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MacAlpine J, Liu Z, Hossain S, Whitesell L, Robbins N, Cowen LE. DYRK-family kinases regulate Candida albicans morphogenesis and virulence through the Ras1/PKA pathway. mBio 2023; 14:e0218323. [PMID: 38015416 PMCID: PMC10746247 DOI: 10.1128/mbio.02183-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/12/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Candida albicans is an opportunistic human fungal pathogen that frequently causes life-threatening infections in immunocompromised individuals. To cause disease, the fungus employs several virulence traits, including its ability to transition between yeast and filamentous states. Previous work identified a role for the kinase Yak1 in regulating C. albicans filamentation. Here, we demonstrate that Yak1 regulates morphogenesis through the canonical cAMP/PKA pathway and that this regulation is environmentally contingent, as host-relevant concentrations of CO2 bypass the requirement of Yak1 for C. albicans morphogenesis. We show a related kinase, Pom1, is important for filamentation in the absence of Yak1 under these host-relevant conditions, as deletion of both genes blocked filamentous growth under all conditions tested. Finally, we demonstrate that Yak1 is required for filamentation in a mouse model of C. albicans dermatitis using genetic and pharmacological approaches. Overall, our results expand our understanding of how Yak1 regulates an important virulence trait in C. albicans.
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Affiliation(s)
- Jessie MacAlpine
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Zhongle Liu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Saif Hossain
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Luke Whitesell
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Leah E. Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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2
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Ng AWR, Li L, Ng EWL, Li C, Qiao Y. Molecular Docking Reveals Critical Residues in Candida albicans Cyr1 for Peptidoglycan Recognition and Hyphal Growth. ACS Infect Dis 2023; 9:1362-1371. [PMID: 37318518 DOI: 10.1021/acsinfecdis.3c00115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The key virulent characteristic of Candida albicans, the major fungal pathogen in humans, lies in its ability to switch between the benign yeast state and the invasive hyphal form upon exposure to specific stimuli. Among the numerous hyphal-inducing signals, bacterial peptidoglycan fragments (PGNs) represent the most potent inducers of C. albicans hyphal growth. The sole adenylyl cyclase Cyr1 in C. albicans is a known sensor for PGNs and activates downstream signaling of hyphal growth, yet the molecular details of PGN-Cyr1 interactions have remained unclear. In this study, we performed in silico docking of a PGN motif to the modeled structure of the Cyr1 leucine-rich repeat (LRR) domain and uncovered four putative PGN-interacting residues in Cyr1_LRR. The critical roles of these residues in PGN binding and supporting C. albicans hyphal growth were demonstrated by in-gel fluorescence binding assay and hyphal induction assay, respectively. Remarkably, the C. albicans mutant harboring the cyr1 variant allele that is defective for PGN recognition exhibits significantly reduced cytotoxicity in macrophage infection assay. Overall, our work offered important insights into the molecular recognition of PGNs by C. albicans Cyr1 sensor protein, establishing that disruption of PGN recognition by Cyr1 results in defective hyphal growth and reduced virulence of C. albicans. Our findings provide an exciting starting point for the future development of Cyr1 antagonists as novel anti-virulence therapeutics to combat C. albicans invasive growth and infection.
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Affiliation(s)
- Allan Wee Ren Ng
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore S637371, Singapore
| | - Lanxin Li
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore S637371, Singapore
| | - Evan Wei Long Ng
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore S637371, Singapore
| | - Chenyu Li
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore S637371, Singapore
| | - Yuan Qiao
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, Singapore S637371, Singapore
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3
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The Antifungal and Antibiofilm Activities of Caffeine against Candida albicans on Polymethyl Methacrylate Denture Base Material. Biomedicines 2022; 10:biomedicines10092078. [PMID: 36140179 PMCID: PMC9495344 DOI: 10.3390/biomedicines10092078] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/17/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022] Open
Abstract
Background: In this study, the effect of pure caffeine was established against Candida albicans (C. albicans) using different microbiological techniques. Methods: Broth microdilution and colony forming units (CFUs) assays were used to detect the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The Live/Dead fluorescent dyes were implemented to determine the yeast viability. Polymethyl methacrylate acrylic resin (PMMA) discs were prepared to evaluate caffeine’s effects against adherent C. albicans using microplate reader, CFUs, and scanning electron microscope (SEM). Results: caffeine’s MIC was detected around 30 mg/mL, while the MFC was considered at 60 mg/mL. In an agar-well diffusion test, the inhibition zones were wider in caffeine groups. The Live/Dead viability test verified caffeine’s antifungal effects. The optical density of the adherent C. albicans on PMMA discs were lower at 620 nm or 410 nm in caffeine groups. CFU count was also reduced by caffeine treatments. SEM revealed the lower adherent C. albicans count in caffeine groups. The effect of caffeine was dose-dependent at which the 60 mg/mL dose demonstrated the most prominent effect. Conclusion: The study reinforced caffeine’s antifungal and antibiofilm properties and suggested it as an additive, or even an alternative, disinfectant solution for fungal biofilms on denture surfaces.
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Martínez-Soto D, Ortiz-Castellanos L, Robledo-Briones M, León-Ramírez CG. Molecular Mechanisms Involved in the Multicellular Growth of Ustilaginomycetes. Microorganisms 2020; 8:E1072. [PMID: 32708448 PMCID: PMC7409079 DOI: 10.3390/microorganisms8071072] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 07/12/2020] [Accepted: 07/16/2020] [Indexed: 12/23/2022] Open
Abstract
Multicellularity is defined as the developmental process by which unicellular organisms became pluricellular during the evolution of complex organisms on Earth. This process requires the convergence of genetic, ecological, and environmental factors. In fungi, mycelial and pseudomycelium growth, snowflake phenotype (where daughter cells remain attached to their stem cells after mitosis), and fruiting bodies have been described as models of multicellular structures. Ustilaginomycetes are Basidiomycota fungi, many of which are pathogens of economically important plant species. These fungi usually grow unicellularly as yeasts (sporidia), but also as simple multicellular forms, such as pseudomycelium, multicellular clusters, or mycelium during plant infection and under different environmental conditions: Nitrogen starvation, nutrient starvation, acid culture media, or with fatty acids as a carbon source. Even under specific conditions, Ustilago maydis can form basidiocarps or fruiting bodies that are complex multicellular structures. These fungi conserve an important set of genes and molecular mechanisms involved in their multicellular growth. In this review, we will discuss in-depth the signaling pathways, epigenetic regulation, required polyamines, cell wall synthesis/degradation, polarized cell growth, and other cellular-genetic processes involved in the different types of Ustilaginomycetes multicellular growth. Finally, considering their short life cycle, easy handling in the laboratory and great morphological plasticity, Ustilaginomycetes can be considered as model organisms for studying fungal multicellularity.
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Affiliation(s)
- Domingo Martínez-Soto
- Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521, USA
- Tecnológico Nacional de México, Instituto Tecnológico Superior de Los Reyes, Los Reyes 60300, Mexico
| | - Lucila Ortiz-Castellanos
- Departamento de Ingeniería Genética, Unidad Irapuato, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato 36821, Mexico; (L.O.-C.); (C.G.L.-R.)
| | - Mariana Robledo-Briones
- Departamento de Microbiología y Genética, Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, 37185 Salamanca, Spain;
| | - Claudia Geraldine León-Ramírez
- Departamento de Ingeniería Genética, Unidad Irapuato, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato 36821, Mexico; (L.O.-C.); (C.G.L.-R.)
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5
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Min K, Naseem S, Konopka JB. N-Acetylglucosamine Regulates Morphogenesis and Virulence Pathways in Fungi. J Fungi (Basel) 2019; 6:jof6010008. [PMID: 31878148 PMCID: PMC7151181 DOI: 10.3390/jof6010008] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 12/17/2022] Open
Abstract
N-acetylglucosamine (GlcNAc) is being increasingly recognized for its ability to stimulate cell signaling. This amino sugar is best known as a component of cell wall peptidoglycan in bacteria, cell wall chitin in fungi and parasites, exoskeletons of arthropods, and the extracellular matrix of animal cells. In addition to these structural roles, GlcNAc is now known to stimulate morphological and stress responses in a wide range of organisms. In fungi, the model organisms Saccharomyces cerevisiae and Schizosaccharomyces pombe lack the ability to respond to GlcNAc or catabolize it, so studies with the human pathogen Candida albicans have been providing new insights into the ability of GlcNAc to stimulate cellular responses. GlcNAc potently induces C. albicans to transition from budding to filamentous hyphal growth. It also promotes an epigenetic switch from White to Opaque cells, which differ in morphology, metabolism, and virulence properties. These studies have led to new discoveries, such as the identification of the first eukaryotic GlcNAc transporter. Other results have shown that GlcNAc can induce signaling in C. albicans in two ways. One is to act as a signaling molecule independent of its catabolism, and the other is that its catabolism can cause the alkalinization of the extracellular environment, which provides an additional stimulus to form hyphae. GlcNAc also induces the expression of virulence genes in the C. albicans, indicating it can influence pathogenesis. Therefore, this review will describe the recent advances in understanding the role of GlcNAc signaling pathways in regulating C. albicans morphogenesis and virulence.
