue for engagement of degradation pathways. Thus, TMD-recognition factors in the cytosol and ER are essential for membrane protein biogenesis and quality control. Here, we discuss the growing assortment of cytosolic and membrane-embedded TMD-recognition factors, the pathways within which they operate, and mechanistic principles of recognition.
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30
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Haßdenteufel S, Johnson N, Paton AW, Paton JC, High S, Zimmermann R. Chaperone-Mediated Sec61 Channel Gating during ER Import of Small Precursor Proteins Overcomes Sec61 Inhibitor-Reinforced Energy Barrier. Cell Rep 2019; 23:1373-1386. [PMID: 29719251 PMCID: PMC5946456 DOI: 10.1016/j.celrep.2018.03.122] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/15/2018] [Accepted: 03/27/2018] [Indexed: 11/24/2022] Open
Abstract
Protein transport into the mammalian endoplasmic reticulum (ER) is mediated by the heterotrimeric Sec61 channel. The signal recognition particle (SRP) and TRC systems and Sec62 have all been characterized as membrane-targeting components for small presecretory proteins, whereas Sec63 and the lumenal chaperone BiP act as auxiliary translocation components. Here, we report the transport requirements of two natural, small presecretory proteins and engineered variants using semipermeabilized human cells after the depletion of specific ER components. Our results suggest that hSnd2, Sec62, and SRP and TRC receptor each provide alternative targeting pathways for short secretory proteins and define rules of engagement for the actions of Sec63 and BiP during their membrane translocation. We find that the Sec62/Sec63 complex plus BiP can facilitate Sec61 channel opening, thereby allowing precursors that have weak signal peptides or other inhibitory features to translocate. A Sec61 inhibitor can mimic the effect of BiP depletion on Sec61 gating, suggesting that they both act at the same essential membrane translocation step. Small human presecretory proteins use all known targeting routes to the Sec61 complex Their insertion into Sec61 is selectively facilitated by BiP, Sec62, and Sec63 Selectivity is driven by weak signal peptides plus downstream inhibitory features Cyclic heptadepsipeptides phenocopy the effect of BiP depletion on Sec61 gating
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Affiliation(s)
- Sarah Haßdenteufel
- Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany.
| | - Nicholas Johnson
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Adrienne W Paton
- Research Centre for Infectious Disease, University of Adelaide, Adelaide, SA 5005, Australia
| | - James C Paton
- Research Centre for Infectious Disease, University of Adelaide, Adelaide, SA 5005, Australia
| | - Stephen High
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Richard Zimmermann
- Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany.
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31
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Haßdenteufel S, Nguyen D, Helms V, Lang S, Zimmermann R. ER import of small human presecretory proteins: components and mechanisms. FEBS Lett 2019; 593:2506-2524. [PMID: 31325177 DOI: 10.1002/1873-3468.13542] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/10/2019] [Accepted: 07/13/2019] [Indexed: 11/12/2022]
Abstract
Protein transport into the mammalian endoplasmic reticulum (ER) used to be seen as strictly cotranslational, that is temporarily and mechanistically coupled to protein synthesis. In the course of the last decades, however, several classes of precursors of soluble and membrane proteins were found to be post-translationally imported into the ER, without any involvement of the ribosome. The first such class to be identified were the small presecretory proteins; tail-anchored membrane proteins followed next. In both classes, the inherent address tag is released from the translating ribosome before the initiation of ER import, as part of the fully synthesized precursor. In small presecretory proteins, the information for ER targeting and -translocation via the polypeptide-conducting Sec61-channel is encoded by a classical N-terminal signal peptide, which is released from the ribsosome before targeting due to the small size of the full-length precursor. Here, we discuss the current state of research on targeting and translocation of small presecretory proteins into the mammalian ER. In closing, we present a unifying hypothesis for ER protein translocation in terms of an energy diagram for Sec61-channel gating.
