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Sass G, Larwood DJ, Stevens DA. Synergy In Vitro of Nikkomycin Z with Azole Against the Invasive Form of Candida albicans. Mycopathologia 2023; 188:949-956. [PMID: 37713047 DOI: 10.1007/s11046-023-00788-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 08/18/2023] [Indexed: 09/16/2023]
Abstract
In a previous study, therapeutic activity of nikkomycin Z (NZ) in a model of invasive candidiasis did not appear to correlate with lesser activity in vitro (using classical MIC methods) with planktonic organisms. However, NZ potency was much greater assaying activity in vitro against germ tubes, the initiator of the invasive mycelial form of the fungus, as occurs in infected tissues. Synergy has been demonstrated for NZ and other drugs, notably fluconazole (the most commonly used drug against candidiasis), in planktonic testing, which correlated with results in vivo. This raised the question whether activity shown by NZ alone against germ tubes would be reflected in drug combinations, and even whether synergy testing against germ tubes might be a better correlate of synergy in future in vivo studies. We show in this study significant NZ synergy with fluconazole against germ tubes, for several C. albicans isolates, with testing in many drug ratios. This observation opens the way for further explorations of this method of susceptibility testing for synergy, and correlation with combination therapy against candidiasis.
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Affiliation(s)
- Gabriele Sass
- California Institute for Medical Research, San Jose, CA, USA.
| | - David J Larwood
- California Institute for Medical Research, San Jose, CA, USA
- Valley Fever Solutions, Tucson, AZ, USA
| | - David A Stevens
- California Institute for Medical Research, San Jose, CA, USA
- Division of Infectious Diseases and Geographic Medicine, Stanford University Medical School, Stanford, CA, USA
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F. Q. Smith D, Casadevall A. Fungal immunity and pathogenesis in mammals versus the invertebrate model organism Galleria mellonella. Pathog Dis 2021; 79:ftab013. [PMID: 33544836 PMCID: PMC7981337 DOI: 10.1093/femspd/ftab013] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/03/2021] [Indexed: 02/07/2023] Open
Abstract
In recent decades, Galleria mellonella (Lepidoptera: Pyralidae) have emerged as a model system to explore experimental aspects of fungal pathogenesis. The benefits of the G. mellonella model include being faster, cheaper, higher throughput and easier compared with vertebrate models. Additionally, as invertebrates, their use is subject to fewer ethical and regulatory issues. However, for G. mellonella models to provide meaningful insight into fungal pathogenesis, the G. mellonella-fungal interactions must be comparable to mammalian-fungal interactions. Indeed, as discussed in the review, studies suggest that G. mellonella and mammalian immune systems share many similarities, and fungal virulence factors show conserved functions in both hosts. While the moth model has opened novel research areas, many comparisons are superficial and leave large gaps of knowledge that need to be addressed concerning specific mechanisms underlying G. mellonella-fungal interactions. Closing these gaps in understanding will strengthen G. mellonella as a model for fungal virulence in the upcoming years. In this review, we provide comprehensive comparisons between fungal pathogenesis in mammals and G. mellonella from immunological and virulence perspectives. When information on an antifungal immune component is unknown in G. mellonella, we include findings from other well-studied Lepidoptera. We hope that by outlining this information available in related species, we highlight areas of needed research and provide a framework for understanding G. mellonella immunity and fungal interactions.
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Affiliation(s)
- Daniel F. Q. Smith
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Garcia-Rubio R, de Oliveira HC, Rivera J, Trevijano-Contador N. The Fungal Cell Wall: Candida, Cryptococcus, and Aspergillus Species. Front Microbiol 2020; 10:2993. [PMID: 31993032 PMCID: PMC6962315 DOI: 10.3389/fmicb.2019.02993] [Citation(s) in RCA: 351] [Impact Index Per Article: 87.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/10/2019] [Indexed: 01/23/2023] Open
Abstract
The fungal cell wall is located outside the plasma membrane and is the cell compartment that mediates all the relationships of the cell with the environment. It protects the contents of the cell, gives rigidity and defines the cellular structure. The cell wall is a skeleton with high plasticity that protects the cell from different stresses, among which osmotic changes stand out. The cell wall allows interaction with the external environment since some of its proteins are adhesins and receptors. Since, some components have a high immunogenic capacity, certain wall components can drive the host's immune response to promote fungus growth and dissemination. The cell wall is a characteristic structure of fungi and is composed mainly of glucans, chitin and glycoproteins. As the components of the fungal cell wall are not present in humans, this structure is an excellent target for antifungal therapy. In this article, we review recent data on the composition and synthesis, influence of the components of the cell wall in fungi-host interaction and the role as a target for the next generation of antifungal drugs in yeasts (Candida and Cryptococcus) and filamentous fungi (Aspergillus).