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6
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Chen S, Xia J, Li C, Zuo L, Wei X. The possible molecular mechanisms of farnesol on the antifungal resistance of C. albicans biofilms: the regulation of CYR1 and PDE2. BMC Microbiol 2018; 18:203. [PMID: 30509171 PMCID: PMC6278051 DOI: 10.1186/s12866-018-1344-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/16/2018] [Indexed: 12/19/2022] Open
Abstract
Background Farnesol has potential antifungal activity against Candida albicans biofilms, but the molecular mechanism of this activity is still unclear. Farnesol inhibits hyphal growth by regulating the cyclic AMP (cAMP) signalling pathway in C. albicans, and CYR1 and PDE2 regulate a pair of enzymes that are directly responsible for cAMP synthesis and degradation. Here, we hypothesize that farnesol enhances the antifungal susceptibility of C. albicans biofilms by regulating CYR1 and PDE2. Results The resistance of the CYR1- and PDE2-overexpressing strains to caspofungin, itraconazole and terbinafine was increased in planktonic cells, and that to amphotericin B was increased in biofilms. Meanwhile, the biofilms of the CYR1- and PDE2-overexpressing strains were thicker (all p < 0.05) and consisted of more hyphae than that of the wild strain. The intracellular cAMP levels were higher in the biofilms of the CYR1-overexpressing strain than that in the biofilms of the wild strain (all p < 0.01), while no changes were found in the PDE2-overexpressing strain. Exogenous farnesol decreased the resistance of the CYR1- and PDE2-overexpressing strains to these four antifungals, repressed the hyphal and biofilm formation of the strains, and decreased the intracellular cAMP level in the biofilms (all p < 0.05) compared to the untreated controls. In addition, farnesol decreased the expression of the gene CYR1 and the protein CYR1 in biofilms of the CYR1-overexpressing strain (all p < 0.05) but increased the expression of the gene PDE2 and the protein PDE2 in biofilms of the PDE2-overexpressing strain (all p < 0.01). Conclusions The results indicate that CYR1 and PDE2 regulate the resistance of C. albicans biofilms to antifungals. Farnesol suppresses the resistance of C. albicans biofilms to antifungals by regulating the expression of the gene CYR1 and PDE2, while PDE2 regulation was subordinate to CYR1 regulation.
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Affiliation(s)
- Shengyan Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China
| | - Jinping Xia
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China
| | - Chengxi Li
- Suzhou Hospital Affiliated to Nanjing Medical University, Suzhou Science and Technology Town Hospital, Suzhou, 215153, China
| | - Lulu Zuo
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China
| | - Xin Wei
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China. .,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China.
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7
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Chaturvedi V, Bouchara JP, Hagen F, Alastruey-Izquierdo A, Badali H, Bocca AL, Cano-Lira JF, Cao C, Chaturvedi S, Chotirmall SH, van Diepeningen AD, Gangneux JP, Guinea J, de Hoog S, Ilkit M, Kano R, Liu W, Martinez-Rossi NM, de Souza Carvalho Melhem M, Ono MA, Ran Y, Ranque S, de Almeida Soares CM, Sugita T, Thomas PA, Vecchiarelli A, Wengenack NL, Woo PCY, Xu J, Zancope-Oliveira RM. Eighty Years of Mycopathologia: A Retrospective Analysis of Progress Made in Understanding Human and Animal Fungal Pathogens. Mycopathologia 2018; 183:859-877. [PMID: 30506286 DOI: 10.1007/s11046-018-0306-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 11/09/2018] [Indexed: 11/30/2022]
Abstract
Mycopathologia was founded in 1938 to 'diffuse the understanding of fungal diseases in man and animals among mycologists.' This was an important mission considering that pathogenic fungi for humans and animals represent a tiny minority of the estimated 1.5-5 million fungal inhabitants on Earth. These pathogens have diverged from the usual saprotrophic lifestyles of most fungi to colonize and infect humans and animals. Medical and veterinary mycology is the subdiscipline of microbiology that dwells into the mysteries of parasitic, fungal lifestyles. Among the oldest continuing scientific publications on the subject, Mycopathologia had its share of 'classic papers' since the first issue was published in 1938. An analysis of the eight decades of notable contributions reveals many facets of host-pathogen interactions among 183 volumes comprising about 6885 articles. We have analyzed the impact and relevance of this body of work using a combination of citation tools (Google Scholar and Scopus) since no single citation metric gives an inclusive perspective. Among the highly cited Mycopathologia publications, those on experimental mycology accounted for the major part of the articles (36%), followed by diagnostic mycology (16%), ecology and epidemiology (15%), clinical mycology (14%), taxonomy and classification (10%), and veterinary mycology (9%). The first classic publication, collecting nearly 200 citations, appeared in 1957, while two articles published in 2010 received nearly 150 citations each, which is notable for a journal covering a highly specialized field of study. An empirical analysis of the publication trends suggests continuing interests in novel diagnostics, fungal pathogenesis, review of clinical diseases especially with relevance to the laboratory scientists, taxonomy and classification of fungal pathogens, fungal infections and carriage in pets and wildlife, and changing ecology and epidemiology of fungal diseases around the globe. We anticipate that emerging and re-emerging fungal pathogens will continue to cause significant health burden in the coming decades. It remains vital that scientists and physicians continue to collaborate by learning each other's language for the study of fungal diseases, and Mycopathologia will strive to be their partner in this increasingly important endeavor to its 100th anniversary in 2038 and beyond.
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Affiliation(s)
- Vishnu Chaturvedi
- New York State Department of Health and University at Albany, Albany, NY, USA.
| | | | - Ferry Hagen
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | | | - Hamid Badali
- Mazandaran University of Medical Sciences, Sari, Iran
| | | | | | - Cunwei Cao
- Guangxi Medical University, Nanning, China
| | - Sudha Chaturvedi
- New York State Department of Health and University at Albany, Albany, NY, USA
| | | | | | | | | | - Sybren de Hoog
- Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands
| | | | - Rui Kano
- Nihon University College of Bioresource Sciences, Fujisawa, Japan
| | - Weida Liu
- Peking Union Medical College, Nanjing, China
| | | | | | | | | | | | | | | | - Philip A Thomas
- Institute of Ophthalmology, Joseph Eye Hospital, Tiruchirappalli, India
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Parrino SM, Si H, Naseem S, Groudan K, Gardin J, Konopka JB. cAMP-independent signal pathways stimulate hyphal morphogenesis in Candida albicans. Mol Microbiol 2016; 103:764-779. [PMID: 27888610 DOI: 10.1111/mmi.13588] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2016] [Indexed: 11/29/2022]
Abstract
The fungal pathogen Candida albicans can transition from budding to hyphal growth, which promotes biofilm formation and invasive growth into tissues. Stimulation of adenylyl cyclase to form cAMP induces hyphal morphogenesis. The failure of cells lacking adenylyl cyclase (cyr1Δ) to form hyphae has suggested that cAMP signaling is essential for hyphal growth. However, cyr1Δ mutants also grow slowly and have defects in morphogenesis, making it unclear whether hyphal inducers must stimulate cAMP, or if normal basal levels of cAMP are required to maintain cellular health needed for hyphal growth. Interestingly, supplementation of cyr1Δ cells with low levels of cAMP enabled them to form hyphae in response to the inducer N-acetylglucosamine (GlcNAc), suggesting that a basal level of cAMP is sufficient for stimulation. Furthermore, we isolated faster-growing cyr1Δ pseudorevertant strains that can be induced to form hyphae even though they lack cAMP. The pseudorevertant strains were not induced by CO2 , consistent with reports that CO2 directly stimulates adenylyl cyclase. Mutational analysis showed that induction of hyphae in a pseudorevertant strain was independent of RAS1, but was dependent on the EFG1 transcription factor that acts downstream of protein kinase A. Thus, cAMP-independent signals contribute to the induction of hyphal responses.
