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Draper-Barr G, Defelipe LA, Ruiz-Carrillo D, Gustavsson E, Landau M, García-Alai M. Sla2 is a core interaction hub for clathrin light chain and the Pan1/End3/Sla1 complex. Structure 2025:S0969-2126(25)00147-9. [PMID: 40347949 DOI: 10.1016/j.str.2025.04.013] [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: 11/19/2024] [Revised: 03/25/2025] [Accepted: 04/15/2025] [Indexed: 05/14/2025]
Abstract
The interaction network of Sla2, a vital endocytic mid-coat adaptor protein, undergoes constant rearrangement. Sla2 serves as a scaffold linking the membrane to the actin cytoskeleton, with its role modulated by the clathrin light chain (CLC), which inhibits Sla2's function under certain conditions. We show that Sla2 has two independent binding sites for CLC: one previously described in homologs of fungi (Sla2) and metazoa (Hip1R), and a second found only in Fungi. We present the structural model of the Sla2 actin-binding domains in the context of regulatory structural domains by cryoelectron microscopy. We provide an interaction map of Sla2 and the regulatory proteins Sla1 and Pan1, predicted by AI modeling and confirmed by molecular biophysics techniques. Pan1 may compete with CLC for the conserved Sla2-binding site. These results enhance the mapping of crucial interactions at endocytic checkpoints and highlight the divergence between Metazoa and Fungi in this vital process.
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Affiliation(s)
- George Draper-Barr
- European Molecular Biology Laboratory, DESY, Building 25a, Hamburg 22607, Germany; Centre for Structural Systems Biology (CSSB), DESY, Building 15, Hamburg 22607, Germany
| | - Lucas A Defelipe
- European Molecular Biology Laboratory, DESY, Building 25a, Hamburg 22607, Germany; Centre for Structural Systems Biology (CSSB), DESY, Building 15, Hamburg 22607, Germany
| | - David Ruiz-Carrillo
- European Molecular Biology Laboratory, DESY, Building 25a, Hamburg 22607, Germany; Centre for Structural Systems Biology (CSSB), DESY, Building 15, Hamburg 22607, Germany
| | - Emil Gustavsson
- Centre for Structural Systems Biology (CSSB), DESY, Building 15, Hamburg 22607, Germany
| | - Meytal Landau
- European Molecular Biology Laboratory, DESY, Building 25a, Hamburg 22607, Germany; Centre for Structural Systems Biology (CSSB), DESY, Building 15, Hamburg 22607, Germany; University Medical Center Hamburg-Eppendorf, Martinistraße 52, Hamburg 20251, Germany; Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Maria García-Alai
- European Molecular Biology Laboratory, DESY, Building 25a, Hamburg 22607, Germany; Centre for Structural Systems Biology (CSSB), DESY, Building 15, Hamburg 22607, Germany.
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2
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Mousavi SI, Lacy MM, Li X, Berro J. Fast Actin Disassembly and Fimbrin Mechanosensitivity Support Rapid Turnover in a Model of Clathrin-Mediated Endocytosis. Cytoskeleton (Hoboken) 2025. [PMID: 40035221 DOI: 10.1002/cm.22002] [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: 11/19/2024] [Revised: 01/20/2025] [Accepted: 01/21/2025] [Indexed: 03/05/2025]
Abstract
The actin cytoskeleton is central to force production in numerous cellular processes in eukaryotic cells. During clathrin-mediated endocytosis (CME), a dynamic actin meshwork is required to deform the membrane against high membrane tension or turgor pressure. Previous experimental work from our lab showed that several endocytic proteins, including actin and actin-interacting proteins, turn over several times during the formation of a vesicle during CME in yeast, and their dwell time distributions were reminiscent of gamma distributions with a peak around 1 s. However, the distribution for the filament cross-linking protein fimbrin contains a second peak around 0.5 s. To better understand the nature of these dwell time distributions, we developed a stochastic model for the dynamics of actin and its binding partners. Our model demonstrates that very fast actin filament disassembly is necessary to reproduce experimental dwell time distributions. Our model also predicts that actin-binding proteins bind rapidly to nascent filaments and filaments are fully decorated. Last, our model predicts that fimbrin detachment from actin endocytic structures is mechanosensitive to explain the extra peak observed in the dwell time distribution.
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Affiliation(s)
- Sayed Iman Mousavi
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
- Nanobiology Institute, Yale University, West Haven, Connecticut, USA
| | - Michael M Lacy
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
- Nanobiology Institute, Yale University, West Haven, Connecticut, USA
| | - Xiaobai Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
- Nanobiology Institute, Yale University, West Haven, Connecticut, USA
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
- Nanobiology Institute, Yale University, West Haven, Connecticut, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA
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3
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LaFoya B, Prehoda KE. Membrane oscillations driven by Arp2/3 constrict the intercellular bridge during neural stem cell divisions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.28.620743. [PMID: 39554021 PMCID: PMC11565815 DOI: 10.1101/2024.10.28.620743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/19/2024]
Abstract
After the first furrowing step of animal cell division, the nascent sibling cells remain connected by a thin intercellular bridge (ICB). In isolated cells nascent siblings migrate away from each other to generate tension and constrict the ICB, but less is known about how cells complete cytokinesis when constrained within tissues. We examined the ICBs formed by Drosophila larval brain neural stem cell (NSC) asymmetric divisions and find that they rely on constriction focused at the central midbody region rather than the flanking arms of isolated cell ICBs. Super-resolution, full volume imaging revealed unexpected oscillatory waves in plasma membrane sheets surrounding the ICB pore during its formation and constriction. We find that these membrane dynamics are driven by Arp2/3-dependent branched actin networks. Inhibition of Arp2/3 complex activity blocks membrane oscillations and prevents ICB formation and constriction. Our results identify a previously unrecognized role for localized membrane oscillations in ICB function when cells cannot generate tension through migration.
