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Mazheika IS, Kamzolkina OV. Does macrovesicular endocytosis occur in fungal hyphae? FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2021.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bartnicki-Garcia S, Garduño-Rosales M, Delgado-Alvarez DL, Mouriño-Pérez RR. Experimental measurement of endocytosis in fungal hyphae. Fungal Genet Biol 2018; 118:32-36. [PMID: 30017938 DOI: 10.1016/j.fgb.2018.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/27/2018] [Accepted: 07/01/2018] [Indexed: 11/15/2022]
Abstract
The present study examines the notion that polarized exocytosis in the tips of growing hyphae creates an excess of plasma membrane and thus the need for its removal by endocytosis. To measure endocytosis experimentally, we developed a photobleaching (FRAP) procedure to count endocytic events in hyphae of Neurospora crassa carrying a fluorescent tag on the actin-binding protein fimbrin (FIM-1-GFP). Given 40 nm as the average diameter of endocytic vesicles, we calculated that about 12.5% of the plasma membrane discharged in the apex becomes endocytosed in the subapex. According to our calculations, the GFP-tagged hyphae of N. crassa, measured under the constrained conditions of confocal microscopic examination, needed about 8800 vesicles/min to extend their plasma membrane or about 9800/min, if we include predicted demands for cell wall growth and extracellular secretion. Our findings support the notion that exocytosis and endocytosis operate in tandem with the latter serving as a compensatory process to remove any excess of plasma membrane generated by the intense exocytosis in the hyphal tips. Presumably, this tandem arrangement evolved to support the hallmark features of fungi namely rapid cell extension and abundant secretion of hydrolytic enzymes.
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Affiliation(s)
- Salomon Bartnicki-Garcia
- Departamento de Microbiología, CICESE (Centro de Investigación Científica y Educación Superior de Ensenada), Mexico
| | - Marisela Garduño-Rosales
- Departamento de Microbiología, CICESE (Centro de Investigación Científica y Educación Superior de Ensenada), Mexico
| | - Diego Luis Delgado-Alvarez
- Departamento de Microbiología, CICESE (Centro de Investigación Científica y Educación Superior de Ensenada), Mexico
| | - Rosa Reyna Mouriño-Pérez
- Departamento de Microbiología, CICESE (Centro de Investigación Científica y Educación Superior de Ensenada), Mexico.
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Abstract
Filamentous fungi have proven to be a better-suited model system than unicellular yeasts in analyses of cellular processes such as polarized growth, exocytosis, endocytosis, and cytoskeleton-based organelle traffic. For example, the filamentous fungus
Neurospora crassa develops a variety of cellular forms. Studying the molecular basis of these forms has led to a better, yet incipient, understanding of polarized growth. Polarity factors as well as Rho GTPases, septins, and a localized delivery of vesicles are the central elements described so far that participate in the shift from isotropic to polarized growth. The growth of the cell wall by apical biosynthesis and remodeling of polysaccharide components is a key process in hyphal morphogenesis. The coordinated action of motor proteins and Rab GTPases mediates the vesicular journey along the hyphae toward the apex, where the exocyst mediates vesicle fusion with the plasma membrane. Cytoplasmic microtubules and actin microfilaments serve as tracks for the transport of vesicular carriers as well as organelles in the tubular cell, contributing to polarization. In addition to exocytosis, endocytosis is required to set and maintain the apical polarity of the cell. Here, we summarize some of the most recent breakthroughs in hyphal morphogenesis and apical growth in