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Affiliation(s)
- Salvatore M Parrino
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA.,Graduate Program in Molecular and Cellular Biology, Stony Brook University, Stony Brook, NY, USA
| | - Haoyu Si
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Shamoon Naseem
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Kevin Groudan
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Justin Gardin
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA.,Graduate Program in Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - James B Konopka
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
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Rodrigues L, Russo-Abrahão T, Cunha RA, Gonçalves T, Meyer-Fernandes JR. Characterization of extracellular nucleotide metabolism in Candida albicans. FEMS Microbiol Lett 2015; 363:fnv212. [PMID: 26538575 DOI: 10.1093/femsle/fnv212] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2015] [Indexed: 12/17/2022] Open
Abstract
Candida albicans is the most frequent agent of human disseminated fungal infection. Ectophosphatase and ectonucleotidase activities are known to influence the infectious potential of several microbes, including other non-albicans species of Candida. With the present work we aim to characterize these ecto-enzymatic activities in C. albicans. We found that C. albicans does not have a classical ecto-5'-nucleotidase enzyme and 5'AMP is cleaved by a phosphatase instead of exclusively by a nucleotidase that also can use 3'AMP as a substrate. Moreover, these enzymatic activities are not dependent on secreted soluble enzymes and change when the yeast cells are under infection conditions, including low pH, and higher temperature and CO2 content.
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Affiliation(s)
- Lisa Rodrigues
- CNC-Center for Neurosciences and Cell Biology, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal FMUC-Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Thais Russo-Abrahão
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro (UFRJ), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
| | - Rodrigo A Cunha
- CNC-Center for Neurosciences and Cell Biology, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal FMUC-Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Teresa Gonçalves
- CNC-Center for Neurosciences and Cell Biology, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal FMUC-Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - José Roberto Meyer-Fernandes
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro (UFRJ), CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
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10
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The Absence of N-Acetyl-D-glucosamine Causes Attenuation of Virulence of Candida albicans upon Interaction with Vaginal Epithelial Cells In Vitro. BIOMED RESEARCH INTERNATIONAL 2015; 2015:398045. [PMID: 26366412 PMCID: PMC4558442 DOI: 10.1155/2015/398045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 06/15/2015] [Accepted: 07/28/2015] [Indexed: 11/28/2022]
Abstract
To better understand the molecular events underlying vulvovaginal candidiasis, we established an in vitro system. Immortalized vaginal epithelial cells were infected with live, yeast form C. albicans and C. albicans cultured in the same medium without vaginal epithelial cells were used as control. In both cases a yeast to hyphae transition was robustly induced. Whole transcriptome sequencing was used to identify specific gene expression changes in C. albicans. Numerous genes leading to a yeast to hyphae transition and hyphae specific genes were upregulated in the control hyphae and the hyphae in response to vaginal epithelial cells. Strikingly, the GlcNAc pathway was exclusively triggered by vaginal epithelial cells. Functional analysis in our in vitro system revealed that the GlcNAc biosynthesis is involved in the adherence to, and the ability to kill, vaginal epithelial cells in vitro, thus indicating the key role for this pathway in the virulence of C. albicans upon vulvovaginal candidiasis.
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Koch L, Lodin A, Herold I, Ilan M, Carmeli S, Yarden O. Sensitivity of Neurospora crassa to a marine-derived Aspergillus tubingensis anhydride exhibiting antifungal activity that is mediated by the MAS1 protein. Mar Drugs 2014; 12:4713-31. [PMID: 25257783 PMCID: PMC4178490 DOI: 10.3390/md12094713] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 02/04/2023] Open
Abstract
The fungus Aspergillustubingensis (strain OY907) was isolated from the Mediterranean marine sponge Ircinia variabilis. Extracellular extracts produced by this strain were found to inhibit the growth of several fungi. Among the secreted extract components, a novel anhydride metabolite, tubingenoic anhydride A (1) as well as the known 2-carboxymethyl-3-hexylmaleic acid anhydride, asperic acid, and campyrone A and C were purified and their structure elucidated. Compound 1 and 2-carboxymethyl-3-hexylmaleic acid anhydride inhibited Neurospora crassa growth (MIC = 330 and 207 μM, respectively) and affected hyphal morphology. We produced a N. crassa mutant exhibiting tolerance to 1 and found that a yet-uncharacterized gene, designated mas-1, whose product is a cytosolic protein, confers sensitivity to this compound. The ∆mas-1 strain showed increased tolerance to sublethal concentrations of the chitin synthase inhibitor polyoxin D, when compared to the wild type. In addition, the expression of chitin synthase genes was highly elevated in the ∆mas-1 strain, suggesting the gene product is involved in cell wall biosynthesis and the novel anhydride interferes with its function.
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Affiliation(s)
- Liat Koch
- Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Anat Lodin
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv 69978, Israel.
| | - Inbal Herold
- Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
| | - Micha Ilan
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Shmuel Carmeli
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv 69978, Israel.
| | - Oded Yarden
- Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
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12
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Regulatory role of the PKA pathway in dimorphism and mating in Yarrowia lipolytica. Fungal Genet Biol 2009; 46:390-9. [DOI: 10.1016/j.fgb.2009.02.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 02/06/2009] [Accepted: 02/10/2009] [Indexed: 11/18/2022]
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13
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Bazzolli D, Ribon ADO, Reis K, de Queiroz M, de Araújo E. Differential expression ofplggenes fromPenicillium griseoroseum:plg1 a pectinolytic gene is expressed in sucrose and yeast extract. J Appl Microbiol 2008; 105:1595-603. [DOI: 10.1111/j.1365-2672.2008.03905.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Biswas S, Van Dijck P, Datta A. Environmental sensing and signal transduction pathways regulating morphopathogenic determinants of Candida albicans. Microbiol Mol Biol Rev 2007; 71:348-76. [PMID: 17554048 PMCID: PMC1899878 DOI: 10.1128/mmbr.00009-06] [Citation(s) in RCA: 392] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Candida albicans is an opportunistic fungal pathogen that is found in the normal gastrointestinal flora of most healthy humans. However, under certain environmental conditions, it can become a life-threatening pathogen. The shift from commensal organism to pathogen is often correlated with the capacity to undergo morphogenesis. Indeed, under certain conditions, including growth at ambient temperature, the presence of serum or N-acetylglucosamine, neutral pH, and nutrient starvation, C. albicans can undergo reversible transitions from the yeast form to the mycelial form. This morphological plasticity reflects the interplay of various signal transduction pathways, either stimulating or repressing hyphal formation. In this review, we provide an overview of the different sensing and signaling pathways involved in the morphogenesis and pathogenesis of C. albicans. Where appropriate, we compare the analogous pathways/genes in Saccharomyces cerevisiae in an attempt to highlight the evolution of the different components of the two organisms. The downstream components of these pathways, some of which may be interesting antifungal targets, are also discussed.
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Affiliation(s)
- Subhrajit Biswas
- National Centre for Plant Genome Research, New Delhi 110 067, India
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15
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Singh A, Sharma S, Khuller GK. cAMP regulates vegetative growth and cell cycle in Candida albicans. Mol Cell Biochem 2007; 304:331-41. [PMID: 17557192 DOI: 10.1007/s11010-007-9516-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Accepted: 05/16/2007] [Indexed: 11/24/2022]
Abstract
We demonstrate here the regulatory role of cAMP in cell cycle of Candida albicans. cAMP was found to be a positive signal for growth and morphogenesis. Phosphodiesterase inhibitor aminophylline exhibited significant effects, i.e., increased growth, as well as induced morphogenesis. Atropine and trifluoperazine negatively regulated (inhibited) growth and did not induce morphogenesis. These changes were attributed to increase in cAMP levels and protein kinase A (PKA) activity in presence of aminophylline, while reduction was observed in atropine and trifluoperazine (TFP) grown cells. Alteration in cAMP signaling pathway affected the cell cycle progression in Candida albicans. Increased cAMP levels in aminophylline grown cells reduced the duration of cell cycle by inciting the cell cycle-specific expression of G1 cyclins (CLN1 and CLN2). However atropine and trifluoperazine delayed the expression of G1 cyclins and hence prolonged the cell cycle. Implication of cAMP signaling pathway in both the cell cycle and morphogenesis further opened the channels to explore the potential of this pathway to serve as a target for development of new antifungal drugs.
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Affiliation(s)
- Ajay Singh
- Department of Biochemistry, Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh 160012, India
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16
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Watanabe H, Azuma M, Igarashi K, Ooshima H. Relationship between cell morphology and intracellular potassium concentration in Candida albicans. J Antibiot (Tokyo) 2006; 59:281-7. [PMID: 16883777 DOI: 10.1038/ja.2006.39] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Previously we reported that valinomycin inhibited hyphal growth and induced growth as a chain of yeast cells under hyphal growth induction conditions in Candida albicans. To elucidate the hyphal growth inhibition by valinomycin, we examined the effect of various chemicals on the morphology and found that miconazole inhibited hyphal growth as well as valinomycin: both compounds promoted the leakage of potassium from cells. Analysis of intracellular potassium suggested that hyphal cells contain potassium at high concentrations in comparison with yeast cells. Hyphal growth inhibition by valinomycin was obstructed by the addition of serum. Potassium measurement showed that the addition of serum causes an increase in intracellular potassium, suggesting that the obstruction by serum might be due to an increase in intracellular potassium. The above-mentioned results strongly suggest that the addition of valinomycin and miconazole decreased interacellular potassium and this decrease inhibited hyphal transition.