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Affiliation(s)
- Bryce LaFoya
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, 1229 University of Oregon, Eugene, OR 97403
| | - Kenneth E. Prehoda
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, 1229 University of Oregon, Eugene, OR 97403
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4
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Suo C, Gao Y, Yang S, Zhang W, Li C, Ma L, Xu Y, Lei J, Ding C, Li H, Zhang H, Sun T. The Endocytosis Adaptor Sla1 Facilitates Drug Susceptibility and Fungal Pathogenesis Through Sla1-Efg1 Regulating System in Candida albicans. Infect Drug Resist 2024; 17:4577-4588. [PMID: 39464835 PMCID: PMC11512525 DOI: 10.2147/idr.s483623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Accepted: 10/16/2024] [Indexed: 10/29/2024] Open
Abstract
Introduction The role of endocytosis in Candida albicans drug-resistance and pathogenicity remains poorly understood, despite its importance as a fundamental component of intracellular trafficking. Objective In order to understand the role of endocytosis in Candida albicans cell wall integrity, drug resistance, and virulence. Methods Detection of intracellular endocytosis by FM4-64 staining; Scanning electron microscopy is used to detect cell wall components; Spot assay for detecting drug sensitivity; Co-ip is used to detect protein interactions. Results In this study, we found the functions of Sla1 in regulating endocytosis is conserved among pathogenic fungi. Our results also revealed that the deletion of the SLA1 gene altered cell wall properties, composition, and gene expression. In addition, we showed that C. albicans Sla1 was responsible for hyphal development in vitro and for fungal pathogenicity in a murine infection model. Intriguingly, sla1∆/∆ mutant demonstrated enhanced drug resistance, and Sla1 was found to interact with the transcription factor Efg1; the relationship between Sla1 and Efg1 impacts the expression of genes encoding components of the ergosterol biosynthesis pathway, including ERG1, EGR11, and ERG25. Discussion These findings have expanded our knowledge of the capabilities of Sla1 beyond its role as an endocytosis adapter and provided insights into a potential new therapeutic target for the treatment of fungal infections.
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Affiliation(s)
- Chenhao Suo
- Laboratory Animal Department, Northern Theater General Hospital, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Yiru Gao
- College of Life and Health Science, Northeastern University, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Sheng Yang
- College of Life and Health Science, Northeastern University, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Wanli Zhang
- College of Life and Health Science, Northeastern University, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Chao Li
- Department of Emergency Medicine, the Second Affiliated Hospital of Army Medical University, Chongqing, 400037, People’s Republic of China
| | - Lanjing Ma
- College of Life and Health Science, Northeastern University, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Yingchun Xu
- Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, 100730, People’s Republic of China
- Medical Research Centre, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, 100730, People’s Republic of China
| | - Jianjun Lei
- Laboratory Animal Department, Northern Theater General Hospital, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Chen Ding
- College of Life and Health Science, Northeastern University, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Hailong Li
- Pulmonary and Critical Care Medicine, University of Michigan, Ann Arbor, MI, 48109, USA
| | - He Zhang
- Laboratory Animal Department, Northern Theater General Hospital, Shenyang, Liaoning, 110000, People’s Republic of China
| | - Tianshu Sun
- Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, 100730, People’s Republic of China
- Clinical Biobank, Medical Research Center, National Science and Technology Key Infrastructure on Translational Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, People’s Republic of China
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5
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Hill JM, Cai S, Carver MD, Drubin DG. A role for cross-linking proteins in actin filament network organization and force generation. Proc Natl Acad Sci U S A 2024; 121:e2407838121. [PMID: 39405356 PMCID: PMC11513903 DOI: 10.1073/pnas.2407838121] [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: 04/22/2024] [Accepted: 08/20/2024] [Indexed: 10/23/2024] Open
Abstract
The high turgor pressure across the plasma membrane of yeasts creates a requirement for substantial force production by actin polymerization and myosin motor activity for clathrin-mediated endocytosis (CME). Endocytic internalization is severely impeded in the absence of fimbrin, an actin filament crosslinking protein called Sac6 in budding yeast. Here, we combine live-cell imaging and mathematical modeling to gain insights into the role of actin filament crosslinking proteins in force generation. Genetic manipulation showed that CME sites with more crosslinking proteins are more effective at internalization under high load. Simulations of an experimentally constrained, agent-based mathematical model recapitulate the result that endocytic networks with more double-bound fimbrin molecules internalize the plasma membrane against elevated turgor pressure more effectively. Networks with large numbers of crosslinks also have more growing actin filament barbed ends at the plasma membrane, where the addition of new actin monomers contributes to force generation and vesicle internalization. Our results provide a richer understanding of the crucial role played by actin filament crosslinking proteins during actin network force generation, highlighting the contribution of these proteins to the self-organization of the actin filament network and force generation under increased load.
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Affiliation(s)
- Jennifer M. Hill
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Songlin Cai
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Michael D. Carver
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
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6
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Ramos M, Martín-García R, Curto MÁ, Gómez-Delgado L, Moreno MB, Sato M, Portales E, Osumi M, Rincón SA, Pérez P, Ribas JC, Cortés JC. Fission yeast Bgs1 glucan synthase participates in the control of growth polarity and membrane traffic. iScience 2024; 27:110477. [PMID: 39156640 PMCID: PMC11326927 DOI: 10.1016/j.isci.2024.110477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/14/2024] [Accepted: 07/05/2024] [Indexed: 08/20/2024] Open
Abstract
Rod-shaped fission yeast grows through cell wall expansion at poles and septum, synthesized by essential glucan synthases. Bgs1 synthesizes the linear β(1,3)glucan of primary septum at cytokinesis. Linear β(1,3)glucan is also present in the wall poles, suggesting additional Bgs1 roles in growth polarity. Our study reveals an essential collaboration between Bgs1 and Tea1-Tea4, but not other polarity factors, in controlling growth polarity. Simultaneous absence of Bgs1 function and Tea1-Tea4 causes complete loss of growth polarity, spread of other glucan synthases, and spherical cell formation, indicating this defect is specifically due to linear β(1,3)glucan absence. Furthermore, linear β(1,3)glucan absence induces actin patches delocalization and sterols spread, which are ultimately responsible for the growth polarity loss without Tea1-Tea4. This suggests strong similarities in Bgs1 functions controlling actin structures during cytokinesis and polarized growth. Collectively, our findings unveil that cell wall β(1,3)glucan regulates polarized growth, like the equivalent extracellular matrix in neuronal cells.
