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Mayer A, Li J, McLaughlin G, Gladfelter A, Roper M. Mitigating transcription noise via protein sharing in syncytial cells. Biophys J 2024; 123:968-978. [PMID: 38459697 PMCID: PMC11052695 DOI: 10.1016/j.bpj.2024.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 02/19/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024] Open
Abstract
Bursty transcription allows nuclei to concentrate the work of transcribing mRNA into short, intermittent intervals, potentially reducing transcriptional interference. However, bursts of mRNA production can increase noise in protein abundances. Here, we formulate models for gene expression in syncytia, or multinucleate cells, showing that protein abundance noise may be mitigated locally via spatial averaging of diffuse proteins. Our modeling shows a universal reduction in protein noise, which increases with the average number of nuclei per cell and persists even when the number of nuclei is itself a random variable. Experimental data comparing distributions of a cyclin mRNA that is conserved between brewer's yeast and a closely related filamentous fungus Ashbya gossypii confirm that syncytism is permissive of greater levels of transcriptional noise. Our findings suggest that division of transcriptional labor between nuclei allows syncytia to sidestep tradeoffs between efficiency and precision of gene expression.
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Affiliation(s)
- Alex Mayer
- Department of Mathematics, UCLA, Los Angeles, California.
| | - Jiayu Li
- Department of Mathematics, UCLA, Los Angeles, California
| | - Grace McLaughlin
- Department of Biology, Duke University, Durham, North Carolina; Department of Biology, UNC, Chapel Hill, North Carolina
| | - Amy Gladfelter
- Department of Biology, Duke University, Durham, North Carolina
| | - Marcus Roper
- Department of Mathematics, UCLA, Los Angeles, California; Department of Computational Medicine, UCLA, Los Angeles, California
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2
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Mayer A, McLaughlin G, Gladfelter A, Glass NL, Mela A, Roper M. Syncytial Assembly Lines: Consequences of Multinucleate Cellular Compartments for Fungal Protein Synthesis. Results Probl Cell Differ 2024; 71:159-183. [PMID: 37996678 DOI: 10.1007/978-3-031-37936-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Fast growth and prodigious cellular outputs make fungi powerful tools in biotechnology. Recent modeling work has exposed efficiency gains associated with dividing the labor of transcription over multiple nuclei, and experimental innovations are opening new windows on the capacities and adaptations that allow nuclei to behave autonomously or in coordination while sharing a single, common cytoplasm. Although the motivation of our review is to motivate and connect recent work toward a greater understanding of fungal factories, we use the analogy of the assembly line as an organizing idea for studying coordinated gene expression, generally.
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Affiliation(s)
- Alex Mayer
- Department of Mathematics, University of California Los Angeles, Los Angeles, CA, USA
| | - Grace McLaughlin
- Department of Cell Biology, Duke University, Durham, NC, USA
- Department of Biology, University of North Carolina Chapel Hill, Chapel Hill, NC, USA
| | - Amy Gladfelter
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Alexander Mela
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Marcus Roper
- Department of Mathematics, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Computational Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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3
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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] [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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4
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Cannon KS, Vargas-Muniz JM, Billington N, Seim I, Ekena J, Sellers JR, Gladfelter AS. A gene duplication of a septin reveals a developmentally regulated filament length control mechanism. J Cell Biol 2023; 222:e202204063. [PMID: 36786832 PMCID: PMC9960279 DOI: 10.1083/jcb.202204063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 11/20/2022] [Accepted: 01/19/2023] [Indexed: 02/15/2023] Open
Abstract
Septins are a family of conserved filament-forming proteins that function in multiple cellular processes. The number of septin genes within an organism varies, and higher eukaryotes express many septin isoforms due to alternative splicing. It is unclear if different combinations of septin proteins in complex alter the polymers' biophysical properties. We report that a duplication event within the CDC11 locus in Ashbya gossypii gave rise to two similar but distinct Cdc11 proteins: Cdc11a and Cdc1b. CDC11b transcription is developmentally regulated, producing different amounts of Cdc11a- and Cdc11b-complexes in the lifecycle of Ashbya gossypii. Deletion of either gene results in distinct cell polarity defects, suggesting non-overlapping functions. Cdc11a and Cdc11b complexes have differences in filament length and membrane-binding ability. Thus, septin subunit composition has functional consequences on filament properties and cell morphogenesis. Small sequence differences elicit distinct biophysical properties and cell functions of septins, illuminating how gene duplication could be a driving force for septin gene expansions seen throughout the tree of life.
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Affiliation(s)
- Kevin S. Cannon
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Jose M. Vargas-Muniz
- Microbiology Program, School of Biological Sciences, Southern Illinois University, Carbondale, IL, USA
| | - Neil Billington
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ian Seim
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
- Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Joanne Ekena
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
| | - James R. Sellers
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Amy. S. Gladfelter
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
- Marine Biological Laboratory, Woods Hole, MA, USA
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Oktalira FT, May TW, Dearnaley JDW, Linde CC. Seven new Serendipita species associated with Australian terrestrial orchids. Mycologia 2021; 113:968-987. [PMID: 34338610 DOI: 10.1080/00275514.2021.1919848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Serendipita is one of the main fungal genera that form mutualistic associations with species of orchids (Orchidaceae). Here, seven new Serendipita species associated with various Australian orchid genera are described. These Serendipita species were originally characterized by multilocus DNA sequence species delimitation analyses (three mtDNA and four nuclear genes) and confirmed as distinct with addition of further isolates and reanalysis of nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and nuc 28S rDNA (28S). Culture morphology and microscopic features are presented for each species, three of which are binucleate and four multinucleate. For the ITS region, the seven species have within-species sequence divergence between 1.07% and 4.31%, and all but one of the species pairs is separated by interspecific divergence of at least 4.35%. The newly described Serendipita species, S. australiana, S. communis, S. occidentalis, S. rarihospitum, S. secunda, S. talbotii, and S. warcupii, are shown to be separate species from S. vermifera on the basis of comparison against a sequence from the type. Isolates originally identified by Warcup as Sebacina "vermifera" from Caladenia orchids are revised and shown to belong to three of the species newly described here. Some non-Caladenia isolates identified by Warcup as S. "vermifera" are also shown to be non-conspecific with the type of S. vermifera. On the basis of ITS sequences, 346 isolates from 26 other studies, previously identified under provisional designations, are accommodated under the novel species. The species of Serendipta described here associate with the Australian orchid genera Caladenia, Cyanicula, Elythranthera, Ericksonella, Eriochilus, Glossodia, and Pheladenia. Most of the novel Serendipita species occur widely across Australia, often with widely distributed hosts, but one species, Serendipita rarihospitum, associates with narrowly distributed orchid species.