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Affiliation(s)
- Rocio Garcia-Rubio
- Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, United States
| | | | - Johanna Rivera
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY, United States
| | - Nuria Trevijano-Contador
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, New York, NY, United States
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Mello TPD, Aor AC, Gonçalves DDS, Seabra SH, Branquinha MH, Santos ALSD. Scedosporium apiospermum, Scedosporium aurantiacum, Scedosporium minutisporum and Lomentospora prolificans: a comparative study of surface molecules produced by conidial and germinated conidial cells. Mem Inst Oswaldo Cruz 2018; 113:e180102. [PMID: 29924142 PMCID: PMC6001581 DOI: 10.1590/0074-02760180102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 04/02/2018] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Scedosporium/Lomentospora species are opportunistic mould pathogens, presenting notable antifungal resistance. OBJECTIVES/METHODS We analysed the conidia and germinated conidia of S. apiospermum (Sap), S. aurantiacum (Sau), S. minutisporum (Smi) and L. prolificans (Lpr) by scanning electron microscopy and exposition of surface molecules by fluorescence microscopy. FINDINGS Conidia of Sap, Smi and Sau had oval, ellipsoidal and cylindrical shape, respectively, with several irregularities surrounding all surface areas, whereas Lpr conidia were rounded with a smooth surface. The germination of Sap occurred at the conidial bottom, while Smi and Sau germination primarily occurred at the centre of the conidial cell, and Lpr germination initiated at any part of the conidial surface. The staining of N-acetylglucosamine-containing molecules by fluorescein-labelled WGA primarily occurred during the germination of all studied fungi and in the conidial scars, which is the primary location of germination. Calcofluor white, which recognises the polysaccharide chitin, strongly stained the conidial cells and, to a lesser extent, the germination. Both mannose-rich glycoconjugates (evidenced by fluoresceinated-ConA) and cell wall externally located polypeptides presented distinct surface locations and expression according to both morphotypes and fungal species. In contrast, sialic acid and galactose-containing structures were not detected at fungal surfaces. MAIN CONCLUSIONS The present study demonstrated the differential production/exposition of surface molecules on distinct morphotypes of Scedosporium/Lomentospora species.
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Affiliation(s)
- Thaís Pereira de Mello
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - Ana Carolina Aor
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - Diego de Souza Gonçalves
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - Sergio Henrique Seabra
- Laboratório de Tecnologia em Cultura de Células, Centro Universitário Estadual da Zona Oeste, Rio de Janeiro, RJ, Brasil
| | - Marta Helena Branquinha
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - André Luis Souza Dos Santos
- Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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Li Z, You XL, Wang LL, Yan ZT, Zhou ZY. Spore morphology and ultrastructure of an Ascosphaera apis strain from the honeybees (Apis mellifera) in southwest China. Mycologia 2018; 110:325-338. [PMID: 29852093 DOI: 10.1080/00275514.2018.1442084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Ascosphaera apis is an intestinally infective, spore-forming, filamentous fungus that infects honeybees and causes deadly chalkbrood disease. Although A. apis has been known for 60 y, little is known about the ultrastructure of the spores. In this study, the fine morphology and ultrastructure of an isolate, A. apis CQ1 from southwest China, was comprehensively identified by transmission electron microscopy, confocal laser scanning microscopy, scanning electron microscopy, and optical microscopy. The high sequence similarity and phylogenetic data based on nuc rDNA ITS1-5.8S-ITS2 (ITS) supported the hypothesis that the CQ1 strain is a new member of the A. apis species. Morphological observation indicated that the mature spores are long ovals with an average size of 2 × 1.2 µm and are tightly packed inside spherical spore balls. More than 10 spore balls that were 8-16 µm in diameter were wrapped and formed a spherical, nearly hyaline spore cyst of 50-60 µm in diameter. Ultrastructural analysis showed that mature spores have two nuclei with distinctly different sizes. A large nucleus with double nuclear membranes was found in the center of the spore, whereas the small nucleus was only one-fifth of the large nucleus volume and was located near the end of the spore. Numerous ribosomes filled the cytoplasm, and many mitochondria with well-defined structures were arranged along the inner spore wall. The spore wall consists of an electron-dense outer surface layer, an electron-lucent layer, and an inner plasma membrane. Chitin is the major component of the spore wall. The germinated spore was observed as an empty spore coat, whereas the protoplasts, including the nuclei, mitochondria, and ribosomes, had been discharged. In addition to these typical fungal spore organelles, an unknown electron-dense regular structure might be the growing mycelium, which was arranged close to the inner spore wall and almost covered the entire wall area.
