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Sethi SC, Bharati M, Kumar Y, Yadav U, Saini H, Alam P, Komath SS. The ER-Resident Ras Inhibitor 1 (Eri1) of Candida albicans Inhibits Hyphal Morphogenesis via the Ras-Independent cAMP-PKA Pathway. ACS Infect Dis 2024. [PMID: 39119676 DOI: 10.1021/acsinfecdis.4c00175] [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: 08/10/2024]
Abstract
Ras signaling and glycosylphosphatidylinositol (GPI) biosynthesis are mutually inhibitory in S. cerevisiae (Sc). The inhibition is mediated via an interaction of yeast Ras2 with the Eri1 subunit of its GPI-N-acetylglucosaminyl transferase (GPI-GnT), the enzyme catalyzing the very first GPI biosynthetic step. In contrast, Ras signaling and GPI biosynthesis in C. albicans (Ca) are mutually activated and together control the virulence traits of the human fungal pathogen. What might be the role of Eri1 in this pathogen? The present manuscript addresses this question while simultaneously characterizing the cellular role of CaEri1. It is either nonessential or required at very low levels for cell viability in C. albicans. Severe depletion of CaEri1 results in reduced GPI biosynthesis and cell wall defects. It also produces hyperfilamentation phenotypes in Spider medium as well as in bicarbonate medium containing 5% CO2, suggesting that both the Ras-dependent and Ras-independent cAMP-PKA pathways for hyphal morphogenesis are activated in these cells. Pull-down and acceptor-photobleaching FRET experiments suggest that CaEri1 does not directly interact with CaRas1 but does so through CaGpi2, another GPI-GnT subunit. We showed previously that CaGpi2 is downstream of CaEri1 in cross talk with CaRas1 and for Ras-dependent hyphal morphogenesis. Here we show that CaEri1 is downstream of all GPI-GnT subunits in inhibiting Ras-independent filamentation. CaERI1 also participates in intersubunit transcriptional cross talk within the GPI-GnT, a feature unique to C. albicans. Virulence studies using G. mellonella larvae show that a heterozygous strain of CaERI1 is better cleared by the host and is attenuated in virulence.
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Affiliation(s)
| | - Monika Bharati
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Yatin Kumar
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Usha Yadav
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Harshita Saini
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Parvez Alam
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sneha Sudha Komath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Trieu TA, Nguyen PA, Le MN, Chu HN. Myosin-II proteins are involved in the growth, morphogenesis, and virulence of the human pathogenic fungus Mucor circinelloides. Front Cell Infect Microbiol 2022; 12:1031463. [PMID: 36590583 PMCID: PMC9800795 DOI: 10.3389/fcimb.2022.1031463] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/25/2022] [Indexed: 12/23/2022] Open
Abstract
Mucormycosis is an emerging lethal invasive fungal infection. The infection caused by fungi belonging to the order Mucorales has been reported recently as one of the most common fungal infections among COVID-19 patients. The lack of understanding of pathogens, particularly at the molecular level, is one of the reasons for the difficulties in the management of the infection. Myosin is a diverse superfamily of actin-based motor proteins that have various cellular roles. Four families of myosin motors have been found in filamentous fungi, including myosin I, II, V, and fungus-specific chitin synthase with myosin motor domains. Our previous study on Mucor circinelloides, a common pathogen of mucormycosis, showed that the Myo5 protein (ID 51513) belonging to the myosin type V family had a critical impact on the growth and virulence of this fungus. In this study, to investigate the roles of myosin II proteins in M. circinelloides, silencing phenotypes and null mutants corresponding to myosin II encoding genes, designated mcmyo2A (ID 149958) and mcmyo2B (ID 136314), respectively, were generated. Those mutant strains featured a significantly reduced growth rate and impaired sporulation in comparison with the wild-type strain. Notably, the disruption of mcmyo2A led to an almost complete lack of sporulation. Both mutant strains displayed abnormally short, septate, and inflated hyphae with the presence of yeast-like cells and an unusual accumulation of pigment-filled vesicles. In vivo virulence assays of myosin-II mutant strains performed in the invertebrate model Galleria mellonella indicated that the mcmyo2A-knockout strain was avirulent, while the pathogenesis of the mcmyo2B null mutant was unaltered despite the low growth rate and impaired sporulation. The findings provide suggestions for critical contributions of the myosin II proteins to the polarity growth, septation, morphology, pigment transportation, and pathogenesis of M. circinelloides. The findings also implicate the myosin family as a potential target for future therapy to treat mucormycosis.
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Affiliation(s)
- Trung Anh Trieu
- Department of Genetics - Biochemistry, Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam,*Correspondence: Trung Anh Trieu,
| | - Phuong Anh Nguyen
- Department of Genetics - Biochemistry, Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam
| | - Mai Ngoc Le
- Department of Genetics - Biochemistry, Faculty of Biology, Hanoi National University of Education, Hanoi, Vietnam
| | - Huy Nhat Chu
- Environmental Bioremediation Laboratory, Institute of Biotechnology, Vietnam Academy of Science and Technology, Hanoi, Vietnam,Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Hanoi, Vietnam
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Kumpakha R, Gordon DM. Inhibition of morphological transition and hyphae extension in Candida spp. by occidiofungin. J Appl Microbiol 2021; 132:3038-3048. [PMID: 34941005 DOI: 10.1111/jam.15425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/05/2021] [Accepted: 12/20/2021] [Indexed: 11/28/2022]
Abstract
AIMS To assess the efficacy of the antifungal, occidiofungin, against Candida albicans and Candida tropicalis morphological transformation. METHODS AND RESULTS Susceptibility assays and morphological data were used to demonstrate that occidiofungin effectively targets C. albicans and C. tropicalis undergoing morphological transformation. Susceptibility assays found that cell sensitivity to occidiofungin varied with the media conditions used for morphological switching. Microscopy data showed that occidiofungin inhibited hyphae formation when added at the time of morphological induction and hyphal extension when added within the first hour following hyphae induction. Immunoblot analysis demonstrated that occidiofungin addition prevented activation of Cek1p MAPK signalling. CONCLUSIONS The data indicated that the antimicrobial compound, occidiofungin, effectively targets hyphae elongation in Candida spp. and suggests the biological target of occidiofungin is necessary for the morphological changes associated with yeast-to-hyphae switching. SIGNIFICANCE AND IMPACT OF THE STUDY Findings from this study demonstrated that occidiofungin effectively targets the invasive growth of dimorphic Candida which suggests this compound may also inhibit the heterogenous population of cells present in a clinical setting. This presents occidiofungin as a promising candidate for the treatment of Candida associated infections.
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Affiliation(s)
- Rabina Kumpakha
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Donna M Gordon
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
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Chow EWL, Pang LM, Wang Y. From Jekyll to Hyde: The Yeast-Hyphal Transition of Candida albicans. Pathogens 2021; 10:pathogens10070859. [PMID: 34358008 PMCID: PMC8308684 DOI: 10.3390/pathogens10070859] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/22/2022] Open
Abstract
Candida albicans is a major fungal pathogen of humans, accounting for 15% of nosocomial infections with an estimated attributable mortality of 47%. C. albicans is usually a benign member of the human microbiome in healthy people. Under constant exposure to highly dynamic environmental cues in diverse host niches, C. albicans has successfully evolved to adapt to both commensal and pathogenic lifestyles. The ability of C. albicans to undergo a reversible morphological transition from yeast to filamentous forms is a well-established virulent trait. Over the past few decades, a significant amount of research has been carried out to understand the underlying regulatory mechanisms, signaling pathways, and transcription factors that govern the C. albicans yeast-to-hyphal transition. This review will summarize our current understanding of well-elucidated signal transduction pathways that activate C. albicans hyphal morphogenesis in response to various environmental cues and the cell cycle machinery involved in the subsequent regulation and maintenance of hyphal morphogenesis.
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Affiliation(s)
- Eve Wai Ling Chow
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
| | - Li Mei Pang
- National Dental Centre Singapore, National Dental Research Institute Singapore (NDRIS), 5 Second Hospital Ave, Singapore 168938, Singapore;
| | - Yue Wang
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
- Correspondence:
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Abstract
Morphological changes are critical for the virulence of a range of plant and human fungal pathogens.