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Affiliation(s)
- Mariona Ramos
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Rebeca Martín-García
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - M. Ángeles Curto
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Laura Gómez-Delgado
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - M. Belén Moreno
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Mamiko Sato
- Laboratory of Electron Microscopy and Bio-imaging Center, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, Japan
| | - Elvira Portales
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Masako Osumi
- Laboratory of Electron Microscopy and Bio-imaging Center, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, Japan
- Integrated Imaging Research Support (IIRS), Villa Royal Hirakawa 103, 1-7-5 Hirakawa-cho, Chiyoda-ku, Tokyo, Japan
| | - Sergio A. Rincón
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Juan C. Ribas
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
| | - Juan C.G. Cortés
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad de Salamanca, Salamanca, Spain
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7
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Liu J. Roles of membrane mechanics-mediated feedback in membrane traffic. Curr Opin Cell Biol 2024; 89:102401. [PMID: 39018789 PMCID: PMC11297666 DOI: 10.1016/j.ceb.2024.102401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/23/2024] [Accepted: 06/26/2024] [Indexed: 07/19/2024]
Abstract
Synthesizing the recent progresses, we present our perspectives on how local modulations of membrane curvature, tension, and bending energy define the feedback controls over membrane traffic processes. We speculate the potential mechanisms of, and the control logic behind, the different membrane mechanics-mediated feedback in endocytosis and exo-endocytosis coupling. We elaborate the path forward with the open questions for theoretical considerations and the grand challenges for experimental validations.
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Affiliation(s)
- Jian Liu
- Department of Cell Biology, Center for Cell Dynamics, School of Medicine, Johns Hopkins University, Baltimore, MD, United States.
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8
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Hill JM, Cai S, Carver MD, Drubin DG. A Role for Cross-linking Proteins in Actin Filament Network Organization and Force Generation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.19.590161. [PMID: 38659919 PMCID: PMC11042252 DOI: 10.1101/2024.04.19.590161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The high turgor pressure across the plasma membrane of yeasts creates a requirement for substantial force production by actin polymerization and myosin motor activity for clathrin-mediated endocytosis (CME). Endocytic internalization is severely impeded in the absence of fimbrin, an actin filament crosslinking protein called Sac6 in budding yeast. Here, we combine live-cell imaging and mathematical modeling to gain new insights into the role of actin filament crosslinking proteins in force generation. Genetic manipulation showed that CME sites with more crosslinking proteins are more effective at internalization under high load. Simulations of an experimentally constrained, agent-based mathematical model recapitulate the result that endocytic networks with more double-bound fimbrin molecules internalize the plasma membrane against elevated turgor pressure more effectively. Networks with large numbers of crosslinks also have more growing actin filament barbed ends at the plasma membrane, where the addition of new actin monomers contributes to force generation and vesicle internalization. Our results provide a richer understanding of the crucial role played by actin filament crosslinking proteins during actin network force generation, highlighting the contribution of these proteins to the self-organization of the actin filament network and force generation under increased load.
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Affiliation(s)
- Jennifer M Hill
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Songlin Cai
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Michael D Carver
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
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9
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Narvaez-Ortiz HY, Lynch MJ, Liu SL, Fries A, Nolen BJ. Both Las17-binding sites on Arp2/3 complex are important for branching nucleation and assembly of functional endocytic actin networks in S. cerevisiae. J Biol Chem 2024; 300:105766. [PMID: 38367669 PMCID: PMC10944109 DOI: 10.1016/j.jbc.2024.105766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 02/07/2024] [Accepted: 02/12/2024] [Indexed: 02/19/2024] Open
Abstract
Arp2/3 complex nucleates branched actin filaments that drive membrane invagination during endocytosis and leading-edge protrusion in lamellipodia. Arp2/3 complex is maximally activated in vitro by binding of a WASP family protein to two sites-one on the Arp3 subunit and one spanning Arp2 and ARPC1-but the importance of each site in the regulation of force-producing actin networks is unclear. Here, we identify mutations in budding yeast Arp2/3 complex that decrease or block engagement of Las17, the budding yeast WASP, at each site. As in the mammalian system, both sites are required for maximal activation in vitro. Dimerization of Las17 partially restores activity of mutations at both CA-binding sites. Arp2/3 complexes defective at either site assemble force-producing actin networks in a bead motility assay, but their reduced activity hinders motility by decreasing actin assembly near the bead surface and by failing to suppress actin filament bundling within the networks. While even the most defective Las17-binding site mutants assembled actin filaments at endocytic sites, they showed significant internalization defects, potentially because they lack the proper architecture to drive plasma membrane remodeling. Together, our data indicate that both Las17-binding sites are important to assemble functional endocytic actin networks in budding yeast, but Arp2/3 complex retains some activity in vitro and in vivo even with a severe defect at either Las17-binding site.
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Affiliation(s)
- Heidy Y Narvaez-Ortiz
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Michael J Lynch
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Su-Ling Liu
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Adam Fries
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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10
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Basant A, Way M. The amount of Nck rather than N-WASP correlates with the rate of actin-based motility of Vaccinia virus. Microbiol Spectr 2023; 11:e0152923. [PMID: 37855608 PMCID: PMC10883800 DOI: 10.1128/spectrum.01529-23] [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: 04/11/2023] [Accepted: 09/03/2023] [Indexed: 10/20/2023] Open
Abstract
IMPORTANCE Vaccinia virus is a large double-stranded DNA virus and a close relative of Mpox and Variola virus, the causative agent of smallpox. During infection, Vaccinia hijacks its host's transport systems and promotes its spread into neighboring cells by recruiting a signaling network that stimulates actin polymerization. Over the years, Vaccinia has provided a powerful model to understand how signaling networks regulate actin polymerization. Nevertheless, we still lack important quantitative information about the system, including the precise number of viral and host molecules required to induce actin polymerization. Using quantitative fluorescence microscopy techniques, we have determined the number of viral and host signaling proteins accumulating on virions during their egress. Our analysis has uncovered two unexpected new aspects of this process: the number of viral proteins in the virion is not fixed and the velocity of virus movement depends on the level of a single adaptor within the signaling network.
