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El Alaoui F, Al-Akiki I, Ibanes S, Lyonnais S, Sanchez-Fuentes D, Desgarceaux R, Cazevieille C, Blanchard MP, Parmeggiani A, Carretero-Genevrier A, Piatti S, Picas L. Septin assemblies promote the lipid organization of membranes. Structure 2025; 33:451-464.e5. [PMID: 39892381 DOI: 10.1016/j.str.2025.01.005] [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: 05/02/2024] [Revised: 12/10/2024] [Accepted: 01/07/2025] [Indexed: 02/03/2025]
Abstract
Cytoskeletal-mediated membrane compartmentalization is essential to support cellular functions, from signaling to cell division, migration, or phagocytosis. Septins are cytoskeletal proteins that directly interact with membranes, acting as scaffolds to recruit proteins to cellular locations and as structural diffusion barriers. How septins interact with and remodel the lipid organization of membranes is unclear. Here, we combined minimal reconstituted systems and yeast cell imaging to study septin-mediated membrane organization. Our results show that at low concentrations membrane-diffusive septins self-assemble into sub-micrometric patches that co-exist with the septin collar at the division site. We found that patches are made of short septin filaments and that are able to modulate the lipid organization of membranes. Furthermore, we show that the polybasic domain of Cdc11 influences the membrane-organizing and curvature-sensing properties of septins. Collectively, our work provides understanding of the molecular mechanisms by which septins can support cellular functions intimately linked to membranes.
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Affiliation(s)
- Fatima El Alaoui
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier - CNRS UMR 9004, Montpellier, France
| | - Isabelle Al-Akiki
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier - CNRS UMR 9004, Montpellier, France
| | - Sandy Ibanes
- Centre de Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier - CNRS UMR UMR 5237, Montpellier, France
| | - Sébastien Lyonnais
- Centre d'Etudes des Maladies Infectieuses et Pharmacologie Anti-Infectieuse (CEMIPAI), Université de Montpellier, UAR 3725 CNRS, Montpellier, France
| | - David Sanchez-Fuentes
- Institut d'Électronique et des Systèmes (IES), Université de Montpellier - CNRS UMR 5214, Montpellier, France
| | - Rudy Desgarceaux
- Institut d'Électronique et des Systèmes (IES), Université de Montpellier - CNRS UMR 5214, Montpellier, France
| | - Chantal Cazevieille
- COMET Electron Microscopy Platform, Institute for Neurosciences of Montpellier (INM), Université de Montpellier, INSERM U 1298, Montpellier, France
| | - Marie-Pierre Blanchard
- Montpellier Ressources Imagerie, BioCampus Montpellier, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Andrea Parmeggiani
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, Montpellier, France
| | - Adrian Carretero-Genevrier
- Institut d'Électronique et des Systèmes (IES), Université de Montpellier - CNRS UMR 5214, Montpellier, France
| | - Simonetta Piatti
- Centre de Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier - CNRS UMR UMR 5237, Montpellier, France
| | - Laura Picas
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier - CNRS UMR 9004, Montpellier, France.
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Magliozzi JO, Runyan LA, Dutta P, Hoeprich GJ, Goode BL. Sequential recruitment of F-BAR proteins controls cytoskeletal crosstalk at the yeast bud neck. Curr Biol 2025; 35:574-590.e10. [PMID: 39798561 PMCID: PMC11794016 DOI: 10.1016/j.cub.2024.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2024] [Revised: 11/14/2024] [Accepted: 12/04/2024] [Indexed: 01/15/2025]
Abstract
In vivo functions of the septin and actin cytoskeletons are closely intertwined, yet the mechanisms underlying septin-actin crosstalk have remained poorly understood. Here, we show that the yeast-bud-neck-associated Fes/CIP4 homology Bar-amphiphysin-Rvs (F-BAR) protein suppressor of yeast profilin 1 (Syp1)/FCHo uses its intrinsically disordered region (IDR) to directly bind and bundle filamentous actin (F-actin) and to physically link septins and F-actin. Interestingly, the only other F-BAR protein found at the neck during bud development, Hof1, has related activities and also potently inhibits the bud-neck-associated formin Bnr1. However, we find that Syp1 enhances rather than inhibits Bnr1-mediated actin assembly and fully overcomes Hof1-mediated inhibition of Bnr1. Further, during bud development, Syp1 and Hof1 show reciprocal patterns of arrival and departure from the bud neck, and in vitro Syp1 and Hof1 compete for septin binding. Together, our observations suggest that as the bud grows, the relative levels of these two F-BAR proteins at the bud neck invert, driving changes in septin organization, septin-actin linkage, and formin activity. More broadly, our findings expand the functional roles of Syp1/FCHo family proteins and our understanding of the working relationships among F-BAR proteins in cytoskeletal regulation.