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Affiliation(s)
- Hiroshi Watanabe
- Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan
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17
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Roze LV, Beaudry RM, Keller NP, Linz JE. Regulation of aflatoxin synthesis by FadA/cAMP/protein kinase A signaling in Aspergillus parasiticus. Mycopathologia 2004; 158:219-32. [PMID: 15518351 DOI: 10.1023/b:myco.0000041841.71648.6e] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Analysis of fadA and pkaA mutants in the filamentous fungus Aspergillus nidulans demonstrated that FadA (Galpha) stimulates cyclic AMP (cAMP)-dependent protein kinase A (PKA) activity resulting, at least in part, in inhibition of conidiation and sterigmatocystin (ST) biosynthesis. In contrast, cAMP added to the growth medium stimulates aflatoxin (AF) synthesis in Aspergillus parasiticus. Our goal was to explain these conflicting reports and to provide mechanistic detail on the role of FadA, cAMP, and PKA in regulation of AF synthesis and conidiation in A. parasiticus. cAMP or dibutyryl-cAMP (DcAMP) were added to a solid growth medium and intracellular cyclic nucleotide levels, PKA activity, and nor-1 promoter activity were measured in A. parasiticus D8D3 (nor1::GUS reporter) and TJYP1-22 (fadAGA2R, activated allele). Similar to Tice and Buchanan [34], cAMP or DcAMP stimulated AF synthesis (and conidiation) associated with an AflR-dependent increase in nor-1 promoter activity. However, treatment resulted in a 100-fold increase in intracellular cAMP/DcAMP accompanied by a 40 to 80 fold decrease in total PKA activity. ThefadAG42R allele in TJYP1-22 decreased AF synthesis and conidiation, increased basal PKA activity 10 fold, and decreased total PKA activity 2 fold. In TJYP1-22, intracellular cAMP increased 2 fold without cAMP or DcAMP treatment; treatment did not stimulate conidiation or AF synthesis. Based on these data, we conclude that: (1) FadA/PKA regulate toxin synthesis and conidiation via similar mechanisms in Aspergillus spp.; and (2) intracellular cAMP levels, at least in part, mediate a PKA-dependent regulatory influence on conidiation and AF synthesis.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University (MSU), USA
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18
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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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19
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Gabriel I, Olchowy J, StanisÅawska-Sachadyn A, Mio T, Kur JÃ, Milewski SÅ. Phosphorylation of glucosamine-6-phosphate synthase is important but not essential for germination and mycelial growth ofCandida albicans. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09569.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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20
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Jung WH, Stateva LI. The cAMP phosphodiesterase encoded by CaPDE2 is required for hyphal development in Candida albicans. MICROBIOLOGY-SGM 2003; 149:2961-2976. [PMID: 14523128 DOI: 10.1099/mic.0.26517-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The cAMP-dependent pathway, which regulates yeast-to-hypha morphogenesis in Candida albicans, is controlled by changes in cAMP levels determined by the processes of synthesis and hydrolysis. Both low- and high-affinity cAMP phosphodiesterases are encoded in the C. albicans genome. CaPDE2, encoding the high-affinity cAMP phosphodiesterase, has been cloned and shown to be toxic in Saccharomyces cerevisiae upon overexpression under pGAL1, but functional under the moderate pMET3. Deletion of CaPDE2 causes elevated cAMP levels and responsiveness to exogenous cAMP, higher sensitivity to heat shock, severe growth defects at 42 degrees C and highly reduced levels of EFG1 transcription. In vitro in hypha-inducing liquid medium CaPDE2, deletion prohibits normal hyphal, but not pseudohyphal growth. On solid medium capde2 mutants form aberrant hyphae, with fewer branches and almost no lateral buds, which are deficient in hypha-to-yeast reversion. The phenotypic defects of capde2 mutants show that the cAMP-dependent pathway plays specific roles in hyphal and pseudohyphal development, its regulatory role however, being greater in liquid than on solid medium in vitro. The increased expression of CaPDE2 after serum addition correlates well with a drop in cAMP levels following the initial rise in response to the hyphal inducer. These results suggest that Capde2p mediates a desensitization mechanism by lowering basal cAMP levels in response to environmental stimuli in C. albicans.
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Affiliation(s)
- Won Hee Jung
- Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK
| | - Lubomira I Stateva
- Department of Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD, UK
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21
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Loewen SK, Ng AML, Mohabir NN, Baldwin SA, Cass CE, Young JD. Functional characterization of a H+/nucleoside co-transporter (CaCNT) from Candida albicans, a fungal member of the concentrative nucleoside transporter (CNT) family of membrane proteins. Yeast 2003; 20:661-75. [PMID: 12794928 DOI: 10.1002/yea.1000] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human and other mammalian concentrative (Na(+)-linked) nucleoside transport proteins belong to a membrane protein family (CNT, TC 2.A.41) that also includes Escherichia coli H(+)-dependent nucleoside transport protein NupC. Here, we report the cDNA cloning and functional characterization of a CNT family member from the pathogenic yeast Candida albicans. This 608 amino acid residue H(+)/nucleoside symporter, designated CaCNT, contains 13 predicted transmembrane domains (TMs), but lacks the exofacial, glycosylated carboxyl-terminus of its mammalian counterparts. When produced in Xenopus oocytes, CaCNT exhibited transport activity for adenosine, uridine, inosine and guanosine but not cytidine, thymidine or the nucleobase hypoxanthine. Apparent K(m) values were in the range 16-64 micro M, with V(max) : K(m) ratios of 0.58-1.31. CaCNT also accepted purine and uridine analogue nucleoside drugs as permeants, including cordycepin (3'-deoxyadenosine), a nucleoside analogue with anti-fungal activity. Electrophysiological measurements under voltage clamp conditions gave a H(+) to [(14)C]uridine coupling ratio of 1 : 1. CaCNT, obtained from logarithmically growing cells, is the first described cation-coupled nucleoside transporter in yeast, and the first member of the CNT family of proteins to be characterized from a unicellular eukaryotic organism.
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Affiliation(s)
- Shaun K Loewen
- Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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22
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Andrianopoulos A. Control of morphogenesis in the human fungal pathogen Penicillium marneffei. Int J Med Microbiol 2002; 292:331-47. [PMID: 12452280 DOI: 10.1078/1438-4221-00217] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fungal pathogens are an increasing threat to human health due to the increasing population of immunocompromised individuals and the increased incidence of treatment-derived infections. Penicillium marneffei is an emerging fungal pathogen endemic to South-east Asia, where it is AIDS defining. Like many other fungal pathogens, P. marneffei is capable of alternating between a filamentous and a yeast growth form, known as dimorphic switching, in response to environmental stimuli. P. marneffei grows in the filamentous form at 25 degrees C and in the yeast form at 37 degrees C. During filamentous growth and in response to environmental cues, P. marneffei undergoes asexual development to form complex multicellular structures from which the infectious agents, the conidia, are produced. At 37 degrees C, P. marneffei undergoes the dimorphic switching program to produce the pathogenic yeast cells. These yeast cells are found intracellularly in the mononuclear phagocyte system of the host and divide by fission, in contrast to the budding mode of division exhibited by most other fungal pathogens. In addition, P. marneffei is evolutionarily distinct from most other dimorphic fungal pathogens and is the only known Penicillium species which exhibits dimorphic growth. The unique evolutionary history of P. marneffei and the rapidly increasing incidence of infection, coupled with the presence of both complex asexual development and dimorphic switching programs in one organism, makes this system a valuable one for the study of morphogenesis and pathogenicity. Recent development of molecular genetic techniques for P. marneffei, including DNA-mediated transformation, have greatly facilitated the study of these two important morphogenetic programs, asexual development and dimorphic switching, and we are beginning to uncover important determinants which control these events. Understand these programs is providing insights into the biology of P. marneffei and its pathogenic capacity.
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Affiliation(s)
- Alex Andrianopoulos
- Department of Genetics, University of Melbourne, Parkville, Victoria, 3010, Australia.
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23
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Zelada A, Castilla R, Passeron S, Giasson L, Cantore ML. Interactions between regulatory and catalytic subunits of the Candida albicans cAMP-dependent protein kinase are modulated by autophosphorylation of the regulatory subunit. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1542:73-81. [PMID: 11853881 DOI: 10.1016/s0167-4889(01)00168-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The cAMP-dependent protein kinase (PKA) from Candida albicans is a tetramer composed of two catalytic subunits (C) and two type II regulatory subunits (R). To evaluate the role of a putative autophosphorylation site of the R subunit (Ser(180)) in the interaction with C, this site was mutated to an Ala residue. Recombinant wild-type and mutant forms of the R subunit were expressed in Escherichia coli and purified. The wild-type recombinant R subunit was fully phosphorylated by the purified C subunit, while the mutant form was not, confirming that Ser(180) is the target for the autophosphorylation reaction. Association and dissociation experiments conducted with both recombinant R subunits and purified C subunit showed that intramolecular phosphorylation of the R subunit led to a decreased affinity for C. This diminished affinity was reflected by an 8-fold increase in the concentration of R subunit needed to reach half-maximal inhibition of the kinase activity and in a 5-fold decrease in the cAMP concentration necessary to obtain half-maximal dissociation of the reconstituted holoenzyme. Dissociation of the mutant holoenzyme by cAMP was not affected by the presence of MgATP. Metabolic labeling of yeast cells with [(32)P]orthophosphate indicated that the R subunit exists as a serine phosphorylated protein. The possible involvement of R subunit autophosphorylation in modulating C. albicans PKA activity in vivo is discussed.