Candida albicans is a major human fungal pathogen whose ability to switch between different morphological states is associated with its adaptability and pathogenicity. In particular,
C. albicans can switch from an oval yeast form to a filamentous hyphal form, which is characteristic of filamentous fungi. What mechanisms underlie hyphal growth and how are they affected by environmental stimuli from the host or resident microbiota? These questions are the focus of intensive research, as understanding
C. albicans hyphal growth has broad implications for cell biological and medical research.
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Affiliation(s)
- Robert A Arkowitz
- Université Côte d'Azur, CNRS, Inserm, Institute of Biology Valrose, Parc Valrose, Nice, France
| | - Martine Bassilana
- Université Côte d'Azur, CNRS, Inserm, Institute of Biology Valrose, Parc Valrose, Nice, France
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AP-2-Dependent Endocytic Recycling of the Chitin Synthase Chs3 Regulates Polarized Growth in Candida albicans. mBio 2019; 10:mBio.02421-18. [PMID: 30890602 PMCID: PMC6426607 DOI: 10.1128/mbio.02421-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The human fungal pathogen Candida albicans is known to require endocytosis to enable its adaptation to diverse niches and to maintain its highly polarized hyphal growth phase. While studies have identified changes in transcription leading to the synthesis and secretion of new proteins to facilitate hyphal growth, effective maintenance of hyphae also requires concomitant removal or relocalization of other cell surface molecules. The key molecules which must be removed from the cell surface, and the mechanisms behind this, have, however, remained elusive. In this study, we show that the AP-2 endocytic adaptor complex is required for the internalization of the major cell wall biosynthesis enzyme Chs3. We demonstrate that this interaction is mediated by the AP-2 mu subunit (Apm4) YXXΦ binding domain. We also show that in the absence of Chs3 recycling via AP-2, cells have abnormal cell wall composition, defective polarized cell wall deposition, and morphological defects. The study also highlights key distinctions between endocytic requirements of growth at yeast buds compared to that at hyphal tips and different requirements of AP-2 in maintaining the polarity of mannosylated proteins and ergosterol at hyphal tips. Together, our findings highlight the importance of correct cell wall deposition in cell shape maintenance and polarized growth and the key regulatory role of endocytic recycling via the AP-2 complex.IMPORTANCE Candida albicans is a human commensal yeast that can cause significant morbidity and mortality in immunocompromised individuals. Within humans, C. albicans can adopt different morphologies as yeast or filamentous hyphae and can occupy different niches with distinct temperatures, pHs, CO2 levels, and nutrient availability. Both morphological switching and growth in different environments require cell surface remodelling, which involves both the addition of newly synthesized proteins as well as the removal of other proteins. In our study, we demonstrate the importance of an adaptor complex AP-2 in internalizing and recycling a specific cell surface enzyme to maintain effective polarized hyphal growth. Defects in formation of the complex or in its ability to interact directly with cargo inhibit enzyme uptake and lead to defective cell walls and aberrant hyphal morphology. Our data indicate that the AP-2 adaptor plays a central role in regulating cell surface composition in Candida.
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Feng Z, Tian J, Han L, Geng Y, Sun J, Kong Z. The Myosin5-mediated actomyosin motility system is required for Verticillium
pathogenesis of cotton. Environ Microbiol 2018; 20:1607-1621. [DOI: 10.1111/1462-2920.14101] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 03/05/2018] [Accepted: 03/11/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Zhidi Feng
- The Key Laboratory of Oasis Eco-Agriculture; College of Agriculture, Shihezi University; Shihezi Xinjiang 832000 China
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Juan Tian
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Libo Han
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Yuan Geng
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Jie Sun
- The Key Laboratory of Oasis Eco-Agriculture; College of Agriculture, Shihezi University; Shihezi Xinjiang 832000 China
| | - Zhaosheng Kong
- State Key Laboratory of Plant Genomic; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
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Ras hyperactivation versus overexpression: Lessons from Ras dynamics in Candida albicans. Sci Rep 2018; 8:5248. [PMID: 29588468 PMCID: PMC5869725 DOI: 10.1038/s41598-018-23187-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 03/06/2018] [Indexed: 12/25/2022] Open
Abstract
Ras signaling in response to environmental cues is critical for cellular morphogenesis in eukaryotes. This signaling is tightly regulated and its activation involves multiple players. Sometimes Ras signaling may be hyperactivated. In C. albicans, a human pathogenic fungus, we demonstrate that dynamics of hyperactivated Ras1 (Ras1G13V or Ras1 in Hsp90 deficient strains) can be reliably differentiated from that of normal Ras1 at (near) single molecule level using fluorescence correlation spectroscopy (FCS). Ras1 hyperactivation results in significantly slower dynamics due to actin polymerization. Activating actin polymerization by jasplakinolide can produce hyperactivated Ras1 dynamics. In a sterol-deficient hyperfilamentous GPI mutant of C. albicans too, Ras1 hyperactivation results from Hsp90 downregulation and causes actin polymerization. Hyperactivated Ras1 co-localizes with G-actin at the plasma membrane rather than with F-actin. Depolymerizing actin with cytochalasin D results in faster Ras1 dynamics in these and other strains that show Ras1 hyperactivation. Further, ergosterol does not influence Ras1 dynamics.
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Bar-Yosef H, Gildor T, Ramírez-Zavala B, Schmauch C, Weissman Z, Pinsky M, Naddaf R, Morschhäuser J, Arkowitz RA, Kornitzer D. A Global Analysis of Kinase Function in Candida albicans Hyphal Morphogenesis Reveals a Role for the Endocytosis Regulator Akl1. Front Cell Infect Microbiol 2018; 8:17. [PMID: 29473018 PMCID: PMC5809406 DOI: 10.3389/fcimb.2018.00017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/12/2018] [Indexed: 11/22/2022] Open
Abstract
The human pathogenic fungus Candida albicans can switch between yeast and hyphal morphologies as a function of environmental conditions and cellular physiology. The yeast-to-hyphae morphogenetic switch is activated by well-established, kinase-based signal transduction pathways that are induced by extracellular stimuli. In order to identify possible inhibitory pathways of the yeast-to-hyphae transition, we interrogated a collection of C. albicans protein kinases and phosphatases ectopically expressed under the regulation of the TETon promoter. Proportionately more phosphatases than kinases were identified that inhibited hyphal morphogenesis, consistent with the known role of protein phosphorylation in hyphal induction. Among the kinases, we identified AKL1 as a gene that significantly suppressed hyphal morphogenesis in serum. Akl1 specifically affected hyphal elongation rather than initiation: overexpression of AKL1 repressed hyphal growth, and deletion of AKL1 resulted in acceleration of the rate of hyphal elongation. Akl1 suppressed fluid-phase endocytosis, probably via Pan1, a putative clathrin-mediated endocytosis scaffolding protein. In the absence of Akl1, the Pan1 patches were delocalized from the sub-apical region, and fluid-phase endocytosis was intensified. These results underscore the requirement of an active endocytic pathway for hyphal morphogenesis. Furthermore, these results suggest that under standard conditions, endocytosis is rate-limiting for hyphal elongation.
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Affiliation(s)
- Hagit Bar-Yosef
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Tsvia Gildor
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | | | - Christian Schmauch
- Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institute Biology Valrose, Université Côte d'Azur, Nice, France
| | - Ziva Weissman
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Mariel Pinsky
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Rawi Naddaf
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Joachim Morschhäuser
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany
| | - Robert A Arkowitz
- Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institute Biology Valrose, Université Côte d'Azur, Nice, France
| | - Daniel Kornitzer
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
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10
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Oscarsson T, Walther A, Lengeler KB, Wendland J. An Arf-GAP promotes endocytosis and hyphal growth of Ashbya gossypii. FEMS Microbiol Lett 2017; 364:4600504. [DOI: 10.1093/femsle/fnx240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/06/2017] [Indexed: 12/18/2022] Open
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Bar-Yosef H, Vivanco Gonzalez N, Ben-Aroya S, Kron SJ, Kornitzer D. Chemical inhibitors of Candida albicans hyphal morphogenesis target endocytosis. Sci Rep 2017; 7:5692. [PMID: 28720834 PMCID: PMC5515890 DOI: 10.1038/s41598-017-05741-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/01/2017] [Indexed: 01/12/2023] Open
Abstract
Candida albicans is an opportunistic pathogen, typically found as a benign commensal yeast living on skin and mucosa, but poised to invade injured tissue to cause local infections. In debilitated and immunocompromised individuals, C. albicans may spread to cause life-threatening systemic infections. Upon contact with serum and at body temperature, C. albicans performs a regulated switch to filamentous morphology, characterized by emergence of a germ tube from the yeast cell followed by mold-like growth of branching hyphae. The ability to switch between growth morphologies is an important virulence factor of C. albicans. To identify compounds able to inhibit hyphal morphogenesis, we screened libraries of existing drugs for inhibition of the hyphal switch under stringent conditions. Several compounds that specifically inhibited hyphal morphogenesis were identified. Chemogenomic analysis suggested an interaction with the endocytic pathway, which was confirmed by direct measurement of fluid-phase endocytosis in the presence of these compounds. These results suggest that the activity of the endocytic pathway, which is known to be particularly important for hyphal growth, represents an effective target for hyphae-inhibiting drugs.
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Affiliation(s)
- Hagit Bar-Yosef
- Department of Molecular Microbiology, B. Rappaport Faculty of Medicine, Technion - I.I.T. and the Rappaport Institute for Research in the Medical Sciences, Haifa, 31096, Israel
| | - Nora Vivanco Gonzalez
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Shay Ben-Aroya
- Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Stephen J Kron
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, 60637, USA.
| | - Daniel Kornitzer
- Department of Molecular Microbiology, B. Rappaport Faculty of Medicine, Technion - I.I.T. and the Rappaport Institute for Research in the Medical Sciences, Haifa, 31096, Israel.
