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Sánchez WN, Driessen AJM, Wilson CAM. Protein targeting to the ER membrane: multiple pathways and shared machinery. Crit Rev Biochem Mol Biol 2025:1-47. [PMID: 40377270 DOI: 10.1080/10409238.2025.2503746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2025] [Revised: 05/04/2025] [Accepted: 05/06/2025] [Indexed: 05/18/2025]
Abstract
The endoplasmic reticulum (ER) serves as a central hub for protein production and sorting in eukaryotic cells, processing approximately one-third of the cellular proteome. Protein targeting to the ER occurs through multiple pathways that operate both during and independent of translation. The classical translation-dependent pathway, mediated by cytosolic factors like signal recognition particle, recognizes signal peptides or transmembrane helices in nascent proteins, while translation-independent mechanisms utilize RNA-based targeting through specific sequence elements and RNA-binding proteins. At the core of these processes lies the Sec61 complex, which undergoes dynamic conformational changes and coordinates with numerous accessory factors to facilitate protein translocation and membrane insertion across and into the endoplasmic reticulum membrane. This review focuses on the molecular mechanisms of protein targeting to the ER, from the initial recognition of targeting signals to the dynamics of the translocation machinery, highlighting recent discoveries that have revealed unprecedented complexity in these cellular trafficking pathways.
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Affiliation(s)
- Wendy N Sánchez
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands
- Biochemistry and Molecular Biology Department, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
- Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Arnold J M Driessen
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands
| | - Christian A M Wilson
- Biochemistry and Molecular Biology Department, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
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2
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Wu H, Diao H, Zhang F, Jiang W, Pan T, Bian Y. Organelle interplay in cardiovascular diseases: Mechanisms, pathogenesis, and therapeutic perspectives. Biomed Pharmacother 2025; 185:117978. [PMID: 40073746 DOI: 10.1016/j.biopha.2025.117978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2024] [Revised: 02/16/2025] [Accepted: 03/07/2025] [Indexed: 03/14/2025] Open
Abstract
Cardiovascular diseases (CVDs) are the leading cause of rising morbidity and mortality among humans worldwide; however, our approach to the pathogenesis, exploration, and management of CVDs still remains limited. As the heart consists of cardiomyocytes, cardiac fibroblasts, endothelial cells, smooth muscle cells, and several types of cells, different types of dysfunction in the interplay between organelles play an important damaging role, resulting in cardiac pathologies. The interplay between cellular organelles is intricate and vital for maintaining cellular homeostasis, as highlighted by multiple diseases linked to the dysfunction of both organelles. Many studies have revealed the potential mechanisms by which organelles communicate with each other and regulate the pathological processes of CVDs together. However, gaps remain in fully understanding the complexity of these interactions and translating these insights into therapeutic approaches. In this review, we summarized how the interplay between cellular organelles in the cardiomyocytes alters in various heart diseases. We find underexplored areas, such as the crucial signaling pathways governing organelle communication, and discuss their implications for disease future progression. Furthermore, we evaluate emerging potential medicines aimed at restoring organelle interactions. Finally, we propose future directions for researching to advance the development of novel medicines and therapies, addressing current gaps and providing a theoretical basis for improved clinical outcomes in CVDs.
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Affiliation(s)
- Han Wu
- Department of Pharmacology (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Hongtao Diao
- Department of Pharmacology (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Feng Zhang
- Department of Pharmacology (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Weitao Jiang
- Department of Pharmacology (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Tengfei Pan
- Department of Pharmacology (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Yu Bian
- Department of Pharmacology (The State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China.
