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Delic S, Shuman B, Lee S, Bahmanyar S, Momany M, Onishi M. The Evolutionary Origins and Ancestral Features of Septins. bioRxiv 2024:2024.03.25.586683. [PMID: 38585751 PMCID: PMC10996617 DOI: 10.1101/2024.03.25.586683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Septins are a family of membrane-associated cytoskeletal GTPases that play crucial roles in various cellular processes, such as cell division, phagocytosis, and organelle fission. Despite their importance, the evolutionary origins and ancestral function of septins remain unclear. In opisthokonts, septins form five distinct groups of orthologs, with subunits from multiple groups assembling into heteropolymers, thus supporting their diverse molecular functions. Recent studies have revealed that septins are also conserved in algae and protists, indicating an ancient origin from the last eukaryotic common ancestor. However, the phylogenetic relationships among septins across eukaryotes remained unclear. Here, we expanded the list of non-opisthokont septins, including previously unrecognized septins from rhodophyte red algae and glaucophyte algae. Constructing a rooted phylogenetic tree of 254 total septins, we observed a bifurcation between the major non-opisthokont and opisthokont septin clades. Within the non-opisthokont septins, we identified three major subclades: Group 6 representing chlorophyte green algae (6A mostly for species with single septins, 6B for species with multiple septins), Group 7 representing algae in chlorophytes, heterokonts, haptophytes, chrysophytes, and rhodophytes, and Group 8 representing ciliates. Glaucophyte and some ciliate septins formed orphan lineages in-between all other septins and the outgroup. Combining ancestral-sequence reconstruction and AlphaFold predictions, we tracked the structural evolution of septins across eukaryotes. In the GTPase domain, we identified a conserved GAP-like arginine finger within the G-interface of at least one septin in most algal and ciliate species. This residue is required for homodimerization of the single Chlamydomonas septin, and its loss coincided with septin duplication events in various lineages. The loss of the arginine finger is often accompanied by the emergence of the α0 helix, a known NC-interface interaction motif, potentially signifying the diversification of septin-septin interaction mechanisms from homo-dimerization to hetero-oligomerization. Lastly, we found amphipathic helices in all septin groups, suggesting that curvature-sensing is an ancestral trait of septin proteins. Coiled-coil domains were also broadly distributed, while transmembrane domains were found in some septins in Group 6A and 7. In summary, this study advances our understanding of septin distribution and phylogenetic groupings, shedding light on their ancestral features, potential function, and early evolution.
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Affiliation(s)
- Samed Delic
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Brent Shuman
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, Georgia, USA
| | - Shoken Lee
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Shirin Bahmanyar
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, Georgia, USA
| | - Masayuki Onishi
- Department of Biology, Duke University, Durham, North Carolina, USA
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Chen X, Feng J, Li Z, Feng H, Song C, Cai L, Joosten MHAJ, Du Y. Lipid transfer protein StLTPa enhances potato disease resistance against different pathogens by binding and disturbing the integrity of pathogens plasma membrane. Plant Biotechnol J 2024. [PMID: 38366362 DOI: 10.1111/pbi.14310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 01/20/2024] [Accepted: 02/02/2024] [Indexed: 02/18/2024]
Abstract
Potato is the third most important food crop worldwide. Potato production suffers from severe diseases caused by multiple detrimental plant pathogens, and broad-spectrum disease resistance genes are rarely identified in potato. Here we identified the potato non-specific lipid transfer protein StLTPa, which enhances species none-specific disease resistance against various pathogens, such as the oomycete pathogen Phytophthora infestans, the fungal pathogens Botrytis cinerea and Verticillium dahliae, and the bacterial pathogens Pectobacterium carotovorum and Ralstonia solanacearum. The StLTPa overexpression potato lines do not show growth penalty. Furthermore, we provide evidence that StLTPa binds to lipids present in the plasma membrane (PM) of the hyphal cells of P. infestans, leading to an increased permeability of the PM. Adding of PI(3,5)P2 and PI(3)P could compete the binding of StLTPa to pathogen PM and reduce the inhibition effect of StLTPa. The lipid-binding activity of StLTPa is essential for its role in pathogen inhibition and promotion of potato disease resistance. We propose that StLTPa enhances potato broad-spectrum disease resistance by binding to, and thereby promoting the permeability of the PM of the cells of various pathogens. Overall, our discovery illustrates that increasing the expression of a single gene in potato enhances potato disease resistance against different pathogens without growth penalty.
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Affiliation(s)
- Xiaokang Chen
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production and College of Horticulture, Northwest A&F University, Yangling, China
| | - Jiashu Feng
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production and College of Horticulture, Northwest A&F University, Yangling, China
| | - Zhenzhen Li
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production and College of Horticulture, Northwest A&F University, Yangling, China
| | - Hui Feng
- College of Tobacco Science of Guizhou University/Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education)/Guizhou Key Lab of Agro-Bioengineering, Guiyang, China
| | - Chunxu Song
- State Key Laboratory of Nutrient Use and Management, College of Resources and Environmental Sciences, China Agricultural University, Beijing, China
- National Academy of Agriculture Green Development, China Agricultural University, Beijing, China
| | - Lin Cai
- College of Tobacco Science of Guizhou University/Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education)/Guizhou Key Lab of Agro-Bioengineering, Guiyang, China
| | | | - Yu Du
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production and College of Horticulture, Northwest A&F University, Yangling, China
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Zheng S, Zheng B, Fu C. The Roles of Septins in Regulating Fission Yeast Cytokinesis. J Fungi (Basel) 2024; 10:115. [PMID: 38392788 PMCID: PMC10890454 DOI: 10.3390/jof10020115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/24/2024] Open
Abstract
Cytokinesis is required to separate two daughter cells at the end of mitosis, and septins play crucial roles in many aspects of cytokinesis. While septins have been intensively studied in many model organisms, including the budding yeast Saccharomyces cerevisiae, septins have been relatively less characterized in the fission yeast Schizosaccharomyces pombe, which has proven to be an excellent model organism for studying fundamental cell biology. In this review, we summarize the findings of septins made in fission yeasts mainly from four aspects: the domain structure of septins, the localization of septins during the cell cycle, the roles of septins in regulating cytokinesis, and the regulatory proteins of septins.
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Affiliation(s)
- Shengnan Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Biyu Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Chuanhai Fu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
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Perry JA, Werner ME, Heck BW, Maddox PS, Maddox AS. Septins throughout phylogeny are predicted to have a transmembrane domain, which in Caenorhabditis elegans is functionally important. bioRxiv 2023:2023.11.20.567915. [PMID: 38045322 PMCID: PMC10690161 DOI: 10.1101/2023.11.20.567915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Septins, a conserved family of filament-forming proteins, contribute to eukaryotic cell division, polarity, and membrane trafficking. Septins are thought to act in these processes by scaffolding other proteins to the plasma membrane. The mechanisms by which septins associate with the plasma membrane are not well understood but can involve two polybasic domains and/or an amphipathic helix. We discovered that the genomes of organisms throughout phylogeny, but not most commonly used model organisms, encode one or more septins predicted to have transmembrane domains. The nematode Caenorhabditis elegans, which was thought to express only two septin proteins, UNC-59 and UNC-61, translates multiple isoforms of UNC-61, and one isoform, UNC-61a, is predicted to contain a transmembrane domain. UNC-61a localizes specifically to the apical membrane of the C. elegans vulva and is important for maintaining vulval morphology. UNC-61a partially compensates for the loss of the other two UNC-61 isoforms, UNC-61b and UNC-61c. The UNC-61a transmembrane domain is sufficient to localize a fluorophore to membranes in mammalian cells, and its deletion from UNC-61a recapitulates the phenotypes of unc-61a null animals. The localization and loss-of-function phenotypes of UNC-61a and its transmembrane domain suggest roles in cell polarity and secretion and help explain the cellular and tissue biological underpinnings of C. elegans septin null alleles' enigmatically hypomorphic phenotypes. Together, our findings reveal a novel mechanism of septin-membrane association with profound implications for the dynamics and regulation of this association.
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Affiliation(s)
- Jenna A Perry
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Michael E Werner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Bryan W Heck
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Paul S Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
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Eisermann I, Garduño‐Rosales M, Talbot NJ. The emerging role of septins in fungal pathogenesis. Cytoskeleton (Hoboken) 2023; 80:242-253. [PMID: 37265147 PMCID: PMC10952683 DOI: 10.1002/cm.21765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Revised: 05/13/2023] [Accepted: 05/16/2023] [Indexed: 06/03/2023]
Abstract
Fungal pathogens undergo specific morphogenetic transitions in order to breach the outer surfaces of plants and invade the underlying host tissue. The ability to change cell shape and switch between non-polarised and polarised growth habits is therefore critical to the lifestyle of plant pathogens. Infection-related development involves remodelling of the cytoskeleton, plasma membrane and cell wall at specific points during fungal pathogenesis. Septin GTPases are components of the cytoskeleton that play pivotal roles in actin remodelling, micron-scale plasma membrane curvature sensing and cell polarity. Septin assemblages, such as rings, collars and gauzes, are known to have important roles in cell shape changes and are implicated in formation of specialised infection structures to enter plant cells. Here, we review and compare the reported functions of septins of plant pathogenic fungi, with a special focus on invasive growth. Finally, we discuss septins as potential targets for broad-spectrum antifungal plant protection strategies.
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Affiliation(s)
- Iris Eisermann
- The Sainsbury LaboratoryUniversity of East AngliaNorwichUK
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Werner B, Yadav S. Phosphoregulation of the septin cytoskeleton in neuronal development and disease. Cytoskeleton (Hoboken) 2023; 80:275-289. [PMID: 36127729 PMCID: PMC10025170 DOI: 10.1002/cm.21728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/13/2022] [Accepted: 09/12/2022] [Indexed: 11/06/2022]
Abstract
Septins are highly conserved GTP-binding proteins that oligomerize and form higher order structures. The septin cytoskeleton plays an important role in cellular organization, intracellular transport, and cytokinesis. Kinase-mediated phosphorylation of septins regulates various aspects of their function, localization, and dynamics. Septins are enriched in the mammalian nervous system where they contribute to neurodevelopment and neuronal function. Emerging research has implicated aberrant changes in septin cytoskeleton in several human diseases. The mechanisms through which aberrant phosphorylation by kinases contributes to septin dysfunction in neurological disorders are poorly understood and represent an important question for future research with therapeutic implications. This review summarizes the current state of knowledge of the diversity of kinases that interact with and phosphorylate mammalian septins, delineates how phosphoregulation impacts septin dynamics, and describes how aberrant septin phosphorylation contributes to neurological disorders.