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12
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Guo M, Tan L, Nie X, Zhang Z. A class-II myosin is required for growth, conidiation, cell wall integrity and pathogenicity of Magnaporthe oryzae. Virulence 2017; 8:1335-1354. [PMID: 28448785 DOI: 10.1080/21505594.2017.1323156] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
In eukaryotic organisms, myosin proteins are the major ring components that are involved in cytokinesis. To date, little is known about the biologic functions of myosin proteins in Magnaporthe oryzae. In this study, insertional mutagenesis conducted in M. oryzae led to identification of Momyo2, a pathogenicity gene predicted to encode a class-II myosin protein homologous to Saccharomyces cerevisiae Myo1. According to qRT-PCR, Momyo2 is highly expressed during early infectious stage. When this gene was disrupted, the resultant mutant isolates were attenuated in virulence on rice and barley. These were likely caused by defective mycelial growth and frequent emergence of branch hyphae and septum. The Momyo2 mutants were also defective in conidial and appressorial development, characterized by abnormal conidia and appressoria. These consequently resulted in plant tissue penetration defects that the wild type strain lacked, and mutants being less pathogenic. Cytorrhysis assay, CFW staining of appressorium and monitoring of protoplast release suggested that appressorial wall was altered, presumably affecting the level of turgor pressure within appressorium. Furthermore, impairments in conidial germination, glycogen metabolites, tolerance to exogenous stresses and scavenging of host-derived reactive oxygen species were associated with defects on appressorium mediated penetration, and therefore attenuated the virulence of Momyo2 mutants. Taken together, these results suggest that Momyo2 plays pleiotropic roles in fungal development, and is required for the full pathogenicity of M. oryzae.
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Affiliation(s)
- Min Guo
- a Department of Plant Pathology , College of Plant Protection, Anhui Agricultural University , Hefei , China
| | - Leyong Tan
- a Department of Plant Pathology , College of Plant Protection, Anhui Agricultural University , Hefei , China
| | - Xiang Nie
- a Department of Plant Pathology , College of Plant Protection, Anhui Agricultural University , Hefei , China
| | - Zhengguang Zhang
- b Department of Plant Pathology , College of Plant Protection, Nanjing Agricultural University , Nanjing , China
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13
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Liu Z, Wu S, Chen Y, Han X, Gu Q, Yin Y, Ma Z. The microtubule end-binding protein FgEB1 regulates polar growth and fungicide sensitivity via different interactors in Fusarium graminearum. Environ Microbiol 2017; 19:1791-1807. [PMID: 28028881 DOI: 10.1111/1462-2920.13651] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/18/2016] [Indexed: 11/30/2022]
Abstract
In yeasts, the end-binding protein 1 (EB1) homologs regulate microtubule dynamics, cell polarization, and chromosome stability. However, functions of EB1 orthologs in plant pathogenic fungi have not been characterized yet. Here, we observed that the FgEB1 deletion mutant (ΔFgEB1) of Fusarium graminearum exhibits twisted hyphae, increased hyphal branching and curved conidia, indicating that FgEB1 is involved in the regulation of cellular polarity. Microscopic examination further showed that the microtubules of ΔFgEB1 exhibited less organized in comparison with those of the wild type. In addition, the lack of FgEB1 also altered the distribution of polarity-related class I myosin via the interaction with the actin. On the other hand, we identified four core septins as FgEB1-interacting proteins, and found that FgEB1 and septins regulated conidial polar growth in the opposite orientation. Interestingly, FgEB1 and FgKar9 constituted another complex that modulated the response to carbendazim, a microtubule-damaging agent specifically. In addition, the deletion of FgEB1 led to dramatically decreased deoxynivalenol (DON) biosynthesis. Taken together, results of this study indicate that FgEB1 regulates cellular polarity, fungicide sensitivity and DON biosynthesis via different interactors in F. graminarum, which provides a novel insight into understanding of the biological functions of EB1 in filamentous fungi.
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Affiliation(s)
- Zunyong Liu
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Sisi Wu
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Yun Chen
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Xinyue Han
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Qin Gu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yanni Yin
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Zhonghua Ma
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.,State Key Laboratory of Rice Biology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
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14
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Prospéri MT, Lépine P, Dingli F, Paul-Gilloteaux P, Martin R, Loew D, Knölker HJ, Coudrier E. Myosin 1b functions as an effector of EphB signaling to control cell repulsion. J Cell Biol 2016. [PMID: 26195670 PMCID: PMC4508888 DOI: 10.1083/jcb.201501018] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Myosin 1b functions as an effector of EphB2/ephrinB signaling and controls cell morphology and cell repulsion. Eph receptors and their membrane-tethered ligands, the ephrins, have important functions in embryo morphogenesis and in adult tissue homeostasis. Eph/ephrin signaling is essential for cell segregation and cell repulsion. This process is accompanied by morphological changes and actin remodeling that drives cell segregation and tissue patterning. The actin cortex must be mechanically coupled to the plasma membrane to orchestrate the cell morphology changes. Here, we demonstrate that myosin 1b that can mechanically link the membrane to the actin cytoskeleton interacts with EphB2 receptors via its tail and is tyrosine phosphorylated on its tail in an EphB2-dependent manner. Myosin 1b regulates the redistribution of myosin II in actomyosin fibers and the formation of filopodia at the interface of ephrinB1 and EphB2 cells, which are two processes mediated by EphB2 signaling that contribute to cell repulsion. Together, our results provide the first evidence that a myosin 1 functions as an effector of EphB2/ephrinB signaling, controls cell morphology, and thereby cell repulsion.
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Affiliation(s)
| | - Priscilla Lépine
- Institut Curie, Centre de Recherche, F-75248 Paris, France Université Pierre et Marie Curie, F-75252 Paris, France
| | - Florent Dingli
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, Centre de Recherche, F-75248 Paris, France
| | - Perrine Paul-Gilloteaux
- Institut Curie, Centre de Recherche, F-75248 Paris, France Cell and Tissue Imaging Facility (PICT-IBiSA), Centre National de la Recherche Scientifique, UMR 144, Paris F-75248, France
| | - René Martin
- Department of Chemistry, Technische Univesität, 01069 Dresden, Germany
| | - Damarys Loew
- Laboratoire de Spectrométrie de Masse Protéomique, Institut Curie, Centre de Recherche, F-75248 Paris, France
| | | | - Evelyne Coudrier
- Institut Curie, Centre de Recherche, F-75248 Paris, France Cell and Tissue Imaging Facility (PICT-IBiSA), Centre National de la Recherche Scientifique, UMR 144, Paris F-75248, France
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15
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Lara-Rojas F, Bartnicki-García S, Mouriño-Pérez RR. Localization and role of MYO-1, an endocytic protein in hyphae of Neurospora crassa. Fungal Genet Biol 2016; 88:24-34. [DOI: 10.1016/j.fgb.2016.01.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Revised: 01/15/2016] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
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Zhang C, Chen Y, Yin Y, Ji HH, Shim WB, Hou Y, Zhou M, Li XD, Ma Z. A small molecule species specifically inhibits Fusarium myosin I. Environ Microbiol 2015; 17:2735-46. [PMID: 25404531 DOI: 10.1111/1462-2920.12711] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/03/2014] [Accepted: 11/05/2014] [Indexed: 11/28/2022]
Abstract
Fusarium head blight (FHB) caused by Fusarium graminearum is a devastating disease of cereal crops worldwide. Recently, a novel fungicide JS399-19 has been launched into the marketplace to manage FHB. It is compelling that JS399-19 shows highly inhibitory activity towards some Fusarium species, but not to other fungi, indicating that it is an environmentally compatible fungicide. To explore the mode of action of this species-specific compound, we conducted a whole-genome transcript profiling together with genetic and biochemical assays, and discovered that JS399-19 targets the myosin I of F. graminearum (FgMyo1). FgMyo1 is essential for F. graminearum growth. A point mutation S217L or E420K in FgMyo1 is responsible for F. graminearum resistance to JS399-19. In addition, transformation of F. graminearum with the myosin I gene of Magnaporthe grisea, the causal agent of rice blast, also led to JS399-19 resistance. JS399-19 strongly inhibits the ATPase activity of the wild-type FgMyo1, but not the mutated FgMyo1(S217L/E420K) . These results provide us a new insight into the design of species-specific antifungal compounds. Furthermore, our strategy can be applied to identify novel drug targets in various pathogenic organisms.
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Affiliation(s)
- Chengqi Zhang
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yun Chen
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yanni Yin
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Huan-Hong Ji
- National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Won-Bo Shim
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77843-2132, USA
| | - Yiping Hou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Mingguo Zhou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xiang-Dong Li
- National Laboratory of Integrated Management of Insect Pests and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhonghua Ma
- Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
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The actin-related protein Sac1 is required for morphogenesis and cell wall integrity in Candida albicans. Fungal Genet Biol 2015; 81:261-70. [PMID: 25575432 DOI: 10.1016/j.fgb.2014.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/22/2014] [Accepted: 12/27/2014] [Indexed: 01/10/2023]
Abstract
Candida albicans is a common pathogenic fungus and has aroused widespread attention recently. Actin cytoskeleton, an important player in polarized growth, protein secretion and organization of cell shape, displays irreplaceable role in hyphal development and cell integrity. In this study, we demonstrated a homologue of Saccharomyces cerevisiae Sac1, in C. albicans. It is a potential PIP phosphatase with Sac domain which is related to actin organization, hyphal development, biofilm formation and cell wall integrity. Deletion of SAC1 did not lead to insitiol-auxotroph phenotype in C. albicans, but this gene rescued the growth defect of S. cerevisiae sac1Δ in the insitiol-free medium. Hyphal induction further revealed the deficiency of sac1Δ/Δ in hyphal development and biofilm formation. Fluorescence observation and real time PCR (RT-PCR) analysis suggested both actin and the hyphal cell wall protein Hwp1 were overexpressed and mislocated in this mutant. Furthermore, cell wall integrity (CWI) was largely affected by deletion of SAC1, due to the hypersensitivity to cell wall stress, changed content and distribution of chitin in the mutant. As a result, the virulence of sac1Δ/Δ was seriously attenuated. Taken together, this study provides evidence that Sac1, as a potential PIP phosphatase, is essential for actin organization, hyphal development, CWI and pathogenicity in C. albicans.
