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Rivetta A, Allen K, Graham M, Potapova T, Slayman C, Liu X. Morphodynamics of non-canonical autophagic structures in Neurospora crassa. mSphere 2023; 8:e0046023. [PMID: 37847028 PMCID: PMC10732065 DOI: 10.1128/msphere.00460-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/08/2023] [Indexed: 10/18/2023] Open
Abstract
IMPORTANCE Neurospora is a quintessential tip-growing organism, which is well known for packaging and longitudinal transport of tip-building blocks. Thus far, however, little attention has been paid to the co-essential process of reclamation, that is-taking apart of upstream, older structural elements, otherwise known as "autophagy". We are not yet prepared to set out the chemistry of that elaborate process, but its morphological start alone is worthy of attention. Carbon starvation triggers significant autophagic changes, beginning with prolific vacuolation along the plasma membrane, and eventual filling of 70% (or more) of cytoplasmic volume. Additionally, the Neurospora plasma membrane elaborates a variety of phagophores which themselves often look lytic. These have either dual enclosing membranes, like the familiar autophagosomes, can be doubled and have four wrapping membranes, or can be compounded with multiple membrane layers. These reclamation processes must be accommodated by the mechanism of tip growth.
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Affiliation(s)
- Alberto Rivetta
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Kenneth Allen
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Morven Graham
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Tatiana Potapova
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
- Belozersky Institute of Physicochemical Biology, Moscow State University, Moscow, Russia
| | - Clifford Slayman
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Xinran Liu
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut, USA
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Blancard C, Salin B. Plunge Freezing: A Tool for the Ultrastructural and Immunolocalization Studies of Suspension Cells in Transmission Electron Microscopy. J Vis Exp 2017. [PMID: 28518127 DOI: 10.3791/54874] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Transmission Electron Microscopy (TEM) is an extraordinary tool for studying cell ultrastructure, in order to localize proteins and visualize macromolecular complexes at very high resolution. However, to get as close as possible to the native state, perfect sample preservation is required. Conventional electron microscopy (EM) fixation with aldehydes, for instance, does not provide good ultrastructural preservation. The slow penetration of fixatives induces cell reorganization and loss of various cell components. Therefore, conventional EM fixation does not allow for an instantaneous stabilization and preservation of structures and antigenicity. The best choice for examining intracellular events is to use cryofixation followed by the freeze-substitution fixation method that keeps cells in their native state. High-pressure freezing/freeze-substitution, which preserves the integrity of cellular ultrastructure, is the most commonly used method, but requires expensive equipment. Here, an easy-to-use and low-cost freeze fixation method followed by freeze-substitution for suspension cell cultures is presented.
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Affiliation(s)
- Corinne Blancard
- Institut de Biochimie et Génétique Cellulaires, Centre National de la Recherche Scientifique, UMR 5095, Université de Bordeaux
| | - Bénédicte Salin
- Institut de Biochimie et Génétique Cellulaires, Centre National de la Recherche Scientifique, UMR 5095, Université de Bordeaux;
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Yang X, Cui H, Cheng J, Xie J, Jiang D, Hsiang T, Fu Y. A HOPS protein, CmVps39, is required for vacuolar morphology, autophagy, growth, conidiogenesis and mycoparasitic functions of Coniothyrium minitans. Environ Microbiol 2016; 18:3785-3797. [PMID: 27105005 DOI: 10.1111/1462-2920.13334] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Coniothyrium minitans is an important sclerotial and hyphal parasite of the plant pathogen Sclerotinia sclerotiorum. Previously, a conidiation-deficient mutant, ZS-1N22225, was screened from a T-DNA insertional library of C. minitans. CmVps39, a homologue of Vam6p/Vps39p that plays a critical role in vacuolar morphogenesis in yeast, was disrupted by a T-DNA insertion in this mutant. CmVps39 is composed of 1071 amino acids with an amino-terminal citron homology domain and a central clathrin homology domain, as observed for other Vam6p/Vps39p family proteins. Abnormal fragmented vacuoles were observed in ΔCmVps39 under light microscopy and transmission electron microscopy, and ΔCmVps39 showed impairment in autophagy. ΔCmVps39 also exhibited significantly reduced hyphal development, poor conidiation and decreased sclerotial mycoparasitism. In addition, deletion of CmVps39 affected osmotic adaptation, pH homeostasis and cell wall integrity. Taken together, our results suggest that CmVps39 has an essential function in vacuolar morphology, autophagy, fungal development and mycoparasitism in C. minitans.