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Affiliation(s)
- Fitria T Oktalira
- Ecology and Evolution, Research School of Biology, College of Science, The Australian National University, Canberra, ACT 2601, Australia
| | - Tom W May
- Royal Botanic Gardens Victoria, Birdwood Avenue, Melbourne, VIC 3004, Australia
| | - John D W Dearnaley
- Centre for Crop Health, The University of Southern Queensland, Toowoomba, Queensland 4350, Australia
| | - Celeste C Linde
- Ecology and Evolution, Research School of Biology, College of Science, The Australian National University, Canberra, ACT 2601, Australia
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6
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Sporulation in Ashbya gossypii. J Fungi (Basel) 2020; 6:jof6030157. [PMID: 32872517 PMCID: PMC7558398 DOI: 10.3390/jof6030157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/26/2020] [Accepted: 08/28/2020] [Indexed: 12/28/2022] Open
Abstract
Ashbya gossypii is a filamentous ascomycete belonging to the yeast family of Saccharomycetaceae. At the end of its growth phase Ashbya generates abundant amounts of riboflavin and spores that form within sporangia derived from fragmented cellular compartments of hyphae. The length of spores differs within species of the genus. Needle-shaped Ashbya spores aggregate via terminal filaments. A. gossypii is a homothallic fungus which may possess a and α mating types. However, the solo-MATa type strain is self-fertile and sporulates abundantly apparently without the need of prior mating. The central components required for the regulation of sporulation, encoded by IME1, IME2, IME4, KAR4, are conserved with Saccharomyces cerevisiae. Nutrient depletion generates a strong positive signal for sporulation via the cAMP-PKA pathway and SOK2, which is also essential for sporulation. Strong inhibitors of sporulation besides mutations in the central regulatory genes are the addition of exogenous cAMP or the overexpression of the mating type gene MATα2. Sporulation has been dissected using gene-function analyses and global RNA-seq transcriptomics. This revealed a role of Msn2/4, another potential PKA-target, for spore wall formation and a key dual role of the protein A kinase Tpk2 at the onset of sporulation as well as for breaking the dormancy of spores to initiate germination. Recent work has provided an overview of ascus development, regulation of sporulation and spore maturation. This will be summarized in the current review with a focus on the central regulatory genes. Current research and open questions will also be discussed.
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7
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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] [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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8
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Aguiar TQ, Silva R, Domingues L. Ashbya gossypii beyond industrial riboflavin production: A historical perspective and emerging biotechnological applications. Biotechnol Adv 2015; 33:1774-86. [DOI: 10.1016/j.biotechadv.2015.10.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 09/28/2015] [Accepted: 10/04/2015] [Indexed: 10/22/2022]
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9
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Dynamics of the establishment of multinucleate compartments in Fusarium oxysporum. EUKARYOTIC CELL 2014; 14:78-85. [PMID: 25398376 DOI: 10.1128/ec.00200-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nuclear dynamics can vary widely between fungal species and between stages of development of fungal colonies. Here we compared nuclear dynamics and mitotic patterns between germlings and mature hyphae in Fusarium oxysporum. Using fluorescently labeled nuclei and live-cell imaging, we show that F. oxysporum is subject to a developmental transition from a uninucleate to a multinucleate state after completion of colony initiation. We observed a special type of hypha that exhibits a higher growth rate, possibly acting as a nutrient scout. The higher growth rate is associated with a higher nuclear count and mitotic waves involving 2 to 6 nuclei in the apical compartment. Further, we found that dormant nuclei of intercalary compartments can reenter the mitotic cycle, resulting in multinucleate compartments with up to 18 nuclei in a single compartment.
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10
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Ramsubramaniam N, Harris SD, Marten MR. The phosphoproteome of Aspergillus nidulans reveals functional association with cellular processes involved in morphology and secretion. Proteomics 2014; 14:2454-9. [PMID: 25116090 DOI: 10.1002/pmic.201400063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/13/2014] [Accepted: 08/08/2014] [Indexed: 11/08/2022]
Abstract
We describe the first phosphoproteome of the model filamentous fungus Aspergillus nidulans. Phosphopeptides were enriched using titanium dioxide, separated using a convenient ultra-long reverse phase gradient, and identified using a "high-high" strategy (high mass accuracy on the parent and fragment ions) with higher-energy collisional dissociation. Using this approach 1801 phosphosites, from 1637 unique phosphopeptides, were identified. Functional classification revealed phosphoproteins were overrepresented under GO categories related to fungal morphogenesis: "sites of polar growth," "vesicle mediated transport," and "cytoskeleton organization." In these same GO categories, kinase-substrate analysis of phosphoproteins revealed the majority were target substrates of CDK and CK2 kinase families, indicating these kinase families play a prominent role in fungal morphogenesis. Kinase-substrate analysis also identified 57 substrates for kinases known to regulate secretion of hydrolytic enzymes (e.g. PkaA, SchA, and An-Snf1). Altogether this data will serve as a benchmark that can be used to elucidate regulatory networks functionally associated with fungal morphogenesis and secretion. All MS data have been deposited in the ProteomeXchange with identifier PXD000715 (http://proteomecentral.proteomexchange.org/dataset/PXD000715).