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Affiliation(s)
- Zhi Li
- a College of Life Sciences, Chongqing Normal University , University Town, Shapingba District, Chongqing , China 401331
| | - Xiao-Lin You
- b Department of Hepatobiliary Surgery , Southwest Hospital, Third Military Medical University (Army Medical University) , Chongqing , China
| | - Lin-Ling Wang
- a College of Life Sciences, Chongqing Normal University , University Town, Shapingba District, Chongqing , China 401331
| | - Zhen-Tian Yan
- a College of Life Sciences, Chongqing Normal University , University Town, Shapingba District, Chongqing , China 401331
| | - Ze-Yang Zhou
- a College of Life Sciences, Chongqing Normal University , University Town, Shapingba District, Chongqing , China 401331
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Zhu H, Yuan Y, Liu J, Zheng L, Chen L, Ma A. Comparing the sugar profiles and primary structures of alkali-extracted water-soluble polysaccharides in cell wall between the yeast and mycelial phases from Tremella fuciformis. J Microbiol 2016; 54:381-6. [PMID: 27095457 DOI: 10.1007/s12275-016-5533-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 03/04/2016] [Accepted: 03/18/2016] [Indexed: 11/24/2022]
Abstract
To gain insights into dimorphism, cell wall polysaccharides from Tremella fuciformis strains were obtained from alkali-extracted water-soluble fractions PTF-M38 (from the mycelial form), PTF-Y3 and PTF-Y8 (from the yeast form) of T. fuciformis strains were used to gain some insights into dimorphism study. Their chemical properties and structural features were investigated using gel permeation chromatography, gas chromatography, UV and IR spectrophotometry and Congo red binding reactions. The results indicated that the backbones of PTF-M38, PTF-Y3 and PTF-Y8 were configured with α-linkages with average molecular weights of 1.24, 1.08, and 1.19 kDa, respectively. PTF-M38 was mainly composed of xylose, mannose, glucose, and galactose in a ratio of 1:1.47:0.48:0.34, while PTF-Y3 and PTF-Y8 were mainly composed of xylose, mannose and glucose in a ratio of 1:1.65:4.06 and 1:1.21:0.44, respectively. The sugar profiles of PTF-M38, PTF-Y3 and PTF-Y8 were also established for further comparison. These profiles showed that all three polysaccharides contained the same sugars but in different ratios, and the carbon sources (xylose, mannose, glucose, and galactose) affected the sugar ratios within the polysaccharides.
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Affiliation(s)
- Hanyu Zhu
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Yuan Yuan
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Juan Liu
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Liesheng Zheng
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Liguo Chen
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China
| | - Aimin Ma
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, P. R. China. .,Key Laboratory of Agro-Microbial Resources and Utilization, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, P. R. China.
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Benadé E, Stone W, Mouton M, Postma F, Wilsenach J, Botha A. Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions. MICROBIAL ECOLOGY 2016; 71:645-659. [PMID: 26566932 DOI: 10.1007/s00248-015-0706-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/02/2015] [Indexed: 06/05/2023]
Abstract
We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria.