N. crassa and the emerging questions that we believe should be addressed.
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Affiliation(s)
- Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, 22860, Mexico
| | - Leonora Martínez-Núñez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, 22860, Mexico
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The Podosphaera xanthii haustorium, the fungal Trojan horse of cucurbit-powdery mildew interactions. Fungal Genet Biol 2014; 71:21-31. [PMID: 25151531 DOI: 10.1016/j.fgb.2014.08.006] [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] [Received: 05/29/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 01/04/2023]
Abstract
The powdery mildew fungi are obligate biotrophic plant pathogens that develop a specialized structure for parasitism termed haustorium, which is responsible for nutrient uptake and factor exchange with the plant. In this work, we present a detailed microscopy analysis of the haustoria of the cucurbit powdery mildew fungus Podosphaera xanthii, a major limiting factor for cucurbit production worldwide. Despite being located inside plant epidermal cells, transmission electron microscopy (TEM) analysis showed the characteristic highly irregular outline of the extrahaustorial membrane that separates the extrahaustorial matrix of haustoria from the cytoplasm of the plant cell. TEM analysis also revealed the presence of some vesicles and electron-dense plaques of material surrounding the haustoria. In confocal microscopy analysis and aniline blue staining we found a positive correlation between haustorial development and deposition of callose, which is distributed as plaques around haustorial complex. In this study, a method for the isolation of P. xanthii haustoria was also adapted, which permitted the analysis of the formation of haustorial lobes and the visualization of vacuoles and the pool of vesicles inside the haustorial complex. Our findings suggested that the haustorial lobes were responsible for vesicular trafficking and most likely act as the main mediators of the fungus-plant dialogue. All of these findings were integrated into a model of the P. xanthii-host cellular interactions.
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Steinberg G. Endocytosis and early endosome motility in filamentous fungi. Curr Opin Microbiol 2014; 20:10-8. [PMID: 24835422 PMCID: PMC4148197 DOI: 10.1016/j.mib.2014.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 04/21/2014] [Indexed: 10/25/2022]
Abstract
Hyphal growth of filamentous fungi requires microtubule-based long-distance motility of early endosomes. Since the discovery of this process in Ustilago maydis, our understanding of its molecular basis and biological function has greatly advanced. Studies in U. maydis and Aspergillus nidulans reveal a complex interplay of the motor proteins kinesin-3 and dynein, which co-operate to support bi-directional motion of early endosomes. Genetic screening has shed light on the molecular mechanisms underpinning motor regulation, revealing Hook protein as general motor adapters on early endosomes. Recently, fascinating insight into unexpected roles for endosome motility has emerged. This includes septin filament formation and cellular distribution of the machinery for protein translation.
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Affiliation(s)
- Gero Steinberg
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
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Affiliation(s)
- Meritxell Riquelme
- Departamento de Microbiología, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, Mexico 22860;
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Deacon J. Fungal Structure and Ultrastructure. Fungal Biol 2013. [DOI: 10.1002/9781118685068.ch3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Dijksterhuis J, Molenaar D. Vesicle trafficking via the Spitzenkörper during hyphal tip growth in Rhizoctonia solani. Antonie van Leeuwenhoek 2013; 103:921-31. [DOI: 10.1007/s10482-012-9873-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 12/27/2012] [Indexed: 10/27/2022]
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Richards A, Gow NAR, Veses V. Identification of vacuole defects in fungi. J Microbiol Methods 2012; 91:155-63. [PMID: 22902527 DOI: 10.1016/j.mimet.2012.08.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Revised: 07/30/2012] [Accepted: 08/02/2012] [Indexed: 11/25/2022]
Abstract
Fungal vacuoles are involved in a diverse range of cellular functions, participating in cellular homeostasis, degradation of intracellular components, and storage of ions and molecules. In recent years there has been a significant increase in the number of studies linking these organelles with the regulation of growth and control of cellular morphology, particularly in those fungal species able to undergo yeast-hypha morphogenetic transitions. This has contributed to the refinement of previously published protocols and the development of new techniques, particularly in the area of live-cell imaging of membrane trafficking events and vacuolar dynamics. The current review outlines recent advances in the imaging of fungal vacuoles and assays for characterization of trafficking pathways, and other physiological activities of this important cell organelle.
