1
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A focus on yeast mating: From pheromone signaling to cell-cell fusion. Semin Cell Dev Biol 2023; 133:83-95. [PMID: 35148940 DOI: 10.1016/j.semcdb.2022.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 12/14/2022]
Abstract
Cells live in a chemical environment and are able to orient towards chemical cues. Unicellular haploid fungal cells communicate by secreting pheromones to reproduce sexually. In the yeast models Saccharomyces cerevisiae and Schizosaccharomyces pombe, pheromonal communication activates similar pathways composed of cognate G-protein-coupled receptors and downstream small GTPase Cdc42 and MAP kinase cascades. Local pheromone release and sensing, at a mobile surface polarity patch, underlie spatial gradient interpretation to form pairs between two cells of distinct mating types. Concentration of secretion at the point of cell-cell contact then leads to local cell wall digestion for cell fusion, forming a diploid zygote that prevents further fusion attempts. A number of asymmetries between mating types may promote efficiency of the system. In this review, we present our current knowledge of pheromone signaling in the two model yeasts, with an emphasis on how cells decode the pheromone signal spatially and ultimately fuse together. Though overall pathway architectures are similar in the two species, their large evolutionary distance allows to explore how conceptually similar solutions to a general biological problem can arise from divergent molecular components.
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2
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Krapp A, Hamelin R, Armand F, Chiappe D, Krapp L, Cano E, Moniatte M, Simanis V. Analysis of the S. pombe Meiotic Proteome Reveals a Switch from Anabolic to Catabolic Processes and Extensive Post-transcriptional Regulation. Cell Rep 2020; 26:1044-1058.e5. [PMID: 30673600 DOI: 10.1016/j.celrep.2018.12.075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 11/09/2018] [Accepted: 12/17/2018] [Indexed: 12/31/2022] Open
Abstract
Meiotic progression in S. pombe is regulated by stage-specific gene expression and translation, changes in RNA stability, expression of anti-sense transcripts, and targeted proteolysis of regulatory proteins. We have used SILAC labeling to examine the relative levels of proteins in diploid S. pombe cells during meiosis. Among the 3,268 proteins quantified at all time points, the levels of 880 proteins changed at least 2-fold; the majority of proteins showed stepwise increases or decreases during the meiotic divisions, while some changed transiently. Overall, we observed reductions in proteins involved in anabolism and increases in proteins involved in catabolism. We also observed increases in the levels of proteins of the ESCRT-III complex and revealed a role for ESCRT-III components in chromosome segregation and spore formation. Correlation with studies of meiotic gene expression and ribosome occupancy reveals that many of the changes in steady-state protein levels are post-transcriptional.
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Affiliation(s)
- Andrea Krapp
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, 1015 Lausanne, Switzerland
| | - Romain Hamelin
- EPFL Proteomics Core Facility, EPFL SV PTECH PTP, AI 0149, Station 15, 1015 Lausanne, Switzerland
| | - Florence Armand
- EPFL Proteomics Core Facility, EPFL SV PTECH PTP, AI 0149, Station 15, 1015 Lausanne, Switzerland
| | - Diego Chiappe
- EPFL Proteomics Core Facility, EPFL SV PTECH PTP, AI 0149, Station 15, 1015 Lausanne, Switzerland
| | - Lucien Krapp
- EPFL SV IBI-SV UPDALPE, AAB 1 17, Station 19, 1015 Lausanne, Switzerland
| | - Elena Cano
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, 1015 Lausanne, Switzerland
| | - Marc Moniatte
- EPFL Proteomics Core Facility, EPFL SV PTECH PTP, AI 0149, Station 15, 1015 Lausanne, Switzerland
| | - Viesturs Simanis
- EPFL SV ISREC UPSIM, SV2.1830, Station 19, 1015 Lausanne, Switzerland.