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Affiliation(s)
- Sarah Haßdenteufel
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Duy Nguyen
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Richard Zimmermann
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
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32
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Zong G, Hu Z, O’Keefe S, Tranter D, Iannotti MJ, Baron L, Hall B, Corfield K, Paatero AO, Henderson MJ, Roboti P, Zhou J, Sun X, Govindarajan M, Rohde JM, Blanchard N, Simmonds R, Inglese J, Du Y, Demangel C, High S, Paavilainen VO, Shi WQ. Ipomoeassin F Binds Sec61α to Inhibit Protein Translocation. J Am Chem Soc 2019; 141:8450-8461. [PMID: 31059257 PMCID: PMC6627486 DOI: 10.1021/jacs.8b13506] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ipomoeassin F is a potent natural cytotoxin that inhibits growth of many tumor cell lines with single-digit nanomolar potency. However, its biological and pharmacological properties have remained largely unexplored. Building upon our earlier achievements in total synthesis and medicinal chemistry, we used chemical proteomics to identify Sec61α (protein transport protein Sec61 subunit alpha isoform 1), the pore-forming subunit of the Sec61 protein translocon, as a direct binding partner of ipomoeassin F in living cells. The interaction is specific and strong enough to survive lysis conditions, enabling a biotin analogue of ipomoeassin F to pull down Sec61α from live cells, yet it is also reversible, as judged by several experiments including fluorescent streptavidin staining, delayed competition in affinity pulldown, and inhibition of TNF biogenesis after washout. Sec61α forms the central subunit of the ER protein translocation complex, and the binding of ipomoeassin F results in a substantial, yet selective, inhibition of protein translocation in vitro and a broad ranging inhibition of protein secretion in live cells. Lastly, the unique resistance profile demonstrated by specific amino acid single-point mutations in Sec61α provides compelling evidence that Sec61α is the primary molecular target of ipomoeassin F and strongly suggests that the binding of this natural product to Sec61α is distinctive. Therefore, ipomoeassin F represents the first plant-derived, carbohydrate-based member of a novel structural class that offers new opportunities to explore Sec61α function and to further investigate its potential as a therapeutic target for drug discovery.
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Affiliation(s)
- Guanghui Zong
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Chemistry and Biochemistry, University
of Maryland, College Park, Maryland 20742, United States
| | - Zhijian Hu
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Sarah O’Keefe
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Dale Tranter
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland
| | - Michael J. Iannotti
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Ludivine Baron
- Immunobiology
of Infection Unit, Institut Pasteur, 75015 Paris, France,INSERM, U1221, 75005 Paris, France
| | - Belinda Hall
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Katherine Corfield
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Anja O. Paatero
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland
| | - Mark J. Henderson
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Peristera Roboti
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Jianhong Zhou
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Xianwei Sun
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Radiology, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Mugunthan Govindarajan
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Emory
Institute for Drug Development, Emory University, 954 Gatewood Road, Atlanta, Georgia 30329, United States
| | - Jason M. Rohde
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Nicolas Blanchard
- Université
de Haute-Alsace, Université de Strasbourg, CNRS, LIMA, UMR 7042, 68000 Mulhouse, France
| | - Rachel Simmonds
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom,
| | - James Inglese
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States,
| | - Yuchun Du
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,
| | - Caroline Demangel
- Immunobiology
of Infection Unit, Institut Pasteur, 75015 Paris, France,INSERM, U1221, 75005 Paris, France,
| | - Stephen High
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom,
| | - Ville O. Paavilainen
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland,
| | - Wei Q. Shi
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Chemistry, Ball State University, Muncie, Indiana 47306, United States,;
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33
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Elia F, Yadhanapudi L, Tretter T, Römisch K. The N-terminus of Sec61p plays key roles in ER protein import and ERAD. PLoS One 2019; 14:e0215950. [PMID: 31017954 PMCID: PMC6481919 DOI: 10.1371/journal.pone.0215950] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 04/11/2019] [Indexed: 01/24/2023] Open
Abstract
Sec61p is the channel-forming subunit of the heterotrimeric Sec61 complex that mediates co-translational protein import into the endoplasmic reticulum (ER). In yeast, proteins can also be post-translationally translocated by the hetero-heptameric Sec complex, composed of the Sec61 and the Sec63 complexes. The Sec61 channel is also a candidate for the dislocation channel for misfolded proteins from the ER to the cytosol during ER-associated degradation (ERAD). The structure of the Sec61 complex is highly conserved, but the roles of its N-terminal acetylation and its amphipathic N-terminal helix are unknown so far. To gain insight into the function of the Sec61p N-terminus, we mutated its N-acetylation site, deleted its amphipathic helix, or both the helix and the N-acetylation site. Mutation of the N-acetylation site on its own had no effect on protein import into the ER in intact cells, but resulted in an ERAD defect. Yeast expressing sec61 without the N-terminal amphipathic helix displayed severe growth defects and had profound defects in post-translational protein import into the ER. Nevertheless the formation of the hetero-heptameric Sec complex was not affected. Instead, the lack of the N-terminal amphipathic helix compromised the integrity of the heterotrimeric Sec61 complex. We conclude that the N-terminal helix of Sec61p is required for post-translational protein import into the ER and Sec61 complex stability, whereas N-terminal acetylation of Sec61p plays a role in ERAD.