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Affiliation(s)
- Angika Basant
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute , London, United Kingdom
| | - Michael Way
- Cellular Signalling and Cytoskeletal Function Laboratory, The Francis Crick Institute , London, United Kingdom
- Department of Infectious Disease, Imperial College , London, United Kingdom
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11
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Ren Y, Yang J, Fujita B, Jin H, Zhang Y, Berro J. Force redistribution in clathrin-mediated endocytosis revealed by coiled-coil force sensors. SCIENCE ADVANCES 2023; 9:eadi1535. [PMID: 37831774 PMCID: PMC10575576 DOI: 10.1126/sciadv.adi1535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/13/2023] [Indexed: 10/15/2023]
Abstract
Forces are central to countless cellular processes, yet in vivo force measurement at the molecular scale remains difficult if not impossible. During clathrin-mediated endocytosis, forces produced by the actin cytoskeleton are transmitted to the plasma membrane by a multiprotein coat for membrane deformation. However, the magnitudes of these forces remain unknown. Here, we present new in vivo force sensors that induce protein condensation under force. We measured the forces on the fission yeast Huntingtin-Interacting Protein 1 Related (HIP1R) homolog End4p, a protein that links the membrane to the actin cytoskeleton. End4p is under ~19-piconewton force near the actin cytoskeleton, ~11 piconewtons near the clathrin lattice, and ~9 piconewtons near the plasma membrane. Our results demonstrate that forces are collected and redistributed across the endocytic machinery.
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Affiliation(s)
- Yuan Ren
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
- Nanobiology Institute, Yale University, West Haven, CT 06516, USA
| | - Jie Yang
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Barbara Fujita
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
- Nanobiology Institute, Yale University, West Haven, CT 06516, USA
| | - Huaizhou Jin
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Yongli Zhang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
- Nanobiology Institute, Yale University, West Haven, CT 06516, USA
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
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12
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Pedersen RT, Snoberger A, Pyrpassopoulos S, Safer D, Drubin DG, Ostap EM. Endocytic myosin-1 is a force-insensitive, power-generating motor. J Cell Biol 2023; 222:e202303095. [PMID: 37549220 PMCID: PMC10406613 DOI: 10.1083/jcb.202303095] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/17/2023] [Accepted: 07/24/2023] [Indexed: 08/09/2023] Open
Abstract
Myosins are required for clathrin-mediated endocytosis, but their precise molecular roles in this process are not known. This is, in part, because the biophysical properties of the relevant motors have not been investigated. Myosins have diverse mechanochemical activities, ranging from powerful contractility against mechanical loads to force-sensitive anchoring. To better understand the essential molecular contribution of myosin to endocytosis, we studied the in vitro force-dependent kinetics of the Saccharomyces cerevisiae endocytic type I myosin called Myo5, a motor whose role in clathrin-mediated endocytosis has been meticulously studied in vivo. We report that Myo5 is a low-duty-ratio motor that is activated ∼10-fold by phosphorylation and that its working stroke and actin-detachment kinetics are relatively force-insensitive. Strikingly, the in vitro mechanochemistry of Myo5 is more like that of cardiac myosin than that of slow anchoring myosin-1s found on endosomal membranes. We, therefore, propose that Myo5 generates power to augment actin assembly-based forces during endocytosis in cells.
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Affiliation(s)
- Ross T.A. Pedersen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Aaron Snoberger
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Serapion Pyrpassopoulos
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Daniel Safer
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - E. Michael Ostap
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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13
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Lemière J, Chang F. Quantifying turgor pressure in budding and fission yeasts based upon osmotic properties. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.07.544129. [PMID: 37333400 PMCID: PMC10274794 DOI: 10.1101/2023.06.07.544129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Walled cells, such as plants, fungi, and bacteria cells, possess a high internal hydrostatic pressure, termed turgor pressure, that drives volume growth and contributes to cell shape determination. Rigorous measurement of turgor pressure, however, remains challenging, and reliable quantitative measurements, even in budding yeast are still lacking. Here, we present a simple and robust experimental approach to access turgor pressure in yeasts based upon the determination of isotonic concentration using protoplasts as osmometers. We propose three methods to identify the isotonic condition - 3D cell volume, cytoplasmic fluorophore intensity, and mobility of a cytGEMs nano-rheology probe - that all yield consistent values. Our results provide turgor pressure estimates of 1.0 ± 0.1 MPa for S. pombe, 0.49 ± 0.01 MPa for S. japonicus, 0.5 ± 0.1 MPa for S. cerevisiae W303a and 0.31 ± 0.03 MPa for S. cerevisiae BY4741. Large differences in turgor pressure and nano-rheology measurements between the S. cerevisiae strains demonstrate how fundamental biophysical parameters can vary even among wildtype strains of the same species. These side-by-side measurements of turgor pressure in multiple yeast species provide critical values for quantitative studies on cellular mechanics and comparative evolution.
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Affiliation(s)
- Joël Lemière
- Department of Cell and Tissue Biology, University of San Francisco, CA, USA
| | - Fred Chang
- Department of Cell and Tissue Biology, University of San Francisco, CA, USA
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14
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Willet AH, Chen JS, Ren L, Gould KL. Membrane binding of endocytic myosin-1s is inhibited by a class of ankyrin repeat proteins. Mol Biol Cell 2023; 34:br17. [PMID: 37531259 PMCID: PMC10559312 DOI: 10.1091/mbc.e23-06-0233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/24/2023] [Accepted: 07/27/2023] [Indexed: 08/04/2023] Open
Abstract
Myosin-1s are monomeric actin-based motors that function at membranes. Myo1 is the single myosin-1 isoform in Schizosaccharomyces pombe that works redundantly with Wsp1-Vrp1 to activate the Arp2/3 complex for endocytosis. Here, we identified Ank1 as an uncharacterized cytoplasmic Myo1 binding partner. We found that in ank1Δ cells, Myo1 dramatically redistributed from endocytic patches to decorate the entire plasma membrane and endocytosis was defective. Biochemical analysis and structural predictions suggested that the Ank1 ankyrin repeats bind the Myo1 lever arm and the Ank1 acidic tail binds the Myo1 TH1 domain to prevent TH1-dependent Myo1 membrane binding. Indeed, Ank1 overexpression precluded Myo1 membrane localization and recombinant Ank1 reduced purified Myo1 liposome binding in vitro. Based on biochemical and cell biological analyses, we propose budding yeast Ank1 and human OSTF1 are functional Ank1 orthologs and that cytoplasmic sequestration by small ankyrin repeat proteins is a conserved mechanism regulating myosin-1s in endocytosis.