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3
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Wabner D, Overhageböck T, Nordmann D, Kronenberg J, Kramer F, Schmitz HP. Analysis of the protein composition of the spindle pole body during sporulation in Ashbya gossypii. PLoS One 2019; 14:e0223374. [PMID: 31581259 PMCID: PMC6776394 DOI: 10.1371/journal.pone.0223374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/19/2019] [Indexed: 11/28/2022] Open
Abstract
The spores of fungi come in a wide variety of forms and sizes, highly adapted to the route of dispersal and to survival under specific environmental conditions. The ascomycete Ashbya gossypii produces needle shaped spores with a length of 30 μm and a diameter of 1 μm. Formation of these spores relies on actin and actin regulatory proteins and is, therefore, distinct from the minor role that actin plays for spore formation in Saccharomyces cerevisiae. Using in vivo FRET-measurements of proteins labeled with fluorescent proteins, we investigate how the formin AgBnr2, a protein that promotes actin polymerization, integrates into the structure of the spindle pole body during sporulation. We also investigate the role of the A. gossypii homologs to the S. cerevisiae meiotic outer plaque proteins Spo74, Mpc54 and Ady4 for sporulation in A. gossypii. We found highest FRET of AgBnr2 with AgSpo74. Further experiments indicated that AgSpo74 is a main factor for targeting AgBnr2 to the spindle pole body. In agreement with these results, the Agspo74 deletion mutant produces no detectable spores, whereas deletion of Agmpc54 only has an effect on spore length and deletion of Agady4 has no detectable sporulation phenotype. Based on this study and in relation to previous results we suggest a model where AgBnr2 resides within an analogous structure to the meiotic outer plaque of S. cerevisiae. There it promotes formation of actin cables important for shaping the needle shaped spore structure.
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Affiliation(s)
- Dario Wabner
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Tom Overhageböck
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Doris Nordmann
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Julia Kronenberg
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Florian Kramer
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Hans-Peter Schmitz
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
- * E-mail:
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4
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Zhang N, Yao LL, Li XD. Regulation of class V myosin. Cell Mol Life Sci 2018; 75:261-273. [PMID: 28730277 PMCID: PMC11105390 DOI: 10.1007/s00018-017-2599-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/27/2017] [Accepted: 07/17/2017] [Indexed: 01/26/2023]
Abstract
Class V myosin (myosin-5) is a molecular motor that functions as an organelle transporter. The activation of myosin-5's motor function has long been known to be associated with a transition from the folded conformation in the off-state to the extended conformation in the on-state, but only recently have we begun to understand the underlying mechanism. The globular tail domain (GTD) of myosin-5 has been identified as the inhibitory domain and has recently been shown to function as a dimer in regulating the motor function. The folded off-state of myosin-5 is stabilized by multiple intramolecular interactions, including head-GTD interactions, GTD-GTD interactions, and interactions between the GTD and the C-terminus of the first coiled-coil segment. Any cellular factor that affects these intramolecular interactions and thus the stability of the folded conformation of myosin-5 would be expected to regulate myosin-5 motor function. Both the adaptor proteins of myosin-5 and Ca2+ are potential regulators of myosin-5 motor function, because they can destabilize its folded conformation. A combination of these regulators provides a versatile scheme in regulating myosin-5 motor function in the cell.
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Affiliation(s)
- Ning Zhang
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Lin-Lin Yao
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiang-Dong Li
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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5
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Dudin O, Merlini L, Martin SG. Spatial focalization of pheromone/MAPK signaling triggers commitment to cell-cell fusion. Genes Dev 2017; 30:2226-2239. [PMID: 27798845 PMCID: PMC5088570 DOI: 10.1101/gad.286922.116] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/21/2016] [Indexed: 12/14/2022]
Abstract
Here, Dudin et al. show that cell fusion does not require a dedicated signal but is triggered by spatial focalization of the same pheromone–GPCR–MAPK signaling cascade that drives earlier mating events in Schizosaccharomyces pombe. Cell fusion is universal in eukaryotes for fertilization and development, but what signals this process is unknown. Here, we show in Schizosaccharomyces pombe that fusion does not require a dedicated signal but is triggered by spatial focalization of the same pheromone–GPCR (G-protein-coupled receptor)–MAPK signaling cascade that drives earlier mating events. Autocrine cells expressing the receptor for their own pheromone trigger fusion attempts independently of cell–cell contact by concentrating pheromone release at the fusion focus, a dynamic actin aster underlying the secretion of cell wall hydrolases. Pheromone receptor and MAPK cascade are similarly enriched at the fusion focus, concomitant with fusion commitment in wild-type mating pairs. This focalization promotes cell fusion by immobilizing the fusion focus, thus driving local cell wall dissolution. We propose that fusion commitment is imposed by a local increase in MAPK concentration at the fusion focus, driven by a positive feedback between fusion focus formation and focalization of pheromone release and perception.