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Affiliation(s)
- Bailey Werner
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Smita Yadav
- Department of Pharmacology, University of Washington, Seattle, WA, United States
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Kakizaki T, Abe H, Kotouge Y, Matsubuchi M, Sugou M, Honma C, Tsukuta K, Satoh S, Shioya T, Nakamura H, Cannon KS, Woods BL, Gladfelter A, Takeshita N, Muraguchi H. Live-cell imaging of septins and cell polarity proteins in the growing dikaryotic vegetative hypha of the model mushroom Coprinopsis cinerea. Sci Rep 2023; 13:10132. [PMID: 37349479 PMCID: PMC10287680 DOI: 10.1038/s41598-023-37115-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 06/15/2023] [Indexed: 06/24/2023] Open
Abstract
The developmental biology underlying the morphogenesis of mushrooms remains poorly understood despite the essential role of fungi in the terrestrial environment and global carbon cycle. The mushroom Coprinopsis cinerea is a leading model system for the molecular and cellular basis of fungal morphogenesis. The dikaryotic vegetative hyphae of this fungus grow by tip growth with clamp cell formation, conjugate nuclear division, septation, subapical peg formation, and fusion of the clamp cell to the peg. Studying these processes provides many opportunities to gain insights into fungal cell morphogenesis. Here, we report the dynamics of five septins, as well as the regulators CcCla4, CcSpa2, and F-actin, visualized by tagging with fluorescent proteins, EGFP, PA-GFP or mCherry, in the growing dikaryotic vegetative hyphae. We also observed the nuclei using tagged Sumo proteins and histone H1. The five septins colocalized at the hyphal tip in the shape of a dome with a hole (DwH). CcSpa2-EGFP signals were observed in the hole, while CcCla4 signals were observed as the fluctuating dome at the hyphal tip. Before septation, CcCla4-EGFP was also occasionally recruited transiently around the future septum site. Fluorescent protein-tagged septins and F-actin together formed a contractile ring at the septum site. These distinct specialized growth machineries at different sites of dikaryotic vegetative hyphae provide a foundation to explore the differentiation program of various types of cells required for fruiting body formation.
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Affiliation(s)
- Tetsuya Kakizaki
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Haruki Abe
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Yuuka Kotouge
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Mitsuki Matsubuchi
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Mayu Sugou
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Chiharu Honma
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Kouki Tsukuta
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Souichi Satoh
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Tatsuhiro Shioya
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Hiroe Nakamura
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan
| | - Kevin S Cannon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Benjamin L Woods
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Amy Gladfelter
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Cell Biology, Duke University, Durham, USA
| | - Norio Takeshita
- Microbiology Research Center for Sustainability (MiCS), Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8572, Japan
| | - Hajime Muraguchi
- Department of Biotechnology, Faculty of Bioresource Sciences, Akita Prefectural University, Shimoshinjo-nakano, Akita, 010-0195, Japan.
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K S V Castro D, V D Rosa H, Mendonça DC, Cavini IA, P U Araujo A, Garratt RC. Dissecting the binding interface of the septin polymerization enhancer Borg BD3. J Mol Biol 2023; 435:168132. [PMID: 37121395 DOI: 10.1016/j.jmb.2023.168132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/02/2023]
Abstract
The molecular basis for septin filament assembly has begun to emerge over recent years. These filaments are essential for many septin functions which depend on their association with biological membranes or components of the cytoskeleton. Much less is known about how septins specifically interact with their binding partners. Here we describe the essential role played by the C-terminal domains in both septin polymerization and their association with the BD3 motif of the Borg family of Cdc42 effector proteins. We provide a detailed description, at the molecular level, of a previously reported interaction between BD3 and the NC-interface between SEPT6 and SEPT7. Upon ternary complex formation, the heterodimeric coiled coil formed by the C-terminal domains of the septins becomes stabilized and filament formation is promoted under conditions of ionic strength/protein concentration which are not normally permissible, likely by favouring hexamers over smaller oligomeric states. This demonstrates that binding partners, such as Borg's, have the potential to control filament assembly/disassembly in vivo in a way which can be emulated in vitro by altering the ionic strength. Experimentally validated models indicate that the BD3 peptide lies antiparallel to the coiled coil and is stabilized by a mixture of polar and apolar contacts. At its center, an LGPS motif, common to all human Borg sequences, interacts with charged residues from both helices of the coiled coil (K368 from SEPT7 and the conserved E354 from SEPT6) suggesting a universal mechanism which governs Borg-septin interactions.
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Affiliation(s)
- Danielle K S V Castro
- São Carlos Institute of Chemistry, University of São Paulo, São Carlos, Brazil; São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Higor V D Rosa
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Deborah C Mendonça
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Italo A Cavini
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Ana P U Araujo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.
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Abstract
The plasma membrane of eukaryotic cells is composed of a large number of lipid species that are laterally segregated into functional domains as well as asymmetrically distributed between the outer and inner leaflets. Additionally, the spatial distribution and organization of these lipids dramatically change in response to various cellular states, such as cell division, differentiation, and apoptosis. Division of one cell into two daughter cells is one of the most fundamental requirements for the sustenance of growth in all living organisms. The successful completion of cytokinesis, the final stage of cell division, is critically dependent on the spatial distribution and organization of specific lipids. In this review, we discuss the properties of various lipid species associated with cytokinesis and the mechanisms involved in their polarization, including forward trafficking, endocytic recycling, local synthesis, and cortical flow models. The differences in lipid species requirements and distribution in mitotic vs. male meiotic cells will be discussed. We will concentrate on sphingolipids and phosphatidylinositols because their transbilayer organization and movement may be linked via the cytoskeleton and thus critically regulate various steps of cytokinesis.
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Rubio-Miranda JÁ, Cázares-Raga FE, Coy-Arechavaleta AS, Viettri M, Cortes-Martínez L, Lagunes-Guillén A, Chavez-Munguía B, Ludert JE, Hernández-Hernández FDLC. Septin 2 interacts with dengue virus replication complex proteins and participates in virus replication in mosquito cells. Virology 2022; 570:67-80. [DOI: 10.1016/j.virol.2022.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/05/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022]
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12
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Zheng S, Zheng B, Liu Z, Ma X, Liu X, Yao X, Wei W, Fu C. The Cdc42 GTPase activating protein Rga6 promotes the cortical localization of Septin. J Cell Sci 2022; 135:274388. [DOI: 10.1242/jcs.259228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 01/06/2022] [Indexed: 11/20/2022] Open
Abstract
Septins are a family of filament-forming GTP-binding proteins that regulate fundamental cellular activities such as cytokinesis and cell polarity. In general, Septin filaments function as barriers and scaffolds on the cell cortex. However, little is known about the mechanism that governs the recruitment and localization of the Septin complex to the cell cortex. Here, we identified the Cdc42 GTPase activating protein Rga6 as a key protein involved in promoting the localization of the Septin complex to the cell cortex in the fission yeast Schizosaccharomyces pombe. Rga6 interacts with the Septin complex and partially colocalizes with the Septin complex on the cell cortex. Live-cell microscopic analysis further showed Septin enrichment at the cortical regions adjacent to the growing cell tip. The Septin enrichment likely plays a crucial role in confining active Cdc42 to the growing cell tip. Hence, our findings support a model that Rga6 regulates polarized cell growth partly through promoting targeted localization of the Septin complex on the cell cortex.
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Affiliation(s)
- Shengnan Zheng
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Biyu Zheng
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Zhenbang Liu
- Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Xiaopeng Ma
- Department of General Surgery, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, PR China
| | - Xing Liu
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Xuebiao Yao
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Wenfan Wei
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Chuanhai Fu
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
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13
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Abstract
Septin GTPases form nonpolar heteropolymers that play important roles in cytokinesis and other cellular processes. The ability to form heteropolymers appears to be critical to many septin functions and to have been a major driver of the high conservation of many septin domains. Septins fall into five orthologous groups. Members of Groups 1–4 interact with each other to form heterooligomers and are known as the “core septins.” Representative core septins are present in all fungi and animals so far examined and show positional orthology with monomer location in the heteropolymer conserved within groups. In contrast, members of Group 5 are not part of canonical heteropolymers and appear to interact only transiently, if at all, with core septins. Group 5 septins have a spotty distribution, having been identified in specific fungi, ciliates, chlorophyte algae, and brown algae. In this review we compare the septins from nine well-studied model organisms that span the tree of life (Homo sapiens, Drosophila melanogaster, Schistosoma mansoni, Caenorhabditis elegans, Saccharomyces cerevisiae, Aspergillus nidulans, Magnaporthe oryzae, Tetrahymena thermophila, and Chlamydomonas reinhardtii). We focus on classification, evolutionary relationships, conserved motifs, interfaces between monomers, and positional orthology within heteropolymers. Understanding the relationships of septins across kingdoms can give new insight into their functions.
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14
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Cavini IA, Leonardo DA, Rosa HVD, Castro DKSV, D'Muniz Pereira H, Valadares NF, Araujo APU, Garratt RC. The Structural Biology of Septins and Their Filaments: An Update. Front Cell Dev Biol 2021; 9:765085. [PMID: 34869357 PMCID: PMC8640212 DOI: 10.3389/fcell.2021.765085] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/27/2021] [Indexed: 01/22/2023] Open
Abstract
In order to fully understand any complex biochemical system from a mechanistic point of view, it is necessary to have access to the three-dimensional structures of the molecular components involved. Septins and their oligomers, filaments and higher-order complexes are no exception. Indeed, the spontaneous recruitment of different septin monomers to specific positions along a filament represents a fascinating example of subtle molecular recognition. Over the last few years, the amount of structural information available about these important cytoskeletal proteins has increased dramatically. This has allowed for a more detailed description of their individual domains and the different interfaces formed between them, which are the basis for stabilizing higher-order structures such as hexamers, octamers and fully formed filaments. The flexibility of these structures and the plasticity of the individual interfaces have also begun to be understood. Furthermore, recently, light has been shed on how filaments may bundle into higher-order structures by the formation of antiparallel coiled coils involving the C-terminal domains. Nevertheless, even with these advances, there is still some way to go before we fully understand how the structure and dynamics of septin assemblies are related to their physiological roles, including their interactions with biological membranes and other cytoskeletal components. In this review, we aim to bring together the various strands of structural evidence currently available into a more coherent picture. Although it would be an exaggeration to say that this is complete, recent progress seems to suggest that headway is being made in that direction.