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Affiliation(s)
- Nikhil Ramsubramaniam
- Department of Chemical, Biochemical and Environmental Engineering, UMBC, Baltimore, MD, USA
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11
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Perez-Nadales E, Nogueira MFA, Baldin C, Castanheira S, El Ghalid M, Grund E, Lengeler K, Marchegiani E, Mehrotra PV, Moretti M, Naik V, Oses-Ruiz M, Oskarsson T, Schäfer K, Wasserstrom L, Brakhage AA, Gow NAR, Kahmann R, Lebrun MH, Perez-Martin J, Di Pietro A, Talbot NJ, Toquin V, Walther A, Wendland J. Fungal model systems and the elucidation of pathogenicity determinants. Fungal Genet Biol 2014; 70:42-67. [PMID: 25011008 PMCID: PMC4161391 DOI: 10.1016/j.fgb.2014.06.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 06/23/2014] [Accepted: 06/25/2014] [Indexed: 12/05/2022]
Abstract
Fungi have the capacity to cause devastating diseases of both plants and animals, causing significant harvest losses that threaten food security and human mycoses with high mortality rates. As a consequence, there is a critical need to promote development of new antifungal drugs, which requires a comprehensive molecular knowledge of fungal pathogenesis. In this review, we critically evaluate current knowledge of seven fungal organisms used as major research models for fungal pathogenesis. These include pathogens of both animals and plants; Ashbya gossypii, Aspergillus fumigatus, Candida albicans, Fusarium oxysporum, Magnaporthe oryzae, Ustilago maydis and Zymoseptoria tritici. We present key insights into the virulence mechanisms deployed by each species and a comparative overview of key insights obtained from genomic analysis. We then consider current trends and future challenges associated with the study of fungal pathogenicity.
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Affiliation(s)
- Elena Perez-Nadales
- Department of Genetics, Edificio Gregor Mendel, Planta 1. Campus de Rabanales, University of Cordoba, 14071 Cordoba, Spain.
| | | | - Clara Baldin
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (HKI), Beutembergstr. 11a, 07745 Jena, Germany; Department of Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University Jena, Beutenbergstr. 11a, 07745 Jena, Germany
| | - Sónia Castanheira
- Instituto de Biología Funcional y GenómicaCSIC, Universidad de Salamanca, 37007 Salamanca, Spain
| | - Mennat El Ghalid
- Department of Genetics, Edificio Gregor Mendel, Planta 1. Campus de Rabanales, University of Cordoba, 14071 Cordoba, Spain
| | - Elisabeth Grund
- Functional Genomics of Plant Pathogenic Fungi, UMR 5240 CNRS-UCB-INSA-Bayer SAS, Bayer CropScience, 69263 Lyon, France
| | - Klaus Lengeler
- Carlsberg Laboratory, Department of Yeast Genetics, Gamle Carlsberg Vej 10, DK-1799, Copenhagen V, Denmark
| | - Elisabetta Marchegiani
- Evolution and Genomics of Plant Pathogen Interactions, UR 1290 INRA, BIOGER-CPP, Campus AgroParisTech, 78850 Thiverval-Grignon, France
| | - Pankaj Vinod Mehrotra
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Marino Moretti
- Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse 10, D-35043 Marburg, Germany
| | - Vikram Naik
- Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse 10, D-35043 Marburg, Germany
| | - Miriam Oses-Ruiz
- School of Biosciences, Geoffrey Pope Building, University of Exeter, Exeter EX4 4QD, UK
| | - Therese Oskarsson
- Carlsberg Laboratory, Department of Yeast Genetics, Gamle Carlsberg Vej 10, DK-1799, Copenhagen V, Denmark
| | - Katja Schäfer
- Department of Genetics, Edificio Gregor Mendel, Planta 1. Campus de Rabanales, University of Cordoba, 14071 Cordoba, Spain
| | - Lisa Wasserstrom
- Carlsberg Laboratory, Department of Yeast Genetics, Gamle Carlsberg Vej 10, DK-1799, Copenhagen V, Denmark
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute (HKI), Beutembergstr. 11a, 07745 Jena, Germany; Department of Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University Jena, Beutenbergstr. 11a, 07745 Jena, Germany
| | - Neil A R Gow
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Regine Kahmann
- Max-Planck-Institute for Terrestrial Microbiology, Department of Organismic Interactions, Karl-von-Frisch-Strasse 10, D-35043 Marburg, Germany
| | - Marc-Henri Lebrun
- Evolution and Genomics of Plant Pathogen Interactions, UR 1290 INRA, BIOGER-CPP, Campus AgroParisTech, 78850 Thiverval-Grignon, France
| | - José Perez-Martin
- Instituto de Biología Funcional y GenómicaCSIC, Universidad de Salamanca, 37007 Salamanca, Spain
| | - Antonio Di Pietro
- Department of Genetics, Edificio Gregor Mendel, Planta 1. Campus de Rabanales, University of Cordoba, 14071 Cordoba, Spain
| | - Nicholas J Talbot
- School of Biosciences, Geoffrey Pope Building, University of Exeter, Exeter EX4 4QD, UK
| | - Valerie Toquin
- Biochemistry Department, Bayer SAS, Bayer CropScience, CRLD, 69263 Lyon, France
| | - Andrea Walther
- Carlsberg Laboratory, Department of Yeast Genetics, Gamle Carlsberg Vej 10, DK-1799, Copenhagen V, Denmark
| | - Jürgen Wendland
- Carlsberg Laboratory, Department of Yeast Genetics, Gamle Carlsberg Vej 10, DK-1799, Copenhagen V, Denmark
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12
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Genomes of Ashbya fungi isolated from insects reveal four mating-type loci, numerous translocations, lack of transposons, and distinct gene duplications. G3-GENES GENOMES GENETICS 2013; 3:1225-39. [PMID: 23749448 PMCID: PMC3737163 DOI: 10.1534/g3.112.002881] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The filamentous fungus Ashbya gossypii is a cotton pathogen transmitted by insects. It is readily grown and manipulated in the laboratory and is commercially exploited as a natural overproducer of vitamin B2. Our previous genome analysis of A. gossypii isolate ATCC10895, collected in Trinidad nearly 100 years ago, revealed extensive synteny with the Saccharomyces cerevisiae genome, leading us to use it as a model organism to understand the evolution of filamentous growth. To further develop Ashbya as a model system, we have investigated the ecological niche of A. gossypii and isolated additional strains and a sibling species, both useful in comparative analysis. We isolated fungi morphologically similar to A. gossypii from different plant-feeding insects of the suborder Heteroptera, generated a phylogenetic tree based on rDNA-ITS sequences, and performed high coverage short read sequencing with one A. gossypii isolate from Florida, a new species, Ashbya aceri, isolated in North Carolina, and a genetically marked derivative of ATCC10895 intensively used for functional studies. In contrast to S. cerevisiae, all strains carry four not three mating type loci, adding a new puzzle in the evolution of Ashbya species. Another surprise was the genome identity of 99.9% between the Florida strain and ATCC10895, isolated in Trinidad. The A. aceri and A. gossypii genomes show conserved gene orders rearranged by eight translocations, 90% overall sequence identity, and fewer tandem duplications in the A. aceri genome. Both species lack transposable elements. Finally, our work identifies plant-feeding insects of the suborder Heteroptera as the most likely natural reservoir of Ashbya, and that infection of cotton and other plants may be incidental to the growth of the fungus in its insect host.