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Affiliation(s)
- Omaya Dudin
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Laura Merlini
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
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6
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Dudin O, Merlini L, Bendezú FO, Groux R, Vincenzetti V, Martin SG. A systematic screen for morphological abnormalities during fission yeast sexual reproduction identifies a mechanism of actin aster formation for cell fusion. PLoS Genet 2017; 13:e1006721. [PMID: 28410370 PMCID: PMC5409535 DOI: 10.1371/journal.pgen.1006721] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/28/2017] [Accepted: 03/29/2017] [Indexed: 01/15/2023] Open
Abstract
In non-motile fungi, sexual reproduction relies on strong morphogenetic changes in response to pheromone signaling. We report here on a systematic screen for morphological abnormalities of the mating process in fission yeast Schizosaccharomyces pombe. We derived a homothallic (self-fertile) collection of viable deletions, which, upon visual screening, revealed a plethora of phenotypes affecting all stages of the mating process, including cell polarization, cell fusion and sporulation. Cell fusion relies on the formation of the fusion focus, an aster-like F-actin structure that is marked by strong local accumulation of the myosin V Myo52, which concentrates secretion at the fusion site. A secondary screen for fusion-defective mutants identified the myosin V Myo51-associated coiled-coil proteins Rng8 and Rng9 as critical for the coalescence of the fusion focus. Indeed, rng8Δ and rng9Δ mutant cells exhibit multiple stable dots at the cell-cell contact site, instead of the single focus observed in wildtype. Rng8 and Rng9 accumulate on the fusion focus, dependent on Myo51 and tropomyosin Cdc8. A tropomyosin mutant allele, which compromises Rng8/9 localization but not actin binding, similarly leads to multiple stable dots instead of a single focus. By contrast, myo51 deletion does not strongly affect fusion focus coalescence. We propose that focusing of the actin filaments in the fusion aster primarily relies on Rng8/9-dependent cross-linking of tropomyosin-actin filaments.
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Affiliation(s)
- Omaya Dudin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Laura Merlini
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Felipe O. Bendezú
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Raphaël Groux
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Vincent Vincenzetti
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Sophie G. Martin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
- * E-mail:
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7
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Role and organization of the actin cytoskeleton during cell-cell fusion. Semin Cell Dev Biol 2016; 60:121-126. [PMID: 27476112 DOI: 10.1016/j.semcdb.2016.07.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 11/23/2022]
Abstract
Cell-cell fusion is a ubiquitous process that underlies fertilization and development of eukaryotes. This process requires fusogenic machineries to promote plasma membrane merging, and also relies on the organization of dedicated sub-cortical cytoskeletal assemblies. This review describes the role of actin structures, so called actin fusion foci, essential for the fusion of two distinct cell types: Drosophila myoblast cells, which fuse to form myotubes, and sexually differentiated cells of the fission yeast Schizosaccharomyces pombe, which fuse to form a zygote. I describe the respective composition and organization of the two structures, discuss their proposed role in promoting plasma membrane apposition, and consider the universality of similar structures for cell-cell fusion.
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8
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Tang Q, Billington N, Krementsova EB, Bookwalter CS, Lord M, Trybus KM. A single-headed fission yeast myosin V transports actin in a tropomyosin-dependent manner. J Cell Biol 2016; 214:167-79. [PMID: 27432898 PMCID: PMC4949448 DOI: 10.1083/jcb.201511102] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 06/15/2016] [Indexed: 12/20/2022] Open
Abstract
Myo51, a class V myosin in fission yeast, localizes to and assists in the assembly of the contractile ring, a conserved eukaryotic actomyosin structure that facilitates cytokinesis. Rng8 and Rng9 are binding partners that dictate the cellular localization and function of Myo51. Myo51 was expressed in insect cells in the presence or absence of Rng8/9. Surprisingly, electron microscopy of negatively stained images and hydrodynamic measurements showed that Myo51 is single headed, unlike most class V myosins. When Myo51-Rng8/9 was bound to actin-tropomyosin, two attachment sites were observed: the typical ATP-dependent motor domain attachment and a novel ATP-independent binding of the tail mediated by Rng8/9. A modified motility assay showed that this additional binding site anchors Myo51-Rng8/9 so that it can cross-link and slide actin-tropomyosin filaments relative to one another, functions that may explain the role of this motor in contractile ring assembly.