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Affiliation(s)
- Alaina H. Willet
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Jun-Song Chen
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Liping Ren
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
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15
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Stoops EH, Ferrin MA, Jorgens DM, Drubin DG. Self-organizing actin networks drive sequential endocytic protein recruitment and vesicle release on synthetic lipid bilayers. Proc Natl Acad Sci U S A 2023; 120:e2302622120. [PMID: 37216532 PMCID: PMC10235984 DOI: 10.1073/pnas.2302622120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/21/2023] [Indexed: 05/24/2023] Open
Abstract
Forces generated by actin assembly assist membrane invagination during clathrin-mediated endocytosis (CME). The sequential recruitment of core endocytic proteins and regulatory proteins, and assembly of the actin network, are well documented in live cells and are highly conserved from yeasts to humans. However, understanding of CME protein self-organization, as well as the biochemical and mechanical principles that underlie actin's role in CME, is lacking. Here, we show that supported lipid bilayers coated with purified yeast Wiskott Aldrich Syndrome Protein (WASP), an endocytic actin assembly regulator, and incubated in cytoplasmic yeast extracts, recruit downstream endocytic proteins and assemble actin networks. Time-lapse imaging of WASP-coated bilayers revealed sequential recruitment of proteins from different endocytic modules, faithfully replicating in vivo behavior. Reconstituted actin networks assemble in a WASP-dependent manner and deform lipid bilayers, as seen by electron microscopy. Time-lapse imaging revealed that vesicles are released from the lipid bilayers with a burst of actin assembly. Actin networks pushing on membranes have previously been reconstituted; here, we have reconstituted a biologically important variation of these actin networks that self-organize on bilayers and produce pulling forces sufficient to bud off membrane vesicles. We propose that actin-driven vesicle generation may represent an ancient evolutionary precursor to diverse vesicle forming processes adapted for a wide array of cellular environments and applications.
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Affiliation(s)
- Emily H. Stoops
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Michael A. Ferrin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | | | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
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16
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Willet AH, Chen JS, Ren L, Gould KL. Membrane binding of endocytic myosin-1s is inhibited by a class of ankyrin repeat proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.26.538419. [PMID: 37163016 PMCID: PMC10168314 DOI: 10.1101/2023.04.26.538419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Myosin-1s are monomeric actin-based motors that function at membranes. Myo1 is the single myosin-1 isoform in Schizosaccharomyces pombe that works redundantly with Wsp1-Vrp1 to activate the Arp2/3 complex for endocytosis. Here, we identified Ank1 as an uncharacterized cytoplasmic Myo1 binding partner. We found that in ank1Δ cells, Myo1 dramatically redistributed from endocytic patches to decorate the entire plasma membrane and endocytosis was defective. Biochemical analysis and structural predictions suggested that the Ank1 ankyrin repeats bind the Myo1 lever arm and the Ank1 acidic tail binds the Myo1 TH1 domain to prevent TH1-dependent Myo1 membrane binding. Indeed, Ank1 over-expression precluded Myo1 membrane localization and recombinant Ank1 blocked purified Myo1 liposome binding in vitro. Based on biochemical and cell biology analyses, we propose budding yeast Ank1 and human OSTF1 are functional Ank1 orthologs and that cytoplasmic sequestration by small ankyrin repeat proteins is a conserved mechanism regulating myosin-1s in endocytosis. Summary Fission yeast long-tailed myosin-1 binds Ank1. Ank1 ankyrin repeats associate with the Myo1 lever arm and Ank1 acidic tail binds the Myo1 TH1 domain to inhibit Myo1 membrane binding. Ank1 orthologs exists in budding yeast (Ank1) and humans (OSTF1).
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Affiliation(s)
- Alaina H Willet
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Jun-Song Chen
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Liping Ren
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
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17
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Liu PJ, Gunther LK, Garone ME, Zhang C, Perez D, Bi-Karchin J, Pellenz CD, Chase SE, Presti MF, Plante EL, Martin CE, Lovric S, Yengo CM, Hildebrandt F, Krendel M. Steroid-Resistant Nephrotic Syndrome-Associated MYO1E Mutations Have Differential Effects on Myosin 1e Localization, Dynamics, and Activity. J Am Soc Nephrol 2022; 33:1989-2007. [PMID: 36316095 PMCID: PMC9678034 DOI: 10.1681/asn.2021111505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 08/22/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Myo1e is a nonmuscle motor protein enriched in podocytes. Mutations in MYO1E are associated with steroid-resistant nephrotic syndrome (SRNS). Most of the MYO1E variants identified by genomic sequencing have not been functionally characterized. Here, we set out to analyze two mutations in the Myo1e motor domain, T119I and D388H, which were selected on the basis of protein sequence conservation. METHODS EGFP-tagged human Myo1e constructs were delivered into the Myo1e-KO mouse podocyte-derived cells via adenoviral infection to analyze Myo1e protein stability, Myo1e localization, and clathrin-dependent endocytosis, which is known to involve Myo1e activity. Furthermore, truncated Myo1e constructs were expressed using the baculovirus expression system and used to measure Myo1e ATPase and motor activity in vitro. RESULTS Both mutants were expressed as full-length proteins in the Myo1e-KO cells. However, unlike wild-type (WT) Myo1e, the T119I variant was not enriched at the cell junctions or clathrin-coated vesicles (CCVs). In contrast, D388H variant localization was similar to that of WT. The rate of dissociation of the D388H variant from cell-cell junctions and CCVs was decreased, suggesting this mutation affects Myo1e interactions with binding partners. ATPase activity and ability to translocate actin filaments were drastically reduced for the D388H mutant, supporting findings from cell-based experiments. CONCLUSIONS T119I and D388H mutations are deleterious to Myo1e functions. The experimental approaches used in this study can be applied to future characterization of novel MYO1E variants associated with SRNS.