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Affiliation(s)
- Italo A Cavini
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Diego A Leonardo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Higor V D Rosa
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Danielle K S V Castro
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.,São Carlos Institute of Chemistry, University of São Paulo, São Carlos, Brazil
| | | | | | - Ana P U Araujo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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15
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Iv F, Martins CS, Castro-Linares G, Taveneau C, Barbier P, Verdier-Pinard P, Camoin L, Audebert S, Tsai FC, Ramond L, Llewellyn A, Belhabib M, Nakazawa K, Di Cicco A, Vincentelli R, Wenger J, Cabantous S, Koenderink GH, Bertin A, Mavrakis M. Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms. J Cell Sci 2021; 134:jcs258484. [PMID: 34350965 DOI: 10.1242/jcs.258484] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 07/02/2021] [Indexed: 01/22/2023] Open
Abstract
Septin GTP-binding proteins contribute essential biological functions that range from the establishment of cell polarity to animal tissue morphogenesis. Human septins in cells form hetero-octameric septin complexes containing the ubiquitously expressed SEPT9 subunit (also known as SEPTIN9). Despite the established role of SEPT9 in mammalian development and human pathophysiology, biochemical and biophysical studies have relied on monomeric SEPT9, thus not recapitulating its native assembly into hetero-octameric complexes. We established a protocol that enabled, for the first time, the isolation of recombinant human septin octamers containing distinct SEPT9 isoforms. A combination of biochemical and biophysical assays confirmed the octameric nature of the isolated complexes in solution. Reconstitution studies showed that octamers with either a long or a short SEPT9 isoform form filament assemblies, and can directly bind and cross-link actin filaments, raising the possibility that septin-decorated actin structures in cells reflect direct actin-septin interactions. Recombinant SEPT9-containing octamers will make it possible to design cell-free assays to dissect the complex interactions of septins with cell membranes and the actin and microtubule cytoskeleton.
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Affiliation(s)
- Francois Iv
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Carla Silva Martins
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Gerard Castro-Linares
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Cyntia Taveneau
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Australia; Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, 3800 Clayton, Australia
| | - Pascale Barbier
- Aix-Marseille Univ, CNRS, UMR 7051, Institut de Neurophysiopathologie (INP), 13005 Marseille, France
| | - Pascal Verdier-Pinard
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Luc Camoin
- Aix-Marseille Univ, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, Marseille, France
| | - Stéphane Audebert
- Aix-Marseille Univ, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, Marseille, France
| | - Feng-Ching Tsai
- Department of Living Matter, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Laurie Ramond
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Alex Llewellyn
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Mayssa Belhabib
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Koyomi Nakazawa
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Aurélie Di Cicco
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Renaud Vincentelli
- Architecture et Fonction des Macromolécules Biologiques (AFMB), CNRS UMR7257, Aix Marseille Univ, 13009 Marseille, France
| | - Jerome Wenger
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), Inserm, Université Paul Sabatier-Toulouse III, CNRS, 31037 Toulouse, France
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
- Department of Living Matter, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Aurélie Bertin
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
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16
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Abstract
Septins, a conserved family of GTP-binding proteins, are widely recognized as an essential cytoskeletal component, playing important roles in a variety of biological processes, including division, polarity, and membrane remodeling, in different eukaryotes. Although the roles played by septins were identified in the model organism Saccharomyces cerevisiae, their importance in other fungi, especially pathogenic fungi, have recently been determined. In this review, we summarize the functions of septins in pathogenic fungi in the cell cycle, autophagy, endocytosis and invasion host-microbe interactions that were reported in the last two years in the field of septin cell biology. These new discoveries may be expanded to investigate the functions of septin proteins in fungal pathogenesis and may be of wide interest to the readers of Microbiology and Molecular Pathology.
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Affiliation(s)
- Lin Li
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.,State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Xue-Ming Zhu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Zhen-Zhu Su
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Maurizio Del Poeta
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, USA.,Division of Infectious Diseases, Stony Brook University, Stony Brook, New York, USA.,Veterans Affairs Medical Center, Northport, New York, USA
| | - Xiao-Hong Liu
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, China
| | - Fu-Cheng Lin
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.,State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Biotechnology, Zhejiang University, Hangzhou, China
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17
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Szuba A, Bano F, Castro-Linares G, Iv F, Mavrakis M, Richter RP, Bertin A, Koenderink GH. Membrane binding controls ordered self-assembly of animal septins. eLife 2021; 10:63349. [PMID: 33847563 PMCID: PMC8099429 DOI: 10.7554/elife.63349] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 04/12/2021] [Indexed: 12/23/2022] Open
Abstract
Septins are conserved cytoskeletal proteins that regulate cell cortex mechanics. The mechanisms of their interactions with the plasma membrane remain poorly understood. Here, we show by cell-free reconstitution that binding to flat lipid membranes requires electrostatic interactions of septins with anionic lipids and promotes the ordered self-assembly of fly septins into filamentous meshworks. Transmission electron microscopy reveals that both fly and mammalian septin hexamers form arrays of single and paired filaments. Atomic force microscopy and quartz crystal microbalance demonstrate that the fly filaments form mechanically rigid, 12- to 18-nm thick, double layers of septins. By contrast, C-terminally truncated septin mutants form 4-nm thin monolayers, indicating that stacking requires the C-terminal coiled coils on DSep2 and Pnut subunits. Our work shows that membrane binding is required for fly septins to form ordered arrays of single and paired filaments and provides new insights into the mechanisms by which septins may regulate cell surface mechanics.
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Affiliation(s)
- Agata Szuba
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands
| | - Fouzia Bano
- School of Biomedical Sciences, Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.,Bragg Centre for Materials Research, University of Leeds, Leeds, United Kingdom
| | - Gerard Castro-Linares
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Francois Iv
- Institut Fresnel, CNRS, Aix-Marseille Univ, Centrale Marseille, Marseille, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS, Aix-Marseille Univ, Centrale Marseille, Marseille, France
| | - Ralf P Richter
- School of Biomedical Sciences, Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.,Bragg Centre for Materials Research, University of Leeds, Leeds, United Kingdom
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, Paris, France.,Sorbonne Université, Paris, France
| | - Gijsje H Koenderink
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
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18
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Herianto S, Rathod J, Shah P, Chen YZ, Wu WS, Liang B, Chen CS. Systematic Analysis of Phosphatidylinositol-5-phosphate-Interacting Proteins Using Yeast Proteome Microarrays. Anal Chem 2020; 93:868-877. [PMID: 33302626 DOI: 10.1021/acs.analchem.0c03463] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We used yeast proteome microarrays (∼5800 purified proteins) to conduct a high-throughput and systematic screening of PI5P-interacting proteins with PI5P-tagged fluorescent liposomal nanovesicles. Lissamine rhodamine B-dipalmitoyl phosphatidylethanol was incorporated into the liposome bilayer to provide the nanovesicles with fluorescence without any encapsulants, which not only made the liposome fabrication much easier without the need for purification but also improved the chip-probing quality. A special chip assay was washed very gently without the traditional spin-dry step. Forty-five PI5P-interacting proteins were identified in triplicate with this special chip assay. Subsequently, we used flow cytometry to validate these interactions, and a total of 41 PI5P-interacting proteins were confirmed. Enrichment analysis revealed that these proteins have significant functions associated with ribosome biogenesis, rRNA processing, ribosome binding, GTP binding, and hydrolase activity. Their component enrichment is located in the nucleolus. The InterPro domain analysis indicated that PI5P-interacting proteins are enriched in the P-loop containing nucleoside triphosphate hydrolases domain (P-loop). Additionally, using the MEME program, we identified a consensus motif (IVGPAGTGKSTLF) that contains the Walker A sequence, a well-known nucleotide-binding motif. Furthermore, using a quartz crystal microbalance, both the consensus motif and Walker A motif showed strong affinities to PI5P-containing liposomes but not to PI5P-deprived liposomes or PI-containing liposomes. Additionally, the glycine (G6) and lysine (K7) residues of the Walker A motif (-GPAGTG6K7S-) were found to be critical to the PI5P-binding ability. This study not only identified an additional set of PI5P-interacting proteins but also revealed the strong PI5P-binding affinity (Kd = 1.81 × 10-7 M) of the Walker A motif beyond the motif's nucleotide-binding characteristic.
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Affiliation(s)
- Samuel Herianto
- Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Jagat Rathod
- Department of Earth Sciences, College of Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Pramod Shah
- Department of Biomedical Sciences and Engineering, College of Health Sciences and Technology, National Central University, Jhongli 300, Taiwan
| | - You-Zuo Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Wei-Sheng Wu
- Department of Electrical Engineering, College of Electrical Engineering and Computer Science, National Cheng Kung University, Tainan 701, Taiwan
| | - Biqing Liang
- Department of Earth Sciences, College of Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Chien-Sheng Chen
- Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
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19
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He M, Su J, Xu Y, Chen J, Chern M, Lei M, Qi T, Wang Z, Ryder LS, Tang B, Osés-Ruiz M, Zhu K, Cao Y, Yan X, Eisermann I, Luo Y, Li W, Wang J, Yin J, Lam SM, Peng G, Sun X, Zhu X, Ma B, Wang J, Liu J, Qing H, Song L, Wang L, Hou Q, Qin P, Li Y, Fan J, Li D, Wang Y, Wang X, Jiang L, Shui G, Xia Y, Gong G, Huang F, Wang W, Wu X, Li P, Zhu L, Li S, Talbot NJ, Chen X. Discovery of broad-spectrum fungicides that block septin-dependent infection processes of pathogenic fungi. Nat Microbiol 2020; 5:1565-75. [PMID: 32958858 DOI: 10.1038/s41564-020-00790-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 08/24/2020] [Indexed: 11/09/2022]
Abstract
Many pathogenic fungi depend on the development of specialized infection structures called appressoria to invade their hosts and cause disease. Impairing the function of fungal infection structures therefore provides a potential means by which diseases could be prevented. In spite of this extraordinary potential, however, relatively few anti-penetrant drugs have been developed to control fungal diseases, of either plants or animals. In the present study, we report the identification of compounds that act specifically to prevent fungal infection. We found that the organization of septin GTPases, which are essential for appressorium-mediated infection in the rice blast fungus Magnaporthe oryzae, requires very-long-chain fatty acids (VLCFAs), which act as mediators of septin organization at membrane interfaces. VLCFAs promote septin recruitment to curved plasma membranes and depletion of VLCFAs prevents septin assembly and host penetration by M. oryzae. We observed that VLCFA biosynthesis inhibitors not only prevent rice blast disease, but also show effective, broad-spectrum fungicidal activity against a wide range of fungal pathogens of maize, wheat and locusts, without affecting their respective hosts. Our findings reveal a mechanism underlying septin-mediated infection structure formation in fungi and provide a class of fungicides to control diverse diseases of plants and animals.