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Berepiki A, Read ND. Septins are important for cell polarity, septation and asexual spore formation in Neurospora crassa and show different patterns of localisation at germ tube tips. PLoS One 2013; 8:e63843. [PMID: 23691103 PMCID: PMC3653863 DOI: 10.1371/journal.pone.0063843] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Accepted: 04/10/2013] [Indexed: 12/24/2022] Open
Abstract
Septins are GTP-binding cytoskeletal proteins that contribute to cell polarity, vesicle trafficking, cytokinesis and cell morphogenesis. Here we have characterised the six septins encoded by the genome of the model filamentous fungus Neurospora crassa. Analysis of septin null mutants demonstrated that septins limit the sites of emergence of germ tubes and are important for septation and conidiation in N. crassa. Septins constituted a range of different higher-order structures in N. crassa – rings, loops, fibres, bands, and caps – which can co-exist within the same cell. They showed different patterns of localisation at germ tube tips, with GFP-CDC-10 and CDC-11-GFP forming a subapical collar with lower signal intensity at the tip apex, CDC-3-GFP and CDC-12-GFP organized as a cap at the tip apex and GFP-ASP-1 forming an extended subapical collar. Purification of the septin complex and mass spectrometry of isolated proteins revealed that the septin complex consists predominantly of CDC-3, CDC-10, CDC-11 and CDC-12. Immunoprecipitation of the putative septin ASP-1 revealed that this protein interacts with the core septin complex.
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Affiliation(s)
| | - Nick D. Read
- Fungal Cell Biology Group, Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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Hof1 and Rvs167 have redundant roles in actomyosin ring function during cytokinesis in budding yeast. PLoS One 2013; 8:e57846. [PMID: 23469085 PMCID: PMC3585203 DOI: 10.1371/journal.pone.0057846] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 01/28/2013] [Indexed: 11/19/2022] Open
Abstract
The Hof1 protein (Homologue of Fifteen) regulates formation of the primary septum during cytokinesis in the budding yeast Saccharomyces cerevisiae, whereas the orthologous Cdc15 protein in fission yeast regulates the actomyosin ring by using its F-BAR domain to recruit actin nucleators to the cleavage site. Here we show that budding yeast Hof1 also contributes to actin ring assembly in parallel with the Rvs167 protein. Simultaneous deletion of the HOF1 and RVS167 genes is lethal, and cells fail to assemble the actomyosin ring as they progress through mitosis. Although Hof1 and Rvs167 are not orthologues, they both share an analogous structure, with an F-BAR or BAR domain at the amino terminus, capable of inducing membrane curvature, and SH3 domains at the carboxyl terminus that bind to specific proline-rich targets. The SH3 domain of Rvs167 becomes essential for assembly of the actomyosin ring in cells lacking Hof1, suggesting that it helps to recruit a regulator of the actin cytoskeleton. This new function of Rvs167 appears to be independent of its known role as a regulator of the Arp2/3 actin nucleator, as actin ring assembly is not abolished by the simultaneous inactivation of Hof1 and Arp2/3. Instead we find that recruitment to the bud-neck of the Iqg1 actin regulator is defective in cells lacking Hof1 and Rvs167, though future studies will be needed to determine if this reflects a direct interaction between these factors. The redundant role of Hof1 in actin ring assembly suggests that the mechanism of actin ring assembly has been conserved to a greater extent across evolution than anticipated previously.
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15
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Stockstill KE, Park J, Wille R, Bay G, Joseph A, Shannon KB. Mutation of Hof1 PEST motif phosphorylation sites leads to retention of Hof1 at the bud neck and a decrease in the rate of myosin contraction. Cell Biol Int 2013; 37:314-25. [PMID: 23359466 DOI: 10.1002/cbin.10042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 12/31/2012] [Indexed: 11/07/2022]
Abstract
Regulation of actomyosin ring contraction is important for the coordination of cytokinesis with mitosis. Hof1, a member of the Pombe Cdc15 homology (PCH) family of proteins, is required for efficient cytokinesis in budding yeast. Phosphorylation of Hof1 depends on the mitotic exit network (MEN), and its degradation at the end of mitosis depends on its PEST motif and interaction with the E3 ligase Grr1. To test the hypothesis that targeted destruction of Hof1 temporally couples mitotic exit with contraction of the actomyosin ring, we mutated the Hof1 PEST motif to prevent phosphorylation and subsequent degradation. These mutations increased the amount of Hof1 at the bud neck during cytokinesis, resulted in smaller bud neck diameter, and slowed the rate of myosin contraction. However, Hof1 PEST motif phosphorylation site mutants did not have cytokinesis defects, indicating that regulation of Hof1 levels does not control the onset of actomyosin ring contraction as predicted.
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Affiliation(s)
- Katherine E Stockstill
- Department of Biological Sciences, Missouri University of Science and Technology, 105 Schrenk Hall, 400 W. 11th St., Rolla, Missouri, 65401, USA.