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Affiliation(s)
- Pei-Ju Liu
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Laura K. Gunther
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
| | - Michael E. Garone
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Chunling Zhang
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York
| | - Diana Perez
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Jing Bi-Karchin
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Christopher D. Pellenz
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Sharon E. Chase
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Maria F. Presti
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Eric L. Plante
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Claire E. Martin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario, Canada
| | - Svjetlana Lovric
- Divison of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
| | - Friedhelm Hildebrandt
- Divison of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
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18
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Skruzny M. The endocytic protein machinery as an actin-driven membrane-remodeling machine. Eur J Cell Biol 2022; 101:151267. [PMID: 35970066 DOI: 10.1016/j.ejcb.2022.151267] [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: 06/02/2022] [Revised: 08/02/2022] [Accepted: 08/02/2022] [Indexed: 12/14/2022] Open
Abstract
In clathrin-mediated endocytosis, a principal membrane trafficking route of all eukaryotic cells, forces are applied to invaginate the plasma membrane and form endocytic vesicles. These forces are provided by specific endocytic proteins and the polymerizing actin cytoskeleton. One of the best-studied endocytic systems is endocytosis in yeast, known for its simplicity, experimental amenability, and overall similarity to human endocytosis. Importantly, the yeast endocytic protein machinery generates and transmits tremendous force to bend the plasma membrane, making this system beneficial for mechanistic studies of cellular force-driven membrane reshaping. This review summarizes important protein players, molecular functions, applied forces, and open questions and perspectives of this robust, actin-powered membrane-remodeling protein machine.
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Affiliation(s)
- Michal Skruzny
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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19
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Liu SL, Narvaez-Ortiz HY, Miner M, Kiemel J, Oberhelman N, Watt A, Wagner AR, Luan Q, Helgeson LA, Nolen BJ. Analysis of functional surfaces on the actin nucleation promoting factor Dip1 required for Arp2/3 complex activation and endocytic actin network assembly. J Biol Chem 2022; 298:102019. [PMID: 35533728 PMCID: PMC9168731 DOI: 10.1016/j.jbc.2022.102019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 11/30/2022] Open
Abstract
Arp2/3 complex nucleates branched actin filaments that drive processes like endocytosis and lamellipodial protrusion. WISH/DIP/SPIN90 (WDS) proteins form a class of Arp2/3 complex activators or nucleation promoting factors (NPFs) that, unlike WASP family NPFs, activate Arp2/3 complex without requiring preformed actin filaments. Therefore, activation of Arp2/3 complex by WDS proteins is thought to produce the initial actin filaments that seed branching nucleation by WASP-bound Arp2/3 complexes. However, whether activation of Arp2/3 complex by WDS proteins is important for the initiation of branched actin assembly in cells has not been directly tested. Here, we used structure-based point mutations of the Schizosaccharomyces pombe WDS protein Dip1 to test the importance of its Arp2/3-activating activity in cells. Six of thirteen Dip1 mutants caused severe defects in Arp2/3 complex activation in vitro, and we found a strong correlation between the ability of mutants to activate Arp2/3 complex and to rescue endocytic actin assembly defects caused by deleting Dip1. These data support a model in which Dip1 activates Arp2/3 complex to produce actin filaments that initiate branched actin assembly at endocytic sites. Dip1 mutants that synergized with WASP in activating Arp2/3 complex in vitro showed milder defects in cells compared to those that did not, suggesting that in cells the two NPFs may coactivate Arp2/3 complex to initiate actin assembly. Finally, the mutational data reveal important complementary electrostatic contacts at the Dip1-Arp2/3 complex interface and corroborate the previously proposed wedge model, which describes how Dip1 binding triggers structural changes that activate Arp2/3 complex.
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Affiliation(s)
- Su-Ling Liu
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Heidy Y Narvaez-Ortiz
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Matt Miner
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Jack Kiemel
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Nicholas Oberhelman
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - April Watt
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Andrew R Wagner
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Qing Luan
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Luke A Helgeson
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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20
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Structure of Arp2/3 complex at a branched actin filament junction resolved by single-particle cryo-electron microscopy. Proc Natl Acad Sci U S A 2022; 119:e2202723119. [PMID: 35622886 DOI: 10.1073/pnas.2202723119] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
SignificanceActin filament nucleation by Arp2/3 complex must be triggered by activators like WASP family proteins. Understanding how WASP proteins activate Arp2/3 complex has been a major challenge due to a lack of high-resolution structures of the complex in an activated state. We determined a high-resolution (∼3.9 Å) structure of the WASP-activated Arp2/3 complex at a branch junction and used biochemical, cell biological, and molecular dynamic simulations to understand the mechanism of WASP-mediated activation. This work shows in detail the contacts between the fully activated Arp2/3 complex, the nucleated daughter actin filament, and the mother actin filament and provides important insights into how conformational rearrangements in the Arp2/3 complex are stimulated during activation.
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21
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Nickaeen M, Berro J, Pollard TD, Slepchenko BM. A model of actin-driven endocytosis explains differences of endocytic motility in budding and fission yeast. Mol Biol Cell 2022; 33:ar16. [PMID: 34910589 PMCID: PMC9250386 DOI: 10.1091/mbc.e21-07-0362] [Citation(s) in RCA: 1] [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: 07/20/2021] [Revised: 11/23/2021] [Accepted: 12/10/2021] [Indexed: 11/15/2022] Open
Abstract
A comparative study (Sun et al., 2019) showed that the abundance of proteins at sites of endocytosis in fission and budding yeast is more similar in the two species than previously thought, yet membrane invaginations in fission yeast elongate twofold faster and are nearly twice as long as in budding yeast. Here we use a three-dimensional model of a motile endocytic invagination (Nickaeen et al., 2019) to investigate factors affecting elongation of the invaginations. We found that differences in turgor pressure in the two yeast species can largely explain the paradoxical differences observed experimentally in endocytic motility.