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20
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Abstract
The septins constitute a conserved family of guanosine phosphate-binding and filament-forming proteins widespread across eukaryotic species. Septins appear to have two principal functions. One is to form a cortical diffusion barrier, like the septin collar at the bud neck of Saccharomyces cerevisiae, which prevents movement of membrane-associated proteins between the mother and daughter cells. The second is to serve as a polymeric scaffold for recruiting the proteins required for critical cellular processes to particular subcellular areas. In the last decade, structural information about the different levels of septin organization has appeared, but crucial structural determinants and factors responsible for septin assembly remain largely unknown. This review highlights recent findings on the architecture and function of septins and their remodeling with an emphasis on mitotically dividing budding yeasts.
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Affiliation(s)
- Marian Farkašovský
- Department of Biochemistry and Protein Structure, Institute of Molecular Biology SAS, Dubravska cesta 21, 84551 Bratislava, Slovak Republic
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21
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Castro DKSDV, da Silva SMDO, Pereira HD, Macedo JNA, Leonardo DA, Valadares NF, Kumagai PS, Brandão-Neto J, Araújo APU, Garratt RC. A complete compendium of crystal structures for the human SEPT3 subgroup reveals functional plasticity at a specific septin interface. IUCrJ 2020; 7:462-479. [PMID: 32431830 PMCID: PMC7201284 DOI: 10.1107/s2052252520002973] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/03/2020] [Indexed: 06/11/2023]
Abstract
Human septins 3, 9 and 12 are the only members of a specific subgroup of septins that display several unusual features, including the absence of a C-terminal coiled coil. This particular subgroup (the SEPT3 septins) are present in rod-like octameric protofilaments but are lacking in similar hexameric assemblies, which only contain representatives of the three remaining subgroups. Both hexamers and octamers can self-assemble into mixed filaments by end-to-end association, implying that the SEPT3 septins may facilitate polymerization but not necessarily function. These filaments frequently associate into higher order complexes which associate with biological membranes, triggering a wide range of cellular events. In the present work, a complete compendium of crystal structures for the GTP-binding domains of all of the SEPT3 subgroup members when bound to either GDP or to a GTP analogue is provided. The structures reveal a unique degree of plasticity at one of the filamentous interfaces (dubbed NC). Specifically, structures of the GDP and GTPγS complexes of SEPT9 reveal a squeezing mechanism at the NC interface which would expel a polybasic region from its binding site and render it free to interact with negatively charged membranes. On the other hand, a polyacidic region associated with helix α5', the orientation of which is particular to this subgroup, provides a safe haven for the polybasic region when retracted within the interface. Together, these results suggest a mechanism which couples GTP binding and hydrolysis to membrane association and implies a unique role for the SEPT3 subgroup in this process. These observations can be accounted for by constellations of specific amino-acid residues that are found only in this subgroup and by the absence of the C-terminal coiled coil. Such conclusions can only be reached owing to the completeness of the structural studies presented here.
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Affiliation(s)
- Danielle Karoline Silva do Vale Castro
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, São Carlos-SP 13566-590, Brazil
| | - Sabrina Matos de Oliveira da Silva
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, São Carlos-SP 13566-590, Brazil
| | - Humberto D’Muniz Pereira
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - Joci Neuby Alves Macedo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
- Federal Institute of Education, Science and Technology of Rondonia, Rodovia BR-174, Km 3, Vilhena-RO 76980-000, Brazil
| | - Diego Antonio Leonardo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - Napoleão Fonseca Valadares
- Departamento de Biologia Celular, Universidade de Brasília, Instituto de Ciências Biológicas, Brasília-DF 70910900, Brazil
| | - Patricia Suemy Kumagai
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - José Brandão-Neto
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Ana Paula Ulian Araújo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - Richard Charles Garratt
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
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22
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Collins KB, Kang H, Matsche J, Klomp JE, Rehman J, Malik AB, Karginov AV. Septin2 mediates podosome maturation and endothelial cell invasion associated with angiogenesis. J Cell Biol 2020; 219:e201903023. [PMID: 31865373 PMCID: PMC7041690 DOI: 10.1083/jcb.201903023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/14/2019] [Accepted: 11/08/2019] [Indexed: 12/13/2022] Open
Abstract
Podosomes are compartmentalized actin-rich adhesions, defined by their ability to locally secrete proteases and remodel extracellular matrix. Matrix remodeling by endothelial podosomes facilitates invasion and thereby vessel formation. However, the mechanisms underlying endothelial podosome formation and function remain unclear. Here, we demonstrate that Septin2, Septin6, and Septin7 are required for maturation of nascent endothelial podosomes into matrix-degrading organelles. We show that podosome development occurs through initial mobilization of the scaffolding protein Tks5 and F-actin accumulation, followed by later recruitment of Septin2. Septin2 localizes around the perimeter of podosomes in close proximity to the basolateral plasma membrane, and phosphoinositide-binding residues of Septin2 are required for podosome function. Combined, our results suggest that the septin cytoskeleton forms a diffusive barrier around nascent podosomes to promote their maturation. Finally, we show that Septin2-mediated regulation of podosomes is critical for endothelial cell invasion associated with angiogenesis. Therefore, targeting of Septin2-mediated podosome formation is a potentially attractive anti-angiogenesis strategy.
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Affiliation(s)
| | | | | | | | | | | | - Andrei V. Karginov
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL
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23
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Gönczi M, Dienes B, Dobrosi N, Fodor J, Balogh N, Oláh T, Csernoch L. Septins, a cytoskeletal protein family, with emerging role in striated muscle. J Muscle Res Cell Motil 2020; 42:251-265. [PMID: 31955380 PMCID: PMC8332580 DOI: 10.1007/s10974-020-09573-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 01/06/2020] [Indexed: 12/15/2022]
Abstract
Appropriate organization of cytoskeletal components are required for normal distribution and intracellular localization of different ion channels and proteins involved in calcium homeostasis, signal transduction, and contractile function of striated muscle. Proteins of the contractile system are in direct or indirect connection with the extrasarcomeric cytoskeleton. A number of other molecules which have essential role in regulating stretch-, voltage-, and chemical signal transduction from the surface into the cytoplasm or other intracellular compartments are already well characterized. Sarcomere, the basic contractile unit, is comprised of a precisely organized system of thin (actin), and thick (myosin) filaments. Intermediate filaments connect the sarcomeres and other organelles (mitochondria and nucleus), and are responsible for the cellular integrity. Interacting proteins have a very diverse function in coupling of the intracellular assembly components and regulating the normal physiological function. Despite the more and more intense investigations of a new cytoskeletal protein family, the septins, only limited information is available regarding their expression and role in striated, especially in skeletal muscles. In this review we collected basic and specified knowledge regarding this protein group and emphasize the importance of this emerging field in skeletal muscle biology.
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Affiliation(s)
- Mónika Gönczi
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, 4012, Hungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, 4012, Hungary
| | - Nóra Dobrosi
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, 4012, Hungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, 4012, Hungary
| | - Norbert Balogh
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, 4012, Hungary.,Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, 4012, Hungary
| | - Tamás Oláh
- Center of Experimental Orthopaedics, Saarland University, 66421, Homburg, Saar, Germany
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, 4012, Hungary.
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24
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Moore K, Moore R, Wang C, Norris RA. Tugging at the Heart Strings: The Septin Cytoskeleton in Heart Development and Disease. J Cardiovasc Dev Dis 2020; 7:E3. [PMID: 31936541 DOI: 10.3390/jcdd7010003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 12/26/2019] [Accepted: 12/31/2019] [Indexed: 12/25/2022] Open
Abstract
Septin genes were originally identified in budding yeast in 1971. Since their original discovery, at least 13 mammalian genes have now been found, which give rise to a vast array of alternatively spliced proteins that display unique spatial-temporal function across organs systems. Septin’s are now recognized as the 4th major component of the cytoskeleton. Their role in regulating ciliogenesis, actin and microtubule organization and their involvement in mechanotransduction clearly solidify their place as both a responder and driver of cellular activity. Although work on septin’s has escalated over the past decades, knowledge of septin function in the heart remains rudimentary. Whereas many cardiovascular diseases have been associated with genetic loci that include septin genes, new and additional concerted efforts will likely uncover previously unrecognized mechanisms by which the septin class of proteins contribute to clinical cardiac phenotypes. In this review, we place known function of septin proteins in the context of heart development and disease and provide perspectives on how increased knowledge of these proteins can mechanistically inform cardiac pathologies.
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25
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Omrane M, Camara AS, Taveneau C, Benzoubir N, Tubiana T, Yu J, Guérois R, Samuel D, Goud B, Poüs C, Bressanelli S, Garratt RC, Thiam AR, Gassama-Diagne A. Septin 9 has Two Polybasic Domains Critical to Septin Filament Assembly and Golgi Integrity. iScience 2019; 13:138-153. [PMID: 30831549 PMCID: PMC6403118 DOI: 10.1016/j.isci.2019.02.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/12/2018] [Accepted: 02/13/2019] [Indexed: 12/11/2022] Open
Abstract
Septins are GTP-binding proteins involved in several membrane remodeling mechanisms. They associate with membranes, presumably using a polybasic domain (PB1) that interacts with phosphoinositides (PIs). Membrane-bound septins assemble into microscopic structures that regulate membrane shape. How septins interact with PIs and then assemble and shape membranes is poorly understood. Here, we found that septin 9 has a second polybasic domain (PB2) conserved in the human septin family. Similar to PB1, PB2 binds specifically to PIs, and both domains are critical for septin filament formation. However, septin 9 membrane association is not dependent on these PB domains, but on putative PB-adjacent amphipathic helices. The presence of PB domains guarantees protein enrichment in PI-contained membranes, which is critical for PI-enriched organelles. In particular, we found that septin 9 PB domains control the assembly and functionality of the Golgi apparatus. Our findings offer further insight into the role of septins in organelle morphology. Two polybasic domains mediate septin 9 interactions with PIs Human septins have amphipathic helices suitable for membrane binding Septin 9 polybasic domains mediate the formation of septin higher-order structures The mutation or depletion of septin polybasic domains induces Golgi fragmentation
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Affiliation(s)
- Mohyeddine Omrane
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France; Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Amanda Souza Camara
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - Cyntia Taveneau
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France
| | - Nassima Benzoubir
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France
| | - Thibault Tubiana
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France
| | - Jinchao Yu
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, 91191 Gif-Sur- Yvette Cedex, France
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, 91191 Gif-Sur- Yvette Cedex, France
| | - Didier Samuel
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France
| | - Bruno Goud
- Institute Curie, PSL Research University, CNRS UMR 144, Paris, France
| | - Christian Poüs
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France
| | - Stéphane Bressanelli
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France
| | | | - Abdou Rachid Thiam
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France.