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Sengupta S, Kaufmann A, Chandra TS. Development of fluorescent reporter tagged RIB gene cassettes for replicative transformation, early expression, and enhanced riboflavin production in Eremothecium ashbyi. Fungal Biol 2012; 116:1042-51. [PMID: 23063183 DOI: 10.1016/j.funbio.2012.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 07/16/2012] [Accepted: 07/27/2012] [Indexed: 11/28/2022]
Abstract
Eremothecium ashbyi is a riboflavin overproducing filamentous fungus in which the metabolic pathways have not been genetically characterized. Two genes of the riboflavin biosynthetic (RIB) pathway, RIB1 and RIB3, which encode GTP-cyclohydrolase II (GCH II) and 3,4-dihydroxy-2-butanone 4-phosphate (DHBP) synthase respectively, were selected for the present study. The two RIB genes under their native promoters were obtained from Ashbya gossypii genomic library. Yeast enhanced green fluorescent protein (yEGFP) and mCherry genes were tagged to the C-terminal ends of RIB1 and RIB3 genes to analyse the functionality of the RIB transgenes in E. ashbyi. Shuttle vectors with the reporter tagged RIB genes contained the Escherichia coli kan(R) gene and Saccharomyces cerevisiae ARS element. On transformation with these plasmids, the ARS element was found to be functional in E. ashbyi. The E. ashbyi transcription factors could recognize the Ashbya RIB gene promoters and express the reporter tagged RIB genes as cytoplasmic proteins, in early cell development. Replicative transformants carrying RIB1-mCherry plasmids showed 2.95 times more GCH II activity and 2.44 times more riboflavin production when compared to untransformed. This is the first report of genetic transformation of E. ashbyi and is of significance as the first step towards genetic engineering of this genus.
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Affiliation(s)
- Sudeshna Sengupta
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India
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17
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IQGAP Family Members in Yeast, Dictyostelium, and Mammalian Cells. Int J Cell Biol 2012; 2012:894817. [PMID: 22505937 PMCID: PMC3296274 DOI: 10.1155/2012/894817] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/06/2011] [Accepted: 10/23/2011] [Indexed: 01/04/2023] Open
Abstract
IQGAPs are a family of scaffolding proteins with multiple domains, named for the IQ motifs and GTPase activating protein (GAP) related domains. Despite their GAP homology, IQGAP proteins act as effectors for GTP-bound GTPases of the Ras superfamily and do not stimulate GTP hydrolysis. IQGAPs are found in eukaryotic cells from yeast to human, and localize to actin-containing structures such as lamellipodia, membrane ruffles, cell-cell adhesions, phagocytic cups, and the actomyosin ring formed during cytokinesis. Mammalian IQGAPs also act as scaffolds for signaling pathways. IQGAPs perform their myriad functions through association with a large number of proteins including filamentous actin (F-actin), GTPases, calcium-binding proteins, microtubule binding proteins, kinases, and receptors. The focus of this paper is on recent studies describing new binding partners, mechanisms of regulation, and biochemical and physiological functions of IQGAPs in yeast, amoeba, and mammalian cells.
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Heterogeneity in mitochondrial morphology and membrane potential is independent of the nuclear division cycle in multinucleate fungal cells. EUKARYOTIC CELL 2012; 11:353-67. [PMID: 22267774 DOI: 10.1128/ec.05257-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In the multinucleate filamentous fungus Ashbya gossypii, nuclei divide asynchronously in a common cytoplasm. We hypothesize that the division cycle machinery has a limited zone of influence in the cytoplasm to promote nuclear autonomy. Mitochondria in cultured mammalian cells undergo cell cycle-specific changes in morphology and membrane potential and therefore can serve as a reporter of the cell cycle state of the cytoplasm. To evaluate if the cell cycle state of nuclei in A. gossypii can influence the adjacent cytoplasm, we tested whether local mitochondrial morphology and membrane potential in A. gossypii are associated with the division state of a nearby nucleus. We found that mitochondria exhibit substantial heterogeneity in both morphology and membrane potential within a single multinucleated cell. Notably, differences in mitochondrial morphology or potential are not associated with a specific nuclear division state. Heterokaryon mutants with a mixture of nuclei with deletions of and wild type for the mitochondrial fusion/fission genes DNM1 and FZO1 exhibit altered mitochondrial morphology and severe growth and sporulation defects. This dominant effect suggests that the gene products may be required locally near their expression site rather than diffusing widely in the cell. Our results demonstrate that mitochondrial dynamics are essential in these large syncytial cells, yet morphology and membrane potential are independent of nuclear cycle state.
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Abstract
Genetic variation between individuals is essential to evolution and adaptation. However, intra-organismic genetic variation also shapes the life histories of many organisms, including filamentous fungi. A single fungal syncytium can harbor thousands or millions of mobile and potentially genotypically different nuclei, each having the capacity to regenerate a new organism. Because the dispersal of asexual or sexual spores propagates individual nuclei in many of these species, selection acting at the level of nuclei creates the potential for competitive and cooperative genome dynamics. Recent work in Neurospora crassa and Sclerotinia sclerotiorum has illuminated how nuclear populations are coordinated for fungal growth and other behaviors and has revealed both molecular and physical mechanisms for preventing and policing inter-genomic conflict. Recent results from population-level genomic studies in a variety of filamentous fungi suggest that nuclear exchange between mycelia and recombination between heterospecific nuclei may be of more importance to fungal evolution, diversity and the emergence of newly virulent strains than has previously been recognized.
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Affiliation(s)
- Marcus Roper
- Department of Mathematics, University of California, Berkeley, USA
- Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK
| | - Chris Ellison
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
| | - John W. Taylor
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
| | - N. Louise Glass
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
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20
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The cell cycle gene MoCDC15 regulates hyphal growth, asexual development and plant infection in the rice blast pathogen Magnaporthe oryzae. Fungal Genet Biol 2011; 48:784-92. [DOI: 10.1016/j.fgb.2011.05.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 05/02/2011] [Accepted: 05/04/2011] [Indexed: 11/18/2022]
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Finlayson MR, Helfer-Hungerbühler AK, Philippsen P. Regulation of exit from mitosis in multinucleate Ashbya gossypii cells relies on a minimal network of genes. Mol Biol Cell 2011; 22:3081-93. [PMID: 21737675 PMCID: PMC3164456 DOI: 10.1091/mbc.e10-12-1006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In Saccharomyces cerevisiae, mitosis is coupled to cell division by the action of the Cdc fourteen early anaphase release (FEAR) and mitotic exit network (MEN) regulatory networks, which mediate exit from mitosis by activation of the phosphatase Cdc14. The closely related filamentous ascomycete Ashbya gossypii provides a unique cellular setting to study the evolution of these networks. Within its multinucleate hyphae, nuclei are free to divide without the spatial and temporal constraints described for budding yeast. To investigate how this highly conserved system has adapted to these circumstances, we constructed a series of mutants lacking homologues of core components of MEN and FEAR and monitored phenomena such as progression through mitosis and Cdc14 activation. MEN homologues in A. gossypii were shown to have diverged from their anticipated role in Cdc14 release and exit from mitosis. We observed defects in septation, as well as a partial metaphase arrest, in Agtem1Δ, Agcdc15Δ, Agdbf2/dbf20Δ, and Agmob1Δ. A. gossypii homologues of the FEAR network, on the other hand, have a conserved and more pronounced role in regulation of the M/G1 transition. Agcdc55Δ mutants are unable to sequester AgCdc14 throughout interphase. We propose a reduced model of the networks described in yeast, with a low degree of functional redundancy, convenient for further investigations into these networks.