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Affiliation(s)
- Masoud Nickaeen
- Richard D. Berlin Center for Cell Analysis and Modeling, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Yale University, and Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06511, and
- Nanobiology Institute, Yale University, New Haven, CT 06520
| | - Thomas D. Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University
- Department of Molecular Biophysics and Biochemistry, Yale University, and Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06511, and
| | - Boris M. Slepchenko
- Richard D. Berlin Center for Cell Analysis and Modeling, Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030
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22
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Ren Y, Berro J. Isolated THATCH domain of End4 is unable to bind F-actin independently in the fission yeast Schizosaccharomyces pombe. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000508. [PMID: 35024575 PMCID: PMC8738963 DOI: 10.17912/micropub.biology.000508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/03/2022] [Accepted: 01/03/2022] [Indexed: 11/06/2022]
Abstract
Clathrin mediated endocytosis (CME) in the fission yeast Schizosaccharomyces pombe critically depends on the connection between the lipid membrane and F-actin. The fission yeast endocytic protein End4 (homologous to Sla2 in budding yeast and HIP1R in human) contains a N-terminal domain that binds to PIP2 on the membrane, and a C-terminal THATCH domain that is postulated to be a binding partner of F-actin in vivo. Purified THATCH domain of the budding yeast Sla2, however, shows low affinity to F-actin in vitro. We tested if isolated THATCH domain still has low affinity to F-actin in vivo, using TEV protease (TEVp)-mediated protein cleaving to separate the THATCH domain from the rest of End4. Our results indicate that the isolated THATCH domain of End4 is unable to bind F-actin independently in vivo, consistent with the low affinity of the THATCH domain to F-actin measured from in vitro binding assays.
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Affiliation(s)
- Yuan Ren
- Department of Molecular Biophysics and Biochemistry, Yale University
- Nanobiology Institute, Yale University
| | - Julien Berro
- Department of Molecular Biophysics and Biochemistry, Yale University
- Nanobiology Institute, Yale University
- Department of Cell Biology, Yale University School of Medicine
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23
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Abella M, Andruck L, Malengo G, Skruzny M. Actin-generated force applied during endocytosis measured by Sla2-based FRET tension sensors. Dev Cell 2021; 56:2419-2426.e4. [PMID: 34473942 DOI: 10.1016/j.devcel.2021.08.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/27/2021] [Accepted: 08/11/2021] [Indexed: 11/17/2022]
Abstract
Mechanical forces are integral to many cellular processes, including clathrin-mediated endocytosis, a principal membrane trafficking route into the cell. During endocytosis, forces provided by endocytic proteins and the polymerizing actin cytoskeleton reshape the plasma membrane into a vesicle. Assessing force requirements of endocytic membrane remodeling is essential for understanding endocytosis. Here, we determined actin-generated force applied during endocytosis using FRET-based tension sensors inserted into the major force-transmitting protein Sla2 in yeast. We measured at least 8 pN force transmitted over Sla2 molecule, hence possibly more than 300-880 pN applied during endocytic vesicle formation. Importantly, decreasing cell turgor pressure and plasma membrane tension reduced force transmitted over the Sla2. The measurements in hypotonic conditions and mutants lacking BAR-domain membrane scaffolds then showed the limits of the endocytic force-transmitting machinery. Our study provides force values and force profiles critical for understanding the mechanics of endocytosis and potentially other key cellular membrane-remodeling processes.
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Affiliation(s)
- Marc Abella
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
| | - Lynell Andruck
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
| | - Gabriele Malengo
- Flow Cytometry and Imaging Facility, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany
| | - Michal Skruzny
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany; LOEWE Center for Synthetic Microbiology (SYNMIKRO), 35043 Marburg, Germany.
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24
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Chakrabarti R, Lee M, Higgs HN. Multiple roles for actin in secretory and endocytic pathways. Curr Biol 2021; 31:R603-R618. [PMID: 34033793 DOI: 10.1016/j.cub.2021.03.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Actin filaments play multiple roles in the secretory pathway and in endosome dynamics in mammals, including maintenance of Golgi structure, release of membrane cargo from the trans-Golgi network (TGN), endocytosis, and endosomal sorting dynamics. In addition, TGN carrier transport and endocytosis both occur by multiple mechanisms in mammals. Actin likely plays a role in at least four mammalian endocytic pathways, five pathways for membrane release from the TGN, and three processes involving endosomes. Also, the mammalian Golgi structure is highly dynamic, and actin is likely important for these dynamics. One challenge for many of these processes is the need to deal with other membrane-associated structures, such as the cortical actin network at the plasma membrane or the matrix that surrounds the Golgi. Arp2/3 complex is a major actin assembly factor in most of the processes mentioned, but roles for formins and tandem WH2-motif-containing assembly factors are being elucidated and are anticipated to grow with further study. The specific role for actin has not been defined for most of these processes, but is likely to involve the generation of force for membrane dynamics, either by actin polymerization itself or by myosin motor activity. Defining these processes mechanistically is necessary for understanding membrane dynamics in general, as well as pathways that utilize these processes, such as autophagy.
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Affiliation(s)
- Rajarshi Chakrabarti
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Miriam Lee
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Henry N Higgs
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
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25
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Papalazarou V, Machesky LM. The cell pushes back: The Arp2/3 complex is a key orchestrator of cellular responses to environmental forces. Curr Opin Cell Biol 2021; 68:37-44. [PMID: 32977244 PMCID: PMC7938217 DOI: 10.1016/j.ceb.2020.08.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/21/2022]
Abstract
The Arp2/3 complex orchestrates the formation of branched actin networks at the interface between the cytoplasm and membranes. Although it is widely appreciated that these networks are useful for scaffolding, creating pushing forces and delineating zones at the membrane interface, it has only recently come to light that branched actin networks are mechanosensitive, giving them special properties. Here, we discuss recent advances in our understanding of how Arp2/3-generated actin networks respond to load forces and thus allow cells to create pushing forces in responsive and tuneable ways to effect cellular processes such as migration, invasion, phagocytosis, adhesion and even nuclear and DNA damage repair.
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Affiliation(s)
- Vassilis Papalazarou
- CRUK Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK
| | - Laura M Machesky
- CRUK Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, UK; Institute of Cancer Sciences, Garscube Estate, University of Glasgow, Glasgow, G61 1BD, UK.