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Affiliation(s)
- Francesco Elia
- Faculty of Natural Sciences and Technology, Saarland University, Saarbruecken, Germany
| | - Lalitha Yadhanapudi
- Faculty of Natural Sciences and Technology, Saarland University, Saarbruecken, Germany
| | - Thomas Tretter
- Faculty of Natural Sciences and Technology, Saarland University, Saarbruecken, Germany
| | - Karin Römisch
- Faculty of Natural Sciences and Technology, Saarland University, Saarbruecken, Germany
- * E-mail:
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34
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Spiess M, Junne T, Janoschke M. Membrane Protein Integration and Topogenesis at the ER. Protein J 2019; 38:306-316. [DOI: 10.1007/s10930-019-09827-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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35
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Lang S, Nguyen D, Pfeffer S, Förster F, Helms V, Zimmermann R. Functions and Mechanisms of the Human Ribosome-Translocon Complex. Subcell Biochem 2019; 93:83-141. [PMID: 31939150 DOI: 10.1007/978-3-030-28151-9_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The membrane of the endoplasmic reticulum (ER) in human cells harbors the protein translocon, which facilitates membrane insertion and translocation of almost every newly synthesized polypeptide targeted to organelles of the secretory pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins, which are associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, Sec61 channel opening and closing, and modification of precursor polypeptides in transit through the Sec61 complex. Recently, cryoelectron tomography of translocons in native ER membranes has given unprecedented insights into the architecture and dynamics of the native, ribosome-associated translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion or translocation of newly synthesized polypeptides as well as the possible roles of the Sec61 channel as a passive ER calcium leak channel and regulator of ATP/ADP exchange between cytosol and ER.
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Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, 66421, Homburg, Germany.
| | - Duy Nguyen
- Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152, Martinsried, Germany
- ZMBH, 69120, Heidelberg, Germany
| | - Friedrich Förster
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152, Martinsried, Germany
- Center for Biomolecular Research, Utrecht University, 3584 CH, Utrecht, The Netherlands
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, 66421, Homburg, Germany
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36
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Ojha R, Leli NM, Onorati A, Piao S, Verginadis II, Tameire F, Rebecca VW, Chude CI, Murugan S, Fennelly C, Noguera-Ortega E, Chu CT, Liu S, Xu X, Krepler C, Xiao M, Xu W, Wei Z, Frederick DT, Boland G, Mitchell TC, Karakousis GC, Schuchter LM, Flaherty KT, Zhang G, Herlyn M, Koumenis C, Amaravadi RK. ER Translocation of the MAPK Pathway Drives Therapy Resistance in BRAF-Mutant Melanoma. Cancer Discov 2018; 9:396-415. [PMID: 30563872 DOI: 10.1158/2159-8290.cd-18-0348] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 09/01/2018] [Accepted: 12/07/2018] [Indexed: 12/11/2022]
Abstract
Resistance to BRAF and MEK inhibitors (BRAFi + MEKi) in BRAF-mutant tumors occurs through heterogeneous mechanisms, including ERK reactivation and autophagy. Little is known about the mechanisms by which ERK reactivation or autophagy is induced by BRAFi + MEKi. Here, we report that in BRAF-mutant melanoma cells, BRAFi + MEKi induced SEC61-dependent endoplasmic reticulum (ER) translocation of the MAPK pathway via GRP78 and KSR2. Inhibition of ER translocation prevented ERK reactivation and autophagy. Following ER translocation, ERK exited the ER and was rephosphorylated by PERK. Reactivated ERK phosphorylated ATF4, which activated cytoprotective autophagy. Upregulation of GRP78 and phosphorylation of ATF4 were detected in tumors of patients resistant to BRAFi + MEKi. ER translocation of the MAPK pathway was demonstrated in therapy-resistant patient-derived xenografts. Expression of a dominant-negative ATF4 mutant conferred sensitivity to BRAFi + MEKi in vivo. This mechanism reconciles two major targeted therapy resistance pathways and identifies druggable targets, whose inhibition would likely enhance the response to BRAFi + MEKi. SIGNIFICANCE: ERK reactivation and autophagy are considered distinct resistance pathways to BRAF + MEK inhibition (BRAFi + MEKi) in BRAF V600E cancers. Here, we report BRAFi + MEKi-induced ER translocation of the MAPK pathway is necessary for ERK reactivation, which drives autophagy. The ER translocation mechanism is a major druggable driver of resistance to targeted therapy.This article is highlighted in the In This Issue feature, p. 305.