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Affiliation(s)
- Andrea Richards
- The Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
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Lewis MW, Robalino IV, Keyhani NO. Uptake of the fluorescent probe FM4-64 by hyphae and haemolymph-derived in vivo hyphal bodies of the entomopathogenic fungus Beauveria bassiana. Microbiology (Reading) 2009; 155:3110-3120. [DOI: 10.1099/mic.0.029165-0] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The entomopathogenic fungus Beauveria bassiana is under intensive study as a pest biological control agent. B. bassiana produces several distinct single-cell types that include aerial conidia, in vitro blastospores and submerged conidia. Under appropriate nutrient conditions these cells can elaborate germ tubes that form hyphae, which in turn lead to the formation of a fungal mycelium. In addition, B. bassiana displays a dimorphic transition, producing in vivo specific yeast-like hyphal bodies during growth in the arthropod haemolymph. The amphiphilic styryl dye FM4-64 was used to investigate internalization and morphological features of in vitro and in vivo insect haemolymph-derived B. bassiana cells. In vitro blastospores and submerged conidia displayed a punctate pattern of internal labelling, whereas aerial conidia failed to internalize the dye under the conditions tested. FM4-64 was also taken up into both apical and subapical compartments of living hyphae in a time-dependent manner, with clearly observable vesicle labelling. Internalization, where occurring, was reversibly disrupted by lowering the temperature of the assay or by treatment with azide/fluoride and latrunculin A. Treatment with cytochalasin D and monensin also caused abnormal vesicle trafficking, although some staining of vesicles was noted. Fungal cells derived from infected Heliothis virescens haemolymph (in vivo cells) actively internalized FM4-64. The in vivo blastospores or hyphal bodies displayed bright membrane and internal vesicle staining, although diffuse staining of internal structures was also visible. These results suggest active uptake by different developmental stages of B. bassiana, including haemolymph-derived cells that can evade the insect immune system.
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Affiliation(s)
- Michael W. Lewis
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
| | - Ines V. Robalino
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
| | - Nemat O. Keyhani
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
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Higaki T, Kutsuna N, Sano T, Hasezawa S. Quantitative analysis of changes in actin microfilament contribution to cell plate development in plant cytokinesis. BMC PLANT BIOLOGY 2008; 8:80. [PMID: 18637163 PMCID: PMC2490694 DOI: 10.1186/1471-2229-8-80] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2008] [Accepted: 07/17/2008] [Indexed: 05/19/2023]
Abstract
BACKGROUND Plant cells divide by the formation of new cross walls, known as cell plates, from the center to periphery of each dividing cell. Formation of the cell plate occurs in the phragmoplast, a complex structure composed of membranes, microtubules (MTs) and actin microfilaments (MFs). Disruption of phragmoplast MTs was previously found to completely inhibit cell plate formation and expansion, indicative of their crucial role in the transport of cell plate membranes and materials. In contrast, disruption of MFs only delays cell plate expansion but does not completely inhibit cell plate formation. Despite such findings, the significance and molecular mechanisms of MTs and MFs remain largely unknown. RESULTS Time-sequential changes in MF-distribution were monitored by live imaging of tobacco BY-2 cells stably expressing the GFP-actin binding domain 2 (GFP-ABD2) fusion protein, which vitally co-stained with the endocytic tracer, FM4-64, that labels the cell plate. During cytokinesis, MFs accumulated near the newly-separated daughter nuclei towards the emerging cell plate, and subsequently approached the expanding cell plate edges. Treatment with an actin polymerization inhibitor caused a decrease in the cell plate expansion rate, which was quantified using time-lapse imaging and regression analysis. Our results demonstrated time-sequential changes in the contribution of MFs to cell plate expansion; MF-disruption caused about a 10% decrease in the cell plate expansion rate at the early phase of cytokinesis, but about 25% at the late phase. MF-disruption also caused malformation of the emerging cell plate at the early phase, indicative of MF involvement in early cell plate formation and expansion. The dynamic movement of endosomes around the cell plate was also inhibited by treatment with an actin polymerization inhibitor and a myosin ATPase inhibitor, respectively. Furthermore, time-lapse imaging of the endoplasmic reticulum (ER) revealed that MFs were involved in ER accumulation in the phragmoplast at the late phase. CONCLUSION By expression of GFP-ABD2 and vital staining with FM4-64, the dynamics of MFs and the cell plate could be followed throughout plant cytokinesis in living cells. Pharmacological treatment and live imaging analysis also allowed us to quantify MF contribution to cell plate expansion during cytokinesis. Our results suggest that MFs play significant roles in cell plate formation and expansion via regulation of endomembrane dynamics.