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18
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Herrero-de-Dios C, Alonso-Monge R, Pla J. The lack of upstream elements of the Cek1 and Hog1 mediated pathways leads to a synthetic lethal phenotype upon osmotic stress in Candida albicans. Fungal Genet Biol 2014; 69:31-42. [PMID: 24905535 DOI: 10.1016/j.fgb.2014.05.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 05/19/2014] [Accepted: 05/25/2014] [Indexed: 11/27/2022]
Abstract
Different signal transduction pathways mediated by MAP kinases have been described in Candida albicans. These pathways sense different stimuli and, therefore, elaborate specific responses. Hog1 was identified as the MAPK that is primarily involved in stress response and virulence, while Cek1 was more specific to cell wall biogenesis, mating and biofilm formation. In the present work, mutants defective in both pathways have been characterized under osmotic stress. Both routes are required for a full response against high osmotic challenge, since mutants defective in both pathways displayed aberrant morphology, cell polarity defects and abnormal chitin deposition, which correlate with loss of viability and appearance of apoptotic markers. These alterations occurred in spite of proper Hog1 and Cek1 phosphorylation and increased intra-cellular glycerol accumulation. The relevance of both routes in virulence is shown as ssk1 msb2 sho1 opy2 mutants are avirulent in a mouse systemic model of infection and display reduced virulence in the Galleria mellonella model.
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Affiliation(s)
- Carmen Herrero-de-Dios
- Aberdeen Fungal Group, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, United Kingdom(1)
| | - Rebeca Alonso-Monge
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza de Ramón y Cajal s/n, E-28040 Madrid, Spain.
| | - Jesús Pla
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza de Ramón y Cajal s/n, E-28040 Madrid, Spain
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19
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Greenberg MJ, Ostap EM. Regulation and control of myosin-I by the motor and light chain-binding domains. Trends Cell Biol 2012. [PMID: 23200340 DOI: 10.1016/j.tcb.2012.10.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Members of the myosin-I family of molecular motors are expressed in many eukaryotes, where they are involved in a multitude of critical processes. Humans express eight distinct members of the myosin-I family, making it the second largest family of myosins expressed in humans. Despite the high degree of sequence conservation in the motor and light chain-binding domains (LCBDs) of these myosins, recent studies have revealed surprising diversity of function and regulation arising from isoform-specific differences in these domains. Here we review the regulation of myosin-I function and localization by the motor and LCBDs.
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Affiliation(s)
- Michael J Greenberg
- The Pennsylvania Muscle Institute and Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6085, USA
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20
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Motor protein Myo5p is required to maintain the regulatory circuit controlling WOR1 expression in Candida albicans. EUKARYOTIC CELL 2012; 11:626-37. [PMID: 22408227 DOI: 10.1128/ec.00021-12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Candida albicans MYO5 gene encodes myosin I, a protein required for the formation of germ tubes and true hyphae. Because the polarized growth of opaque-phase cells in response to pheromone results in mating projections that can resemble germ tubes, we examined the role of Myo5p in this process. We localized green fluorescent protein (GFP)-tagged Myo5p in opaque-phase cells of C. albicans during both bud and shmoo formation. In vegetatively growing opaque cells, Myo5p is found at sites of bud emergence and bud growth, while in pheromone-stimulated cells, Myo5p localizes at the growing tips of shmoos. Intriguingly, cells homozygous for MTLa in which the MYO5 gene was deleted failed to switch efficiently from the white phase to the opaque phase, although ectopic expression of WOR1 from the MET3 promoter can convert myo5 mutants into mating-competent opaque cells. However, when WOR1 expression was shut off, the myo5-defective cells rapidly lost both their opaque phenotype and mating competence, suggesting that Myo5p is involved in the maintenance of the opaque state. When MYO5 is expressed conditionally in opaque cells, the opaque phenotype, as well as the mating ability of the cells, becomes unstable under repressive conditions, and quantitative real-time PCR demonstrated that the shutoff of MYO5 expression correlates with a dramatic reduction in WOR1 expression. It appears that while myosin I is not directly required for mating in C. albicans, it is involved in WOR1 expression and the white-opaque transition and thus is indirectly implicated in mating.
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21
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Berepiki A, Lichius A, Read ND. Actin organization and dynamics in filamentous fungi. Nat Rev Microbiol 2011; 9:876-87. [PMID: 22048737 DOI: 10.1038/nrmicro2666] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Growth and morphogenesis of filamentous fungi is underpinned by dynamic reorganization and polarization of the actin cytoskeleton. Actin has crucial roles in exocytosis, endocytosis, organelle movement and cytokinesis in fungi, and these processes are coupled to the production of distinct higher-order structures (actin patches, cables and rings) that generate forces or serve as tracks for intracellular transport. New approaches for imaging actin in living cells are revealing important similarities and differences in actin architecture and organization within the fungal kingdom, and have yielded key insights into cell polarity, tip growth and long-distance intracellular transport. In this Review, we discuss the contribution that recent live-cell imaging and mutational studies have made to our understanding of the dynamics and regulation of actin in filamentous fungi.
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Affiliation(s)
- Adokiye Berepiki
- Fungal Cell Biology Group, Institute of Cell Biology, Rutherford Building, University of Edinburgh, Edinburgh, UK
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Endocytosis-mediated vacuolar accumulation of the human ApoE apolipoprotein-derived ApoEdpL-W antimicrobial peptide contributes to its antifungal activity in Candida albicans. Antimicrob Agents Chemother 2011; 55:4670-81. [PMID: 21807970 DOI: 10.1128/aac.00319-11] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 18-amino-acid cationic, tryptophan-rich ApoEdpL-W peptide derived from human ApoE apolipoprotein was shown to have antifungal activity against pathogenic yeasts of the Candida genus (except C. glabrata). ApoEdpL-W was active against planktonic cells and early-stage biofilms but less active against mature biofilms, possibly because of its affinity for extracellular matrix beta-glucans. Moreover, ApoEdpL-W absorbed to medically relevant materials partially prevented the formation of biofilms on these materials. The exposure of C. albicans cells to sublethal doses of ApoEdpL-W triggered a transcriptional response reminiscent of that associated with the inactivation of the MYO5 gene required for endocytosis as well as the upregulation of amino acid transporter genes. A fluorescent derivative of ApoEdpL-W accumulated at the cytoplasmic membrane and subsequently was translocated to the vacuole. Strikingly, the inactivation of MYO5 or addition of latrunculin, an inhibitor of endocytosis, prevented the vacuolar accumulation of fluorescein-labeled ApoEdpL-W and reduced the antifungal activity of ApoEdpL-W. This, together with the insensitivity of ApoEdpL-W to alterations in membrane fluidity and high salt, suggested that the ApoEdpL-W mode of action was dependent upon vacuolar targeting and differed significantly from that of other antifungal peptides, such as Histatin-5 and Magainin 2.
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Wang P, Shen G. The endocytic adaptor proteins of pathogenic fungi: charting new and familiar pathways. Med Mycol 2011; 49:449-57. [PMID: 21254965 DOI: 10.3109/13693786.2011.553246] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Intracellular transport is an essential biological process that is highly conserved throughout the eukaryotic organisms. In fungi, adaptor proteins implicated in the endocytic cycle of endocytosis and exocytosis were found to be important for growth, differentiation, and/or virulence. For example, Saccharomyces cerevisiae Pan1 is an endocytic protein that regulates membrane trafficking, the actin cytoskeleton, and signaling. In Cryptococcus neoformans, a multi-modular endocytic protein, Cin1, was recently found to have pleiotropic functions in morphogenesis, endocytosis, exocytosis, and virulence. Interestingly, Cin1 is homologous to human intersectin ITSN1, but homologs of Cin1/ITSN1 were not found in ascomycetous S. cerevisiae and Candida albicans, or zygomycetous fungi. Moreover, an Eps15 protein homologous to S. cerevisiae Pan1/Ede1 and additional relevant protein homologs were identified in C. neoformans, suggesting the existence of either a distinct endocytic pathway mediated by Cin1 or pathways by either Cin1 or/and Pan1/Ede1 homologs. Whether and how the Cin1-mediated endocytic pathway represents a unique role in pathogenesis or reflects a redundancy of a transport apparatus remains an open and challenging question. This review discusses recent findings of endocytic adaptor proteins from pathogenic fungi and provides a perspective for novel endocytic machinery operating in C. neoformans. An understanding of intracellular trafficking mechanisms as they relate to pathogenesis will likely reveal the identity of novel antifungal targets.
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Affiliation(s)
- Ping Wang
- The Research Institute for Children, New Orleans, Louisiana, USA.