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Affiliation(s)
- Rani Ojha
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nektaria M Leli
- Department of Radiation Oncology, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Angelique Onorati
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Shengfu Piao
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ioannis I Verginadis
- Department of Radiation Oncology, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Feven Tameire
- Department of Radiation Oncology, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Vito W Rebecca
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Cynthia I Chude
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sengottuvelan Murugan
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Colin Fennelly
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Estela Noguera-Ortega
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Charleen T Chu
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Shujing Liu
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Xiaowei Xu
- Department of Pathology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Clemens Krepler
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, Wistar Institute, Philadelphia, Pennsylvania
| | - Min Xiao
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, Wistar Institute, Philadelphia, Pennsylvania
| | - Wei Xu
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Zhi Wei
- Department of Computer Science, New Jersey Institute of Technology, Newark, New Jersey
| | - Dennie T Frederick
- Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Genevieve Boland
- Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Tara C Mitchell
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Lynn M Schuchter
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Keith T Flaherty
- Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Gao Zhang
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, Wistar Institute, Philadelphia, Pennsylvania
| | - Meenhard Herlyn
- Molecular and Cellular Oncogenesis Program and Melanoma Research Center, Wistar Institute, Philadelphia, Pennsylvania
| | - Constantinos Koumenis
- Department of Radiation Oncology, Smilow Center for Translational Research, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ravi K Amaravadi
- Abramson Cancer Center and Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
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37
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Klein W, Rutz C, Eckhard J, Provinciael B, Specker E, Neuenschwander M, Kleinau G, Scheerer P, von Kries JP, Nazaré M, Vermeire K, Schülein R. Use of a sequential high throughput screening assay to identify novel inhibitors of the eukaryotic SRP-Sec61 targeting/translocation pathway. PLoS One 2018; 13:e0208641. [PMID: 30543669 PMCID: PMC6292634 DOI: 10.1371/journal.pone.0208641] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/20/2018] [Indexed: 11/22/2022] Open
Abstract
The SRP-Sec61 targeting/translocation pathway of eukaryotic cells targets nascent protein chains to the membrane of the endoplasmic reticulum. Using this machinery, secretory proteins are translocated across this membrane whereas membrane proteins are integrated into the lipid bilayer. One of the key players of the pathway is the protein-conducting Sec61 (translocon) complex of the endoplasmic reticulum. The Sec61 complex has no enzymatic activity, is expressed only intracellularly and is difficult to purify and to reconstitute. Screening for small molecule inhibitors impairing its functions is thus notoriously difficult. Such inhibitors may not only be valuable tools for cell biology, they may also represent novel anti-tumor drugs. Here we have developed a two-step, sequential screening assay for inhibitors of the whole SRP-Sec61 targeting/translocation pathway which might include molecules affecting Sec61 complex functions. The resulting hit compounds were analyzed using a whole cell biosynthesis assay and a cell free transcription/translation/translocation assay. Using this methodology, we identified novel compounds inhibiting this pathway. Following structure-based back screening, one of these substances was analyzed in more detail and we could show that it indeed impairs translocation at the level of the Sec61 complex. A slightly modified methodology may be used in the future to screen for substances affecting SecYEG, the bacterial ortholog of the Sec61 complex in order to derive novel antibiotic drugs.
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Affiliation(s)
- Wolfgang Klein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Claudia Rutz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Jamina Eckhard
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Becky Provinciael
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Edgar Specker
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | | | - Gunnar Kleinau
- Charité—Universitätsmedizin Berlin, Campus Charité Mitte, Charité Centrum Grundlagenmedizin CC2, Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | - Patrick Scheerer
- Charité—Universitätsmedizin Berlin, Campus Charité Mitte, Charité Centrum Grundlagenmedizin CC2, Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | | | - Marc Nazaré
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Kurt Vermeire
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Ralf Schülein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
- * E-mail:
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38
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Kida Y, Sakaguchi M. Interaction mapping of the Sec61 translocon identifies two Sec61α regions interacting with hydrophobic segments in translocating chains. J Biol Chem 2018; 293:17050-17060. [PMID: 30213864 DOI: 10.1074/jbc.ra118.003219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 08/26/2018] [Indexed: 01/09/2023] Open
Abstract
Many proteins in organelles of the secretory pathway, as well as secretory proteins, are translocated across and inserted into the endoplasmic reticulum membrane by the Sec61 translocon, a protein-conducting channel. The channel consists of 10 transmembrane (TM) segments of the Sec61α subunit and possesses an opening between TM2b and TM7, termed the lateral gate. Structural and biochemical analyses of complexes of Sec61 and its ortholog SecY have revealed that the lateral gate is the exit for signal sequences and TM segments of translocating polypeptides to the lipid bilayer and also involved in the recognition of such hydrophobic sequences. Moreover, even marginally hydrophobic (mH) segments insufficient for membrane integration can be transiently stalled in surrounding Sec61α regions and cross-linked to them, but how the Sec61 translocon accommodates these mH segments remains unclear. Here, we used Cys-scanned variants of human Sec61α expressed in cultured 293-H cells to examine which channel regions associate with mH segments. A TM segment in a ribosome-associated polypeptide was mainly cross-linked to positions at the lateral gate, whereas an mH segment in a nascent chain was cross-linked to the Sec61α pore-interior positions at TM5 and TM10, as well as the lateral gate. Of note, cross-linking at position 180 in TM5 of Sec61α was reduced by an I179A substitution. We therefore conclude that at least two Sec61α regions, the lateral gate and the pore-interior site around TM5, interact with mH segments and are involved in accommodating them.