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Affiliation(s)
- Takumi Higaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
| | - Natsumaro Kutsuna
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
- Institute for Bioinformatics Research and Development (BIRD), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-8666, Japan
| | - Toshio Sano
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
- Institute for Bioinformatics Research and Development (BIRD), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-8666, Japan
| | - Seiichiro Hasezawa
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha Kashiwa, Chiba 277-8562, Japan
- Institute for Bioinformatics Research and Development (BIRD), Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-8666, Japan
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Upadhyay S, Shaw BD. The role of actin, fimbrin and endocytosis in growth of hyphae in Aspergillus nidulans. Mol Microbiol 2008; 68:690-705. [PMID: 18331474 DOI: 10.1111/j.1365-2958.2008.06178.x] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Filamentous fungi are ideal systems to study the process of polarized growth, as their life cycle is dominated by hyphal growth exclusively at the cell apex. The actin cytoskeleton plays an important role in this growth. Until now, there have been no tools to visualize actin or the actin-binding protein fimbrin in live cells of a filamentous fungus. We investigated the roles of actin (ActA) and fimbrin (FimA) in hyphal growth in Aspergillus nidulans. We examined the localization of ActA::GFP and FimA::GFP in live cells, and each displayed a similar localization pattern. In actively growing hyphae, cortical ActA::GFP and FimA::GFP patches were highly mobile throughout the hypha and were concentrated near hyphal apices. A patch-depleted zone occupied the apical 0.5 microm of growing hypha. Both FimA::GFP and Act::GFP also localize transiently to septa. Movement and later localization of both was compromised after cytochalasin treatment. Disruption of fimA resulted in delayed polarity establishment during conidium germination, abnormal hyphal growth and endocytosis defects in apolar cells. Endocytosis was severely impaired in apolar fimA disruption cells. Our data support a novel apical recycling model which indicates a critical role for actin patch-mediated endocytosis to maintain polarized growth at the apex.
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Affiliation(s)
- Srijana Upadhyay
- Program for the Biology of Filamentous Fungi, Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX 77843, USA
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Suei S, Garrill A. An F-actin-depleted zone is present at the hyphal tip of invasive hyphae of Neurospora crassa. PROTOPLASMA 2008; 232:165-172. [PMID: 18421548 DOI: 10.1007/s00709-008-0289-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 08/30/2007] [Indexed: 05/26/2023]
Abstract
The distribution of filamentous actin (F-actin) in invasive and noninvasive hyphae of the ascomycete Neurospora crassa was investigated. Eighty six percent of noninvasive hyphae had F-actin in the tip region compared to only 9% of invasive hyphae. The remaining 91% of the invasive hyphae had no obvious tip high concentration of F-actin staining; instead they had an F-actin-depleted zone in this region, although some F-actin, possibly associated with the Spitzenkörper, remained at the tip. The size of the F-actin-depleted zone in invasive hyphae increased with an increase in agar concentration. The membrane stain FM 4-64 reveals a slightly larger accumulation of vesicles at the tips of invasive hyphae relative to noninvasive hyphae, although this difference is unlikely to be sufficient to account for the exclusion of F-actin from the depleted zone. Antibodies raised against the actin filament-severing protein cofilin from both yeast and human cells localize to the tips of invasive hyphae. The human cofilin antibody shows a more random distribution in noninvasive hyphae locating primarily at the hyphal periphery but with some diffuse cytoplasmic staining. This antibody also identifies a single band at 21 kDa in immunoblots of whole hyphal fractions. These data suggest that a protein with epitopic similarity to cofilin may function in F-actin dynamics that underlie invasive growth. The F-actin-depleted zone may play a role in the regulation of tip yielding to turgor pressure, thus increasing the protrusive force necessary for invasive growth.