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Affiliation(s)
- Eliska Benadé
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
| | - Wendy Stone
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Marnel Mouton
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, South Africa
| | - Ferdinand Postma
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa
| | - Jac Wilsenach
- Virtual Consulting Engineers (Pty.) Ltd., Groenkloof, South Africa
| | - Alfred Botha
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602, South Africa.
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Fajardo-Somera RA, Jöhnk B, Bayram Ö, Valerius O, Braus GH, Riquelme M. Dissecting the function of the different chitin synthases in vegetative growth and sexual development in Neurospora crassa. Fungal Genet Biol 2015; 75:30-45. [DOI: 10.1016/j.fgb.2015.01.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/17/2014] [Accepted: 01/07/2015] [Indexed: 01/22/2023]
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10
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Abstract
The aim of the present work was to investigate the in situ rheological behavior of yeast biofilms growing on stainless steel under static and turbulent flow. The species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time, with a predominance of C. krusei under static and turbulent flow. Likewise, structural variations occurred, with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness at 11 weeks (p < 0.001) and cell morphology was governed by hyphal structures and rounded cells. Using the in situ growth method introduced here, yeast biofilms were determined to be viscoelastic materials with a predominantly solid-like behavior, and neither this nor the G'0 values were significantly affected by the flow conditions or the growth time, and at large deformations their weak structure collapsed beyond a critical strain of about 1.5-5%. The present work could represent a starting point for developing in situ measurements of yeast rheology and contribute to a thin body of knowledge about fungal biofilm formation.
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Tarifa MC, Brugnoni LI, Lozano JE. Role of hydrophobicity in adhesion of wild yeast isolated from the ultrafiltration membranes of an apple juice processing plant. BIOFOULING 2013; 29:841-853. [PMID: 23837866 DOI: 10.1080/08927014.2013.808628] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The role of cell surface hydrophobicity in the adhesion to stainless steel (SS) of 11 wild yeast strains isolated from the ultrafiltration membranes of an apple juice processing plant was investigated. The isolated yeasts belonged to four species: Candida krusei (5 isolates), Candida tropicalis (2 isolates), Kluyveromyces marxianus (3 isolates) and Rhodotorula mucilaginosa (1 isolate). Surface hydrophobicity was measured by the microbial adhesion to solvents method. Yeast cells and surfaces were incubated in apple juice and temporal measurements of the numbers of adherent cells were made. Ten isolates showed moderate to high hydrophobicity and 1 strain was hydrophilic. The hydrophobicity expressed by the yeast surfaces correlated positively with the rate of adhesion of each strain. These results indicated that cell surface hydrophobicity governs the initial attachment of the studied yeast strains to SS surfaces common to apple juice processing plants.
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Affiliation(s)
- María Clara Tarifa
- Pilot Plant of Chemical Engineering (UNS-CONICET), Bahía Blanca, Argentina
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Schekman R, Brawley V. Localized deposition of chitin on the yeast cell surface in response to mating pheromone. Proc Natl Acad Sci U S A 2010; 76:645-9. [PMID: 16592617 PMCID: PMC383005 DOI: 10.1073/pnas.76.2.645] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Treatment of a mating-type Saccharomyces cerevisiae cells with the pheromone alpha-factor (secreted by alpha mating-type cells) induces the synthesis of chitin. Small daughter cells, which start with no detectable chitin, make 3 times more chitin when grown in the presence of alpha-factor than do untreated exponentially growing cells. Budding cells accumulate chitin in the nascent division septum [Cabib, E. & Bowers, B. (1975) J. Bacteriol. 124, 1586), as detected by staining with the fluorescent dye primulin. In the absence of a division septum, alpha-factor-treated cells accumulate chitin in the area of pheromone-stimulated growth. Enzymatic lysis of budding and pheromone-treated cells allows the separation of membrane-bound chitin synthase (UDP-2-acetamido-2-deoxy-D-glucose: chitin 4-beta-acetamidodeoxyglucosyltransferase, EC 2.4.1.16) activity from a dense particulate fraction containing chitin. Chitin synthase activity is associated with both the plasma membrane and small intracellular particles. During pheromone treatment, the levels of chitin synthase in the plasma membrane and in intracellular particle fractions increase 11- and 4-fold, respectively. Although chitin synthase is made as zymogen that requires proteolytic activation, the plasma membrane of pheromone-treated cells shows a significant fraction of preactivated enzyme; intracellular membrane-bound synthase is found exclusively in the zymogen form.