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26
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Cannon KS, Woods BL, Crutchley JM, Gladfelter AS. An amphipathic helix enables septins to sense micrometer-scale membrane curvature. J Cell Biol 2019; 218:1128-1137. [PMID: 30659102 PMCID: PMC6446858 DOI: 10.1083/jcb.201807211] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/17/2018] [Accepted: 01/07/2019] [Indexed: 02/04/2023] Open
Abstract
The basis of curvature sensing by the septin cytoskeleton is unknown. Cannon et al. now identify a conserved amphipathic helix that is necessary for recruitment of septins to sites of micrometer-scale curvature in vitro and in vivo. Cell shape is well described by membrane curvature. Septins are filament-forming, GTP-binding proteins that assemble on positive, micrometer-scale curvatures. Here, we examine the molecular basis of curvature sensing by septins. We show that differences in affinity and the number of binding sites drive curvature-specific adsorption of septins. Moreover, we find septin assembly onto curved membranes is cooperative and show that geometry influences higher-order arrangement of septin filaments. Although septins must form polymers to stay associated with membranes, septin filaments do not have to span micrometers in length to sense curvature, as we find that single-septin complexes have curvature-dependent association rates. We trace this ability to an amphipathic helix (AH) located on the C-terminus of Cdc12. The AH domain is necessary and sufficient for curvature sensing both in vitro and in vivo. These data show that curvature sensing by septins operates at much smaller length scales than the micrometer curvatures being detected.
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Affiliation(s)
- Kevin S Cannon
- Department of Biology, University of North Carolina at Chapel Hill, NC
| | - Benjamin L Woods
- Department of Biology, University of North Carolina at Chapel Hill, NC
| | - John M Crutchley
- Department of Biology, University of North Carolina at Chapel Hill, NC
| | - Amy S Gladfelter
- Department of Biology, University of North Carolina at Chapel Hill, NC .,Marine Biological Laboratory, Woods Hole, MA
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27
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Abstract
Septins belong to a family of conserved GTP-binding proteins found in majority of eukaryotic species except for higher plants. Septins form nonpolar complexes that further polymerize into filaments and associate with cell membranes, thus comprising newly acknowledged cytoskeletal system. Septins participate in a variety of cell processes and contribute to various pathophysiological states, including tumorigenesis and neurodegeneration. Here, we review the structural and functional properties of septins and the regulation of their dynamics with special emphasis on the role of septin filaments as a cytoskeletal system and its interaction with actin and microtubule cytoskeletons. We also discuss how septins compartmentalize the cell by forming local protein-anchoring scaffolds and by providing barriers for the lateral diffusion of the membrane proteins.
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Affiliation(s)
- K A Akhmetova
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.,University of Alabama at Birmingham, Birmingham, 35294 USA.,Novosibirsk National Research State University, Novosibirsk, 630090 Russia
| | - I N Chesnokov
- University of Alabama at Birmingham, Birmingham, 35294 USA
| | - S A Fedorova
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.,Novosibirsk National Research State University, Novosibirsk, 630090 Russia.,
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28
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Booth DS, Szmidt-Middleton H, King N. Transfection of choanoflagellates illuminates their cell biology and the ancestry of animal septins. Mol Biol Cell 2018; 29:3026-3038. [PMID: 30281390 PMCID: PMC6333174 DOI: 10.1091/mbc.e18-08-0514] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 09/20/2018] [Accepted: 09/24/2018] [Indexed: 12/17/2022] Open
Abstract
As the closest living relatives of animals, choanoflagellates offer unique insights into animal origins and core mechanisms underlying animal cell biology. However, unlike traditional model organisms, such as yeast, flies, and worms, choanoflagellates have been refractory to DNA delivery methods for expressing foreign genes. Here we report a robust method for expressing transgenes in the choanoflagellate Salpingoeca rosetta, overcoming barriers that have previously hampered DNA delivery and expression. To demonstrate how this method accelerates the study of S. rosetta cell biology, we engineered a panel of fluorescent protein markers that illuminate key features of choanoflagellate cells. We then investigated the localization of choanoflagellate septins, a family of GTP-binding cytoskeletal proteins that are hypothesized to regulate multicellular rosette development in S. rosetta. Fluorescently tagged septins localized to the basal poles of S. rosetta single cells and rosettes in a pattern resembling septin localization in animal epithelia. The establishment of transfection in S. rosetta and its application to the study of septins represent critical advances in the use of S. rosetta as an experimental model for investigating choanoflagellate cell biology, core mechanisms underlying animal cell biology, and the origin of animals.
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Affiliation(s)
- David S. Booth
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Heather Szmidt-Middleton
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Nicole King
- Howard Hughes Medical Institute and Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
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29
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Mela A, Momany M. Septin mutations and phenotypes in S. cerevisiae. Cytoskeleton (Hoboken) 2018; 76:33-44. [PMID: 30171672 DOI: 10.1002/cm.21492] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 08/09/2018] [Accepted: 08/22/2018] [Indexed: 11/07/2022]
Abstract
Septins are highly conserved guanosine triphosphate (GTP)-binding proteins that are a component of the cytoskeletal systems of virtually all eukaryotes (except higher plants). Septins play important roles in a multitude of cellular processes, including cytokinesis, establishment of cell polarity, and cellular partitioning. The ease of genetic screens and a fully sequenced genome have made Saccharomyces cerevisiae one of the most extensively studied and well-annotated model organisms in eukaryotic biology. Here, we present a synopsis of the known point mutations in the seven S. cerevisiae septin genes: CDC3, CDC10, CDC11, CDC12, SHS1, SPR3, and SPR28. We map these mutations onto septin protein structures, highlighting important conserved motifs, and relating the functional consequences of mutations in each domain.
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Affiliation(s)
- Alexander Mela
- Department of Plant Biology, University of Georgia, Athens, GA 30602
| | - Michelle Momany
- Department of Plant Biology, University of Georgia, Athens, GA 30602
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30
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Abbey M, Gaestel M, Menon MB. Septins: Active GTPases or just GTP-binding proteins? Cytoskeleton (Hoboken) 2018; 76:55-62. [PMID: 29747238 DOI: 10.1002/cm.21451] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/24/2018] [Accepted: 05/05/2018] [Indexed: 01/19/2023]
Abstract
Septins are conserved cytoskeletal proteins with unique filament forming capabilities and roles in cytokinesis and cell morphogenesis. Septins undergo hetero-oligomerization and assemble into higher order structures including filaments, rings, and cages. Hetero- and homotypic interactions of septin isoforms involve alternating GTPase (G)-domain interfaces and those mediated by N- and C-terminal extensions. While most septins bind GTP, display weak GTP-hydrolysis activity and incorporate guanine nucleotides in their interaction interfaces, studies using GTPase-inactivating mutations have failed to conclusively establish a crucial role for GTPase activity in mediating septin functions. In this mini-review, we will critically assess the role of GTP-binding and -hydrolysis on septin assembly and function. The relevance of G-domain activity will also be discussed in the context of human septin mutations as well as the development of specific small-molecules targeting septin polymerization. As structural determinants of septin oligomer interfaces, G-domains are attractive targets for ligand-based inhibition of septin assembly. Whether such an intervention can predictably alter septin function is a major question for future research.
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Affiliation(s)
- Megha Abbey
- Hannover Medical School, Institute of Cell Biochemistry, Hannover, 30625, Germany
| | - Matthias Gaestel
- Hannover Medical School, Institute of Cell Biochemistry, Hannover, 30625, Germany
| | - Manoj B Menon
- Hannover Medical School, Institute of Cell Biochemistry, Hannover, 30625, Germany
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31
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32
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Abstract
Septins are GTP-binding and membrane-interacting proteins with a highly conserved domain structure involved in various cellular processes, including cytoskeleton organization, cytokinesis, and membrane dynamics. To date, 13 different septin genes have been identified in mammals (SEPT1 to SEPT12 and SEPT14), which can be classified into four distinct subgroups based on the sequence homology of their domain structure (SEPT2, SEPT3, SEPT6, and SEPT7 subgroup). The family members of these subgroups have a strong affinity for other septins and form apolar tri-, hexa-, or octameric complexes consisting of multiple septin polypeptides. The first characterized core complex is the hetero-trimer SEPT2-6-7. Within these complexes single septins can be exchanged in a subgroup-specific manner. Hexamers contain SEPT2 and SEPT6 subgroup members and SEPT7 in two copies each whereas the octamers additionally comprise two SEPT9 subgroup septins. The various isoforms seem to determine the function and regulation of the septin complex. Septins self-assemble into higher-order structures, including filaments and rings in orders, which are typical for different cell types. Misregulation of septins leads to human diseases such as neurodegenerative and bleeding disorders. In non-dividing cells such as neuronal tissue and platelets septins have been associated with exocytosis. However, many mechanistic details and roles attributed to septins are poorly understood. We describe here some important mammalian septin interactions with a special focus on the clinically relevant septin interactions.
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Affiliation(s)
- Katharina Neubauer
- Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg Freiburg, Germany
| | - Barbara Zieger
- Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg Freiburg, Germany
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33
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Kim SW, Lee KJ, Kim S, Kim J, Cho K, Ro HS, Park HS. Genetic incorporation of N ε-acetyllysine reveals a novel acetylation-sumoylation switch in yeast. Biochim Biophys Acta Gen Subj 2017; 1861:3030-3037. [PMID: 28188860 DOI: 10.1016/j.bbagen.2017.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 02/02/2017] [Indexed: 10/20/2022]
Abstract
The lysine acetylation of proteins plays a key role in regulating protein functions, thereby controlling a wide range of cellular processes. Despite the prevalence and significance of lysine acetylation in eukaryotes, however, its systematic study has been challenged by the technical limitations of conventional approaches for selective lysine acetylation in vivo. Here, we report the in vivo study of lysine acetylation via the genetic incorporation of Nε-acetyllysine in yeast. We demonstrate that a newly discovered acetylation-sumoylation switch precisely controls the localization and cellular function of the yeast septin protein, Cdc11, during the cell cycle. This approach should facilitate the comprehensive in vivo study of lysine acetylation across a wide range of proteins in eukaryotic organisms. This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue.