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Affiliation(s)
- S Suei
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
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Park YS, Kim JH, Cho JH, Chang HI, Kim SW, Paik HD, Kang CW, Kim TH, Sung HC, Yun CW. Physical and functional interaction of FgFtr1-FgFet1 and FgFtr2-FgFet2 is required for iron uptake in Fusarium graminearum. Biochem J 2007; 408:97-104. [PMID: 17655522 PMCID: PMC2049074 DOI: 10.1042/bj20070450] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
FgFtr1 and FgFtr2 are putative iron permeases, and FgFet1 and FgFet2 are putative ferroxidases of Fusarium graminearum. They have high homologies with iron permease ScFtr1 and ferroxidase ScFet3 of Saccharomyces cerevisiae at the amino acid level. The genes encoding iron permease and ferroxidase were localized to the same chromosome in the manner of FgFtr1/FgFet1 and FgFtr2/FgFet2. The GFP (green fluorescent protein)-fused versions of FgFtr1 and FgFtr2 showed normal functions when compared with FgFtr1 and FgFtr2 in an S. cerevisiae system, and the cellular localizations of FgFtr1 and FgFtr2 in S. cerevisiae depended on the expression of their putative ferroxidase partners FgFet1 and FgFet2 respectively. Although FgFtr1 was found on the plasma membrane when FgFet1 and FgFtr1 were co-transformed in S. cerevisiae, most of the FgFtr1 was found in the endoplasmic reticulum compartment when co-expressed with FgFet2. Furthermore, FgFtr2 was found on the vacuolar membrane when FgFet2 was co-expressed. From the two-hybrid analysis, we confirmed the interaction of FgFtr1 and FgFet1, and the same result was found between FgFtr2 and FgFet2. Iron-uptake activity also depended on the existence of the respective partner. Finally, the FgFtr1 and FgFtr2 were found on the plasma and vacuolar membrane respectively, in F. graminearum. Taken together, these results strongly suggest that FgFtr1 and FgFtr2 from F. graminearum encode the iron permeases of the plasma membrane and vacuolar membrane respectively, and require their specific ferroxidases to carry out normal function. Furthermore, the present study suggests that the reductive iron-uptake system is conserved from yeast to filamentous fungi.
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Affiliation(s)
- Yong-Sung Park
- *School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
| | - Ji-Hyun Kim
- *School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
| | - Jin-Hwa Cho
- *School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
| | - Hyo-Ihl Chang
- *School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
| | - Seung-Wook Kim
- †Department of Chemical and Biological Engineering, Korea University. Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
| | - Hyun-Dong Paik
- ‡Division of Animal Life Science, Konkuk University, Seoul, 143-701, Korea
| | - Chang-Won Kang
- ‡Division of Animal Life Science, Konkuk University, Seoul, 143-701, Korea
| | - Tae-Hyoung Kim
- §Chosun University School of Medicine, Department of Biochemistry and Molecular Biology, 375 Seosuk-Dong, Dong-gu, Gwangju, 501-759, Korea
| | - Ha-Chin Sung
- *School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
| | - Cheol-Won Yun
- *School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, 143-701, Korea
- To whom correspondence should be addressed (email )
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Navarro FJ, Machín F, Martín Y, Siverio JM. Down-regulation of eukaryotic nitrate transporter by nitrogen-dependent ubiquitinylation. J Biol Chem 2006; 281:13268-13274. [PMID: 16543229 DOI: 10.1074/jbc.m601253200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the yeast Hansenula polymorpha, the YNT1 gene encodes the high affinity nitrate transporter, which is repressed by reduced nitrogen sources such as ammonium or glutamine. Ynt1 protein is degraded in response to glutamine in the growth medium. Ynt1 disappears independently of YNT1 glutamine repression as shown in strains where YNT1 repression is abolished. Ynt1-green fluorescent protein chimera and a mutant defective in vacuolar proteinase A (deltapep4) showed that Ynt1 is degraded in the vacuole in response to glutamine. The central hydrophilic domain of Ynt1 contains PEST-like sequences whose deletion blocked Ynt1 down-regulation. Site-directed mutagenesis showed that Lys-253 and Lys-270, located in this sequence, were involved in internalization and subsequent vacuolar degradation of Ynt1. Ynt1-ubiquitin conjugates were induced by glutamine and not nitrate. We conclude that glutamine triggers Ynt1 down-regulation via ubiquitinylation of lysines in the central hydrophilic domain, and proteolysis in the vacuole.