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Affiliation(s)
- Mark R Finlayson
- Department of Molecular Microbiology, Biozentrum, University of Basel, 4056 Basel, Switzerland
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22
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Schmitz HP, Philippsen P. Evolution of multinucleated Ashbya gossypii hyphae from a budding yeast-like ancestor. Fungal Biol 2011; 115:557-68. [PMID: 21640319 DOI: 10.1016/j.funbio.2011.02.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 02/17/2011] [Accepted: 02/19/2011] [Indexed: 12/14/2022]
Abstract
In the filamentous ascomycete Ashbya gossypii polarity establishment at sites of germ tube and lateral branch emergence depends on homologues of Saccharomyces cerevisiae factors controlling bud site selection and bud emergence. Maintenance of polar growth involves homologues of well-known polarity factors of budding yeast. To achieve the much higher rates of sustained polar surface expansion of hyphae compared to mainly non-polarly growing yeast buds five important alterations had to evolve. Permanent presence of the polarity machinery at a confined area in the rapidly expanding hyphal tip, increased cytoplasmic space with a much enlarged ER surface for generating secretory vesicles, efficient directed transport of secretory vesicles to and accumulation at the tip, increased capacity of the exocytosis system to process these vesicles, and an efficient endocytosis system for membrane and polarity factor recycling adjacent to the zone of exocytosis. Morphological, cell biological, and molecular aspects of this evolution are discussed based on experiments performed within the past 10 y.
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Affiliation(s)
- Hans-Peter Schmitz
- Universität Osnabrück, Institut für Genetik, Barbarastr. 11, 49076 Osnabrück, Germany.
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The fungal type II myosin in Penicillium marneffei, MyoB, is essential for chitin deposition at nascent septation sites but not actin localization. EUKARYOTIC CELL 2010; 10:302-12. [PMID: 21131434 DOI: 10.1128/ec.00201-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cytokinesis is essential for proliferative growth but also plays equally important roles during morphogenesis and development. The human pathogen Penicillium marneffei is capable of dimorphic switching in response to temperature, growing in a multicellular filamentous hyphal form at 25°C and in a unicellular yeast form at 37°C. P. marneffei also undergoes asexual development at 25°C to produce multicellular differentiated conidiophores. Thus, P. marneffei exhibits cell division with and without cytokinesis and division by budding and fission, depending on the cell type. The type II myosin gene, myoB, from P. marneffei plays important roles in the morphogenesis of these cell types. Deletion of myoB leads to chitin deposition defects at sites of cell division without perturbing actin localization. In addition to aberrant hyphal cells, distinct conidiophore cell types are lacking due to malformed septa and nuclear division defects. At 37°C, deletion of myoB prevents uninucleate yeast cell formation, instead producing long filaments resembling hyphae at 25°C. The ΔmyoB cells also often lyse due to defects in cell wall biogenesis. Thus, MyoB is essential for correct morphogenesis of all cell types regardless of division mode (budding or fission) and defines differences between the different types of growth.
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Peñalva MÁ. Endocytosis in filamentous fungi: Cinderella gets her reward. Curr Opin Microbiol 2010; 13:684-92. [PMID: 20920884 DOI: 10.1016/j.mib.2010.09.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/07/2010] [Accepted: 09/08/2010] [Indexed: 12/27/2022]
Abstract
Endocytosis has been the Cinderella of membrane trafficking studies in filamentous fungi until recent work involving genetically tractable models has boosted interest in the field. Endocytic internalization predominates in the hyphal tips, spatially coupled to secretion. Early endosomes (EEs) show characteristic long-distance motility, riding on microtubule motors. The fungal tip contains a region baptised the 'dynein loading zone' where acropetally moving endosomes reaching the tip shift from a kinesin to dynein, reversing the direction of their movement. Multivesicular body biogenesis starts from these motile EEs. Maturation of EEs into late endosomes and vacuoles appears to be essential. The similarities between fungal and mammalian endocytic trafficking suggest that conditional mutant genetic screens would yield valuable information.
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Affiliation(s)
- Miguel Ángel Peñalva
- Department of Molecular and Cellular Medicine, Centro de Investigaciones Biológicas del CSIC, Ramiro de Maeztu 9, Madrid 28040, Spain.
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25
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DeMay BS, Meseroll RA, Occhipinti P, Gladfelter AS. Cellular requirements for the small molecule forchlorfenuron to stabilize the septin cytoskeleton. Cytoskeleton (Hoboken) 2010; 67:383-99. [PMID: 20517926 DOI: 10.1002/cm.20452] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The septins are filament-forming, GTP-binding proteins that are conserved from yeast to humans. Septins assemble into higher-order structures such as rings, bars, and gauzes with diverse functions including serving as membrane diffusion barriers and scaffolds for cell signaling. The basis for septin filament polymerization and the rules governing septin polymer dynamics are presently not well understood. Pharmacological agents are essential tools in studying such properties of the actin and microtubule cytoskeletons however there are only limited reports of a drug specific to the septin cytoskeleton. Forchlorfenuron (FCF) is a synthetic plant cytokinin used in agriculture which has been shown to alter septin organization in yeast and mammalian tissue culture cells. Here we assess cellular requirements and properties of septin-based structures induced by FCF. Treatment of the filamentous fungus Ashbya gossypii with FCF leads to assembly of extensive septin fibers throughout hyphae which is rapidly reversed upon removal of the drug. These fibers do not exchange or add septin subunits after assembly, indicating that FCF suppresses normal septin dynamics and stabilizes the polymers. While FCF-induced septin fibers do not co-localize to actin or microtubules, a polarized F-actin cytoskeleton is likely required for the assembly of drug-induced septin fibers. Thus, FCF is a potent inducer of septin polymerization and acts as a reversible stabilizer of extended septin polymers. This drug will be a powerful tool for studying mechanisms of septin polymerization and function, particularly in cell types where molecular analyses are complicated by the presence of multiple isoforms and limited genetics.