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Affiliation(s)
- Alicia Zelada
- Cátedra de Microbiología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina
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24
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Kinoshita H, Sen K, Iwama H, Samadder PP, Kurosawa SI, Shibai H. Effects of indole and caffeine on cAMP in the ind1 and cfn1 mutant strains of Schizophyllum commune during sexual development. FEMS Microbiol Lett 2002; 206:247-51. [PMID: 11814671 DOI: 10.1111/j.1574-6968.2002.tb11017.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The ind1 and cfn1 mutations of Schizophyllum commune express resistance to high concentrations of indole and caffeine respectively, and also affect sexual development. To clarify molecular events caused by the mutations, it was investigated how cAMP levels in S. commune strains respond to externally supplied indole and caffeine. Both compounds increased the cAMP levels in wild-type strains under several culture conditions. During sexual development of the ind1 mutant, the cAMP level in an early stage (hyphal aggregation) was highly increased by addition of indole, and the phenomenon disappeared in a later stage (fruit body formation). For the cfn1 mutants, the incremental increase in cAMP levels by addition of caffeine was smaller than that of wild-type strains.
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Affiliation(s)
- Hideki Kinoshita
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, 8304 Minamiminowa, Nagano 399-4598, Japan
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25
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Rocha CR, Schröppel K, Harcus D, Marcil A, Dignard D, Taylor BN, Thomas DY, Whiteway M, Leberer E. Signaling through adenylyl cyclase is essential for hyphal growth and virulence in the pathogenic fungus Candida albicans. Mol Biol Cell 2001; 12:3631-43. [PMID: 11694594 PMCID: PMC60281 DOI: 10.1091/mbc.12.11.3631] [Citation(s) in RCA: 291] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The human fungal pathogen Candida albicans switches from a budding yeast form to a polarized hyphal form in response to various external signals. This morphogenetic switching has been implicated in the development of pathogenicity. We have cloned the CaCDC35 gene encoding C. albicans adenylyl cyclase by functional complementation of the conditional growth defect of Saccharomyces cerevisiae cells with mutations in Ras1p and Ras2p. It has previously been shown that these Ras homologues regulate adenylyl cyclase in yeast. The C. albicans adenylyl cyclase is highly homologous to other fungal adenylyl cyclases but has less sequence similarity with the mammalian enzymes. C. albicans cells deleted for both alleles of CaCDC35 had no detectable cAMP levels, suggesting that this gene encodes the only adenylyl cyclase in C. albicans. The homozygous mutant cells were viable but grew more slowly than wild-type cells and were unable to switch from the yeast to the hyphal form under all environmental conditions that we analyzed in vitro. Moreover, this morphogenetic switch was completely blocked in mutant cells undergoing phagocytosis by macrophages. However, morphogenetic switching was restored by exogenous cAMP. On the basis of epistasis experiments, we propose that CaCdc35p acts downstream of the Ras homologue CaRas1p. These epistasis experiments also suggest that the putative transcription factor Efg1p and components of the hyphal-inducing MAP kinase pathway depend on the function of CaCdc35p in their ability to induce morphogenetic switching. Homozygous cacdc35 Delta cells were unable to establish vaginal infection in a mucosal membrane mouse model and were avirulent in a mouse model for systemic infections. These findings suggest that fungal adenylyl cyclases and other regulators of the cAMP signaling pathway may be useful targets for antifungal drugs.
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Affiliation(s)
- C R Rocha
- Eukaryotic Genetics Group, Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
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26
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Lengeler KB, Davidson RC, D'souza C, Harashima T, Shen WC, Wang P, Pan X, Waugh M, Heitman J. Signal transduction cascades regulating fungal development and virulence. Microbiol Mol Biol Rev 2000; 64:746-85. [PMID: 11104818 PMCID: PMC99013 DOI: 10.1128/mmbr.64.4.746-785.2000] [Citation(s) in RCA: 647] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellular differentiation, mating, and filamentous growth are regulated in many fungi by environmental and nutritional signals. For example, in response to nitrogen limitation, diploid cells of the yeast Saccharomyces cerevisiae undergo a dimorphic transition to filamentous growth referred to as pseudohyphal differentiation. Yeast filamentous growth is regulated, in part, by two conserved signal transduction cascades: a mitogen-activated protein kinase cascade and a G-protein regulated cyclic AMP signaling pathway. Related signaling cascades play an analogous role in regulating mating and virulence in the plant fungal pathogen Ustilago maydis and the human fungal pathogens Cryptococcus neoformans and Candida albicans. We review here studies on the signaling cascades that regulate development of these and other fungi. This analysis illustrates both how the model yeast S. cerevisiae can serve as a paradigm for signaling in other organisms and also how studies in other fungi provide insights into conserved signaling pathways that operate in many divergent organisms.
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Affiliation(s)
- K B Lengeler
- Departments of Genetics, Pharmacology and Cancer Biology, Microbiology, and Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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27
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Abstract
MAP kinases in eukaryotic cells are well known for transducing a variety of extracellular signals to regulate cell growth and differentiation. Recently, MAP kinases homologous to the yeast Fus3/Kss1 MAP kinases have been identified in several fungal pathogens and found to be important for appressorium formation, invasive hyphal growth, and fungal pathogenesis. This MAP kinase pathway also controls diverse growth or differentiation processes, including conidiation, conidial germination, and female fertility. MAP kinases homologous to yeast Slt2 and Hog1 have also been characterized in Candida albicans and Magnaporthe grisea. Mutants disrupted of the Slt2 homologues have weak cell walls, altered hyphal growth, and reduced virulence. The Hog1 homologues are dispensable for growth but are essential for regulating responses to hyperosmotic stress in C. albicans and M. grisea. Overall, recent studies have indicated that MAP kinase pathways may play important roles in regulating growth, differentiation, survival, and pathogenesis in fungal pathogens.
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Affiliation(s)
- J R Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907, USA
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28
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Ernst JF. Transcription factors in Candida albicans - environmental control of morphogenesis. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 8):1763-1774. [PMID: 10931884 DOI: 10.1099/00221287-146-8-1763] [Citation(s) in RCA: 225] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Joachim F Ernst
- Institut für Mikrobiologie, Heinrich-Heine-Universität, Universitätsstr. 1/26.12, D-40225 Düsseldorf, Germany1
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29
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Leng P, Sudbery PE, Brown AJ. Rad6p represses yeast-hypha morphogenesis in the human fungal pathogen Candida albicans. Mol Microbiol 2000; 35:1264-75. [PMID: 10712706 DOI: 10.1046/j.1365-2958.2000.01801.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rad6p plays important roles in post-replication DNA repair, chromatin organization, gene silencing and meiosis. In this study, we show that Rad6p also regulates yeast-hypha morphogenesis in the human pathogen Candida albicans. CaRAD6 gene and cDNAs were isolated and characterized revealing that the gene carries two 5'-proximal introns. CaRad6p shows a high degree of sequence similarity to Rad6 proteins from fungi to man (60-83% identity), and it suppresses the UV sensitivity and lack of induced mutagenesis displayed by a Saccharomyces cerevisiae rad6 mutant. In C. albicans, CaRAD6 expression is induced in response to UV, and CaRad6p depletion confers UV sensitivity, confirming that Rad6p serves a role in protecting this fungus against UV damage. CaRAD6 overexpression inhibits hyphal development, whereas CaRad6p depletion enhances hyphal growth. Also, CaRAD6 mRNA levels decrease during the yeast-hypha transition. These effects are dependent on Efg1p, but not Cph1p, indicating that CaRad6p acts specifically through the Efg1p morphogenetic signalling pathway to repress yeast-hypha morphogenesis.