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Affiliation(s)
- Xiaoxiang Yang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China.,The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China
| | - Hui Cui
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China.,The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China
| | - Jiasen Cheng
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China
| | - Jiatao Xie
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China
| | - Daohong Jiang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China.,The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China
| | - Tom Hsiang
- Department of Environmental Biology, University of Guelph, Guelph, ON, Canada
| | - Yanping Fu
- The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, Hubei Province, People's Republic of China
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Voigt O, Pöggeler S. Autophagy genes Smatg8 and Smatg4 are required for fruiting-body development, vegetative growth and ascospore germination in the filamentous ascomycete Sordaria macrospora. Autophagy 2012; 9:33-49. [PMID: 23064313 DOI: 10.4161/auto.22398] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Autophagy is a tightly controlled degradation process involved in various developmental aspects of eukaryotes. However, its involvement in developmental processes of multicellular filamentous ascomycetes is largely unknown. Here, we analyzed the impact of the autophagic proteins SmATG8 and SmATG4 on the sexual and vegetative development of the filamentous ascomycete Sordaria macrospora. A Saccharomyces cerevisiae complementation assay demonstrated that the S. macrospora Smatg8 and Smatg4 genes can functionally replace the yeast homologs. By generating homokaryotic deletion mutants, we showed that the S. macrospora SmATG8 and SmATG4 orthologs were associated with autophagy-dependent processes. Smatg8 and Smatg4 deletions abolished fruiting-body formation and impaired vegetative growth and ascospore germination, but not hyphal fusion. We demonstrated that SmATG4 was capable of processing the SmATG8 precursor. SmATG8 was localized to autophagosomes, whereas SmATG4 was distributed throughout the cytoplasm of S. macrospora. Furthermore, we could show that Smatg8 and Smatg4 are not only required for nonselective macroautophagy, but for selective macropexophagy as well. Taken together, our results suggest that in S. macrospora, autophagy seems to be an essential and constitutively active process to sustain high energy levels for filamentous growth and multicellular development even under nonstarvation conditions.
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Affiliation(s)
- Oliver Voigt
- Institute of Microbiology and Genetics, Department of Genetics of Eukaryotic Microorganisms, Georg-August University, Göttingen, Germany
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Liu XH, Gao HM, Xu F, Lu JP, Devenish RJ, Lin FC. Autophagy vitalizes the pathogenicity of pathogenic fungi. Autophagy 2012; 8:1415-25. [PMID: 22935638 DOI: 10.4161/auto.21274] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Plant pathogenic fungi utilize a series of complex infection structures, in particular the appressorium, to gain entry to and colonize plant tissue. As a consequence of the accumulation of huge quantities of glycerol in the cell the appressorium generates immense intracellular turgor pressure allowing the penetration peg of the appressorium to penetrate the leaf cuticle. Autophagic processes are ubiquitous in eukaryotic cells and facilitate the bulk degradation of macromolecules and organelles. The study of autophagic processes has been extended from the model yeast Saccharomyces cerevisiae to pathogenic fungi such as the rice blast fungus Magnaporthe oryzae. Significantly, null mutants for the expression of M. oryzae autophagy gene homologs lose their pathogenicity for infection of host plants. Clarification of the functions and network of interactions between the proteins expressed by M. oryzae autophagy genes will lead to a better understanding of the role of autophagy in fungal pathogenesis and help in the development of new strategies for disease control.
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Affiliation(s)
- Xiao-Hong Liu
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
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Chevanne D, Saupe SJ, Clavé C, Paoletti M. WD-repeat instability and diversification of the Podospora anserina hnwd non-self recognition gene family. BMC Evol Biol 2010; 10:134. [PMID: 20459612 PMCID: PMC2873952 DOI: 10.1186/1471-2148-10-134] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 05/06/2010] [Indexed: 01/07/2023] Open
Abstract
Background Genes involved in non-self recognition and host defence are typically capable of rapid diversification and exploit specialized genetic mechanism to that end. Fungi display a non-self recognition phenomenon termed heterokaryon incompatibility that operates when cells of unlike genotype fuse and leads to the cell death of the fusion cell. In the fungus Podospora anserina, three genes controlling this allorecognition process het-d, het-e and het-r are paralogs belonging to the same hnwd gene family. HNWD proteins are STAND proteins (signal transduction NTPase with multiple domains) that display a WD-repeat domain controlling recognition specificity. Based on genomic sequence analysis of different P. anserina isolates, it was established that repeat regions of all members of the gene family are extremely polymorphic and undergoing concerted evolution arguing for frequent recombination within and between family members. Results Herein, we directly analyzed the genetic instability and diversification of this allorecognition gene family. We have constituted a collection of 143 spontaneous mutants of the het-R (HNWD2) and het-E (hnwd5) genes with altered recognition specificities. The vast majority of the mutants present rearrangements in the repeat arrays with deletions, duplications and other modifications as well as creation of novel repeat unit variants. Conclusions We investigate the extreme genetic instability of these genes and provide a direct illustration of the diversification strategy of this eukaryotic allorecognition gene family.
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Affiliation(s)
- Damien Chevanne
- Laboratoire de Génétique Moléculaire des Champignons, IBGC, UMR 5095 Université Victor Segalen Bordeaux 2, 1 rue Camille Saint-Saëns, Bordeaux Cedex, France
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Abstract
In fungi, cell fusion between genetically unlike individuals triggers a cell death reaction known as the incompatibility reaction. In Podospora anserina, the genes controlling this process belong to a gene family encoding STAND proteins with an N-terminal cell death effector domain, a central NACHT domain and a C-terminal WD-repeat domain. These incompatibility genes are extremely polymorphic, subject to positive Darwinian selection and display a remarkable genetic plasticity allowing for constant diversification of the WD-repeat domain responsible for recognition of non-self. Remarkably, the architecture of these proteins is related to pathogen-recognition receptors ensuring innate immunity in plants and animals. Here, we hypothesize that these P. anserina incompatibility genes could be components of a yet-unidentified innate immune system of fungi. As already proposed in the case of plant hybrid necrosis or graft rejection in mammals, incompatibility could be a by-product of pathogen-driven divergence in host defense genes.
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Affiliation(s)
- Mathieu Paoletti
- Laboratoire de Génétique Moléculaire des Champignons, Institut de Biochimie et de Génétique Cellulaires, UMR 5095 CNRS-Université de Bordeaux 2, 1 rue Camille St Saëns, 33077 Bordeaux Cedex, France
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