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Affiliation(s)
- Bradley S DeMay
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
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26
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Alvarez-Tabarés I, Pérez-Martín J. Septins from the phytopathogenic fungus Ustilago maydis are required for proper morphogenesis but dispensable for virulence. PLoS One 2010; 5:e12933. [PMID: 20885997 PMCID: PMC2946335 DOI: 10.1371/journal.pone.0012933] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 08/31/2010] [Indexed: 01/09/2023] Open
Abstract
Background Septins are a highly conserved family of GTP-binding proteins involved in multiple cellular functions, including cell division and morphogenesis. Studies of septins in fungal cells underpin a clear correlation between septin-based structures and fungal morphology, providing clues to understand the molecular frame behind the varied morphologies found in fungal world. Methodology/Principal Findings Ustilago maydis genome has the ability to encode four septins. Here, using loss-of-function as well as GFP-tagged alleles of these septin genes, we investigated the roles of septins in the morphogenesis of this basidiomycete fungus. We described that septins in U. maydis could assemble into at least three different structures coexisting in the same cell: bud neck collars, band-like structures at the growing tip, and long septin fibers that run from pole to pole near the cell cortex. We also found that in the absence of septins, U. maydis cells lost their elongated shape, became wider at the central region and ended up losing their polarity, pointing to an important role of septins in the morphogenesis of this fungus. These morphological defects were alleviated in the presence of an osmotic stabilizer suggesting that absence of septins affected the proper formation of the cell wall, which was coherent with a higher sensitivity of septin defective cells to drugs that affect cell wall construction as well as exocytosis. As U. maydis is a phytopathogen, we analyzed the role of septins in virulence and found that in spite of the described morphological defects, septin mutants were virulent in corn plants. Conclusions/Significance Our results indicated a major role of septins in morphogenesis in U. maydis. However, in contrast to studies in other fungal pathogens, in which septins were reported to be necessary during the infection process, we found a minor role of septins during corn infection by U. maydis.
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Affiliation(s)
- Isabel Alvarez-Tabarés
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología CSIC, Madrid, Spain
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27
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Seiler S, Justa-Schuch D. Conserved components, but distinct mechanisms for the placement and assembly of the cell division machinery in unicellular and filamentous ascomycetes. Mol Microbiol 2010; 78:1058-76. [PMID: 21091496 DOI: 10.1111/j.1365-2958.2010.07392.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cytokinesis is essential for cell proliferation, yet its molecular description is challenging, because >100 conserved proteins must be spatially and temporally co-ordinated. Despite the high importance of a tight co-ordination of cytokinesis with chromosome and organelle segregation, the mechanism for determining the cell division plane is one of the least conserved aspects of cytokinesis in eukaryotic cells. Budding and fission yeast have developed fundamentally distinct mechanisms to ensure proper nuclear segregation. The extent to which these pathways are conserved in multicellular fungi remains unknown. Recent progress indicates common components, but different mechanisms that are required for proper selection of the septation site in the different groups of Ascomycota. Cortical cues are used in yeast- and filament-forming species of the Saccharomycotina clade that are established at the incipient bud site or the hyphal tip respectively. In contrast, septum formation in the filament-forming Pezizomycotina species Aspergillus nidulans and Neurospora crassa seems more closely related to the fission yeast programme in that they may combine mitotic signals with a cell end-based marker system and Rho GTPase signalling. Thus, significant differences in the use and connection of conserved signalling modules become apparent that reflect the phylogenetic relationship of the analysed models.
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Affiliation(s)
- Stephan Seiler
- Institut für Mikrobiologie und Genetik, Universität Göttingen, Grisebachstr. 8, D-37077 Göttingen, Germany.
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28
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Justa-Schuch D, Heilig Y, Richthammer C, Seiler S. Septum formation is regulated by the RHO4-specific exchange factors BUD3 and RGF3 and by the landmark protein BUD4 in Neurospora crassa. Mol Microbiol 2010; 76:220-35. [PMID: 20199606 DOI: 10.1111/j.1365-2958.2010.07093.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rho GTPases have multiple, yet poorly defined functions during cytokinesis. By screening a Neurospora crassa knock-out collection for Rho guanine nucleotide exchange factor (GEF) mutants that phenocopy rho-4 defects (i.e. lack of septa, slow growth, abnormal branching and cytoplasmic leakage), we identified two strains defective in homologues of Bud3p and Rgf3 of budding and fission yeast respectively. The function of these proteins as RHO4-specific GEFs was determined by in vitro assays. In vivo microscopy suggested that the two GEFs and their target GTPase act as two independent modules during the selection of the septation site and the actual septation process. Furthermore, we determined that the N. crassa homologue of the anillinrelated protein BUD4 is required for septum initiation and that its deficiency leads to typical rho4 defects. Localization of BUD4 as a cortical ring prior to septation initiation was independent of functional BUD3 or RGF3. These data position BUD4 upstream of both RHO4 functions in the septation process and make BUD4 a prime candidate for a cortical marker protein involved in the selection of future septation sites. The persistence of both BUD proteins and of RHO4 at the septal pore suggests additional functions of these proteins at mature septa.