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Affiliation(s)
- Qing Tang
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
| | - Neil Billington
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Elena B Krementsova
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
| | - Carol S Bookwalter
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
| | - Matthew Lord
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
| | - Kathleen M Trybus
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405
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9
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Baker K, Kirkham S, Halova L, Atkin J, Franz-Wachtel M, Cobley D, Krug K, Maček B, Mulvihill DP, Petersen J. TOR complex 2 localises to the cytokinetic actomyosin ring and controls the fidelity of cytokinesis. J Cell Sci 2016; 129:2613-24. [PMID: 27206859 PMCID: PMC4958305 DOI: 10.1242/jcs.190124] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/06/2016] [Indexed: 01/30/2023] Open
Abstract
The timing of cell division is controlled by the coupled regulation of growth and division. The target of rapamycin (TOR) signalling network synchronises these processes with the environmental setting. Here, we describe a novel interaction of the fission yeast TOR complex 2 (TORC2) with the cytokinetic actomyosin ring (CAR), and a novel role for TORC2 in regulating the timing and fidelity of cytokinesis. Disruption of TORC2 or its localisation results in defects in CAR morphology and constriction. We provide evidence that the myosin II protein Myp2 and the myosin V protein Myo51 play roles in recruiting TORC2 to the CAR. We show that Myp2 and TORC2 are co-dependent upon each other for their normal localisation to the cytokinetic machinery. We go on to show that TORC2-dependent phosphorylation of actin-capping protein 1 (Acp1, a known regulator of cytokinesis) controls CAR stability, modulates Acp1-Acp2 (the equivalent of the mammalian CAPZA-CAPZB) heterodimer formation and is essential for survival upon stress. Thus, TORC2 localisation to the CAR, and TORC2-dependent Acp1 phosphorylation contributes to timely control and the fidelity of cytokinesis and cell division.
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Affiliation(s)
- Karen Baker
- School of Biosciences, University of Kent, Giles Lane, Canterbury, Kent CT2 7NJ, UK
| | - Sara Kirkham
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Lenka Halova
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Jane Atkin
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | | | - David Cobley
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Karsten Krug
- Proteome Center Tübingen, Auf der Morgenstelle 15, Tübingen 72076, Germany
| | - Boris Maček
- Proteome Center Tübingen, Auf der Morgenstelle 15, Tübingen 72076, Germany
| | - Daniel P Mulvihill
- School of Biosciences, University of Kent, Giles Lane, Canterbury, Kent CT2 7NJ, UK
| | - Janni Petersen
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK Flinders Centre for Innovation in Cancer, School of Medicine, Flinders University, Adelaide, SA 5001, Australia South Australia Health and Medical Research Institute, North Terrace, PO Box 11060, Adelaide, SA 5000, Australia
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10
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Dudin O, Bendezú FO, Groux R, Laroche T, Seitz A, Martin SG. A formin-nucleated actin aster concentrates cell wall hydrolases for cell fusion in fission yeast. ACTA ACUST UNITED AC 2015; 208:897-911. [PMID: 25825517 PMCID: PMC4384723 DOI: 10.1083/jcb.201411124] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The formin Fus1 nucleates a novel actin structure in fission yeast, named the actin fusion focus, which consists of an aster of actin filaments whose barbed ends are focalized at a membrane proximal site and serves to focalize cell wall hydrolase delivery for cell fusion. Cell–cell fusion is essential for fertilization. For fusion of walled cells, the cell wall must be degraded at a precise location but maintained in surrounding regions to protect against lysis. In fission yeast cells, the formin Fus1, which nucleates linear actin filaments, is essential for this process. In this paper, we show that this formin organizes a specific actin structure—the actin fusion focus. Structured illumination microscopy and live-cell imaging of Fus1, actin, and type V myosins revealed an aster of actin filaments whose barbed ends are focalized near the plasma membrane. Focalization requires Fus1 and type V myosins and happens asynchronously always in the M cell first. Type V myosins are essential for fusion and concentrate cell wall hydrolases, but not cell wall synthases, at the fusion focus. Thus, the fusion focus focalizes cell wall dissolution within a broader cell wall synthesis zone to shift from cell growth to cell fusion.