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Affiliation(s)
- R Schekman
- Department of Biochemistry, University of California, Berkeley, California 94720
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Hyphal content determines the compression strength of Candida albicans biofilms. Microbiology (Reading) 2009; 155:1997-2003. [DOI: 10.1099/mic.0.021568-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Candida albicans is the most frequently isolated human fungal pathogen among species causing biofilm-related clinical infections. Mechanical properties of Candida biofilms have hitherto been given no attention, despite the fact that mechanical properties are important for selection of treatment or dispersal of biofilm organisms due to a bodily fluid flow. The aim of this study was to identify the factors that determine the compression strength of Candida biofilms. Biofilms of C. albicans wild-type parental strain Caf2-1, mutant strain Chk24 lacking Chk1p [known to be involved in regulation of morphogenesis (yeast-to-hyphae transition)] and gene-reconstructed strain Chk23 were evaluated for their resistance to compression, along with biofilms of Candida tropicalis GB 9/9 and Candida parapsilosis GB 2/8, derived from used voice prosthetic biofilms. Additionally, cell morphologies within the biofilm, cell-surface hydrophobicities and extracellular polymeric substance composition were determined. Our results suggest that the hyphae-to-yeast ratio influences the compression strength of C. albicans biofilms. Biofilms with a hyphal content >50 % possessed significantly higher compressive strength and were more difficult to destroy by vortexing and sonication than biofilms with a lower hyphal content. However, when the amount of extracellular DNA (eDNA) in biofilms of C. albicans Caf2-1 and Chk24 increased, biofilm strength declined, suggesting that eDNA may influence biofilm integrity adversely.
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Cabib E. The synthesis and degradation of chitin. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 59:59-101. [PMID: 2949540 DOI: 10.1002/9780470123058.ch2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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15
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Pardini G, De Groot PWJ, Coste AT, Karababa M, Klis FM, de Koster CG, Sanglard D. The CRH family coding for cell wall glycosylphosphatidylinositol proteins with a predicted transglycosidase domain affects cell wall organization and virulence of Candida albicans. J Biol Chem 2006; 281:40399-411. [PMID: 17074760 DOI: 10.1074/jbc.m606361200] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In Candida albicans UTR2 (CSF4), CRH11, and CRH12 are members of a gene family (the CRH family) that encode glycosylphosphatidylinositol-dependent cell wall proteins with putative transglycosidase activity. Deletion of genes of this family resulted in additive sensitivity to compounds interfering with normal cell wall formation (Congo red, calcofluor white, SDS, and high Ca(2+) concentrations), suggesting that these genes contribute to cell wall organization. A triple mutant lacking UTR2, CRH11, and CRH12 produced a defective cell wall, as inferred from increased sensitivity to cell wall-degrading enzymes, decreased ability of protoplasts to regenerate a new wall, constitutive activation of Mkc1p, the mitogen-activated protein kinase of the cell wall integrity pathway, and an increased chitin content of the cell wall. Importantly, this was accompanied by a decrease in alkali-insoluble 1,3-beta-glucan but not total glucan content, suggesting that formation of the linkage between 1,3-beta-glucan and chitin might be affected. In support of this idea, localization of a Utr2p-GFP fusion protein largely coincided with areas of chitin incorporation in C. albicans. As UTR2 and CRH11 expression is regulated by calcineurin, a serine/threonine protein phosphatase involved in tolerance to antifungal drugs, cell wall morphogenesis, and virulence, this points to a possible relationship between calcineurin and the CRH family. Deletion of UTR2, CRH11, and CRH12 resulted in only a partial overlap with calcineurin-dependent phenotypes, suggesting that calcineurin has additional targets. Interestingly, cells deleted for UTR2, CRH11, and CRH12 were, like a calcineurin mutant, avirulent in a mouse model of systemic infection but retained the capacity to colonize target organs (kidneys) as the wild type. In conclusion, this work establishes the role of UTR2, CRH11, and CRH12 in cell wall organization and integrity.