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Affiliation(s)
- Daniela Justa-Schuch
- Institut für Mikrobiologie und Genetik, Universität Göttingen, Göttingen, Germany
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29
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Lang C, Grava S, van den Hoorn T, Trimble R, Philippsen P, Jaspersen SL. Mobility, microtubule nucleation and structure of microtubule-organizing centers in multinucleated hyphae of Ashbya gossypii. Mol Biol Cell 2009; 21:18-28. [PMID: 19910487 PMCID: PMC2801712 DOI: 10.1091/mbc.e09-01-0063] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
We used live imaging and EM to study migration of multiple nuclei in A. gossypii. Three types of nuclear movements, oscillation, rotation, and bypassing, depend on cytoplasmic microtubules while a fourth type, co-transport with the cytoplasmic stream, does not. Nuclear MTOCs emanating perpendicular and tangential cMTs lead cMT-dependent movements We investigated the migration of multiple nuclei in hyphae of the filamentous fungus Ashbya gossypii. Three types of cytoplasmic microtubule (cMT)-dependent nuclear movements were characterized using live cell imaging: short-range oscillations (up to 4.5 μm/min), rotations (up to 180° in 30 s), and long-range nuclear bypassing (up to 9 μm/min). These movements were superimposed on a cMT-independent mode of nuclear migration, cotransport with the cytoplasmic stream. This latter mode is sufficient to support wild-type-like hyphal growth speeds. cMT-dependent nuclear movements were led by a nuclear-associated microtubule-organizing center, the spindle pole body (SPB), which is the sole site of microtubule nucleation in A. gossypii. Analysis of A. gossypii SPBs by electron microscopy revealed an overall laminar structure similar to the budding yeast SPB but with distinct differences at the cytoplasmic side. Up to six perpendicular and tangential cMTs emanated from a more spherical outer plaque. The perpendicular and tangential cMTs most likely correspond to short, often cortex-associated cMTs and to long, hyphal growth-axis–oriented cMTs, respectively, seen by in vivo imaging. Each SPB nucleates its own array of cMTs, and the lack of overlapping cMT arrays between neighboring nuclei explains the autonomous nuclear oscillations and bypassing observed in A. gossypii hyphae.
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Affiliation(s)
- Claudia Lang
- Department of Molecular Microbiology, Biozentrum University of Basel, 4056 Basel, Switzerland
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Hickman MA, Rusche LN. The Sir2-Sum1 complex represses transcription using both promoter-specific and long-range mechanisms to regulate cell identity and sexual cycle in the yeast Kluyveromyces lactis. PLoS Genet 2009; 5:e1000710. [PMID: 19893609 PMCID: PMC2762165 DOI: 10.1371/journal.pgen.1000710] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 10/05/2009] [Indexed: 01/01/2023] Open
Abstract
Deacetylases of the Sir2 family regulate lifespan and response to stress. We have examined the evolutionary history of Sir2 and Hst1, which arose by gene duplication in budding yeast and which participate in distinct mechanisms of gene repression. In Saccharomyces cerevisiae, Sir2 interacts with the SIR complex to generate long-range silenced chromatin at the cryptic mating-type loci, HMLalpha and HMRa. Hst1 interacts with the SUM1 complex to repress sporulation genes through a promoter-specific mechanism. We examined the functions of the non-duplicated Sir2 and its partners, Sir4 and Sum1, in the yeast Kluyveromyces lactis, a species that diverged from Saccharomyces prior to the duplication of Sir2 and Hst1. KlSir2 interacts with both KlSir4 and KlSum1 and represses the same sets of target genes as ScSir2 and ScHst1, indicating that Sir2 and Hst1 subfunctionalized after duplication. However, the KlSir4-KlSir2 and KlSum1-KlSir2 complexes do not function as the analogous complexes do in S. cerevisiae. KlSir4 contributes to an extended repressive chromatin only at HMLalpha and not at HMRa. In contrast, the role of KlSum1 is broader. It employs both long-range and promoter-specific mechanisms to repress cryptic mating-type loci, cell-type-specific genes, and sporulation genes and represents an important regulator of cell identity and the sexual cycle. This study reveals that a single repressive complex can act through two distinct mechanisms to regulate gene expression and illustrates how mechanisms by which regulatory proteins act can change over evolutionary time.
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Affiliation(s)
- Meleah A. Hickman
- Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina, United States of America
- University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Laura N. Rusche
- Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina, United States of America
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
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Abstract
AbstractSeptins are a conserved family of GTP-binding proteins found in living organisms ranging from yeasts to mammals. They are able to polymerize and form hetero-oligomers that assemble into higher-order structures whose detailed molecular architecture has recently been described in different organisms. In Saccharomyces cerevisiae, septins exert numerous functions throughout the cell cycle, serving as scaffolds for many different proteins or as diffusion barriers at the bud neck. In other fungi, septins are required for the proper completion of diverse functions such as polarized growth or pathogenesis. Recent results from several fungi have revealed important differences in septin organization and regulation as compared with S. cerevisiae, especially during Candida albicans hyphal growth and in Ashbya gossypii. Here we focus on these recent findings, their relevance in the biology of these eukaryotes and in consequence the “renaissance” of the study of septin structures in cells showing a different kind of morphological behaviour.
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32
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Kaufmann A. A plasmid collection for PCR-based gene targeting in the filamentous ascomycete Ashbya gossypii. Fungal Genet Biol 2009; 46:595-603. [PMID: 19460453 DOI: 10.1016/j.fgb.2009.05.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 04/24/2009] [Accepted: 05/06/2009] [Indexed: 10/20/2022]
Abstract
PCR-based gene targeting with heterologous markers is an efficient method to delete genes, generate gene fusions, and modulate gene expression. For the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, several plasmid collections are available covering a wide range of tags and markers. For several reasons, many of these cassettes cannot be used in the filamentous ascomycete Ashbya gossypii. This article describes the construction of 93 heterologous modules for C- and N-terminal tagging and promoter replacements in A. gossypii. The performance of 12 different fluorescent tags was evaluated by monitoring their brightness, detectability, and photostability when fused to the myosin light-chain protein Mlc2. Furthermore, the thiamine-repressible S. cerevisiae THI13 promoter was established to regulate gene expression in A. gossypii. This collection will help accelerate analysis of gene function in A. gossypii and in other ascomycetes where S. cerevisiae promoter elements are functional.
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