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Affiliation(s)
- Omaya Dudin
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Felipe O Bendezú
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Raphael Groux
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Thierry Laroche
- Bioimaging and Optics Core Facility, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Arne Seitz
- Bioimaging and Optics Core Facility, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
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Wang N, Lo Presti L, Zhu YH, Kang M, Wu Z, Martin SG, Wu JQ. The novel proteins Rng8 and Rng9 regulate the myosin-V Myo51 during fission yeast cytokinesis. ACTA ACUST UNITED AC 2014; 205:357-75. [PMID: 24798735 PMCID: PMC4018781 DOI: 10.1083/jcb.201308146] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The myosin-V family of molecular motors is known to be under sophisticated regulation, but our knowledge of the roles and regulation of myosin-Vs in cytokinesis is limited. Here, we report that the myosin-V Myo51 affects contractile ring assembly and stability during fission yeast cytokinesis, and is regulated by two novel coiled-coil proteins, Rng8 and Rng9. Both rng8Δ and rng9Δ cells display similar defects as myo51Δ in cytokinesis. Rng8 and Rng9 are required for Myo51's localizations to cytoplasmic puncta, actin cables, and the contractile ring. Myo51 puncta contain multiple Myo51 molecules and walk continuously on actin filaments in rng8(+) cells, whereas Myo51 forms speckles containing only one dimer and does not move efficiently on actin tracks in rng8Δ. Consistently, Myo51 transports artificial cargos efficiently in vivo, and this activity is regulated by Rng8. Purified Rng8 and Rng9 form stable higher-order complexes. Collectively, we propose that Rng8 and Rng9 form oligomers and cluster multiple Myo51 dimers to regulate Myo51 localization and functions.
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Affiliation(s)
- Ning Wang
- Department of Molecular Genetics, 2 Department of Molecular and Cellular Biochemistry, and 3 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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12
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A genome-wide screen for sporulation-defective mutants in Schizosaccharomyces pombe. G3-GENES GENOMES GENETICS 2014; 4:1173-82. [PMID: 24727291 PMCID: PMC4065261 DOI: 10.1534/g3.114.011049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Yeast sporulation is a highly regulated developmental program by which diploid cells generate haploid gametes, termed spores. To better define the genetic pathways regulating sporulation, a systematic screen of the set of ~3300 nonessential Schizosaccharomyces pombe gene deletion mutants was performed to identify genes required for spore formation. A high-throughput genetic method was used to introduce each mutant into an h(90) background, and iodine staining was used to identify sporulation-defective mutants. The screen identified 34 genes whose deletion reduces sporulation, including 15 that are defective in forespore membrane morphogenesis. In S. pombe, the total number of sporulation-defective mutants is a significantly smaller fraction of coding genes than in S. cerevisiae, which reflects the different evolutionary histories and biology of the two yeasts.
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13
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Membrane organization and cell fusion during mating in fission yeast requires multipass membrane protein Prm1. Genetics 2014; 196:1059-76. [PMID: 24514900 DOI: 10.1534/genetics.113.159558] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The involvement of Schizosaccharomyces pombe prm1(+) in cell fusion during mating and its relationship with other genes required for this process have been addressed. S. pombe prm1Δ mutant exhibits an almost complete blockade in cell fusion and an abnormal distribution of the plasma membrane and cell wall in the area of cell-cell interaction. The distribution of cellular envelopes is similar to that described for mutants devoid of the Fig1-related claudin-like Dni proteins; however, prm1(+) and the dni(+) genes act in different subpathways. Time-lapse analyses show that in the wild-type S. pombe strain, the distribution of phosphatidylserine in the cytoplasmic leaflet of the plasma membrane undergoes some modification before an opening is observed in the cross wall at the cell-cell contact region. In the prm1Δ mutant, this membrane modification does not take place, and the cross wall between the mating partners is not extensively degraded; plasma membrane forms invaginations and fingers that sometimes collapse/retract and that are sometimes strengthened by the synthesis of cell-wall material. Neither prm1Δ nor prm1Δ dniΔ zygotes lyse after cell-cell contact in medium containing and lacking calcium. Response to drugs that inhibit lipid synthesis or interfere with lipids is different in wild-type, prm1Δ, and dni1Δ strains, suggesting that membrane structure/organization/dynamics is different in all these strains and that Prm1p and the Dni proteins exert some functions required to guarantee correct membrane organization that are critical for cell fusion.