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Affiliation(s)
- Sang-Woo Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Kyung Jin Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Sinil Kim
- Division of Applied Life Science and Research Institute for Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Jihyo Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Kyukwang Cho
- Department of Chemistry, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Hyeon-Su Ro
- Division of Applied Life Science and Research Institute for Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea.
| | - Hee-Sung Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
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34
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Akhmetova KA, Dorogova NV, Bolobolova EU, Chesnokov IN, Fedorova SA. The Role of Pnut and its Functional Domains in Drosophila Spermatogenesis. Russ J Genet Appl Res 2017; 7:29-35. [PMID: 34306739 PMCID: PMC8297777 DOI: 10.1134/s2079059717010026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Drosophila Pnut protein belongs to the family of septins, which are conserved GTPases participating in cytokinesis and many more other fundamental cellular processes. Because of their filamentous appearance, membrane association, and functions, septins are considered as the fourth component of the cytoskeleton, along with actin, microtubules, and intermediate filaments. However, septins are much less studied than the other cytoskeleton elements. We had previously demonstrated that the deletion of the pnut gene leads to mitotic abnormalities in somatic cells. The goal of this work was to study the role of the pnut in Drosophila spermatogenesis. We designed a construct for pnut RNA interference allowing pnut expression to be suppressed ectopically. We analyzed the effect of pnut RNA interference on Drosophila spermatogenesis. Germline cells at the earliest stages of spermatogenesis were the most sensitive to Pnut depletion: the suppression of the pnut expression at these stages leads to male sterility as a result of immotile sperm. The testes of these sterile males did not show any significant meiotic defects; the axonemes and mitochondria were normal. We also analyzed the effect of mutations in the Pnut's conservative domains on Drosophila spermatogenesis. Mutations in the GTPase domain resulted in cyst elongation defects. Deletions of the C-terminal domain led to abnormal testis morphology. Both the GTPase domain and C-terminal domain mutant males were sterile and produced immotile sperm. To summarize, we showed that Pnut participates in spermiogenesis, that is, the late stages of spermatogenesis, when major morphological changes in spermatocytes occur.
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Affiliation(s)
- K. A. Akhmetova
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
- University of Alabama at Birmingham, Birmingham, United States
- Novosibirsk State University, Novosibirsk, Russia
| | - N. V. Dorogova
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
| | - E. U. Bolobolova
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
| | - I. N. Chesnokov
- University of Alabama at Birmingham, Birmingham, United States
| | - S. A. Fedorova
- Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
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35
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Dyson JM, Conduit SE, Feeney SJ, Hakim S, DiTommaso T, Fulcher AJ, Sriratana A, Ramm G, Horan KA, Gurung R, Wicking C, Smyth I, Mitchell CA. INPP5E regulates phosphoinositide-dependent cilia transition zone function. J Cell Biol 2016; 216:247-263. [PMID: 27998989 PMCID: PMC5223597 DOI: 10.1083/jcb.201511055] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 09/19/2016] [Accepted: 12/02/2016] [Indexed: 02/07/2023] Open
Abstract
Dyson et al. demonstrate that the inositol polyphosphate 5-phosphatase INPP5E is essential for Hedgehog-dependent embryonic development. By regulating PI(4,5)P2 and PI(3,4,5)P3 signals at cilia, INPP5E contributes to cilia transition zone function and thereby Smoothened accumulation at cilia. Human ciliopathies, including Joubert syndrome (JBTS), arise from cilia dysfunction. The inositol polyphosphate 5-phosphatase INPP5E localizes to cilia and is mutated in JBTS. Murine Inpp5e ablation is embryonically lethal and recapitulates JBTS, including neural tube defects and polydactyly; however, the underlying defects in cilia signaling and the function of INPP5E at cilia are still emerging. We report Inpp5e−/− embryos exhibit aberrant Hedgehog-dependent patterning with reduced Hedgehog signaling. Using mouse genetics, we show increasing Hedgehog signaling via Smoothened M2 expression rescues some Inpp5e−/− ciliopathy phenotypes and “normalizes” Hedgehog signaling. INPP5E’s phosphoinositide substrates PI(4,5)P2 and PI(3,4,5)P3 accumulated at the transition zone (TZ) in Hedgehog-stimulated Inpp5e−/− cells, which was associated with reduced recruitment of TZ scaffolding proteins and reduced Smoothened levels at cilia. Expression of wild-type, but not 5-phosphatase-dead, INPP5E restored TZ molecular organization and Smoothened accumulation at cilia. Therefore, we identify INPP5E as an essential point of convergence between Hedgehog and phosphoinositide signaling at cilia that maintains TZ function and Hedgehog-dependent embryonic development.
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Affiliation(s)
- Jennifer M Dyson
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Sarah E Conduit
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Sandra J Feeney
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Sandra Hakim
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Tia DiTommaso
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Alex J Fulcher
- Monash Micro Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Absorn Sriratana
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Georg Ramm
- Monash Micro Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Kristy A Horan
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Rajendra Gurung
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Carol Wicking
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ian Smyth
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.,Development and Stem Cells Program, Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Christina A Mitchell
- Cancer Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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36
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Booth EA, Sterling SM, Dovala D, Nogales E, Thorner J. Effects of Bni5 Binding on Septin Filament Organization. J Mol Biol 2016; 428:4962-4980. [PMID: 27806918 DOI: 10.1016/j.jmb.2016.10.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/17/2016] [Accepted: 10/24/2016] [Indexed: 12/31/2022]
Abstract
Septins are a protein family found in all eukaryotes (except higher plants) that have roles in membrane remodeling and formation of diffusion barriers and as a scaffold to recruit other proteins. In budding yeast, proper execution of cytokinesis and cell division requires the formation of a collar of circumferential filaments at the bud neck. These filaments are assembled from apolar septin hetero-octamers. Currently, little is known about the mechanisms that control the arrangement and dynamics of septin structures. In this study, we utilized both Förster resonance energy transfer and electron microscopy to analyze the biophysical properties of the septin-binding protein Bni5 and how its association with septin filaments affects their organization. We found that the interaction of Bni5 with the terminal subunit (Cdc11) at the junctions between adjacent hetero-octamers in paired filaments is highly cooperative. Both the C-terminal end of Bni5 and the C-terminal extension of Cdc11 make important contributions to their interaction. Moreover, this binding may stabilize the dimerization of Bni5, which, in turn, forms cross-filament braces that significantly narrow, and impose much more uniform spacing on, the gap between paired filaments.
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Affiliation(s)
- Elizabeth A Booth
- Division of Biochemistry, Biophysics, and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
| | - Sarah M Sterling
- Division of Biochemistry, Biophysics, and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
| | - Dustin Dovala
- Program in Microbial Pathogenesis and Host Defense, Department of Microbiology and Immunology, University of California School of Medicine, San Francisco, CA 94143, USA.
| | - Eva Nogales
- Division of Biochemistry, Biophysics, and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA; Life Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics, and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA.
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37
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Abstract
Septins are GTP-binding proteins that are evolutionarily and structurally related to the RAS oncogenes. Septin expression levels are altered in many cancers and new advances point to how abnormal septin expression may contribute to the progression of cancer. In contrast to the RAS GTPases, which are frequently mutated and actively promote tumorigenesis, little is known about the occurrence and role of septin mutations in human cancers. Here, we review septin missense mutations that are currently in the Catalog of Somatic Mutations in Cancer (COSMIC) database. The majority of septin mutations occur in tumors of the large intestine, skin, endometrium and stomach. Over 25% of the annotated mutations in SEPT2, SEPT4, and SEPT9 belong to large intestine tumors. From all septins, SEPT9 and SEPT14 exhibit the highest mutation frequencies in skin, stomach and large intestine cancers. While septin mutations occur with frequencies lower than 3%, recurring mutations in several invariant and highly conserved amino acids are found across different septin paralogs and tumor types. Interestingly, a significant number of these mutations occur in the GTP-binding pocket and septin dimerization interfaces. Future studies may determine how these somatic mutations affect septin structure and function, whether they contribute to the progression of specific cancers and if they could serve as tumor-specific biomarkers.
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38
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Abstract
The septins are a conserved family of GTP-binding proteins present in all eukaryotic cells except plants. They were originally discovered in the baker's yeast Saccharomyces cerevisiae that serves until today as an important model organism for septin research. In yeast, the septins assemble into a highly ordered array of filaments at the mother bud neck. The septins are regulators of spatial compartmentalization in yeast and act as key players in cytokinesis. This minireview summarizes the recent findings about structural features and cell biology of the yeast septins.
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Affiliation(s)
- Oliver Glomb
- Department of Molecular Genetics and Cell Biology, Ulm University Ulm, Germany
| | - Thomas Gronemeyer
- Department of Molecular Genetics and Cell Biology, Ulm University Ulm, Germany
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39
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Juanes MA, Piatti S. The final cut: cell polarity meets cytokinesis at the bud neck in S. cerevisiae. Cell Mol Life Sci 2016; 73:3115-36. [PMID: 27085703 PMCID: PMC4951512 DOI: 10.1007/s00018-016-2220-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/22/2016] [Accepted: 04/05/2016] [Indexed: 02/07/2023]
Abstract
Cell division is a fundamental but complex process that gives rise to two daughter cells. It includes an ordered set of events, altogether called "the cell cycle", that culminate with cytokinesis, the final stage of mitosis leading to the physical separation of the two daughter cells. Symmetric cell division equally partitions cellular components between the two daughter cells, which are therefore identical to one another and often share the same fate. In many cases, however, cell division is asymmetrical and generates two daughter cells that differ in specific protein inheritance, cell size, or developmental potential. The budding yeast Saccharomyces cerevisiae has proven to be an excellent system to investigate the molecular mechanisms governing asymmetric cell division and cytokinesis. Budding yeast is highly polarized during the cell cycle and divides asymmetrically, producing two cells with distinct sizes and fates. Many components of the machinery establishing cell polarization during budding are relocalized to the division site (i.e., the bud neck) for cytokinesis. In this review we recapitulate how budding yeast cells undergo polarized processes at the bud neck for cell division.