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Affiliation(s)
- Yuichiro Kida
- From the Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan
| | - Masao Sakaguchi
- From the Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan
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39
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Gestwicki JE, Shao H. Inhibitors and chemical probes for molecular chaperone networks. J Biol Chem 2018; 294:2151-2161. [PMID: 30213856 DOI: 10.1074/jbc.tm118.002813] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The molecular chaperones are central mediators of protein homeostasis. In that role, they engage in widespread protein-protein interactions (PPIs) with each other and with their "client" proteins. Together, these PPIs form the backbone of a network that ensures proper vigilance over the processes of protein folding, trafficking, quality control, and degradation. The core chaperones, such as the heat shock proteins Hsp60, Hsp70, and Hsp90, are widely expressed in most tissues, yet there is growing evidence that the PPIs among them may be re-wired in disease conditions. This possibility suggests that these PPIs, and perhaps not the individual chaperones themselves, could be compelling drug targets. Indeed, recent efforts have yielded small molecules that inhibit (or promote) a subset of inter-chaperone PPIs. These chemical probes are being used to study chaperone networks in a range of models, and the successes with these approaches have inspired a community-wide objective to produce inhibitors for a broader set of targets. In this Review, we discuss progress toward that goal and point out some of the challenges ahead.
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Affiliation(s)
- Jason E Gestwicki
- From the Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, California 94158
| | - Hao Shao
- From the Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, California 94158
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40
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Demangel C, High S. Sec61 blockade by mycolactone: A central mechanism in Buruli ulcer disease. Biol Cell 2018; 110:237-248. [PMID: 30055020 DOI: 10.1111/boc.201800030] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/19/2018] [Indexed: 12/14/2022]
Abstract
Infection with Mycobacterium ulcerans results in a necrotising skin disease known as a Buruli ulcer, the pathology of which is directly linked to the bacterial production of the toxin mycolactone. Recent studies have identified the protein translocation machinery of the endoplasmic reticulum (ER) membrane as the primary cellular target of mycolactone, and shown that the toxin binds to the core subunit of the Sec61 complex. Mycolactone binding strongly inhibits the capacity of the Sec61 translocon to transport newly synthesised membrane and secretory proteins into and across the ER membrane. Since the ER acts as the entry point for the mammalian secretory pathway, and hence regulates initial access to the entire endomembrane system, mycolactone-treated cells have a reduced ability to produce a range of proteins including secretory cytokines and plasma membrane receptors. The global effect of this molecular blockade of protein translocation at the ER is that the host is unable to mount an effective immune response to the underlying mycobacterial infection. Prolonged exposure to mycolactone is normally cytotoxic, since it triggers stress responses activating the transcription factor ATF4 and ultimately inducing apoptosis.
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Affiliation(s)
- Caroline Demangel
- Immunobiology of Infection Unit, Institut Pasteur, Paris, France.,INSERM, U1221, Paris, France
| | - Stephen High
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
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41
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Measuring Endoplasmic Reticulum Signal Sequences Translocation Efficiency Using the Xbp1 Arrest Peptide. Cell Chem Biol 2018; 25:880-890.e3. [PMID: 29754956 DOI: 10.1016/j.chembiol.2018.04.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/11/2018] [Accepted: 04/06/2018] [Indexed: 11/20/2022]
Abstract
Secretory proteins translocate across the mammalian ER membrane co-translationally via the ribosome-sec61 translocation machinery. Signal sequences within the polypeptide, which guide this event, are diverse in their hydrophobicity, charge, length, and amino acid composition. Despite the known sequence diversity in the ER signals, it is generally assumed that they have a dominant role in determining co-translational targeting and translocation process. We have analyzed co-translational events experienced by secretory proteins carrying efficient versus inefficient signal sequencing, using an assay based on Xbp1 peptide-mediated translational arrest. With this method we were able to measure the functional efficiency of ER signal sequences. We show that an efficient signal sequence experiences a two-phase event whereby the nascent chain is pulled from the ribosome during its translocation, thus resuming translation and yielding full-length products. Conversely, the inefficient signal sequence experiences a single weaker pulling event, suggesting inadequate engagement by the translocation machinery of these marginally hydrophobic signal sequences.
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42
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43
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Van Puyenbroeck V, Vermeire K. Inhibitors of protein translocation across membranes of the secretory pathway: novel antimicrobial and anticancer agents. Cell Mol Life Sci 2018; 75:1541-1558. [PMID: 29305616 PMCID: PMC5897483 DOI: 10.1007/s00018-017-2743-2] [Citation(s) in RCA: 25] [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: 10/26/2017] [Revised: 12/15/2017] [Accepted: 12/27/2017] [Indexed: 12/22/2022]
Abstract
Proteins routed to the secretory pathway start their journey by being transported across biological membranes, such as the endoplasmic reticulum. The essential nature of this protein translocation process has led to the evolution of several factors that specifically target the translocon and block translocation. In this review, various translocation pathways are discussed together with known inhibitors of translocation. Properties of signal peptide-specific systems are highlighted for the development of new therapeutic and antimicrobial applications, as compounds can target signal peptides from either host cells or pathogens and thereby selectively prevent translocation of those specific proteins. Broad inhibition of translocation is also an interesting target for the development of new anticancer drugs because cancer cells heavily depend on efficient protein translocation into the endoplasmic reticulum to support their fast growth.