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Li P, Bågenholm V, Hägglund P, Lindkvist-Petersson K, Wang K, Gourdon P. The structure and function of P5A-ATPases. Nat Commun 2024; 15:9605. [PMID: 39505844 PMCID: PMC11541931 DOI: 10.1038/s41467-024-53757-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 10/21/2024] [Indexed: 11/08/2024] Open
Abstract
Endoplasmic reticulum (ER) membrane resident P5A-ATPases broadly affect protein biogenesis and quality control, and yet their molecular function remains debated. Here, we report cryo-EM structures of a P5A-ATPase, CtSpf1, covering multiple transport intermediates of the E1 → E1-ATP → E1P-ADP → E1P → E2P → E2.Pi → E2 → E1 cycle. In the E2P and E2.Pi states a cleft spans the entire membrane, holding a polypeptide cargo molecule. The cargo includes an ER luminal extension, pinpointed as the C-terminus in the E2.Pi state, which reenters the membrane in E2P. The E1 structure harbors a cytosol-facing cavity that is blocked by an insertion we refer to as the Plug-domain. The Plug-domain is nestled to key ATPase features and is displaced in the E1P-ADP and E1P states. Collectively, our findings are compatible with a broad range of proteins as cargo, with the P5A-ATPases serving a role in membrane removal of helices, although insertion/secretion cannot be excluded, as well as with a mechanistic role of the Plug-domain.
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Affiliation(s)
- Ping Li
- Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84, Lund, Sweden.
| | - Viktoria Bågenholm
- Department of Biomedical Sciences, University of Copenhagen, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | - Per Hägglund
- Department of Biomedical Sciences, University of Copenhagen, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
| | | | - Kaituo Wang
- Department of Biomedical Sciences, University of Copenhagen, Nørre Allé 14, DK-2200, Copenhagen N, Denmark
- State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Pontus Gourdon
- Department of Experimental Medical Science, Lund University, Sölvegatan 19, SE-221 84, Lund, Sweden.
- Department of Biomedical Sciences, University of Copenhagen, Nørre Allé 14, DK-2200, Copenhagen N, Denmark.
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Jung SJ, Sridhara S, Ott M. Early steps in the biogenesis of mitochondrially encoded oxidative phosphorylation subunits. IUBMB Life 2024; 76:125-139. [PMID: 37712772 DOI: 10.1002/iub.2784] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 08/10/2023] [Indexed: 09/16/2023]
Abstract
The complexes mediating oxidative phosphorylation (OXPHOS) in the inner mitochondrial membrane consist of proteins encoded in the nuclear or the mitochondrial DNA. The mitochondrially encoded membrane proteins (mito-MPs) represent the catalytic core of these complexes and follow complicated pathways for biogenesis. Owing to their overall hydrophobicity, mito-MPs are co-translationally inserted into the inner membrane by the Oxa1 insertase. After insertion, OXPHOS biogenesis factors mediate the assembly of mito-MPs into complexes and participate in the regulation of mitochondrial translation, while protein quality control factors recognize and degrade faulty or excess proteins. This review summarizes the current understanding of these early steps occurring during the assembly of mito-MPs by concentrating on results obtained in the model organism baker's yeast.
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Affiliation(s)
- Sung-Jun Jung
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Sagar Sridhara
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Martin Ott
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
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Botsch JJ, Junker R, Sorgenfrei M, Ogger PP, Stier L, von Gronau S, Murray PJ, Seeger MA, Schulman BA, Bräuning B. Doa10/MARCH6 architecture interconnects E3 ligase activity with lipid-binding transmembrane channel to regulate SQLE. Nat Commun 2024; 15:410. [PMID: 38195637 PMCID: PMC10776854 DOI: 10.1038/s41467-023-44670-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 12/19/2023] [Indexed: 01/11/2024] Open
Abstract
Transmembrane E3 ligases play crucial roles in homeostasis. Much protein and organelle quality control, and metabolic regulation, are determined by ER-resident MARCH6 E3 ligases, including Doa10 in yeast. Here, we present Doa10/MARCH6 structural analysis by cryo-EM and AlphaFold predictions, and a structure-based mutagenesis campaign. The majority of Doa10/MARCH6 adopts a unique circular structure within the membrane. This channel is established by a lipid-binding scaffold, and gated by a flexible helical bundle. The ubiquitylation active site is positioned over the channel by connections between the cytosolic E3 ligase RING domain and the membrane-spanning scaffold and gate. Here, by assaying 95 MARCH6 variants for effects on stability of the well-characterized substrate SQLE, which regulates cholesterol levels, we reveal crucial roles of the gated channel and RING domain consistent with AlphaFold-models of substrate-engaged and ubiquitylation complexes. SQLE degradation further depends on connections between the channel and RING domain, and lipid binding sites, revealing how interconnected Doa10/MARCH6 elements could orchestrate metabolic signals, substrate binding, and E3 ligase activity.