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Affiliation(s)
- Maria Angeles Juanes
- Centre de Recherche en Biologie Cellulaire de Montpellier, 1919 Route de Mende, 34293, Montpellier, France
- Brandeis University, 415 South Street, Waltham, MA, 02454, USA
| | - Simonetta Piatti
- Centre de Recherche en Biologie Cellulaire de Montpellier, 1919 Route de Mende, 34293, Montpellier, France.
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40
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Akil A, Peng J, Omrane M, Gondeau C, Desterke C, Marin M, Tronchère H, Taveneau C, Sar S, Briolotti P, Benjelloun S, Benjouad A, Maurel P, Thiers V, Bressanelli S, Samuel D, Bréchot C, Gassama-Diagne A. Septin 9 induces lipid droplets growth by a phosphatidylinositol-5-phosphate and microtubule-dependent mechanism hijacked by HCV. Nat Commun 2016; 7:12203. [PMID: 27417143 PMCID: PMC4947189 DOI: 10.1038/ncomms12203] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 06/07/2016] [Indexed: 01/09/2023] Open
Abstract
The accumulation of lipid droplets (LD) is frequently observed in hepatitis C virus (HCV) infection and represents an important risk factor for the development of liver steatosis and cirrhosis. The mechanisms of LD biogenesis and growth remain open questions. Here, transcriptome analysis reveals a significant upregulation of septin 9 in HCV-induced cirrhosis compared with the normal liver. HCV infection increases septin 9 expression and induces its assembly into filaments. Septin 9 regulates LD growth and perinuclear accumulation in a manner dependent on dynamic microtubules. The effects of septin 9 on LDs are also dependent on binding to PtdIns5P, which, in turn, controls the formation of septin 9 filaments and its interaction with microtubules. This previously undescribed cooperation between PtdIns5P and septin 9 regulates oleate-induced accumulation of LDs. Overall, our data offer a novel route for LD growth through the involvement of a septin 9/PtdIns5P signalling pathway.
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Affiliation(s)
- Abdellah Akil
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,Laboratoire des Hépatites Virales, Département de Virologie. Institut Pasteur du Maroc, BP 20360 Casablanca, Maroc.,Faculté des Sciences, Laboratoire de Biochimie-Immunologie, Univ. Mohammed V, Rabat, Maroc
| | - Juan Peng
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France
| | - Mohyeddine Omrane
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France
| | - Claire Gondeau
- INSERM U1183, Institute of Regenerative Medicine and Biotherapy, University of Montpellier, 34295 Montpellier, France.,Department of Hepato-Gastroenterology A, Hospital Saint Eloi, CHRU, 34295 Montpellier, France
| | | | - Mickaël Marin
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France
| | - Hélène Tronchère
- INSERM U1048, I2MC and Université Paul Sabatier, 31432 Toulouse, France
| | - Cyntia Taveneau
- Virologie Moléculaire et Structurale CNRS UPR 3296 - INRA UsC 1358, 91198 Gif-sur-Yvette, France
| | - Sokhavuth Sar
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France
| | - Philippe Briolotti
- INSERM U1183, Institute of Regenerative Medicine and Biotherapy, University of Montpellier, 34295 Montpellier, France.,Department of Hepato-Gastroenterology A, Hospital Saint Eloi, CHRU, 34295 Montpellier, France
| | - Soumaya Benjelloun
- Laboratoire des Hépatites Virales, Département de Virologie. Institut Pasteur du Maroc, BP 20360 Casablanca, Maroc
| | - Abdelaziz Benjouad
- Faculté des Sciences, Laboratoire de Biochimie-Immunologie, Univ. Mohammed V, Rabat, Maroc.,Univ. Internationale de Rabat, Sala Al Jadida, Maroc
| | - Patrick Maurel
- INSERM U1183, Institute of Regenerative Medicine and Biotherapy, University of Montpellier, 34295 Montpellier, France.,Department of Hepato-Gastroenterology A, Hospital Saint Eloi, CHRU, 34295 Montpellier, France
| | | | - Stéphane Bressanelli
- Virologie Moléculaire et Structurale CNRS UPR 3296 - INRA UsC 1358, 91198 Gif-sur-Yvette, France
| | - Didier Samuel
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France.,AP-HP Hôpital Paul-Brousse, Centre Hépato-Biliaire, Villejuif F-94800, France
| | - Christian Bréchot
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,Institut Pasteur, 75724 Paris, France
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, F-94800 Villejuif, France.,University of Paris-Sud, UMR-S 1193, F-94800 Villejuif, France.,DHU Hepatinov, Villejuif F-94800, France
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41
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Zander S, Baumann S, Weidtkamp-Peters S, Feldbrügge M. Endosomal assembly and transport of heteromeric septin complexes promote septin cytoskeleton formation. J Cell Sci 2016; 129:2778-92. [PMID: 27252385 DOI: 10.1242/jcs.182824] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 05/26/2016] [Indexed: 02/02/2023] Open
Abstract
Septins are conserved cytoskeletal structures functioning in a variety of biological processes including cytokinesis and cell polarity. A wealth of information exists on the heterooligomeric architecture of septins and their subcellular localization at distinct sites. However, the precise mechanisms of their subcellular assembly and their intracellular transport are unknown. Here, we demonstrate that endosomal transport of septins along microtubules is crucial for formation of higher-order structures in the fungus Ustilago maydis Importantly, endosomal septin transport is dependent on each individual septin providing strong evidence that septin heteromeric complexes are assembled on endosomes. Furthermore, endosomal trafficking of all four septin mRNAs is required for endosomal localization of their translation products. Based on these results, we propose that local translation promotes the assembly of newly synthesized septins in heteromeric structures on the surface of endosomes. This is important for the long-distance transport of septins and the efficient formation of the septin cytoskeleton.
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Affiliation(s)
- Sabrina Zander
- Department of Biology, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
| | - Sebastian Baumann
- Department of Biology, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
| | - Stefanie Weidtkamp-Peters
- Department of Biology, Center for Advanced Imaging (CAi), Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
| | - Michael Feldbrügge
- Department of Biology, Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich Heine University Düsseldorf, 40204 Düsseldorf, Germany
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42
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Abstract
In Saccharomyces cerevisiae, septin mutations have severe effects on colony-forming ability, particularly at high temperatures, allowing the full variety of genetic tools available in this model organism to be applied to the study of septin biology. Although many details of septin function remain unknown, one can exploit a small number of easily scored phenotypes-proliferation capacity, cell morphology, septin localization, and septin ring integrity-as sensitive readouts of properly assembled septin filaments. Accordingly, this chapter focuses on genetic approaches targeted toward understanding the molecular mechanisms of de novo septin folding, heterooligomerization, and polymerization into filaments. The same general methods can be used to interrogate septin function, although interpretation of results can be more complicated. As genetic-based methodologies are technically simple but particularly dependent on interpretation, here I focus on the logic underlying the most common interpretations of results using septin mutants.
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Affiliation(s)
- M A McMurray
- University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
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43
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Ortore MG, Macedo JNA, Araujo APU, Ferrero C, Mariani P, Spinozzi F, Itri R. Structural and Thermodynamic Properties of Septin 3 Investigated by Small-Angle X-Ray Scattering. Biophys J 2016; 108:2896-902. [PMID: 26083929 DOI: 10.1016/j.bpj.2015.05.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 04/30/2015] [Accepted: 05/11/2015] [Indexed: 01/22/2023] Open
Abstract
Septins comprise a family of proteins involved in a variety of cellular processes and related to several human pathologies. They are constituted by three structural domains: the N- and C-terminal domains, highly variable in length and composition, and the central domain, involved in the guanine nucleotide (GTP) binding. Thirteen different human septins are known to form heterogeneous complexes or homofilaments, which are stabilized by specific interactions between the different interfaces present in the domains. In this work, we have investigated by in-solution small-angle x-ray scattering the structural and thermodynamic properties of a human septin 3 construct, SEPT3-GC, which contains both of both interfaces (G and NC) responsible for septin-septin interactions. In order to shed light on the role of these interactions, small-angle x-ray scattering measurements were performed in a wide range of temperatures, from 2 up to 56°C, both with and without a nonhydrolysable form of GTP (GTPγS). The acquired data show a temperature-dependent coexistence of monomers, dimers, and higher-order aggregates that were analyzed using a global fitting approach, taking into account the crystallographic structure of the recently reported SEPT3 dimer, PDB:3SOP. As a result, the enthalpy, entropy, and heat capacity variations that control the dimer-monomer dissociation equilibrium in solution were derived and GTPγS was detected to increase the enthalpic stability of the dimeric species. Moreover, a temperature increase was observed to induce dissociation of SEPT3-GC dimers into monomers just preceding their reassembling into amyloid aggregates, as revealed by the Thioflavin-T fluorescence assays.
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Affiliation(s)
- Maria Grazia Ortore
- Dipartimento di Scienze della Vita e dell'Ambiente and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università Politecnica delle Marche, Ancona, Italy
| | - Joci N A Macedo
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - Ana Paula U Araujo
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | | | - Paolo Mariani
- Dipartimento di Scienze della Vita e dell'Ambiente and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università Politecnica delle Marche, Ancona, Italy
| | - Francesco Spinozzi
- Dipartimento di Scienze della Vita e dell'Ambiente and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università Politecnica delle Marche, Ancona, Italy.
| | - Rosangela Itri
- Instituto de Física da Universidade de São Paulo, São Paulo, Brazil.
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44
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Fu Q, Li Y, Yang Y, Li C, Yao J, Zeng Q, Qin Z, Liu S, Li D, Liu Z. Septin genes in channel catfish (Ictalurus punctatus) and their involvement in disease defense responses. Fish Shellfish Immunol 2016; 49:110-121. [PMID: 26700173 DOI: 10.1016/j.fsi.2015.12.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/09/2015] [Accepted: 12/12/2015] [Indexed: 06/05/2023]
Abstract
Septins are an evolutionarily conserved family of GTP-binding proteins. They are involved in diverse processes including cytokinesis, apoptosis, infection, neurodegeneration and neoplasia. In this study, through thorough data mining of existed channel catfish genomic resources, we identified a complete set of 15 septin genes. Septins were classified into four subgroups according to phylogenetic analysis. Extensive comparative genomic analysis, including domain and syntenic analysis, supported their annotation and orthologies. The expression patterns of septins in channel catfish were examined in healthy tissues and after infection with two major bacterial pathogens, Edwardsiella ictaluri and Flavobacterium columnare. In healthy channel catfish, most septin genes were ubiquitously expressed and presented diversity patterns in various tissues, especially mucosal tissues, proposing the significant roles septin genes may play in maintaining homeostasis and host immune response activities. After bacterial infections, most septin genes were regulated, but opposite direction in expression profiles were found with the two bacterial pathogens: the differentially expressed septin genes were down-regulated in the intestine after E. ictaluri infection while generally up-regulated in the gill after F. columnare infection, suggesting a pathogen-specific and tissue-specific pattern of regulation. Taken together, these results suggested that septin genes may play complex and important roles in the host immune responses to bacterial pathogens in channel catfish.