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26
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Balzer CJ, James ML, Narvaez-Ortiz HY, Helgeson LA, Sirotkin V, Nolen BJ. Synergy between Wsp1 and Dip1 may initiate assembly of endocytic actin networks. eLife 2020; 9:60419. [PMID: 33179595 PMCID: PMC7707826 DOI: 10.7554/elife.60419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/10/2020] [Indexed: 12/30/2022] Open
Abstract
The actin filament nucleator Arp2/3 complex is activated at cortical sites in Schizosaccharomyces pombe to assemble branched actin networks that drive endocytosis. Arp2/3 complex activators Wsp1 and Dip1 are required for proper actin assembly at endocytic sites, but how they coordinately control Arp2/3-mediated actin assembly is unknown. Alone, Dip1 activates Arp2/3 complex without preexisting actin filaments to nucleate ‘seed’ filaments that activate Wsp1-bound Arp2/3 complex, thereby initiating branched actin network assembly. In contrast, because Wsp1 requires preexisting filaments to activate, it has been assumed to function exclusively in propagating actin networks by stimulating branching from preexisting filaments. Here we show that Wsp1 is important not only for propagation but also for initiation of endocytic actin networks. Using single molecule total internal reflection fluorescence microscopy we show that Wsp1 synergizes with Dip1 to co-activate Arp2/3 complex. Synergistic co-activation does not require preexisting actin filaments, explaining how Wsp1 contributes to actin network initiation in cells.
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Affiliation(s)
- Connor J Balzer
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Michael L James
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, United States
| | - Heidy Y Narvaez-Ortiz
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Luke A Helgeson
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Vladimir Sirotkin
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, United States
| | - Brad J Nolen
- Department of Chemistry and Biochemistry, Institute of Molecular Biology, University of Oregon, Eugene, United States
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Pedersen RTA, Hassinger JE, Marchando P, Drubin DG. Spatial regulation of clathrin-mediated endocytosis through position-dependent site maturation. J Cell Biol 2020; 219:211446. [PMID: 33053166 PMCID: PMC7545360 DOI: 10.1083/jcb.202002160] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/08/2020] [Accepted: 09/04/2020] [Indexed: 12/17/2022] Open
Abstract
During clathrin-mediated endocytosis (CME), over 50 different proteins assemble on the plasma membrane to reshape it into a cargo-laden vesicle. It has long been assumed that cargo triggers local CME site assembly in Saccharomyces cerevisiae based on the discovery that cortical actin patches, which cluster near exocytic sites, are CME sites. Quantitative imaging data reported here lead to a radically different view of which CME steps are regulated and which steps are deterministic. We quantitatively and spatially describe progression through the CME pathway and pinpoint a cargo-sensitive regulatory transition point that governs progression from the initiation phase of CME to the internalization phase. Thus, site maturation, rather than site initiation, accounts for the previously observed polarized distribution of actin patches in this organism. While previous studies suggested that cargo ensures its own internalization by regulating either CME initiation rates or frequency of abortive events, our data instead identify maturation through a checkpoint in the pathway as the cargo-sensitive step.
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Affiliation(s)
- Ross T A Pedersen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Julian E Hassinger
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA.,Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA
| | - Paul Marchando
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
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28
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Briant K, Redlingshöfer L, Brodsky FM. Clathrin's life beyond 40: Connecting biochemistry with physiology and disease. Curr Opin Cell Biol 2020; 65:141-149. [PMID: 32836101 DOI: 10.1016/j.ceb.2020.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/23/2020] [Accepted: 06/27/2020] [Indexed: 01/21/2023]
Abstract
Understanding of the range and mechanisms of clathrin functions has developed exponentially since clathrin's discovery in 1975. Here, newly established molecular mechanisms that regulate clathrin activity and connect clathrin pathways to differentiation, disease and physiological processes such as glucose metabolism are reviewed. Diversity and commonalities of clathrin pathways across the tree of life reveal species-specific differences enabling functional plasticity in both membrane traffic and cytokinesis. New structural information on clathrin coat formation and cargo interactions emphasises the interplay between clathrin, adaptor proteins, lipids and cargo, and how this interplay regulates quality control of clathrin's function and is compromised in infection and neurological disease. Roles for balancing clathrin-mediated cargo transport are defined in stem cell development and additional disease states.
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Affiliation(s)
- Kit Briant
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck and University College London, 14 Malet Street, London WC1E 7HX, UK
| | - Lisa Redlingshöfer
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck and University College London, 14 Malet Street, London WC1E 7HX, UK
| | - Frances M Brodsky
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck and University College London, 14 Malet Street, London WC1E 7HX, UK.
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29
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Skruzny M, Pohl E, Gnoth S, Malengo G, Sourjik V. The protein architecture of the endocytic coat analyzed by FRET microscopy. Mol Syst Biol 2020; 16:e9009. [PMID: 32400111 PMCID: PMC7218409 DOI: 10.15252/msb.20199009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/16/2022] Open
Abstract
Endocytosis is a fundamental cellular trafficking pathway, which requires an organized assembly of the multiprotein endocytic coat to pull the plasma membrane into the cell. Although the protein composition of the endocytic coat is known, its functional architecture is not well understood. Here, we determine the nanoscale organization of the endocytic coat by FRET microscopy in yeast Saccharomyces cerevisiae. We assessed pairwise proximities of 18 conserved coat-associated proteins and used clathrin subunits and protein truncations as molecular rulers to obtain a high-resolution protein map of the coat. Furthermore, we followed rearrangements of coat proteins during membrane invagination and their binding dynamics at the endocytic site. We show that the endocytic coat proteins are not confined inside the clathrin lattice, but form distinct functional layers above and below the lattice. Importantly, key endocytic proteins transverse the clathrin lattice deeply into the cytoplasm connecting thus the membrane and cytoplasmic parts of the coat. We propose that this design enables an efficient and regulated function of the endocytic coat during endocytic vesicle formation.
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Affiliation(s)
- Michal Skruzny
- Department of Systems and Synthetic MicrobiologyMax Planck Institute for Terrestrial MicrobiologyMarburgGermany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO)MarburgGermany
| | - Emma Pohl
- Department of Systems and Synthetic MicrobiologyMax Planck Institute for Terrestrial MicrobiologyMarburgGermany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO)MarburgGermany
| | - Sandina Gnoth
- Department of Systems and Synthetic MicrobiologyMax Planck Institute for Terrestrial MicrobiologyMarburgGermany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO)MarburgGermany
| | - Gabriele Malengo
- Department of Systems and Synthetic MicrobiologyMax Planck Institute for Terrestrial MicrobiologyMarburgGermany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO)MarburgGermany
| | - Victor Sourjik
- Department of Systems and Synthetic MicrobiologyMax Planck Institute for Terrestrial MicrobiologyMarburgGermany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO)MarburgGermany
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