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Affiliation(s)
- P Leng
- Department of Molecular and Cell Biology, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
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30
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Cho T, Hamatake H, Hagihara Y, Kaminishi H. Inhibitors of protein phosphorylation including the retinoblastoma protein induce germination of Candida albicans. Med Mycol 2000; 38:41-5. [PMID: 10746226 DOI: 10.1080/mmy.38.1.41.45] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
It has been previously shown that the induction of germination in Candida albicans occurs following its cessation of growth as a yeast. Similarly, mammalian cells undergo a differentiation process that is preceded by a growth cessation associated with a hypophosphorylation of proteins of the retinoblastoma gene family. It is postulated that a similar type of mechanism may be operative in C. albicans and protein phosphorylation inhibitors: forskolin (stimulates cyclic adenosine monophosphate production), okadaic acid (phosphatase inhibitor) and D-erythro-sphingosine (retinoblastoma protein phosphorylation inhibitor) have been used to further strengthen this hypothesis. Okadaic acid (1-1000 nM) and D-erythro-sphingosine (100 microM) significantly inhibited the growth of yeast cells of C. albicans. D-Erythro-sphingosine at 1000 microM was candidicidal. Forskolin did not significantly affect growth. Exponentially grown C. albicans pretreated with forskolin (10 microM), okadaic acid (1000 nM) or D-erythro-sphingosine (100 microM) readily germinated. In comparison, when these inhibitors were incorporated in the same medium, germination of exponentially grown cells did not occur. These results suggest that protein dephosphorylation may be necessary at an early stage of the yeast-hyphae transition in C. albicans.
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Affiliation(s)
- T Cho
- Department of Oral Microbiology, Fukuoka Dental College, Japan.
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31
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Sonneborn A, Bockmühl DP, Gerads M, Kurpanek K, Sanglard D, Ernst JF. Protein kinase A encoded by TPK2 regulates dimorphism of Candida albicans. Mol Microbiol 2000; 35:386-96. [PMID: 10652099 DOI: 10.1046/j.1365-2958.2000.01705.x] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
External signals induce the switch from a yeast to a hyphal growth form in the fungal pathogen Candida albicans. We demonstrate here that the catalytic subunit of a protein kinase A (PKA) isoform encoded by TPK2 is required for internal signalling leading to hyphal differentiation. TPK2 complements the growth defect of a Saccharomyces cerevisiae tpk1-3 mutant and Tpk2p is able to phosphorylate an established PKA-acceptor peptide (kemptide). Deletion of TPK2 blocks morphogenesis and partially reduces virulence, whereas TPK2 overexpression induces hyphal formation and stimulates agar invasion. The defective tpk2 phenotype is suppressed by overproduction of known signalling components, including Efg1p and Cek1p, whereas TPK2 overexpression reconstitutes the cek1 but not the efg1 phenotype. The results indicate that PKA activity of Tpk2p is an important contributing factor in regulating dimorphism of C. albicans.
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Affiliation(s)
- A Sonneborn
- Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1/Geb. 26.12, D-40225 Düsseldorf, Germany
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Roze LV, Mahanti N, Mehigh R, McConnell DG, Linz JE. Evidence that MRas1 and MRas3 proteins are associated with distinct cellular functions during growth and morphogenesis in the fungus Mucor racemosus. Fungal Genet Biol 1999; 28:171-89. [PMID: 10669583 DOI: 10.1006/fgbi.1999.1177] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The filamentous fungus Mucor racemosus provides a simple and unique model system for defining the function of individual ras genes in a gene family which is closely related to mammalian ras genes. The current study was designed to investigate the role of Mras1 and Mras3 in different stages of fungal morphogenesis, including sporangiospore germination, sporulation, and dimorphic transitions. The overall patterns of Mras1 and Mras3 transcript and protein accumulation were markedly different but, in general, transcripts and proteins were present at low levels during spherical growth and their accumulated level increased severalfold during polar growth (germ tube emergence and elongation). In contrast to Mras1, relatively high levels of Mras3 transcript accumulated during sporulation and MRas3 protein accumulated in sporangiospores. Transformation of M. racemosus with an activated allele of Mras3 reduced growth rate during aerobic sporangiospore germination, while a dominant-negative allele of Mras3 caused a 40% decrease in viable asexual spores. An activated allele of Mras1 increased growth rate during sporangiospore germination but neither activated nor dominant-negative alleles of Mras1 affected total number of asexual spores. Expression of MRas3 and MRas1 proteins appear to be subject to different regulatory mechanisms: exogenous dibutyryl-cAMP and fusidienol caused a strong repression of the level of MRas3 protein (but not MRas1) concurrent with the inhibition of polar growth. Differential posttranslational modification and intracellular localization of MRas1 and MRas3 proteins were also observed. The data strongly suggest that Mras3 and Mras1 play different roles in regulation of cell growth and morphogenesis in Mucor.
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Affiliation(s)
- L V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA
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Peltroche-Llacsahuanga H, Jenster A, Lütticken R, Haase G. Novel microtiter plate format for testing germ tube formation and proposal of a cost-effective scheme for yeast identification in a clinical laboratory. Diagn Microbiol Infect Dis 1999; 35:197-204. [PMID: 10626129 DOI: 10.1016/s0732-8893(99)00093-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The germ tube test is most widely used for presumptive identification of Candida albicans. Conventional testing is relatively time-consuming due to the hands-on time involved in preparing and viewing each isolate. In order to reduce work-load and costs we have developed a novel microtiter plate test format that offers several advantages: (i) use of removable strips of microtiter wells placed in lockwell frames, (ii) only one pipetting step for each isolate, (iii) direct micromorphological evaluation using an inverse microscope, (iv) use of a novel synthetic germ tube test medium, (v) reduction of the inoculum, permitting testing of minute colonies, (vi) thus, testing of different colonies in potentially mixed primary cultures of clinical specimens is encouraged and facilitated. Implementing this microtiter based germ tube test with simultaneous trehalase test for presumptive identification of Torulopsis (Candida) glabrata, we propose an identification scheme including this test format. This has been implemented in our routine laboratory permitting cost-effective presumptive identification of almost all clinically relevant yeast species.
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Herrero AB, López MC, García S, Schmidt A, Spaltmann F, Ruiz-Herrera J, Dominguez A. Control of filament formation in Candida albicans by polyamine levels. Infect Immun 1999; 67:4870-8. [PMID: 10456943 PMCID: PMC96821 DOI: 10.1128/iai.67.9.4870-4878.1999] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida albicans, the most common fungal pathogen, regulates its cellular morphology in response to environmental conditions. The ODC gene, which encodes ornithine decarboxylase, a key enzyme in polyamine biosynthesis, was isolated and disrupted. Homozygous null Candida mutants behaved as polyamine auxotrophs and grew exclusively in the yeast form at low polyamine levels (0.01 mM putrescine) under all conditions tested. An increase in the polyamine concentration (10 mM putrescine) restored the capacity to switch from the yeast to the filamentous form. The strain with a deletion mutation also showed increased sensitivity to salts and calcofluor white. This Candida odc/odc mutant was virulent in a mouse model. The results suggest a model in which polyamine levels exert a pleiotrophic effect on transcriptional activity.
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Affiliation(s)
- A B Herrero
- Departamento de Microbiología y Genética, IMB/CSIC, Universidad de Salamanca, 37007 Salamanca, Spain
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Abstract
Candida albicans undergoes reversible morphogenetic transitions between budding, pseudohyphal and hyphal growth forms that promote the virulence of this pathogenic fungus. The regulatory networks that control morphogenesis are being elucidated; however, the primary signals that trigger morphogenesis remain obscure, and the physiological outputs of these networks are complex.
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Affiliation(s)
- A J Brown
- Dept of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK AB25 2ZD.
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36
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Sipiczki M, Takeo K, Grallert A. Growth polarity transitions in a dimorphic fission yeast. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 12):3475-3485. [PMID: 9884240 DOI: 10.1099/00221287-144-12-3475] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fission yeast cells grow by extension at the ends (poles) and divide by transverse fission. It has previously been reported that Schizosaccharomyces japonicus var. japonicus can switch to unipolar, filamentous growth. Here it is shown that the yeast-to-mycelium transition is a gradual process involving a changeover to unipolar growth associated with asymmetric divisions, the development of large polarly located vacuoles, the modifications of the actin and microtubular cytoskeleton and the repression of cell separation after division. High concentrations of glucose in the medium or supplementation of the medium with caffeine or cAMP support the bipolar yeast phase, inhibit the transition to the mycelial phase and induce the conversion of hyphae to yeasts. These effects suggest that cAMP may be involved in the regulation of dimorphism. Temperatures below 18 degrees C or over 35 degrees C are restrictive for the mycelial phase and provoke a return to yeast phase.