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Affiliation(s)
- Victor Van Puyenbroeck
- Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000, Leuven, Belgium
| | - Kurt Vermeire
- Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
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44
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Ogbechi J, Hall BS, Sbarrato T, Taunton J, Willis AE, Wek RC, Simmonds RE. Inhibition of Sec61-dependent translocation by mycolactone uncouples the integrated stress response from ER stress, driving cytotoxicity via translational activation of ATF4. Cell Death Dis 2018. [PMID: 29540678 PMCID: PMC5852046 DOI: 10.1038/s41419-018-0427-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mycolactone is the exotoxin virulence factor of Mycobacterium ulcerans that causes the neglected tropical disease Buruli ulcer. We recently showed it to be a broad spectrum inhibitor of Sec61-dependent co-translational translocation of proteins into the endoplasmic reticulum (ER). An outstanding question is the molecular pathway linking this to its known cytotoxicity. We have now used translational profiling to better understand the reprogramming that occurs in cells exposed to mycolactone. Gene ontology identified enrichment in genes involved in cellular response to stress, and apoptosis signalling among those showing enhanced translation. Validation of these results supports a mechanism by which mycolactone activates an integrated stress response meditated by phosphorylation of eIF2α via multiple kinases (PERK, GCN, PKR) without activation of the ER stress sensors IRE1 or ATF6. The response therefore uncouples the integrated stress response from ER stress, and features translational and transcriptional modes of genes expression that feature the key regulatory transcription factor ATF4. Emphasising the importance of this uncoupled response in cytotoxicity, downstream activation of this pathway is abolished in cells expressing mycolactone-resistant Sec61α variants. Using multiple genetic and biochemical approaches, we demonstrate that eIF2α phosphorylation is responsible for mycolactone-dependent translation attenuation, which initially protects cells from cell death. However, chronic activation without stress remediation enhances autophagy and apoptosis of cells by a pathway facilitated by ATF4 and CHOP. Our findings demonstrate that priming events at the ER can result in the sensing of stress within different cellular compartments.
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Affiliation(s)
- Joy Ogbechi
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Belinda S Hall
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | | | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Anne E Willis
- MRC Toxicology Unit, Lancaster Rd, Leicester, LE1 9HN, UK
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Rachel E Simmonds
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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45
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Murray J, Todd KV, Bakre A, Orr-Burks N, Jones L, Wu W, Tripp RA. A universal mammalian vaccine cell line substrate. PLoS One 2017; 12:e0188333. [PMID: 29176782 PMCID: PMC5703543 DOI: 10.1371/journal.pone.0188333] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/03/2017] [Indexed: 12/22/2022] Open
Abstract
Using genome-wide small interfering RNA (siRNA) screens for poliovirus, influenza A virus and rotavirus, we validated the top 6 gene hits PV, RV or IAV to search for host genes that when knocked-down (KD) enhanced virus permissiveness and replication over wild type Vero cells or HEp-2 cells. The enhanced virus replication was tested for 12 viruses and ranged from 2-fold to >1000-fold. There were variations in virus-specific replication (strain differences) across the cell lines examined. Some host genes (CNTD2, COQ9, GCGR, NDUFA9, NEU2, PYCR1, SEC16G, SVOPL, ZFYVE9, and ZNF205) showed that KD resulted in enhanced virus replication. These findings advance platform-enabling vaccine technology, the creation of diagnostic cells substrates, and are informative about the host mechanisms that affect virus replication in mammalian cells.