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Affiliation(s)
- Francisco J Navarro
- Department of Biochemistry and Molecular Biology, Instituto Universitario de Enfermedades Tropicales, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canarias, Spain
| | - Félix Machín
- Department of Biochemistry and Molecular Biology, Instituto Universitario de Enfermedades Tropicales, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canarias, Spain
| | - Yusé Martín
- Department of Biochemistry and Molecular Biology, Instituto Universitario de Enfermedades Tropicales, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canarias, Spain
| | - José M Siverio
- Department of Biochemistry and Molecular Biology, Instituto Universitario de Enfermedades Tropicales, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Canarias, Spain.
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Shoji JY, Arioka M, Kitamoto K. Vacuolar membrane dynamics in the filamentous fungus Aspergillus oryzae. EUKARYOTIC CELL 2006; 5:411-21. [PMID: 16467481 PMCID: PMC1405889 DOI: 10.1128/ec.5.2.411-421.2006] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Accepted: 10/18/2005] [Indexed: 11/20/2022]
Abstract
Vacuoles in filamentous fungi are highly pleomorphic and some of them, e.g., tubular vacuoles, are implicated in intra- and intercellular transport. In this report, we isolated Aovam3, the homologue of the Saccharomyces cerevisiae VAM3 gene that encodes the vacuolar syntaxin, from Aspergillus oryzae. In yeast complementation analyses, the expression of Aovam3 restored the phenotypes of both Deltavam3 and Deltapep12 mutants, suggesting that AoVam3p is likely the vacuolar and/or endosomal syntaxin in A. oryzae. FM4-64 [N-(3-triethylammoniumpropyl)-4-(p-diethylaminophenyl-hexatrienyl)pyridinium dibromide] and CMAC (7-amino-4-chloromethylcoumarin) staining confirmed that the fusion protein of enhanced green fluorescent protein (EGFP) with AoVam3p (EGFP-AoVam3p) localized on the membrane of the pleomorphic vacuolar networks, including large spherical vacuoles, tubular vacuoles, and putative late endosomes/prevacuolar compartments. EGFP-AoVam3p-expressing strains allowed us to observe the dynamics of vacuoles with high resolutions, and moreover, led to the discovery of several new aspects of fungal vacuoles, which have not been discovered so far with conventional staining methods, during different developmental stages. In old hyphae, EGFP fluorescence was present in the entire lumen of large vacuoles, which occupied most of the cell, indicating that degradation of cytosolic materials had occurred in such hyphae via an autophagic process. In hyphae that were not in contact with nutrients, such as aerial hyphae and hyphae that grew on a glass surface, vacuoles were composed of small punctate structures and tubular elements that often formed reticulum-like networks. These observations imply the presence of so-far-unrecognized roles of vacuoles in the development of filamentous fungi.
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Affiliation(s)
- Jun-ya Shoji
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Abstract
The formation of highly polarized hyphae that grow by apical extension is a defining feature of the filamentous fungi. High-resolution microscopy and mathematical modeling have revealed the importance of the cytoskeleton and the Spitzenkorper (an apical vesicle cluster) in hyphal morphogenesis. However, the underlying molecular mechanisms remain poorly characterized. In this review, the pathways and functions known to be involved in polarized hyphal growth are summarized. A central theme is the notion that the polarized growth of hyphae is more complex than in yeast, though similar sets of core pathways are likely utilized. In addition, a model for the establishment and maintenance of hyphal polarity is presented. Key features of the model include the idea that polarity establishment is a stochastic process that occurs independent of internal landmarks. Moreover, the stabilization of nascent polarity axes may be the critical step that permits the emergence of a new hypha.