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Affiliation(s)
- Qiang Fu
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China; The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Yun Li
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Yujia Yang
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Chao Li
- Marine Science and Engineering College, Qingdao Agricultural University, Qingdao, 266109, China
| | - Jun Yao
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Qifan Zeng
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Zhenkui Qin
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Shikai Liu
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Daoji Li
- State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062, China
| | - Zhanjiang Liu
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
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45
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Pastor-Flores D, Schulze JO, Bahí A, Süß E, Casamayor A, Biondi RM. Lipid regulators of Pkh2 in Candida albicans, the protein kinase ortholog of mammalian PDK1. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:249-59. [PMID: 26743850 DOI: 10.1016/j.bbalip.2015.12.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 12/21/2015] [Accepted: 12/24/2015] [Indexed: 11/18/2022]
Abstract
Pkh is the yeast ortholog of the mammalian 3-phosphoinositide-dependent protein kinase 1 (PDK1). Pkh phosphorylates the activation loop of Ypks, Tpks, Sch9 and also phosphorylates the eisosome components Lsp1 and Pil1, which play fundamental roles upstream of diverse signaling pathways, including the cell wall integrity and sphingosine/long-chain base (LCB) signaling pathways. In S. cerevisiae, two isoforms, ScPkh1 and ScPkh2, are required for cell viability, while only one ortholog exists in C. albicans, CaPkh2. In spite of the extensive information gathered on the role of Pkh in the LCB signaling, the yeast Pkh kinases are not known to bind lipids and previous studies did not identify PH domains in Pkh sequences. We now describe that the C-terminal region of CaPkh2 is required for its intrinsic kinase activity. In addition, we found that the C-terminal region of CaPkh2 enables its interaction with structural and signaling lipids. Our results further show that phosphatidylserine, phosphatidic acid, phosphatidylinositol (3,4 and 4,5)-biphosphates, and phosphatidylinositol (3,4,5)-trisphosphate inhibit Pkh activity, whereas sulfatide binds with high affinity but does not affect the intrinsic activity of CaPkh2. Interestingly, we identified that its human ortholog PDK1 also binds to sulfatide. We propose a mechanism by which lipids and dihydrosphingosine regulate CaPkh2 kinase activity by modulating the interaction of the C-terminal region with the kinase domain, while sulfatide-like lipids support localization CaPkh2 mediated by a C-terminal PH domain, without affecting kinase intrinsic activity.
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Affiliation(s)
- Daniel Pastor-Flores
- Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Jörg O Schulze
- Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Anna Bahí
- Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain; Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain
| | - Evelyn Süß
- Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
| | - Antonio Casamayor
- Departament de Bioquímica i Biologia Molecular, Facultat de Veterinària, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain; Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, Cerdanyola, 08193, Barcelona, Spain.
| | - Ricardo M Biondi
- Research Group PhosphoSites, Medizinische Klinik 1, Universitätsklinikum Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany.
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46
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Abstract
Organelle inheritance is a process whereby organelles are actively distributed between dividing cells at cytokinesis. Much valuable insight into the molecular mechanisms of organelle inheritance has come from the analysis of asymmetrically dividing cells, which transport a portion of their organelles to the bud while retaining another portion in the mother cell. Common principles apply to the inheritance of all organelles, although individual organelles use specific factors for their partitioning. Inheritance factors can be classified as motors, which are required for organelle transport; anchors, which immobilize organelles at distinct cell structures; or connectors, which mediate the attachment of organelles to motors and anchors. Here, we provide an overview of recent advances in the field of organelle inheritance and highlight how motor, anchor, and connector molecules choreograph the segregation of a multicopy organelle, the peroxisome. We also discuss the role of organelle population control in the generation of cellular diversity.
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Affiliation(s)
- Barbara Knoblach
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada;
| | - Richard A Rachubinski
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada;
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47
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Merlini L, Bolognesi A, Juanes MA, Vandermoere F, Courtellemont T, Pascolutti R, Séveno M, Barral Y, Piatti S. Rho1- and Pkc1-dependent phosphorylation of the F-BAR protein Syp1 contributes to septin ring assembly. Mol Biol Cell 2015; 26:3245-62. [PMID: 26179915 PMCID: PMC4569315 DOI: 10.1091/mbc.e15-06-0366] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 07/10/2015] [Indexed: 12/20/2022] Open
Abstract
Septins often form filaments and rings at the neck of cellular appendages. Assembly of these structures must be coordinated with membrane remodeling. In budding yeast, the Rho1 GTPase and its effector, Pkc1, play a role in septin ring stabilization during budding at least partly through phosphorylation of the bud neck–associated F-BAR protein Syp1. In many cell types, septins assemble into filaments and rings at the neck of cellular appendages and/or at the cleavage furrow to help compartmentalize the plasma membrane and support cytokinesis. How septin ring assembly is coordinated with membrane remodeling and controlled by mechanical stress at these sites is unclear. Through a genetic screen, we uncovered an unanticipated link between the conserved Rho1 GTPase and its effector protein kinase C (Pkc1) with septin ring stability in yeast. Both Rho1 and Pkc1 stabilize the septin ring, at least partly through phosphorylation of the membrane-associated F-BAR protein Syp1, which colocalizes asymmetrically with the septin ring at the bud neck. Syp1 is displaced from the bud neck upon Pkc1-dependent phosphorylation at two serines, thereby affecting the rigidity of the new-forming septin ring. We propose that Rho1 and Pkc1 coordinate septin ring assembly with membrane and cell wall remodeling partly by controlling Syp1 residence at the bud neck.
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Affiliation(s)
- Laura Merlini
- Centre de Recherche en Biochimie Macromoléculaire, 34293 Montpellier, France
| | | | | | - Franck Vandermoere
- Functional Proteomic Platform, Institut de Génomique Fonctionnelle, 34094 Montpellier, France
| | | | - Roberta Pascolutti
- Centre de Recherche en Biochimie Macromoléculaire, 34293 Montpellier, France
| | - Martial Séveno
- Functional Proteomic Platform, Institut de Génomique Fonctionnelle, 34094 Montpellier, France
| | - Yves Barral
- Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Simonetta Piatti
- Centre de Recherche en Biochimie Macromoléculaire, 34293 Montpellier, France
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48
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Abstract
Septins are GTP-binding proteins that form filaments and higher-order structures on the cell cortex of eukaryotic cells and associate with actin and microtubule cytoskeletal networks. When assembled, septins coordinate cell division and contribute to cell polarity maintenance and membrane remodeling. These functions manifest themselves via scaffolding of cytosolic proteins and cytoskeletal networks to specific locations on membranes and by forming diffusional barriers that restrict lateral diffusion of proteins embedded in membranes. Notably, many neurodegenerative diseases and cancers have been characterized as having misregulated septins, suggesting that their functions are relevant to diverse diseases. Despite the importance of septins, little is known about what features of the plasma membrane influence septin recruitment and alternatively, how septins influence plasma membrane properties. Septins have been localized to the cell cortex at the base of cilia, the mother-bud neck of yeast, and branch points of filamentous fungi and dendritic spines, in cleavage furrows, and in retracting membrane protrusions in mammalian cells. These sites all possess some degree of curvature and are likely composed of distinct lipid pools. Depending on the context, septins may act alone or in concert with other cytoskeletal elements to influence and sense membrane properties. The degree to which septins react to and/or induce changes in shape and lipid composition are discussed here. As septins are an essential player in basic biology and disease, understanding the interplay between septins and the plasma membrane is critical and may yield new and unexpected functions.
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Affiliation(s)
- Andrew A Bridges
- From the Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
| | - Amy S Gladfelter
- From the Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
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Johnson CR, Weems AD, Brewer JM, Thorner J, McMurray MA. Cytosolic chaperones mediate quality control of higher-order septin assembly in budding yeast. Mol Biol Cell 2015; 26:1323-44. [PMID: 25673805 PMCID: PMC4454179 DOI: 10.1091/mbc.e14-11-1531] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Septin hetero-oligomers polymerize into cytoskeletal filaments with essential functions in many eukaryotic cell types. Mutations within the oligomerization interface that encompasses the GTP-binding pocket of a septin (its "G interface") cause thermoinstability of yeast septin hetero-oligomer assembly, and human disease. When coexpressed with its wild-type counterpart, a G interface mutant is excluded from septin filaments, even at moderate temperatures. We show that this quality control mechanism is specific to G interface mutants, operates during de novo septin hetero-oligomer assembly, and requires specific cytosolic chaperones. Chaperone overexpression lowers the temperature permissive for proliferation of cells expressing a G interface mutant as the sole source of a given septin. Mutations that perturb the septin G interface retard release from these chaperones, imposing a kinetic delay on the availability of nascent septin molecules for higher-order assembly. Un-expectedly, the disaggregase Hsp104 contributes to this delay in a manner that does not require its "unfoldase" activity, indicating a latent "holdase" activity toward mutant septins. These findings provide new roles for chaperone-mediated kinetic partitioning of non-native proteins and may help explain the etiology of septin-linked human diseases.
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Affiliation(s)
- Courtney R Johnson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Andrew D Weems
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Jennifer M Brewer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Jeremy Thorner
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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Abstract
Septins are a family of GTP-binding proteins that assemble into cytoskeletal filaments. Unlike other cytoskeletal components, septins form ordered arrays of defined stoichiometry that can polymerize into long filaments and bundle laterally. Septins associate directly with membranes and have been implicated in providing membrane stability and serving as diffusion barriers for membrane proteins. In addition, septins bind other proteins and have been shown to function as multimolecular scaffolds by recruiting components of signaling pathways. Remarkably, septins participate in a spectrum of cellular processes including cytokinesis, ciliogenesis, cell migration, polarity, and cell-pathogen interactions. Given their breadth of functions, it is not surprising that septin abnormalities have also been linked to human diseases. In this review, we discuss the current knowledge of septin structure, assembly and function, and discuss these in the context of human disease.
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Affiliation(s)
- Karen Y Y Fung
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Lu Dai
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada
| | - William S Trimble
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada.
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