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Affiliation(s)
- Jackelyn Murray
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Kyle V. Todd
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Abhijeet Bakre
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Nichole Orr-Burks
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Les Jones
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Weilin Wu
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
| | - Ralph A. Tripp
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States of America
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46
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Paatero AO, Kellosalo J, Dunyak BM, Almaliti J, Gestwicki JE, Gerwick WH, Taunton J, Paavilainen VO. Apratoxin Kills Cells by Direct Blockade of the Sec61 Protein Translocation Channel. Cell Chem Biol 2017; 23:561-566. [PMID: 27203376 DOI: 10.1016/j.chembiol.2016.04.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 04/04/2016] [Accepted: 04/07/2016] [Indexed: 12/17/2022]
Abstract
Apratoxin A is a cytotoxic natural product that prevents the biogenesis of secretory and membrane proteins. Biochemically, apratoxin A inhibits cotranslational translocation into the ER, but its cellular target and mechanism of action have remained controversial. Here, we demonstrate that apratoxin A prevents protein translocation by directly targeting Sec61α, the central subunit of the protein translocation channel. Mutagenesis and competitive photo-crosslinking studies indicate that apratoxin A binds to the Sec61 lateral gate in a manner that differs from cotransin, a substrate-selective Sec61 inhibitor. In contrast to cotransin, apratoxin A does not exhibit a substrate-selective inhibitory mechanism, but blocks ER translocation of all tested Sec61 clients with similar potency. Our results suggest that multiple structurally unrelated natural products have evolved to target overlapping but non-identical binding sites on Sec61, thereby producing distinct biological outcomes.
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Affiliation(s)
- Anja O Paatero
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, Biocenter 3, Helsinki 00014, Finland
| | - Juho Kellosalo
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, Biocenter 3, Helsinki 00014, Finland
| | - Bryan M Dunyak
- Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Disease, University of California at San Francisco, San Francisco, CA 94038, USA
| | - Jehad Almaliti
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Disease, University of California at San Francisco, San Francisco, CA 94038, USA
| | - William H Gerwick
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ville O Paavilainen
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, Biocenter 3, Helsinki 00014, Finland.
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47
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Lang S, Pfeffer S, Lee PH, Cavalié A, Helms V, Förster F, Zimmermann R. An Update on Sec61 Channel Functions, Mechanisms, and Related Diseases. Front Physiol 2017; 8:887. [PMID: 29163222 PMCID: PMC5672155 DOI: 10.3389/fphys.2017.00887] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/19/2017] [Indexed: 12/18/2022] Open
Abstract
The membrane of the endoplasmic reticulum (ER) of nucleated human cells harbors the protein translocon, which facilitates membrane integration or translocation of almost every newly synthesized polypeptide targeted to organelles of the endo- and exocytotic pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins and complexes that are permanently or transiently associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, modification of precursor polypeptides in transit through the Sec61 complex, and Sec61 channel gating, i.e., dynamic regulation of the pore forming subunit to mediate precursor transport and calcium efflux. Recently, cryoelectron tomography of translocons in native ER membrane vesicles, derived from human cell lines or patient fibroblasts, and even intact cells has given unprecedented insights into the architecture and dynamics of the native translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion, and translocation of newly synthesized polypeptides as well as the putative physiological roles of the Sec61 channel as a passive ER calcium leak channel. Furthermore, the structural insights into the Sec61 channel are incorporated into an overview and update on Sec61 channel-related diseases—the Sec61 channelopathies—and novel therapeutic concepts for their treatment.
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Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Po-Hsien Lee
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Friedrich Förster
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
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48
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McKenna M, Simmonds RE, High S. Mycolactone reveals the substrate-driven complexity of Sec61-dependent transmembrane protein biogenesis. J Cell Sci 2017; 130:1307-1320. [PMID: 28219954 PMCID: PMC5399781 DOI: 10.1242/jcs.198655] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/02/2017] [Indexed: 12/22/2022] Open
Abstract
Mycolactone is the exotoxin virulence factor produced by Mycobacterium ulcerans, the pathogen responsible for Buruli ulcer. The skin lesions and immunosuppression that are characteristic of this disease result from the action of mycolactone, which targets the Sec61 complex and inhibits the co-translational translocation of secretory proteins into the endoplasmic reticulum. In this study, we investigate the effect of mycolactone on the Sec61-dependent biogenesis of different classes of transmembrane protein (TMP). Our data suggest that the effect of mycolactone on TMP biogenesis depends on how the nascent chain initially engages the Sec61 complex. For example, the translocation of TMP lumenal domains driven by an N-terminal cleavable signal sequence is efficiently inhibited by mycolactone. In contrast, the effect of mycolactone on protein translocation that is driven solely by a non-cleavable signal anchor/transmembrane domain depends on which flanking region is translocated. For example, while translocation of the region N-terminal to a signal anchor/transmembrane domain is refractive to mycolactone, C-terminal translocation is efficiently inhibited. Our findings highlight the diversity of Sec61-dependent translocation and provide a molecular basis for understanding the effect of mycolactone on the biogenesis of different TMPs. Highlighted Article: The exotoxin mycolactone interferes with the biogenesis of the majority of transmembrane proteins and its actions highlight differences in how distinct classes of these proteins initially engage the Sec61 translocon.