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Abstract
Many cells are able to orient themselves in a non-uniform environment by responding to localized cues. This leads to a polarized cellular response, where the cell can either grow or move towards the cue source. Fungal haploid cells secrete pheromones to signal mating, and respond by growing a mating projection towards a potential mate. Upon contact of the two partner cells, these fuse to form a diploid zygote. In this review, we present our current knowledge on the processes of mating signalling, pheromone-dependent polarized growth and cell fusion in Saccharomyces cerevisiae and Schizosaccharomyces pombe, two highly divergent ascomycete yeast models. While the global architecture of the mating response is very similar between these two species, they differ significantly both in their mating physiologies and in the molecular connections between pheromone perception and downstream responses. The use of both yeast models helps enlighten both conserved solutions and species-specific adaptations to a general biological problem.
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Affiliation(s)
- Laura Merlini
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne 1015, Switzerland
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15
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Lo Presti L, Chang F, Martin SG. Myosin Vs organize actin cables in fission yeast. Mol Biol Cell 2012; 23:4579-91. [PMID: 23051734 PMCID: PMC3510019 DOI: 10.1091/mbc.e12-07-0499] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/05/2012] [Accepted: 10/03/2012] [Indexed: 11/11/2022] Open
Abstract
Myosin V motors are believed to contribute to cell polarization by carrying cargoes along actin tracks. In Schizosaccharomyces pombe, Myosin Vs transport secretory vesicles along actin cables, which are dynamic actin bundles assembled by the formin For3 at cell poles. How these flexible structures are able to extend longitudinally in the cell through the dense cytoplasm is unknown. Here we show that in myosin V (myo52 myo51) null cells, actin cables are curled, bundled, and fail to extend into the cell interior. They also exhibit reduced retrograde flow, suggesting that formin-mediated actin assembly is impaired. Myo52 may contribute to actin cable organization by delivering actin regulators to cell poles, as myoV defects are partially suppressed by diverting cargoes toward cell tips onto microtubules with a kinesin 7-Myo52 tail chimera. In addition, Myo52 motor activity may pull on cables to provide the tension necessary for their extension and efficient assembly, as artificially tethering actin cables to the nuclear envelope via a Myo52 motor domain restores actin cable extension and retrograde flow in myoV mutants. Together these in vivo data reveal elements of a self-organizing system in which the motors shape their own tracks by transporting cargoes and exerting physical pulling forces.
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Affiliation(s)
- Libera Lo Presti
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Fred Chang
- Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Sophie G. Martin
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland
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16
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Gene expression pattern of myosin Va during spermatogenesis of Chinese mitten crab, Eriocheir sinensis. Gene 2012; 508:78-84. [DOI: 10.1016/j.gene.2012.07.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 07/12/2012] [Accepted: 07/19/2012] [Indexed: 11/19/2022]
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17
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Sandquist JC, Kita AM, Bement WM. And the dead shall rise: actin and myosin return to the spindle. Dev Cell 2011; 21:410-9. [PMID: 21920311 DOI: 10.1016/j.devcel.2011.07.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
The spindle directs chromosome partitioning in eukaryotes and, for the last three decades, has been considered primarily a structure based on microtubules, microtubule motors, and other microtubule binding proteins. However, a surprisingly large body of both old and new studies suggests roles for actin filaments (F-actin) and myosins (F-actin-based motor proteins) in spindle assembly and function. Here we review these data and conclude that in several cases the evidence for the participation of F-actin and myosins in spindle function is very strong, and in the situations where it is less strong, there is nevertheless enough evidence to warrant further investigation.
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Affiliation(s)
- Joshua C Sandquist
- Department of Zoology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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18
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East DA, Mulvihill DP. Regulation and function of the fission yeast myosins. J Cell Sci 2011; 124:1383-90. [PMID: 21502135 DOI: 10.1242/jcs.078527] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
It is now quarter of a century since the actin cytoskeleton was first described in the fission yeast, Schizosaccharomyces pombe. Since then, a substantial body of research has been undertaken on this tractable model organism, extending our knowledge of the organisation and function of the actomyosin cytoskeleton in fission yeast and eukaryotes in general. Yeast represents one of the simplest eukaryotic model systems that has been characterised to date, and its genome encodes genes for homologues of the majority of actin regulators and actin-binding proteins found in metazoan cells. The ease with which diverse methodologies can be used, together with the small number of myosins, makes fission yeast an attractive model system for actomyosin research and provides the opportunity to fully understand the biochemical and functional characteristics of all myosins within a single cell type. In this Commentary, we examine the differences between the five S. pombe myosins, and focus on how these reflect the diversity of their functions. We go on to examine the role that the actin cytoskeleton plays in regulating the myosin motor activity and function, and finally explore how research in this simple unicellular organism is providing insights into the substantial impacts these motors can have on development and viability in multicellular higher-order eukaryotes.