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Affiliation(s)
- Steven D Harris
- Plant Science Initiative and Department of Plant Pathology, University of Nebraska, Lincoln, NE 68588, USA
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Higuchi Y, Nakahama T, Shoji JY, Arioka M, Kitamoto K. Visualization of the endocytic pathway in the filamentous fungus Aspergillus oryzae using an EGFP-fused plasma membrane protein. Biochem Biophys Res Commun 2005; 340:784-91. [PMID: 16380079 DOI: 10.1016/j.bbrc.2005.12.077] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 12/09/2005] [Indexed: 10/25/2022]
Abstract
Endocytosis is an important process for cellular activities. However, in filamentous fungi, the existence of endocytosis has been so far elusive. In this study, we used AoUapC-EGFP, the fusion protein of a putative uric acid-xanthine permease with enhanced green fluorescent protein (EGFP) in Aspergillus oryzae, to examine whether the endocytic process occurs or not. Upon the addition of ammonium into the medium the fusion protein was internalized from the plasma membrane. The internalization of AoUapC-EGFP was completely blocked by sodium azide, cold, and cytochalasin A treatments, suggesting that the internalization possesses the general features of endocytosis. These results demonstrate the occurrence of endocytosis in filamentous fungi. Moreover, we discovered that the endosomal compartments appeared upon the induction of endocytosis and moved in a microtubule-dependent manner.
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Affiliation(s)
- Yujiro Higuchi
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Fuchs U, Steinberg G. Endocytosis in the plant-pathogenic fungus Ustilago maydis. PROTOPLASMA 2005; 226:75-80. [PMID: 16231103 DOI: 10.1007/s00709-005-0109-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 03/30/2005] [Indexed: 05/04/2023]
Abstract
Filamentous fungi are an important group of tip-growing organisms, which include numerous plant pathogens such as Magnaporthe grisea and Ustilago maydis. Despite their ecological and economical relevance, we are just beginning to unravel the importance of endocytosis in filamentous fungi. Most evidence for endocytosis in filamentous fungi is based on the use of endocytic tracer dyes that are taken up into the cell and delivered to the vacuole. Moreover, genomewide screening for candidate genes in Neurospora crassa and U. maydis confirmed the presence of most components of the endocytic machinery, indicating that endocytosis participates in filamentous growth. Indeed, it was shown that in U. maydis early endosomes cluster at sites of growth, where they support morphogenesis and polar growth, most likely via endosome-based membrane recycling. In humans, such recycling processes to the plasma membrane involve small GTPases such as Rab4. A homologue of this protein is encoded in the genome of U. maydis but is absent from the yeast Saccharomyces cerevisiae, suggesting that Rab4-mediated recycling is important for filamentous growth. Furthermore, human Rab4 regulates traffic of early endosomes along microtubules, and a similar microtubule-based transport is described for U. maydis. These observations suggest that Rab4-like GTPases might regulate endosome- and microtubule-based recycling during tip growth of filamentous fungi.
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Affiliation(s)
- U Fuchs
- Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Federal Republic of Germany
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Oberparleiter C, Kaiserer L, Haas H, Ladurner P, Andratsch M, Marx F. Active internalization of the Penicillium chrysogenum antifungal protein PAF in sensitive aspergilli. Antimicrob Agents Chemother 2004; 47:3598-601. [PMID: 14576124 PMCID: PMC253792 DOI: 10.1128/aac.47.11.3598-3601.2003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Penicillium chrysogenum antifungal protein PAF inhibits the growth of various filamentous fungi. In this study, PAF was found to localize to the cytoplasm of sensitive aspergilli by indirect immunofluorescence staining. The internalization process required active metabolism and ATP and was prevented by latrunculin B, suggesting an endocytotic mechanism.
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22
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Harris SD, Momany M. Polarity in filamentous fungi: moving beyond the yeast paradigm. Fungal Genet Biol 2004; 41:391-400. [PMID: 14998522 DOI: 10.1016/j.fgb.2003.11.007] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2003] [Accepted: 11/13/2003] [Indexed: 10/26/2022]
Abstract
Filamentous fungi grow by the polar extension of hyphae. This polar growth requires the specification of sites of germ tube or branch emergence, followed by the recruitment of the morphogenetic machinery to those sites for localized cell wall deposition. Researchers attempting to understand hyphal morphogenesis have relied upon the powerful paradigm of bud emergence in the yeast Saccharomyces cerevisiae. The yeast paradigm has provided a useful framework, however several features of hyphal morphogenesis, such as the ability to maintain multiple axes of polarity and an extremely rapid extension rate, cannot be explained by simple extrapolation from yeast models. We discuss recent polarity research from filamentous fungi focusing on the position of germ tube emergence, the relaying of positional information via RhoGTPase modules, and the recruitment of morphogenetic machinery components including cytoskeleton, polarisome and ARP2/3 complexes, and the vesicle trafficking system.