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Affiliation(s)
- Joseph O Magliozzi
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Lucas A Runyan
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Priyanka Dutta
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Gregory J Hoeprich
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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Varela Salgado M, Piatti S. Septin Organization and Dynamics for Budding Yeast Cytokinesis. J Fungi (Basel) 2024; 10:642. [PMID: 39330402 PMCID: PMC11433133 DOI: 10.3390/jof10090642] [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: 07/26/2024] [Revised: 08/30/2024] [Accepted: 08/31/2024] [Indexed: 09/28/2024] Open
Abstract
Cytokinesis, the process by which the cytoplasm divides to generate two daughter cells after mitosis, is a crucial stage of the cell cycle. Successful cytokinesis must be coordinated with chromosome segregation and requires the fine orchestration of several processes, such as constriction of the actomyosin ring, membrane reorganization, and, in fungi, cell wall deposition. In Saccharomyces cerevisiae, commonly known as budding yeast, septins play a pivotal role in the control of cytokinesis by assisting the assembly of the cytokinetic machinery at the division site and controlling its activity. Yeast septins form a collar at the division site that undergoes major dynamic transitions during the cell cycle. This review discusses the functions of septins in yeast cytokinesis, their regulation and the implications of their dynamic remodelling for cell division.
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Affiliation(s)
- Maritzaida Varela Salgado
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293 Montpellier, France
| | - Simonetta Piatti
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293 Montpellier, France
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Varela Salgado M, Adriaans IE, Touati SA, Ibanes S, Lai-Kee-Him J, Ancelin A, Cipelletti L, Picas L, Piatti S. Phosphorylation of the F-BAR protein Hof1 drives septin ring splitting in budding yeast. Nat Commun 2024; 15:3383. [PMID: 38649354 PMCID: PMC11035697 DOI: 10.1038/s41467-024-47709-3] [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: 07/12/2023] [Accepted: 04/09/2024] [Indexed: 04/25/2024] Open
Abstract
A double septin ring accompanies cytokinesis in yeasts and mammalian cells. In budding yeast, reorganisation of the septin collar at the bud neck into a dynamic double ring is essential for actomyosin ring constriction and cytokinesis. Septin reorganisation requires the Mitotic Exit Network (MEN), a kinase cascade essential for cytokinesis. However, the effectors of MEN in this process are unknown. Here we identify the F-BAR protein Hof1 as a critical target of MEN in septin remodelling. Phospho-mimicking HOF1 mutant alleles overcome the inability of MEN mutants to undergo septin reorganisation by decreasing Hof1 binding to septins and facilitating its translocation to the actomyosin ring. Hof1-mediated septin rearrangement requires its F-BAR domain, suggesting that it may involve a local membrane remodelling that leads to septin reorganisation. In vitro Hof1 can induce the formation of intertwined septin bundles, while a phosphomimetic Hof1 protein has impaired septin-bundling activity. Altogether, our data indicate that Hof1 modulates septin architecture in distinct ways depending on its phosphorylation status.
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Affiliation(s)
- Maritzaida Varela Salgado
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293, Montpellier, France
| | - Ingrid E Adriaans
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293, Montpellier, France
| | - Sandra A Touati
- Université Paris Cité, CNRS, Institut Jacques Monod, 75013, Paris, France
| | - Sandy Ibanes
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293, Montpellier, France
| | - Joséphine Lai-Kee-Him
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 34090, Montpellier, France
| | - Aurélie Ancelin
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 34090, Montpellier, France
| | - Luca Cipelletti
- L2C (Laboratoire Charles Coulomb), University of Montpellier, CNRS 34095, Montpellier, France
- IUF (Institut Universitaire de France, 75231, Paris, France
| | - Laura Picas
- IRIM (Institut de Recherche en Infectiologie de Montpellier), University of Montpellier, CNRS UMR 9004, 34293, Montpellier, France
| | - Simonetta Piatti
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293, Montpellier, France.
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Benson A, McMurray M. Simultaneous co-overexpression of Saccharomyces cerevisiae septins Cdc3 and Cdc10 drives pervasive, phospholipid-, and tag-dependent plasma membrane localization. Cytoskeleton (Hoboken) 2023; 80:199-214. [PMID: 37098755 PMCID: PMC10524705 DOI: 10.1002/cm.21762] [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: 12/01/2022] [Revised: 03/29/2023] [Accepted: 04/17/2023] [Indexed: 04/27/2023]
Abstract
Septin proteins contribute to many eukaryotic processes involving cellular membranes. In the budding yeast Saccharomyces cerevisiae, septin hetero-oligomers interact with the plasma membrane (PM) almost exclusively at the future site of cytokinesis. While multiple mechanisms of membrane recruitment have been identified, including direct interactions with specific phospholipids and curvature-sensitive interactions via amphipathic helices, these do not fully explain why yeast septins do not localize all over the inner leaflet of the PM. While engineering an inducible split-yellow fluorescent protein (YFP) system to measure the kinetics of yeast septin complex assembly, we found that ectopic co-overexpression of two tagged septins, Cdc3 and Cdc10, resulted in nearly uniform PM localization, as well as perturbation of endogenous septin function. Septin localization and function in gametogenesis were also perturbed. PM localization required the C-terminal YFP fragment fused to the C terminus of Cdc3, the septin-associated kinases Cla4 and Gin4, and phosphotidylinositol-4,5-bis-phosphate (PI[4,5]P2 ), but not the putative PI(4,5)P2 -binding residues in Cdc3. Endogenous Cdc10 was recruited to the PM, likely contributing to the functional interference. PM-localized septins did not exchange with the cytosolic pool, indicative of stable polymers. These findings provide new clues as to what normally restricts septin localization to specific membranes.
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Affiliation(s)
- Aleyna Benson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michael McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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