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Affiliation(s)
- Daniel A East
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
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Snaith HA, Thompson J, Yates JR, Sawin KE. Characterization of Mug33 reveals complementary roles for actin cable-dependent transport and exocyst regulators in fission yeast exocytosis. J Cell Sci 2011; 124:2187-99. [PMID: 21652630 PMCID: PMC3113670 DOI: 10.1242/jcs.084038] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Although endocytosis and exocytosis have been extensively studied in budding yeast, there have been relatively few investigations of these complex processes in the fission yeast Schizosaccharomyces pombe. Here we identify and characterize fission yeast Mug33, a novel Tea1-interacting protein, and show that Mug33 is involved in exocytosis. Mug33 is a Sur7/PalI-family transmembrane protein that localizes to the plasma membrane at the cell tips and to cytoplasmic tubulovesicular elements (TVEs). A subset of Mug33 TVEs make long-range movements along actin cables, co-translocating with subunits of the exocyst complex. TVE movement depends on the type V myosin Myo52. Although mug33Δ mutants are viable, with only a mild cell-polarity phenotype, mug33Δ myo52Δ double mutants are synthetically lethal. Combining mug33 Δ with deletion of the formin For3 (for3Δ) leads to synthetic temperature-sensitive growth and strongly reduced levels of exocytosis. Interestingly, mutants in non-essential genes involved in exocyst function behave in a manner similar to mug33Δ when combined with myo52Δ and for3Δ. By contrast, combining mug33Δ with mutants in non-essential exocyst genes has only minor effects on growth. We propose that Mug33 contributes to exocyst function and that actin cable-dependent vesicle transport and exocyst function have complementary roles in promoting efficient exocytosis in fission yeast.
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Affiliation(s)
- Hilary A Snaith
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Swann Building, Mayfield Road, Edinburgh EH93JR, UK
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20
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Three's company: the fission yeast actin cytoskeleton. Trends Cell Biol 2010; 21:177-87. [PMID: 21145239 DOI: 10.1016/j.tcb.2010.11.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 10/22/2010] [Accepted: 11/04/2010] [Indexed: 11/20/2022]
Abstract
How the actin cytoskeleton assembles into different structures to drive diverse cellular processes is a fundamental cell biological question. In addition to orchestrating the appropriate combination of regulators and actin-binding proteins, different actin-based structures must insulate themselves from one another to maintain specificity within a crowded cytoplasm. Actin specification is particularly challenging in complex eukaryotes where a multitude of protein isoforms and actin structures operate within the same cell. Fission yeast Schizosaccharomyces pombe possesses a single actin isoform that functions in three distinct structures throughout the cell cycle. In this review we explore recent studies in fission yeast that help unravel how different actin structures operate in cells.
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Coulton AT, East DA, Galinska-Rakoczy A, Lehman W, Mulvihill DP. The recruitment of acetylated and unacetylated tropomyosin to distinct actin polymers permits the discrete regulation of specific myosins in fission yeast. J Cell Sci 2010; 123:3235-43. [PMID: 20807799 DOI: 10.1242/jcs.069971] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tropomyosin (Tm) is a conserved dimeric coiled-coil protein, which forms polymers that curl around actin filaments in order to regulate actomyosin function. Acetylation of the Tm N-terminal methionine strengthens end-to-end bonds, which enhances actin binding as well as the ability of Tm to regulate myosin motor activity in both muscle and non-muscle cells. In this study we explore the function of each Tm form within fission yeast cells. Electron microscopy and live cell imaging revealed that acetylated and unacetylated Tm associate with distinct actin structures within the cell, and that each form has a profound effect upon the shape and integrity of the polymeric actin filament. We show that, whereas Tm acetylation is required to regulate the in vivo motility of class II myosins, acetylated Tm had no effect on the motility of class I and V myosins. These findings illustrate a novel Tm-acetylation-state-dependent mechanism for regulating specific actomyosin cytoskeletal interactions.
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Affiliation(s)
- Arthur T Coulton
- School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
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22
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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