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Affiliation(s)
- M Sipiczki
- Institute of Biology, University of Debrecen, PO Box 56, H-4010 Debrecen, Hungary
- Department of Genetics, University of Debrecen, PO Box 56, H-4010 Debrecen, Hungary
| | - K Takeo
- Division of Ultrastructure and Function, Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan
| | - A Grallert
- Department of Genetics, University of Debrecen, PO Box 56, H-4010 Debrecen, Hungary
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Lorenz MC, Heitman J. Regulators of pseudohyphal differentiation in Saccharomyces cerevisiae identified through multicopy suppressor analysis in ammonium permease mutant strains. Genetics 1998; 150:1443-57. [PMID: 9832522 PMCID: PMC1460428 DOI: 10.1093/genetics/150.4.1443] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nitrogen-starved diploid cells of the yeast Saccharomyces cerevisiae differentiate into a filamentous, pseudohyphal growth form. Recognition of nitrogen starvation is mediated, at least in part, by the ammonium permease Mep2p and the Galpha subunit Gpa2p. Genetic activation of the pheromone-responsive MAP kinase cascade, which is also required for filamentous growth, only weakly suppresses the filamentation defect of Deltamep2/Deltamep2 and Deltagpa2/Deltagpa2 strain. Surprisingly, deletion of Mep1p, an ammonium permease not previously thought to regulate differentiation, significantly enhances the potency of MAP kinase activation, such that the STE11-4 allele induces filamentation to near wild-type levels in Deltamep1/Deltamep1 Deltamep2/Deltamep2 and Deltamep1/Deltamep1 Deltagpa2/Deltagpa2 strains. To identify additional regulatory components, we isolated high-copy suppressors of the filamentation defect of the Deltamep1/Deltamep1 Deltamep2/Deltamep2 mutant. Multicopy expression of TEC1, PHD1, PHD2 (MSS10/MSN1/FUP4), MSN5, CDC6, MSS11, MGA1, SKN7, DOT6, HMS1, HMS2, or MEP2 each restored filamentation in a Deltamep1/Deltamep1 Deltamep2/Deltamep2 strain. Overexpression of SRK1 (SSD1), URE2, DAL80, MEP1, or MEP3 suppressed only the growth defect of the Deltamep1/Deltamep1 Deltamep2/Deltamep2 mutant strain. Characterization of these genes through deletion analysis and epistasis underscores the complexity of this developmental pathway and suggests that stress conditions other than nitrogen deprivation may also promote filamentous growth.
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Affiliation(s)
- M C Lorenz
- Department of Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA
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Castilla R, Passeron S, Cantore ML. N-acetyl-D-glucosamine induces germination in Candida albicans through a mechanism sensitive to inhibitors of cAMP-dependent protein kinase. Cell Signal 1998; 10:713-9. [PMID: 9884022 DOI: 10.1016/s0898-6568(98)00015-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The present study examines the involvement of cAMP-dependent protein kinase (PKA) in the dimorphic transition of Candida albicans by assessing the in vivo effect of two permeable PKA inhibitors on N-acetyl-D-glucosamine (GlcNAc)- and serum-induced differentiation. The permeable myristoylated derivative of the heat-stable PKA inhibitor (MyrPKI), which inhibited C. albicans PKA in vitro, caused a concentration-dependent inhibition of germ-tube formation in cultures induced to germinate by GlcNAc; germination halted irrespective of the time of addition of the inhibitor. MyrPKI also blocked dibutyryl-cAMP (dbcAMP)- and glucagon-stimulated germination but did not affect serum-induced germination. H-89, another highly specific PKA inhibitor, displayed the same effect on germination. Neither MyrPKI nor H-89 had any effect on budding of yeast cells. In conclusion, our results indicate that cAMP-mediated activation of PKA plays a pivotal role in the biochemical mechanism underlying morphogenesis.
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Affiliation(s)
- R Castilla
- Programa de Investigaciones Bioquímicas y Fisiológicas (CIBYF-CONICET), Cátedra de Microbiología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina
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Alspaugh JA, Perfect JR, Heitman J. Signal transduction pathways regulating differentiation and pathogenicity of Cryptococcus neoformans. Fungal Genet Biol 1998; 25:1-14. [PMID: 9806801 DOI: 10.1006/fgbi.1998.1079] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The basidiomycetous yeast Cryptococcus neoformans is a human pathogen. Several phenotypes of this organism are defined as virulence traits including the polysaccharide capsule, melanin, and the ability to grow at 37 degreesC. The signaling pathways regulating the expression of these phenotypes and other important cellular processes are being defined on a molecular level. For example, the highly conserved signaling molecule calcineurin regulates high temperature growth in C. neoformans. A cryptococcal homolog of Saccharomyces cerevisiae STE12, the gene for a transcriptional regulator activated by the MAP kinase cascade, has also been identified. Additionally, the C. neoformans Galpha protein GPA1 and cAMP regulate mating, melanin production, encapsulation, and pathogenicity. This fungus is an excellent model to further dissect virulence-associated signaling pathways. The conserved role of Galpha proteins and cAMP-associated signaling pathways in fungal differentiation and pathogenicity is also reviewed.
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Affiliation(s)
- J A Alspaugh
- Department of Genetics, Duke University Medical Center, Durham, North Carolina, 27710, USA
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40
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Mayorga ME, Gold SE. Characterization and molecular genetic complementation of mutants affecting dimorphism in the fungus ustilago maydis. Fungal Genet Biol 1998; 24:364-76. [PMID: 9756717 DOI: 10.1006/fgbi.1998.1078] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ustilago maydis, the causal agent of corn smut disease, displays dimorphic growth in which it alternates between a unicellular, nonpathogenic yeast-like form and a dikaryotic, pathogenic filamentous form. Previously, a constitutively filamentous haploid mutant was obtained. Complementation of this mutant led to the isolation of the gene encoding adenylate cyclase, uac1. Secondary mutagenesis of a uac1 disruption strain allowed the isolation of a large number of suppressor mutants, termed ubc, for Ustilago bypass of cyclase, lacking the filamentous phenotype. Analysis of one of these suppressor mutants previously led to the identification of the ubc1 gene, encoding the regulatory subunit of cAMP-dependent protein kinase. In this report we describe the isolation of cosmids containing three new ubc genes, termed ubc2, ubc3, and ubc4. We also describe the morphology of the ubc2, ubc3, and ubc4 mutants in a uac1- background as well as in a background with a functional uac1 gene. In addition, we describe several mutant strains not complemented with any of the genes currently in hand and that are thus presumed to possess mutations in additional ubc genes. Copyright 1998 Academic Press.
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Affiliation(s)
- ME Mayorga
- Department of Plant Pathology, University of Georgia, Athens, Georgia, 30602, USA
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41
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Lorenz MC, Heitman J. The MEP2 ammonium permease regulates pseudohyphal differentiation in Saccharomyces cerevisiae. EMBO J 1998; 17:1236-47. [PMID: 9482721 PMCID: PMC1170472 DOI: 10.1093/emboj/17.5.1236] [Citation(s) in RCA: 325] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In response to nitrogen starvation, diploid cells of the budding yeast Saccharomyces cerevisiae differentiate into a filamentous, pseudohyphal growth form. This dimorphic transition is regulated by the Galpha protein GPA2, by RAS2, and by elements of the pheromone-responsive MAP kinase cascade, yet the mechanisms by which nitrogen starvation is sensed remain unclear. We have found that MEP2, a high affinity ammonium permease, is required for pseudohyphal differentiation in response to ammonium limitation. In contrast, MEP1 and MEP3, which are lower affinity ammonium permeases, are not required for filamentous growth. Deltamep2 mutant strains had no defects in growth rates or ammonium uptake, even at limiting ammonium concentrations. The pseudohyphal defect of Deltamep2/Deltamep2 strains was suppressed by dominant active GPA2 or RAS2 mutations and by addition of exogenous cAMP, but was not suppressed by activated alleles of the MAP kinase pathway. Analysis of MEP1/MEP2 hybrid proteins identified a small intracellular loop of MEP2 involved in the pseudohyphal regulatory function. In addition, mutations in GLN3, URE2 and NPR1, which abrogate MEP2 expression or stability, also conferred pseudohyphal growth defects. We propose that MEP2 is an ammonium sensor, generating a signal to regulate filamentous growth in response to ammonium starvation.
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Affiliation(s)
- M C Lorenz
- Departments of Genetics, Duke University Medical Center, 322 CARL Building, Research Drive, Durham, NC 27710, USA
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42
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Abstract
Pseudohyphal differentiation, a filamentous growth form of the budding yeast Saccharomyces cerevisiae, is induced by nitrogen starvation. The mechanisms by which nitrogen limitation regulates this process are currently unknown. We have found that GPA2, one of the two heterotrimeric G protein alpha subunit homologs in yeast, regulates pseudohyphal differentiation. Deltagpa2/Deltagpa2 mutant strains have a defect in pseudohyphal growth. In contrast, a constitutively active allele of GPA2 stimulates filamentation, even on nitrogen-rich media. Moreover, a dominant negative GPA2 allele inhibits filamentation of wild-type strains. Several findings, including epistasis analysis and reporter gene studies, indicate that GPA2 does not regulate the MAP kinase cascade known to regulate filamentous growth. Previous studies have implicated GPA2 in the control of intracellular cAMP levels; we find that expression of the dominant RAS2(Gly19Val) mutant or exogenous cAMP suppresses the Deltagpa2 pseudohyphal defect. cAMP also stimulates filamentation in strains lacking the cAMP phosphodiesterase PDE2, even in the absence of nitrogen starvation. Our findings suggest that GPA2 is an element of the nitrogen sensing machinery that regulates pseudohyphal differentiation by modulating cAMP levels.