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Affiliation(s)
- Steven D Harris
- Plant Science Initiative and Department of Plant Pathology, University of Nebraska, Lincoln, NE, USA.
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Borkovich KA, Alex LA, Yarden O, Freitag M, Turner GE, Read ND, Seiler S, Bell-Pedersen D, Paietta J, Plesofsky N, Plamann M, Goodrich-Tanrikulu M, Schulte U, Mannhaupt G, Nargang FE, Radford A, Selitrennikoff C, Galagan JE, Dunlap JC, Loros JJ, Catcheside D, Inoue H, Aramayo R, Polymenis M, Selker EU, Sachs MS, Marzluf GA, Paulsen I, Davis R, Ebbole DJ, Zelter A, Kalkman ER, O'Rourke R, Bowring F, Yeadon J, Ishii C, Suzuki K, Sakai W, Pratt R. Lessons from the genome sequence of Neurospora crassa: tracing the path from genomic blueprint to multicellular organism. Microbiol Mol Biol Rev 2004; 68:1-108. [PMID: 15007097 PMCID: PMC362109 DOI: 10.1128/mmbr.68.1.1-108.2004] [Citation(s) in RCA: 434] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present an analysis of over 1,100 of the approximately 10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa. Seven major areas of Neurospora genomics and biology are covered. First, the basic features of the genome, including the automated assembly, gene calls, and global gene analyses are summarized. The second section covers components of the centromere and kinetochore complexes, chromatin assembly and modification, and transcription and translation initiation factors. The third area discusses genome defense mechanisms, including repeat induced point mutation, quelling and meiotic silencing, and DNA repair and recombination. In the fourth section, topics relevant to metabolism and transport include extracellular digestion; membrane transporters; aspects of carbon, sulfur, nitrogen, and lipid metabolism; the mitochondrion and energy metabolism; the proteasome; and protein glycosylation, secretion, and endocytosis. Environmental sensing is the focus of the fifth section with a treatment of two-component systems; GTP-binding proteins; mitogen-activated protein, p21-activated, and germinal center kinases; calcium signaling; protein phosphatases; photobiology; circadian rhythms; and heat shock and stress responses. The sixth area of analysis is growth and development; it encompasses cell wall synthesis, proteins important for hyphal polarity, cytoskeletal components, the cyclin/cyclin-dependent kinase machinery, macroconidiation, meiosis, and the sexual cycle. The seventh section covers topics relevant to animal and plant pathogenesis and human disease. The results demonstrate that a large proportion of Neurospora genes do not have homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The group of unshared genes includes potential new targets for antifungals as well as loci implicated in human and plant physiology and disease.
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Affiliation(s)
- Katherine A Borkovich
- Department of Plant Pathology, University of California, Riverside, California 92521, USA. Katherine/
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Hickey PC, Swift SR, Roca M, Read ND. Live-cell Imaging of Filamentous Fungi Using Vital Fluorescent Dyes and Confocal Microscopy. METHODS IN MICROBIOLOGY 2004. [DOI: 10.1016/s0580-9517(04)34003-1] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Abstract
The evidence and arguments for and against the occurrence of endocytosis in fungal hyphae are summarized. The balance of evidence is in favour of the existence of endocytosis. This is supported by an analysis of the recently sequenced Neurospora genome which strongly suggests that this fungus possesses the complex protein machinery required to conduct endocytosis.
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Affiliation(s)
- Nick D Read
- Fungal Cell Biology Group, Institute of Cell and Molecular Biology, University of Edinburgh, Rutherford Building, EH9 3JH Edinburgh, UK.
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