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Affiliation(s)
- Michael McKenna
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Michael Smith Building, Manchester M13 9PT, UK
| | - Rachel E Simmonds
- Department of Microbial Sciences, School of Bioscience and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Stephen High
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Michael Smith Building, Manchester M13 9PT, UK
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49
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Van Puyenbroeck V, Claeys E, Schols D, Bell TW, Vermeire K. A Proteomic Survey Indicates Sortilin as a Secondary Substrate of the ER Translocation Inhibitor Cyclotriazadisulfonamide (CADA). Mol Cell Proteomics 2016; 16:157-167. [PMID: 27998951 DOI: 10.1074/mcp.m116.061051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 11/04/2016] [Indexed: 11/06/2022] Open
Abstract
The small molecule CADA was shown to down-modulate the expression of human CD4 in a signal peptide-dependent way through inhibition of its cotranslational translocation across the ER membrane. Previous studies characterizing general glycoprotein levels and the expression of 14 different cell surface receptors showed selectivity of CADA for human CD4. Here, a PowerBlot Western Array was used as a screen to analyze the proteome of CADA-treated SUP-T1 human CD4+ T lymphocytes. This high-throughput monoclonal antibody panel-based immunoblotting assay of cellular signaling proteins revealed that only a small subset of the 444 detected proteins was differentially expressed after treatment with CADA. Validation of these proteomic data with optimized immunoblot analysis confirmed the CADA-induced change in expression of the cell cycle progression regulator pRb2 and the transcription factor c-Jun. However, the up-regulation of pRb2 or down-modulation of c-Jun by CADA had no impact on cell cycle transition. Also, the reduced protein level of human CD4 did not inhibit T cell receptor signaling. Interestingly, the signal peptide-containing membrane protein sortilin was identified as a new substrate for CADA. Both cellular expression and in vitro cotranslational translocation of sortilin were significantly reduced by CADA, although to a lesser extent as compared with human CD4. Our data demonstrate that a small signal peptide-binding drug is able to down-modulate the expression of human CD4 and sortilin, apparently with low impact on the cellular proteome.
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Affiliation(s)
- Victor Van Puyenbroeck
- From the ‡KU Leuven - University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, B-3000 Leuven, Belgium
| | - Elisa Claeys
- From the ‡KU Leuven - University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, B-3000 Leuven, Belgium
| | - Dominique Schols
- From the ‡KU Leuven - University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, B-3000 Leuven, Belgium
| | - Thomas W Bell
- §Department of Chemistry, University of Nevada, Reno, NV, USA
| | - Kurt Vermeire
- From the ‡KU Leuven - University of Leuven, Department of Microbiology and Immunology, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, B-3000 Leuven, Belgium;
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50
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Baron L, Paatero AO, Morel JD, Impens F, Guenin-Macé L, Saint-Auret S, Blanchard N, Dillmann R, Niang F, Pellegrini S, Taunton J, Paavilainen VO, Demangel C. Mycolactone subverts immunity by selectively blocking the Sec61 translocon. J Exp Med 2016; 213:2885-2896. [PMID: 27821549 PMCID: PMC5154940 DOI: 10.1084/jem.20160662] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/26/2016] [Accepted: 10/17/2016] [Indexed: 12/29/2022] Open
Abstract
Mycolactone, an immunosuppressive macrolide released by the human pathogen Mycobacterium ulcerans, was previously shown to impair Sec61-dependent protein translocation, but the underlying molecular mechanism was not identified. In this study, we show that mycolactone directly targets the α subunit of the Sec61 translocon to block the production of secreted and integral membrane proteins with high potency. We identify a single-amino acid mutation conferring resistance to mycolactone, which localizes its interaction site near the lumenal plug of Sec61α. Quantitative proteomics reveals that during T cell activation, mycolactone-mediated Sec61 blockade affects a selective subset of secretory proteins including key signal-transmitting receptors and adhesion molecules. Expression of mutant Sec61α in mycolactone-treated T cells rescued their homing potential and effector functions. Furthermore, when expressed in macrophages, the mycolactone-resistant mutant restored IFN-γ receptor-mediated antimicrobial responses. Thus, our data provide definitive genetic evidence that Sec61 is the host receptor mediating the diverse immunomodulatory effects of mycolactone and identify Sec61 as a novel regulator of immune cell functions.
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Affiliation(s)
- Ludivine Baron
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | | | - Jean-David Morel
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Francis Impens
- Unité des Interactions Bactéries-Cellules, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U604, Institut National de la Recherche Agronomique, Unité sous-contrat 2020, 75015 Paris, France
| | - Laure Guenin-Macé
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Sarah Saint-Auret
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7509, École européenne de Chimie, Polymères et Matériaux, Université de Strasbourg, 67087 Strasbourg, France
| | - Nicolas Blanchard
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7509, École européenne de Chimie, Polymères et Matériaux, Université de Strasbourg, 67087 Strasbourg, France
| | - Rabea Dillmann
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Fatoumata Niang
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Sandra Pellegrini
- Unité de Signalisation des Cytokines, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
| | | | - Caroline Demangel
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
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