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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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27
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Borth N, Walther A, Reijnst P, Jorde S, Schaub Y, Wendland J. Candida albicans Vrp1 is required for polarized morphogenesis and interacts with Wal1 and Myo5. Microbiology (Reading) 2010; 156:2962-2969. [DOI: 10.1099/mic.0.041707-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, a link between endocytosis and hyphal morphogenesis has been identified in Candida albicans via the Wiskott–Aldrich syndrome gene homologue WAL1. To get a more detailed mechanistic understanding of this link we have investigated a potentially conserved interaction between Wal1 and the C. albicans WASP-interacting protein (WIP) homologue encoded by VRP1. Deletion of both alleles of VRP1 results in strong hyphal growth defects under serum inducing conditions but filamentation can be observed on Spider medium. Mutant vrp1 cells show a delay in endocytosis – measured as the uptake and delivery of the lipophilic dye FM4-64 into small endocytic vesicles – compared to the wild-type. Vacuolar morphology was found to be fragmented in a subset of cells and the cortical actin cytoskeleton was depolarized in vrp1 daughter cells. The morphology of the vrp1 null mutant could be complemented by reintegration of the wild-type VRP1 gene at the BUD3 locus. Using the yeast two-hybrid system we could demonstrate an interaction between the C-terminal part of Vrp1 and the N-terminal part of Wal1, which contains the WH1 domain. Furthermore, we found that Myo5 has several potential interaction sites on Vrp1. This suggests that a Wal1–Vrp1–Myo5 complex plays an important role in endocytosis and the polarized localization of the cortical actin cytoskeleton to promote polarized hyphal growth in C. albicans.
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Affiliation(s)
- Nicole Borth
- Junior Research Group: Growth Control of Fungal Pathogens, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knöll Institute and Department of Microbiology, Friedrich Schiller University, D-07745 Jena, Germany
- Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
| | - Andrea Walther
- Junior Research Group: Growth Control of Fungal Pathogens, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knöll Institute and Department of Microbiology, Friedrich Schiller University, D-07745 Jena, Germany
- Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
| | - Patrick Reijnst
- Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
| | - Sigyn Jorde
- Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
| | - Yvonne Schaub
- Junior Research Group: Growth Control of Fungal Pathogens, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knöll Institute and Department of Microbiology, Friedrich Schiller University, D-07745 Jena, Germany
| | - Jürgen Wendland
- Junior Research Group: Growth Control of Fungal Pathogens, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knöll Institute and Department of Microbiology, Friedrich Schiller University, D-07745 Jena, Germany
- Carlsberg Laboratory, Yeast Biology, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
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Ferreira C, Silva S, Faria-Oliveira F, Pinho E, Henriques M, Lucas C. Candida albicans virulence and drug-resistance requires the O-acyltransferase Gup1p. BMC Microbiol 2010; 10:238. [PMID: 20843317 PMCID: PMC2945937 DOI: 10.1186/1471-2180-10-238] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 09/15/2010] [Indexed: 11/22/2022] Open
Abstract
Background GUP1 gene was primarily identified in Saccharomyces cerevisiae being connected with glycerol uptake defects in association with osmotic stress response. Soon after, Gup1p was implicated in a complex and extensive series of phenotypes involving major cellular processes. These include membrane and wall maintenance, lipid composition, bud-site selection, cytoskeleton orientation, vacuole morphology, secretory/endocytic pathway, GPI anchors remodelling, and lipid-ordered domains assembly, which is compatible with their inclusion in the Membrane Bound O-acyl transferases (MBOAT) family. In mammals, it has been described as a negative regulator of the Sonic hedgehog pathway involved in morphogenesis, differentiation, proliferation, among other processes. Results We show that Candida albicans Gup1p strongly interferes with the capacity of cells to develop hyphae, to adhere, to invade, and to form a biofilm, all of which are significant virulence factors. Furthermore, the mutant colonies exhibited an aberrant morphology/differentiation pattern. Identically to S. cerevisiae, Cagup1Δ null mutant was more resistant to antifungals like fluconazole, ketoconazole, and clotrimazole, and displayed an abnormal even sterol distribution at the plasma membrane. Conclusions This work is the first study in the opportunistic yeast Candida albicans, showing a role for the GUP1 gene in virulence as well as in the mechanisms underlying antifungal resistance. Moreover, its impact is even more significant since these results, taken together with all the knowledge about GUP1 gene (from S. cerevisiae and mammals) give consistence to the possibility that Gup1p may be part of a yeast morphogenic pathway parallel to the mammalian Hedgehog.
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Affiliation(s)
- Célia Ferreira
- Department of Biology, Centre of Molecular and Environmental Biology, Portugal.
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Jang WS, Bajwa JS, Sun JN, Edgerton M. Salivary histatin 5 internalization by translocation, but not endocytosis, is required for fungicidal activity in Candida albicans. Mol Microbiol 2010; 77:354-70. [PMID: 20487276 PMCID: PMC2909388 DOI: 10.1111/j.1365-2958.2010.07210.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Salivary histatin 5 (Hst 5) is a cationic salivary protein with high fungicidal activity against Candida albicans. Binding to the cell wall followed by intracellular translocation is required for killing; however, specific binding components and critical toxic events are not understood. In this study, laminarin (β-1,3-glucan) but not sialic acid, mannan or pustulan mediated Hst 5 binding to C. albicans, and was disassociated by 100 mM NaCl. Time-lapse confocal microscopy revealed a dose-dependent rate of cytosolic uptake of Hst 5 that invariably preceded propidium iodide (PI) entry, demonstrating that translocation itself does not disrupt membrane integrity. Cell toxicity was manifest by vacuolar expansion followed by PI entrance; however, loss of endocytotic vacuolar trafficking of Hst 5 did not reduce killing. Extracellular NaCl (100 mM), but not sorbitol, prevented vacuolar expansion and PI entry in cells already containing cytosolic Hst 5, thus showing a critical role for ionic balance in Hst 5 toxicity. Hst 5 uptake, but not cell wall binding, was blocked by pretreatment with azide or carbonyl cyanide m-chlorophenylhydrazone; however, 10% of de-energized cells had membrane disruption. Thus, Hst 5 is capable of heterogeneous intracellular entry routes, but only direct cytosolic translocation causes cell death as a result of ionic efflux.
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Affiliation(s)
- Woong Sik Jang
- Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY 14214, USA
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Reijnst P, Jorde S, Wendland J. Candida albicans SH3-domain proteins involved in hyphal growth, cytokinesis, and vacuolar morphology. Curr Genet 2010; 56:309-19. [PMID: 20383711 DOI: 10.1007/s00294-010-0301-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 03/22/2010] [Accepted: 03/29/2010] [Indexed: 12/13/2022]
Abstract
This report describes the analyses of three Candida albicans genes that encode Src Homology 3 (SH3)-domain proteins. Homologs in Saccharomyces cerevisiae are encoded by the SLA1, NBP2, and CYK3 genes. Deletion of CYK3 in C. albicans was not feasible, suggesting it is essential. Promoter shutdown experiments of CaCYK3 revealed cytokinesis defects, which are in line with the localization of GFP-tagged Cyk3 at septal sites. Deletion of SLA1 resulted in strains with decreased ability to form hyphal filaments. The number of cortical actin patches was strongly reduced in Deltasla1 strains during all growth stages. Sla1-GFP localizes in patches that are found concentrated at the hyphal tip. Deletion of the first two SH3-domains of Sla1 still resulted in cortical localization of the truncated protein. However, the actin cytoskeleton in this strain was aberrant like in the Deltasla1 deletion mutant indicating a function of these SH3 domains to recruit actin nucleation to sites of endocytosis. Deletion of NBP2 resulted in a defect in vacuolar fusion in hyphae. Germ cells of Deltanbp2 strains lacked a large vacuole but initiated several germ tubes. The mutant phenotypes of Deltanbp2 and Deltasla1 could be corrected by reintegration of the wild-type genes.
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Affiliation(s)
- Patrick Reijnst
- Carlsberg Laboratory, Yeast Biology, Valby, Copenhagen, Denmark
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Reijnst P, Walther A, Wendland J. Functional analysis of Candida albicans genes encoding SH3-domain-containing proteins. FEMS Yeast Res 2010; 10:452-61. [DOI: 10.1111/j.1567-1364.2010.00624.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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32
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Yamamoto T, Mochida J, Kadota J, Takeda M, Bi E, Tanaka K. Initial polarized bud growth by endocytic recycling in the absence of actin cable-dependent vesicle transport in yeast. Mol Biol Cell 2010; 21:1237-52. [PMID: 20147449 PMCID: PMC2847527 DOI: 10.1091/mbc.e09-05-0412] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Budding yeast mutants in assembly of actin cables, which are thought to be the only actin structures essential for budding, still could form a small bud. Mutations in actin patch endocytic machineries/endocytic recycling factors inhibited this budding, suggesting a mechanism that promotes polarized growth by local recycling of endocytic vesicles. The assembly of filamentous actin is essential for polarized bud growth in budding yeast. Actin cables, which are assembled by the formins Bni1p and Bnr1p, are thought to be the only actin structures that are essential for budding. However, we found that formin or tropomyosin mutants, which lack actin cables, are still able to form a small bud. Additional mutations in components for cortical actin patches, which are assembled by the Arp2/3 complex to play a pivotal role in endocytic vesicle formation, inhibited this budding. Genes involved in endocytic recycling were also required for small-bud formation in actin cable-less mutants. These results suggest that budding yeast possesses a mechanism that promotes polarized growth by local recycling of endocytic vesicles. Interestingly, the type V myosin Myo2p, which was thought to use only actin cables to track, also contributed to budding in the absence of actin cables. These results suggest that some actin network may serve as the track for Myo2p-driven vesicle transport in the absence of actin cables or that Myo2p can function independent of actin filaments. Our results also show that polarity regulators including Cdc42p were still polarized in mutants defective in both actin cables and cortical actin patches, suggesting that the actin cytoskeleton does not play a major role in cortical assembly of polarity regulators in budding yeast.