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Affiliation(s)
- Giacomo Pardini
- Institute of Microbiology, University Hospital Lausanne, CH-1011 Lausanne, Switzerland
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Sanz M, Carrano L, Jiménez C, Candiani G, Trilla JA, Durán A, Roncero C. Candida albicans strains deficient in CHS7, a key regulator of chitin synthase III, exhibit morphogenetic alterations and attenuated virulence. MICROBIOLOGY-SGM 2005; 151:2623-2636. [PMID: 16079341 DOI: 10.1099/mic.0.28093-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Chitin is a structural polysaccharide present in most fungal cell walls, whose synthesis depends on a family of enzymic activities named chitin synthases (CSs). The specific role of each of them, as well as of their regulatory proteins, in cell morphogenesis and virulence is not well understood. Here, it is shown that most chitin synthesis in Candida albicans, one of the fungi most commonly isolated from opportunistic mycoses and infections, depends on CHS7. Thus, C. albicans chs7Delta null mutants showed reduced levels of chitin and CS activity, and were resistant to Calcofluor. Despite the sequence similarity and functional relationship with ScChs7p, CaChs7p was unable to restore CSIII activity in a Saccharomyces cerevisiae chs7Delta null mutant, because it was unable to direct ScChs3p export from the endoplasmic reticulum. C. albicans chs7Delta null mutants did not show any defect in growth rate, but yeast cells displayed minor morphogenetic defects affecting septum formation, and showed an increased tendency to form filaments. CaChs7p was not required for germ-tube emission, and null mutant strains underwent the dimorphic transition correctly. However, colony morphology appeared distinctively affected. chs7Delta hyphae were very curved and had irregular lateral walls, resulting in very compact colonies that seemed unable to spread out radially on the surface, unlike the wild-type. This growth pattern may be associated with the reduced virulence and high clearance rate observed when the chs7Delta strain was used in a murine model of infection. Therefore, CaChs7p is required for normal hyphal morphogenesis, suggesting that in C. albicans CSIII plays an important role in maintaining cell wall integrity, being essential when invading surrounding tissues.
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Affiliation(s)
- María Sanz
- Instituto de Microbiología Bioquímica y Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Edificio Departamental, R-219, Avda Campo Charro s/n, 37007 Salamanca, Spain
| | | | - Cristina Jiménez
- Instituto de Microbiología Bioquímica y Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Edificio Departamental, R-219, Avda Campo Charro s/n, 37007 Salamanca, Spain
| | | | - José A Trilla
- Instituto de Microbiología Bioquímica y Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Edificio Departamental, R-219, Avda Campo Charro s/n, 37007 Salamanca, Spain
| | - Angel Durán
- Instituto de Microbiología Bioquímica y Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Edificio Departamental, R-219, Avda Campo Charro s/n, 37007 Salamanca, Spain
| | - César Roncero
- Instituto de Microbiología Bioquímica y Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Edificio Departamental, R-219, Avda Campo Charro s/n, 37007 Salamanca, Spain
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17
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Kern K, Nunn CD, Pichová A, Dickinson JR. Isoamyl alcohol-induced morphological change in Saccharomyces cerevisiae involves increases in mitochondria and cell wall chitin content. FEMS Yeast Res 2005; 5:43-9. [PMID: 15381121 DOI: 10.1016/j.femsyr.2004.06.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Revised: 05/03/2004] [Accepted: 06/07/2004] [Indexed: 11/29/2022] Open
Abstract
Isoamyl alcohol reduced growth and induced filament formation in Saccharomyces cerevisiae. Isoamyl alcohol-induced filamentation was accompanied by an almost threefold greater increase in the specific activity of succinate dehydrogenase than in untreated cells, which suggested that isoamyl alcohol treatment caused the cells to produce more mitochondria than in normal yeast form proliferation. This was supported by measuring the dry weight of purified, isolated mitochondria. Filaments have an increased chitin content which is distributed over the majority of their surface, and is not confined to bud scars and the chitin ring between mother and daughter cells as in yeast-form cells.