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Affiliation(s)
- J Josephine Botsch
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
- Technical University of Munich, School of Natural Sciences, Munich, Germany
| | - Roswitha Junker
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Michèle Sorgenfrei
- Institute of Medical Microbiology, University of Zurich, Gloriastrasse 28/30, 8006, Zurich, Switzerland
| | - Patricia P Ogger
- Research Group of Immunoregulation, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Luca Stier
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
- Technical University of Munich, School of Natural Sciences, Munich, Germany
| | - Susanne von Gronau
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Peter J Murray
- Research Group of Immunoregulation, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zurich, Gloriastrasse 28/30, 8006, Zurich, Switzerland
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.
| | - Bastian Bräuning
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.
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Bai L, Li H. Structural insights into the membrane chaperones for multi-pass membrane protein biogenesis. Curr Opin Struct Biol 2023; 79:102563. [PMID: 36863267 DOI: 10.1016/j.sbi.2023.102563] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/22/2023] [Accepted: 01/28/2023] [Indexed: 03/04/2023]
Abstract
Certain transmembrane α-helices of multi-pass membrane proteins line substrate transport paths or catalytic pockets and, therefore, are partially hydrophilic. Sec61 alone is insufficient to insert these less hydrophobic segments into the membrane and needs to work with dedicated membrane chaperones. Three such membrane chaperones have been described in the literature-the endoplasmic reticulum membrane protein complex (EMC), the TMCO1 complex, and the PAT complex. Recent structural studies on these membrane chaperones have revealed their overall architecture, multi-subunit assembly, putative substrate transmembrane helix-binding pockets, and cooperative mechanisms with the ribosome and Sec61 translocon. These structures are providing initial insights into the poorly understood processes of multi-pass membrane protein biogenesis.
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Affiliation(s)
- Lin Bai
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University, Beijing, 100083, China.
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, 49503, United States.
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Overduin M, Kervin TA, Klarenbach Z, Adra TRC, Bhat RK. Comprehensive classification of proteins based on structures that engage lipids by COMPOSEL. Biophys Chem 2023; 295:106971. [PMID: 36801589 DOI: 10.1016/j.bpc.2023.106971] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 02/05/2023] [Indexed: 02/11/2023]
Abstract
Structures can now be predicted for any protein using programs like AlphaFold and Rosetta, which rely on a foundation of experimentally determined structures of architecturally diverse proteins. The accuracy of such artificial intelligence and machine learning (AI/ML) approaches benefits from the specification of restraints which assist in navigating the universe of folds to converge on models most representative of a given protein's physiological structure. This is especially pertinent for membrane proteins, with structures and functions that depend on their presence in lipid bilayers. Structures of proteins in their membrane environments could conceivably be predicted from AI/ML approaches with user-specificized parameters that describe each element of the architecture of a membrane protein accompanied by its lipid environment. We propose the Classification Of Membrane Proteins based On Structures Engaging Lipids (COMPOSEL), which builds on existing nomenclature types for monotopic, bitopic, polytopic and peripheral membrane proteins as well as lipids. Functional and regulatory elements are also defined in the scripts, as shown with membrane fusing synaptotagmins, multidomain PDZD8 and Protrudin proteins that recognize phosphoinositide (PI) lipids, the intrinsically disordered MARCKS protein, caveolins, the β barrel assembly machine (BAM), an adhesion G-protein coupled receptor (aGPCR) and two lipid modifying enzymes - diacylglycerol kinase DGKε and fatty aldehyde dehydrogenase FALDH. This demonstrates how COMPOSEL communicates lipid interactivity as well as signaling mechanisms and binding of metabolites, drug molecules, polypeptides or nucleic acids to describe the operations of any protein. Moreover COMPOSEL can be scaled to express how genomes encode membrane structures and how our organs are infiltrated by pathogens such as SARS-CoV-2.
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Affiliation(s)
- Michael Overduin
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
| | - Troy A Kervin
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | | | - Trixie Rae C Adra
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Rakesh K Bhat
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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