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Affiliation(s)
- Takaharu Yamamoto
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan
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Epp E, Walther A, Lépine G, Leon Z, Mullick A, Raymond M, Wendland J, Whiteway M. Forward genetics in Candida albicans that reveals the Arp2/3 complex is required for hyphal formation, but not endocytosis. Mol Microbiol 2010; 75:1182-98. [PMID: 20141603 DOI: 10.1111/j.1365-2958.2009.07038.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Candida albicans is a diploid fungal pathogen lacking a defined complete sexual cycle, and thus has been refractory to standard forward genetic analysis. Instead, transcription profiling and reverse genetic strategies based on Saccharomyces cerevisiae have typically been used to link genes to functions. To overcome restrictions inherent in such indirect approaches, we have investigated a forward genetic mutagenesis strategy based on the UAU1 technology. We screened 4700 random insertion mutants for defects in hyphal development and linked two new genes (ARP2 and VPS52) to hyphal growth. Deleting ARP2 abolished hyphal formation, generated round and swollen yeast phase cells, disrupted cortical actin patches and blocked virulence in mice. The mutants also showed a global lack of induction of hyphae-specific genes upon the yeast-to-hyphae switch. Surprisingly, both arp2 Delta/Delta and arp2 Delta/Delta arp3 Delta/Delta mutants were still able to endocytose FM4-64 and Lucifer Yellow, although as shown by time-lapse movies internalization of FM4-64 was somewhat delayed in mutant cells. Thus the non-essential role of the Arp2/3 complex discovered by forward genetic screening in C. albicans showed that uptake of membrane components from the plasma membrane to vacuolar structures is not dependent on this actin nucleating machinery.
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Affiliation(s)
- Elias Epp
- Biotechnology Research Institute, National Research Council of Canada, Montréal, QC H4P 2R2, Canada
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Casadevall A, Nosanchuk JD, Williamson P, Rodrigues ML. Vesicular transport across the fungal cell wall. Trends Microbiol 2009; 17:158-62. [PMID: 19299133 DOI: 10.1016/j.tim.2008.12.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 11/27/2008] [Accepted: 12/15/2008] [Indexed: 12/17/2022]
Abstract
Recent findings indicate that fungi use vesicular transport to deliver substances across their cell walls. Fungal vesicles are similar to mammalian exosomes and could originate from cytoplasmic multivesicular bodies. Vesicular transport enables the export of large molecules across the cell wall, and vesicles contain lipids, proteins and polysaccharides, many of which are associated with virulence. Concentration of fungal products in vesicles could increase their efficiency in food acquisition and/or delivering potentially noxious substances to other cells, such as amoebae or phagocytes. The discovery of vesicular transport in fungi opens many new avenues for investigation in basic cell biology and pathogenesis.
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Affiliation(s)
- Arturo Casadevall
- Departments of Microbiology and Immunology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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The antimicrobial peptide histatin-5 causes a spatially restricted disruption on the Candida albicans surface, allowing rapid entry of the peptide into the cytoplasm. PLoS Pathog 2008; 4:e1000190. [PMID: 18974864 PMCID: PMC2568956 DOI: 10.1371/journal.ppat.1000190] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 09/26/2008] [Indexed: 11/19/2022] Open
Abstract
Antimicrobial peptides play an important role in host defense against microbial pathogens. Their high cationic charge and strong amphipathic structure allow them to bind to the anionic microbial cell membrane and disrupt the membrane bilayer by forming pores or channels. In contrast to the classical pore-forming peptides, studies on histatin-5 (Hst-5) have suggested that the peptide is transported into the cytoplasm of Candida albicans in a non-lytic manner, and cytoplasmic Hst-5 exerts its candicidal activities on various intracellular targets, consistent with its weak amphipathic structure. To understand how Hst-5 is internalized, we investigated the localization of FITC-conjugated Hst-5. We find that Hst-5 is internalized into the vacuole through receptor-mediated endocytosis at low extracellular Hst-5 concentrations, whereas under higher physiological concentrations, Hst-5 is translocated into the cytoplasm through a mechanism that requires a high cationic charge on Hst-5. At intermediate concentrations, two cell populations with distinct Hst-5 localizations were observed. By cell sorting, we show that cells with vacuolar localization of Hst-5 survived, while none of the cells with cytoplasmic Hst-5 formed colonies. Surprisingly, extracellular Hst-5, upon cell surface binding, induces a perturbation on the cell surface, as visualized by an immediate and rapid internalization of Hst-5 and propidium iodide or rhodamine B into the cytoplasm from the site using time-lapse microscopy, and a concurrent rapid expansion of the vacuole. Thus, the formation of a spatially restricted site in the plasma membrane causes the initial injury to C. albicans and offers a mechanism for its internalization into the cytoplasm. Our study suggests that, unlike classical channel-forming antimicrobial peptides, action of Hst-5 requires an energized membrane and causes localized disruptions on the plasma membrane of the yeast. This mechanism of cell membrane disruption may provide species-specific killing with minimal damage to microflora and the host and may be used by many other antimicrobial peptides.
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Weissman Z, Shemer R, Conibear E, Kornitzer D. An endocytic mechanism for haemoglobin-iron acquisition in Candida albicans. Mol Microbiol 2008; 69:201-17. [PMID: 18466294 DOI: 10.1111/j.1365-2958.2008.06277.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fungal pathogen Candida albicans is able to utilize haemin and haemoglobin as iron sources. Haem-iron utilization is facilitated by Rbt5, an extracellular, glycosylphophatidylinositol (GPI)-anchored, haemin- and haemoglobin-binding protein. Here, we show that Rbt5 and its close homologue Rbt51 are short-lived plasma membrane proteins, degradation of which depends on vacuolar activity. Rbt5 facilitates the rapid endocytosis of haemoglobin into the C. albicans vacuole. We relied on recapitulation of the Rbt51-dependent haem-iron utilization in Saccharomyces cerevisiae to identify mutants defective in haemoglobin utilization. Homologues of representative mutants in S. cerevisiae were deleted in C. albicans and tested for haemoglobin-iron utilization and haemoglobin uptake. These mutants define a novel endocytosis-mediated haemoglobin utilization mechanism that depends on acidification of the lumen of the late secretory pathway, on a type I myosin and on the activity of the ESCRT pathway.
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Affiliation(s)
- Ziva Weissman
- Department of Molecular Microbiology, Technion-B. Rappaport Faculty of Medicine, and the Rappaport Institute for Research in the Medical Sciences, Haifa 31096, Israel
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Côte P, Whiteway M. The role of Candida albicans FAR1 in regulation of pheromone-mediated mating, gene expression and cell cycle arrest. Mol Microbiol 2008; 68:392-404. [DOI: 10.1111/j.1365-2958.2008.06158.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Tsiavaliaris G, Fujita-Becker S, Dürrwang U, Diensthuber RP, Geeves MA, Manstein DJ. Mechanism, regulation, and functional properties of Dictyostelium myosin-1B. J Biol Chem 2007; 283:4520-7. [PMID: 18089562 DOI: 10.1074/jbc.m708113200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Myosin-1B is one of three long tailed class-1 myosins containing an ATP-insensitive actin-binding site in the tail region that are produced in Dictyostelium discoideum. Myosin-1B localizes to actin-rich structures at the leading edge of migrating cells where it has been implicated in the formation and retraction of membrane projections, the recycling of plasma membrane components, and intracellular particle transport. Here, we have used a combination of molecular engineering approaches to describe the kinetic and motile properties of the myosin-1B motor and its regulation by TEDS site phosphorylation. Our results show that myosin-1B is a low duty ratio motor and displays the fastest nucleotide binding kinetics of any of the Dictyostelium class-1 myosins studied so far. Different from Dictyostelium myosin-1D and myosin-1E, dephosphorylated myosin-1B is not inactivated but moves actin filaments efficiently, albeit at an up to 8-fold slower velocity in the in vitro motility assay. A further difference is that myosin-1B lacks the ability to switch between rapid movement and bearing tension upon physiological changes of free Mg2+ ions. In this respect, its motor properties appear to be more closely related to Dictyostelium myosin-2 and rabbit skeletal muscle myosin.
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Affiliation(s)
- Georgios Tsiavaliaris
- Institute for Biophysical Chemistry, OE 4350, Hannover Medical School, Carl-Neuberg-Strasse 1, D-30623 Hannover, Germany.