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Affiliation(s)
- M C Lorenz
- Department of Genetics, Duke University Medical Center, Durham, NC 27710, USA
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Gadd GM, Foster SA. Metabolism of inositol 1,4,5-trisphosphate in Candida albicans: significance as a precursor of inositol polyphosphates and in signal transduction during the dimorphic transition from yeast cells to germ tubes. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 2):437-448. [PMID: 9043121 DOI: 10.1099/00221287-143-2-437] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The metabolism of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] was examined in yeast cells and germ tubes of Candida albicans. Methods have been developed for analysis of the two key metabolic enzymes, Ins(1,4,5)P3, kinase and phosphatase. ATP-dependent Ins(1,4,5)P3 kinase activity was detected predominantly in the soluble fraction of cell extracts and exhibited a Km of approximately 9 microM. The apparent Km of Ins(1,4,5)P3 phosphatase for Ins(1,4,5)P3 was approximately 480 microM. The slow rate of dephosphorylation of Ins(1,4,5_P3 to inositol bisphosphate suggests a lower importance of the phosphatase within cells compared to the kinase. Since both yeast cells and germ tubes of C. albicans rapidly phosphorylated Ins(1,4,5)P3 to inositol tetrakisphosphate and inositol penta/hexakisphosphate, it is suggested that Ins(1,4,5)P3 has an important role as a precursor for production of these compounds. A sustained increase in cellular Ins(1,4,5)P3 levels was observed during germ tube formation and, prior to the onset of germination between 1 and 2 incubation, the Ins(1,4,5)P3 content increased up to eightfold. Transient increases in the level of Ins(1,4,5)P3 were also observed during yeast-like growth of C. albicans. The possible role and relative importance of Ins(1,4,5)P3 as a precursor for inositol polyphosphates and in signal transduction involving Ca2+ release from internal stores is discussed.
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Affiliation(s)
- Geoffrey M Gadd
- Department of Biologica Sciences, University of Dundee, Dundee DD1 4HN, UK
| | - Sally A Foster
- Department of Biologica Sciences, University of Dundee, Dundee DD1 4HN, UK
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Kronstad J, Bakkeren G, Gold S, Yee A, Laity C, Duncan G, Barrett K, Giasson L, Campbell R, Athwal G. Control of filamentous growth by mating and cyclic-AMP inUstilago. ACTA ACUST UNITED AC 1995. [DOI: 10.1139/b95-255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mating between compatible haploid cells of the corn smut fungus, Ustilago maydis, results in a switch from budding to filamentous growth. We are analyzing the multiallelic b incompatibility locus that governs maintenance of the infectious, filamentous dikaryon. Specificity regions have been identified in the N-terminal portions of the bE and bW genes at the b locus. In addition, we have found that heterozygosity at the b locus attenuates fusion. This result suggests that b gene products may exert a negative influence on some processes, in addition to their generally recognized role in maintaining filamentous growth. The b genes have also been characterized in Ustilago hordei. This species has a bipolar mating system in which the b genes are linked to genes required for pheromone production and response to form one large mating-type region (MAT locus) with two allelic specificities. In a separate study, we have discovered that defects in adenylate cyclase result in constitutive filamentous growth and greatly reduce the virulence of U. maydis on corn seedlings. Mutations have been identified that suppress the adenylate cyclase defect and restore budding growth. Sequence analysis revealed that one of the suppressor mutations is in the gene encoding the regulatory subunit of cAMP-dependent protein kinase (PKA). Mutants altered in PKA activity have the interesting phenotype of multiple budding and frequent mislocalization of the bud site. Key words: smut, dimorphism, b locus, sex.
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45
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Gold S, Duncan G, Barrett K, Kronstad J. cAMP regulates morphogenesis in the fungal pathogen Ustilago maydis. Genes Dev 1994; 8:2805-16. [PMID: 7995519 DOI: 10.1101/gad.8.23.2805] [Citation(s) in RCA: 219] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The fungal pathogen Ustilago maydis exhibits a dimorphic switch from budding to filamentous growth in response to mating interactions and environmental conditions. We have found that disruption of the uac1 gene, encoding adenylate cyclase, results in a constitutively filamentous phenotype. Budding is restored to the uac1 mutant upon growth in the presence of cAMP or by extragenic suppression because of a mutation in the ubc1 gene. The ubc1 gene encodes a type II regulatory subunit of cAMP-dependent protein kinase (PKA); defects in this gene attenuate the filamentous growth that normally occurs in response to mating and exposure to air. Growth of wild-type cells in cAMP and mutation of the ubc1 gene also cause defects in the separation of mother and daughter cells (cytokinesis) and alter bud site selection. These results indicate a key role for cAMP and PKA in morphogenesis in U. maydis; this role may be common among dimorphic fungal pathogens.
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Affiliation(s)
- S Gold
- Department of Microbiology, University of British Columbia, Vancouver, Canada
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46
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Abstract
Cytological alterations of Candida albicans following exposure to subinhibitory concentrations of caffeine and caffeine salts were examined by light and transmission electron microscopy (TEM). The effect was different from that induced by ketoconazole. Caffeine and especially caffeine salts caused an increase in unusual modes of proliferation with signs of multiple budding in Candida albicans. Structurally, such yeast cells present some resemblance to Paracoccidioides brasiliensis.
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Affiliation(s)
- H Mittag
- Medizinisches Zentrum für Hautkrankheiten, Philipps-Universität Marburg, Germany
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47
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Swoboda RK, Bertram G, Delbrück S, Ernst JF, Gow NA, Gooday GW, Brown AJ. Fluctuations in glycolytic mRNA levels during morphogenesis in Candida albicans reflect underlying changes in growth and are not a response to cellular dimorphism. Mol Microbiol 1994; 13:663-72. [PMID: 7997178 DOI: 10.1111/j.1365-2958.1994.tb00460.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The levels of pyruvate kinase (PYK1), alcohol dehydrogenase (ADH1), phosphoglycerate kinase (PGK1) and phosphoglycerate mutase (GPM1) mRNAs were measured during batch growth and during the yeast-to-hyphal transition in Candida albicans. The four mRNAs behaved in a similar fashion. PYK1, ADH1, PGK1 and GPM1 mRNA levels were shown to increase dramatically during the exponential growth phase of the yeast form, and then to decrease to relatively low levels in the stationary phase. The dimorphic transition was induced using two sets of conditions: (i) an increase in temperature (from 25 degrees C to 37 degrees C) combined with the addition of serum to the medium; and (ii) an increase in temperature (from 25 degrees C to 37 degrees C) and an increase in pH of the growth medium (from pH 4.5 to pH 6.5). Additional cultures were analysed to control for the addition of serum, and for changes in temperature or pH. Immediately following dilution of late-exponential cells into fresh media the levels of all four glycolytic mRNAs decreased rapidly in contrast to the ACT1 mRNA control, the level of which increased under most conditions. The recovery of glycolytic mRNA levels depended on the culture conditions, but there was no direct correlation with the formation of germ tubes, with the addition of serum to the medium, the increase in culture temperature, the medium pH, or the glucose concentration. This indicates that the changes in glycolytic gene expression that accompany the dimorphic transition in C. albicans reflect the underlying physiological status of the cells during morphogenesis and not alterations to cell shape.
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Affiliation(s)
- R K Swoboda
- University of Aberdeen, Marischal College, UK
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48
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Khale-Kumar A, Deshpande MV. Possible involvement of cyclic adenosine 3',5'-monophosphate in the regulation of NADP-/NAD-glutamate dehydrogenase ratio and in yeast-mycelium transition of Benjaminiella poitrasii. J Bacteriol 1993; 175:6052-5. [PMID: 8397189 PMCID: PMC206690 DOI: 10.1128/jb.175.18.6052-6055.1993] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The effect of different adenine-containing compounds on the NADP-/NAD-glutamate dehydrogenase (GDH) ratio was studied as a function of yeast-mycelium transition in Benjaminiella poitrasii. Under in vivo conditions, at a 5.0 mM concentration, cyclic AMP (cAMP) and dibutyryl cAMP maintained the cells in the yeast form for up to 7 and 5 h, respectively, and this was reflected in the patterns of GDH ratios observed. In vitro studies of phosphorylation and dephosphorylation have also been carried out, and the results suggest a possible correlation between cAMP, the GDH ratio, and cell form in B. poitrasii.
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Affiliation(s)
- A Khale-Kumar
- Biochemical Sciences Division, National Chemical Laboratory, Pune, India
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