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Wolyniak MJ, Sundstrom P. Role of actin cytoskeletal dynamics in activation of the cyclic AMP pathway and HWP1 gene expression in Candida albicans. EUKARYOTIC CELL 2007; 6:1824-40. [PMID: 17715368 PMCID: PMC2043390 DOI: 10.1128/ec.00188-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Changes in gene expression during reversible bud-hypha transitions of the opportunistic fungal pathogen Candida albicans permit adaptation to environmental conditions that are critical for proliferation in host tissues. Our previous work has shown that the hypha-specific adhesin gene HWP1 is up-regulated by the cyclic AMP (cAMP) signaling pathway. However, little is known about the potential influences of determinants of cell morphology on HWP1 gene expression. We found that blocking hypha formation with cytochalasin A, which destabilizes actin filaments, and with latrunculin A, which sequesters actin monomers, led to a loss of HWP1 gene expression. In contrast, high levels of HWP1 gene expression were observed when the F-actin stabilizer jasplakinolide was used to block hypha formation, suggesting that HWP1 expression could be regulated by actin structures. Mutants defective in formin-mediated nucleation of F-actin were reduced in HWP1 gene expression, providing genetic support for the importance of actin structures. Kinetic experiments with wild-type and actin-deficient cells revealed two distinct phases of HWP1 gene expression, with a slow, actin-independent phase preceding a fast, actin-dependent phase. Low levels of HWP1 gene expression that appeared to be independent of stabilized actin and cAMP signaling were detected using indirect immunofluorescence. A connection between actin structures and the cAMP signaling pathway was shown using hyper- and hypomorphic cAMP mutants, providing a possible mechanism for up-regulation of HWP1 gene expression by stabilized actin. The results reveal a new role for F-actin as a regulatory agent of hypha-specific gene expression at the bud-hypha transition.
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Affiliation(s)
- Michael J Wolyniak
- Microbiology and Molecular Pathogenesis Program, Dartmouth Medical School, Vail Building, HB7550, Hanover, NH 03755, USA
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Dünkler A, Wendland J. Candida albicans Rho-type GTPase-encoding genes required for polarized cell growth and cell separation. EUKARYOTIC CELL 2007; 6:844-54. [PMID: 17351079 PMCID: PMC1899239 DOI: 10.1128/ec.00201-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Rho proteins are essential regulators of morphogenesis in eukaryotic cells. In this report, we investigate the role of two previously uncharacterized Rho proteins, encoded by the Candida albicans RHO3 (CaRHO3) and CaCRL1/CaRHO4 genes. The CaRHO3 gene was found to contain one intron. Promoter shutdown experiments using a MET3 promoter-controlled RHO3 revealed a strong cell polarity defect and a partially depolarized actin cytoskeleton. Hyphal growth after promoter shutdown was abolished in rho3 mutants even in the presence of a constitutively active ras1(G13V) allele, and existing germ tubes became swollen. Deletion of C. albicans RHO4 indicated that it is a nonessential gene and that rho4 mutants were phenotypically different from rho3. Two distinct phenotypes of rho4 cells were elongated cell morphology and an unexpected cell separation defect generating chains of cells. Colony morphology of crl1/rho4 resulted in a growth-dependent smooth (long cell cycle length) or wrinkled (short cell cycle length) phenotype. This phenotype was additionally dependent on the rho4 cell separation defect and was also found in a Cacht3 chitinase mutant that shows a strong cytokinesis defect. The overexpression of the endoglucanase encoding the ENG1 gene, but not CHT3, suppressed the cell separation defect of crl1/rho4 but could not suppress the cell elongation phenotype. C. albicans Crl1/Rho4 and Bnr1 both localize to septal sites in yeast and hyphal cells but not to the hyphal tip. Deletion of RHO4 and BNR1 produced similar morphological phenotypes. Based on the localization of Rho4 and on the rho4 mutant phenotype, we propose a model in which Rho4p may function as a regulator of cell polarity, breaking the initial axis of polarity found during early bud growth to promote the construction of a septum.
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Affiliation(s)
- Alexander Dünkler
- Department of Microbiology, Friedrich Schiller University, Jena, Germany
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Oberholzer U, Nantel A, Berman J, Whiteway M. Transcript profiles of Candida albicans cortical actin patch mutants reflect their cellular defects: contribution of the Hog1p and Mkc1p signaling pathways. EUKARYOTIC CELL 2007; 5:1252-65. [PMID: 16896210 PMCID: PMC1539150 DOI: 10.1128/ec.00385-05] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Candida albicans, Myo5p and Sla2p are required for the polarized localization and function of cortical actin patches, for hyphal formation, and for endocytosis. Deletion of either the MYO5 or the SLA2 gene generated a common transcriptional response that involved changes in the transcript levels of cell wall protein- and membrane protein-encoding genes. However, these profiles were distinct from those observed for a mutant with specific deletions of the actin-organizing domains of Myo5p or for wild-type cells treated with cytochalasin A, both of which also generate defects in the organization of cortical actin patches. The profiles observed for the myo5Delta and sla2Delta mutants had similarities to those of wild-type cells subjected to an osmotic shock, and the defects in cortical patch function found with myo5Delta and sla2Delta mutants, but not cortical actin patch distribution per se, affected sensitivity to various stresses, including heat and osmotic shocks and cell wall damage. Secondary effects coupled with defective endocytosis, such as lack of polarized lipid rafts and associated protein Rvs167-GFP (where GFP is green fluorescent protein) and lack of polarized wall remodeling protein GFP-Gsc1, were also observed for the myo5Delta and sla2Delta mutants. The mitogen-activated protein kinases Hog1p and Mkc1p, which mediate signaling in response to osmotic stress and cell wall damage, do not play a major role in regulating the transcript level changes in the myo5Delta and sla2Delta mutants. Hog1p was not hyperphosphorylated in the myo5Delta and sla2Delta mutants, and the transcript levels of only a subset of genes affected in the myo5Delta mutant were dependent upon the presence of Hog1p and Mkc1p. However, it appears that Hog1p and Mkc1p play important roles in the myo5Delta mutant cells because double deletion of myosin I and either Hog1p or Mkc1p resulted in very-slow-growing cells.
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Affiliation(s)
- Ursula Oberholzer
- Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount, Montreal H4P 2R2, Quebec, Canada
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42
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Steinberg G. Hyphal growth: a tale of motors, lipids, and the Spitzenkörper. EUKARYOTIC CELL 2007; 6:351-60. [PMID: 17259546 PMCID: PMC1828937 DOI: 10.1128/ec.00381-06] [Citation(s) in RCA: 229] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Gero Steinberg
- MPI für Terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
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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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Martin R, Walther A, Wendland J. Ras1-induced hyphal development in Candida albicans requires the formin Bni1. EUKARYOTIC CELL 2005; 4:1712-24. [PMID: 16215178 PMCID: PMC1265897 DOI: 10.1128/ec.4.10.1712-1724.2005] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Formins are downstream effector proteins of Rho-type GTPases and are involved in the organization of the actin cytoskeleton and actin cable assembly at sites of polarized cell growth. Here we show using in vivo time-lapse microscopy that deletion of the Candida albicans formin homolog BNI1 results in polarity defects during yeast growth and hyphal stages. Deletion of the second C. albicans formin, BNR1, resulted in elongated yeast cells with cell separation defects but did not interfere with the ability of bnr1 cells to initiate and maintain polarized hyphal growth. Yeast bni1 cells were swollen, showed an increased random budding pattern, and had a severe defect in cytokinesis, with enlarged bud necks. Induction of hyphal development in bni1 cells resulted in germ tube formation but was halted at the step of polarity maintenance. Bni1-green fluorescent protein is found persistently at the hyphal tip and colocalizes with a structure resembling the Spitzenkörper of true filamentous fungi. Introduction of constitutively active ras1G13V in the bni1 strain or addition of cyclic AMP to the growth medium did not bypass bni1 hyphal growth defects. Similarly, these agents were not able to suppress hyphal growth defects in the wal1 mutant which is lacking the Wiskott-Aldrich syndrome protein (WASP) homolog. These results suggest that the maintenance of polarized hyphal growth in C. albicans requires coordinated regulation of two actin cytoskeletal pathways, including formin-mediated secretion and WASP-dependent endocytosis.
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Affiliation(s)
- Ronny Martin
- Junior Research Group: Growth Control of Fungal Pathogens, Leibniz Institute for Natural Products Research and Infection Biology, Friedrich-Schiller-University, Beutenbergstr. 11a, D-07745 Jena, Germany
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45
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Bassilana M, Hopkins J, Arkowitz RA. Regulation of the Cdc42/Cdc24 GTPase module during Candida albicans hyphal growth. EUKARYOTIC CELL 2005; 4:588-603. [PMID: 15755921 PMCID: PMC1087799 DOI: 10.1128/ec.4.3.588-603.2005] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Rho G protein Cdc42 and its exchange factor Cdc24 are required for hyphal growth of the human fungal pathogen Candida albicans. Previously, we reported that strains ectopically expressing Cdc24 or Cdc42 are unable to form hyphae in response to serum. Here we investigated the role of these two proteins in hyphal growth, using quantitative real-time PCR to measure induction of hypha-specific genes together with time lapse microscopy. Expression of the hypha-specific genes examined depends on the cyclic AMP-dependent protein kinase A pathway culminating in the Efg1 and Tec1 transcription factors. We show that strains with reduced levels of CDC24 or CDC42 transcripts induce hypha-specific genes yet cannot maintain their expression in response to serum. Furthermore, in serum these mutants form elongated buds compared to the wild type and mutant budding cells, as observed by time lapse microscopy. Using Cdc24 fused to green fluorescent protein, we also show that Cdc24 is recruited to and persists at the germ tube tip during hyphal growth. Altogether these data demonstrate that the Cdc24/Cdc42 GTPase module is required for maintenance of hyphal growth. In addition, overexpression studies indicate that specific levels of Cdc24 and Cdc42 are important for invasive hyphal growth. In response to serum, CDC24 transcript levels increase transiently in a Tec1-dependent fashion, as do the G-protein RHO3 and the Rho1 GTPase activating protein BEM2 transcript levels. These results suggest that a positive feedback loop between Cdc24 and Tec1 contributes to an increase in active Cdc42 at the tip of the germ tube which is important for hypha formation.
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Affiliation(s)
- Martine Bassilana
- Institute of Signaling, Developmental Biology, and Cancer, UMR 6543 Centre National de la Recherche Scientifique, Centre de Biochimie, University of Nice, 06108 Nice, France.
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Toenjes KA, Munsee SM, Ibrahim AS, Jeffrey R, Edwards JE, Johnson DI. Small-molecule inhibitors of the budded-to-hyphal-form transition in the pathogenic yeast Candida albicans. Antimicrob Agents Chemother 2005; 49:963-72. [PMID: 15728890 PMCID: PMC549276 DOI: 10.1128/aac.49.3.963-972.2005] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pathogenic yeast Candida albicans can exist in multiple morphological states, including budded, pseudohyphal, and true hyphal forms. The ability to convert between the budded and hyphal forms, termed the budded-to-hyphal-form transition, is important for virulence and is regulated by multiple environmental and cellular signals. To identify inhibitors of this morphological transition, a microplate-based morphological assay was developed. With this assay, the known actin-inhibiting drugs latrunculin-A and jasplakinolide were shown to inhibit the transition in a dose-dependent and reversible manner. Five novel small molecules that reversibly inhibited the transition and hyphal elongation without affecting budded growth were identified. These molecules inhibited hyphal growth induced by Spider, Lee's, M199 pH 8, and 10% serum-containing media, with two molecules having a synergistic effect. The molecules also differentially affected the hyphal form-specific gene expression of HWP1 and endocytosis without disrupting the actin cytoskeleton or septin organization. Structural derivatives of one of the molecules were more effective inhibiters than the original molecule, while other derivatives had decreased efficacies. Several of the small molecules were able to reduce C. albicans-dependent damage to endothelial cells by inhibiting the budded-to-hyphal-form transition. These studies substantiated the effectiveness of the morphological assay and identified several novel molecules that, by virtue of their ability to inhibit the budded-to-hyphal-form transition, may be exploited as starting points for effective antifungal therapeutics in the future.
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Affiliation(s)
- Kurt A Toenjes
- Department of Microbiology and Molecular Genetics, 202 Stafford Hall, 95 Carrigan Dr., University of Vermont, Burlington, VT 05405, USA
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47
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Oberholzer U, Iouk TL, Thomas DY, Whiteway M. Functional characterization of myosin I tail regions in Candida albicans. EUKARYOTIC CELL 2005; 3:1272-86. [PMID: 15470256 PMCID: PMC522603 DOI: 10.1128/ec.3.5.1272-1286.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The molecular motor myosin I is required for hyphal growth in the pathogenic yeast Candida albicans. Specific myosin I functions were investigated by a deletion analysis of five neck and tail regions. Hyphal formation requires both the TH1 region and the IQ motifs. The TH2 region is important for optimal hyphal growth. All of the regions, except for the SH3 and acidic (A) regions that were examined individually, were required for the localization of myosin I at the hyphal tip. Similarly, all of the domains were required for the association of myosin I with pelletable actin-bound complexes. Moreover, the hyphal tip localization of cortical actin patches, identified by both rhodamine-phalloidin staining and Arp3-green fluorescent protein signals, was dependent on myosin I. Double deletion of the A and SH3 domains depolarized the distribution of the cortical actin patches without affecting the ability of the mutant to form hyphae, suggesting that myosin I has distinct functions in these processes. Among the six myosin I tail domain mutants, the ability to form hyphae was strictly correlated with endocytosis. We propose that the uptake of cell wall remodeling enzymes and excess plasma membrane is critical for hyphal formation.
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Affiliation(s)
- Ursula Oberholzer
- Genetics Group, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H3A 2B2, Canada.
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48
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Walther A, Wendland J. Polarized hyphal growth in Candida albicans requires the Wiskott-Aldrich Syndrome protein homolog Wal1p. EUKARYOTIC CELL 2004; 3:471-82. [PMID: 15075276 PMCID: PMC387638 DOI: 10.1128/ec.3.2.471-482.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The yeast-to-hypha transition is a key feature in the cell biology of the dimorphic human fungal pathogen Candida albicans. Reorganization of the actin cytoskeleton is required for this dimorphic switch in Candida. We show that C. albicans WAL1 mutants with both copies of the Wiskott-Aldrich syndrome protein (WASP) homolog deleted do not form hyphae under all inducing conditions tested. Growth of the wild-type and wal1 mutant strains was monitored by in vivo time-lapse microscopy both during yeast-like growth and under hypha-inducing conditions. Isotropic bud growth produced round wal1 cells and unusual mother cell growth. Defects in the organization of the actin cytoskeleton resulted in the random localization of actin patches. Furthermore, wal1 cells exhibited defects in the endocytosis of the lipophilic dye FM4-64, contained increased numbers of vacuoles compared to the wild type, and showed defects in bud site selection. Under hypha-inducing conditions wal1 cells were able to initiate polarized morphogenesis, which, however, resulted in the formation of pseudohyphal cells. Green fluorescent protein (GFP)-tagged Wal1p showed patch-like localization in emerging daughter cells during the yeast growth phase and at the hyphal tips under hypha-inducing conditions. Wal1p-GFP localization largely overlapped with that of actin. Our results demonstrate that Wal1p is required for the organization of the actin cytoskeleton and hyphal morphogenesis in C. albicans as well as for endocytosis and vacuole morphology.
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Affiliation(s)
- A Walther
- Junior Research Group: Growth Control of Fungal Pathogens, Hans-Knöll Institute for Natural Products Research and Department of Microbiology, Friedrich-Schiller University, Jena D-07745, Germany
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Nguyen MH, Cheng S, Clancy CJ. Assessment of Candida albicans genes expressed during infections as a tool to understand pathogenesis. Med Mycol 2004; 42:293-304. [PMID: 15473353 DOI: 10.1080/13693780410001722485] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Candida albicans is the most common fungal opportunistic pathogen of humans and causes mucocutaneous, bloodstream and deep organ infections. Screening for C. albicans genes that are preferentially expressed within infected hosts represents a strategy to identify novel virulence factors and define global expression patterns relevant to pathogenesis. Until recently, C. albicans has not been amenable to screening using existing technologies. This has begun to change with the development of new molecular genetic tools and the sequencing of the C. albicans genome. In this paper, we review studies using recently developed techniques to identify genes expressed by C. albicans during infections, as well as work from our laboratory using a human antibody-based strategy. Along with others, we have shown that selected in vivo expressed genes encode known and previously unrecognized candidal virulence factors. Future studies in this area will identify additional novel virulence factors, as well as advance our understanding of pathogenesis.
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Affiliation(s)
- M Hong Nguyen
- Department of Medicine, University of Florida College of Medicine, Gainesville, FL 32610, USA
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Cassola A, Parrot M, Silberstein S, Magee BB, Passeron S, Giasson L, Cantore ML. Candida albicans lacking the gene encoding the regulatory subunit of protein kinase A displays a defect in hyphal formation and an altered localization of the catalytic subunit. EUKARYOTIC CELL 2004; 3:190-9. [PMID: 14871949 PMCID: PMC329502 DOI: 10.1128/ec.3.1.190-199.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The fungal pathogen Candida albicans switches from a yeast-like to a filamentous mode of growth in response to a variety of environmental conditions. We examined the morphogenetic behavior of C. albicans yeast cells lacking the BCY1 gene, which encodes the regulatory subunit of protein kinase A. We cloned the BCY1 gene and generated a bcy1 tpk2 double mutant strain because a homozygous bcy1 mutant in a wild-type genetic background could not be obtained. In the bcy1 tpk2 mutant, protein kinase A activity (due to the presence of the TPK1 gene) was cyclic AMP independent, indicating that the cells harbored an unregulated phosphotransferase activity. This mutant has constitutive protein kinase A activity and displayed a defective germinative phenotype in N-acetylglucosamine and in serum-containing medium. The subcellular localization of a Tpk1-green fluorescent protein (GFP) fusion protein was examined in wild-type, tpk2 null, and bcy1 tpk2 double mutant strains. The fusion protein was observed to be predominantly nuclear in wild-type and tpk2 strains. This was not the case in the bcy1 tpk2 double mutant, where it appeared dispersed throughout the cell. Coimmunoprecipitation of Bcy1p with the Tpk1-GFP fusion protein demonstrated the interaction of these proteins inside the cell. These results suggest that one of the roles of Bcy1p is to tether the protein kinase A catalytic subunit to the nucleus.
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Affiliation(s)
- Alejandro Cassola
- Cátedra de Microbiología, Facultad de Agronomía, Universidad de Buenos Aires, IBYF-CONICET, C1417DSE Buenos Aires, Argentina
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