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Affiliation(s)
- Kerstin Kern
- Cardiff School of Biosciences, Cardiff University, P.O. Box 915, Cardiff CF10 3TL, UK
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18
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Wills EA, Redinbo MR, Perfect JR, Poeta MD. New potential targets for antifungal development. ACTA ACUST UNITED AC 2005. [DOI: 10.1517/14728222.4.3.265] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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19
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Bensen ES, Filler SG, Berman J. A forkhead transcription factor is important for true hyphal as well as yeast morphogenesis in Candida albicans. EUKARYOTIC CELL 2002; 1:787-98. [PMID: 12455696 PMCID: PMC126749 DOI: 10.1128/ec.1.5.787-798.2002] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Candida albicans is an important pathogen of immunocompromised patients which grows with true hyphal, pseudohyphal, and yeast morphologies. The dynamics of cell cycle progression are markedly different in true hyphal relative to pseudohyphal and yeast cells, including nuclear movement and septin ring positioning. In Saccharomyces cerevisiae, two forkhead transcription factors (ScFKH1 and ScFKH2) regulate the expression of B-cyclin genes. In both S. cerevisiae and Schizosaccharomyces pombe, forkhead transcription factors also influence morphogenesis. To explore the molecular mechanisms that connect C. albicans morphogenesis with cell cycle progression, we analyzed CaFKH2, the single homolog of S. cerevisiae FKH1/FKH2. C. albicans cells lacking CaFkh2p formed constitutive pseudohyphae under all yeast and hyphal growth conditions tested. Under hyphal growth conditions levels of hyphae-specific mRNAs were reduced, and under yeast growth conditions levels of several genes encoding proteins likely to be important for cell wall separation were reduced. Together these results imply that Fkh2p is required for the morphogenesis of true hyphal as well as yeast cells. Efglp and Cphlp, two transcription factors that contribute to C. albicans hyphal growth, were not required for the pseudohyphal morphology of fkh2 mutants, implying that Fkh2p acts in pathways downstream of and/or parallel to Efglp and Cphlp. In addition, cells lacking Fkh2p were unable to damage human epithelial or endothelial cells in vitro, suggesting that Fkh2p contributes to C. albicans virulence.
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Affiliation(s)
- Eric S Bensen
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA
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20
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Chitnis MV, Deshpande MV. Isolation and regeneration of protoplasts from the yeast and mycelial form of the dimorphic zygomycete Benjaminiella poitrasii: role of chitin metabolism for morphogenesis during regeneration. Microbiol Res 2002; 157:29-37. [PMID: 11911612 DOI: 10.1078/0944-5013-00129] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Experimental parameters for isolation and regeneration of protoplasts from the mycelial and yeast form cells of the dimorphic zygomycete Benjamininiella poitrasii are reported. Using a chitosanase containing preparation from Streptomyces sp. MCl we obtained protoplasts after 5 h incubation with a yield of 2+/-0.3 x 10(6) ml(-1) and 3+/-0.4 x 10(7) ml(-1) for the mycelial and yeast form, respectively. During regeneration under conditions triggering dimorphism the two morphological forms were observed after 36 h. Initially, for 10-12 h only an irregular mass was formed as a result of deregulated cell wall synthesis. Among the tested inhibitors influencing cell wall metabolism, chitin metabolism inhibitors showed distinctive effects on the regeneration of protoplasts suggesting that the respective enzymes significantly contribute to determining the morphogenesis of the dimorphic fungus B. poitrasii.
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Affiliation(s)
- Manisha V Chitnis
- Biochemical Sciences Division, National Chemical Laboratory, Pune, India
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21
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Singh P, Ghosh S, Datta A. Attenuation of virulence and changes in morphology in Candida albicans by disruption of the N-acetylglucosamine catabolic pathway. Infect Immun 2001; 69:7898-903. [PMID: 11705974 PMCID: PMC98888 DOI: 10.1128/iai.69.12.7898-7903.2001] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A Candida albicans mutant with mutations in the N-acetylglucosamine (GlcNAc) catabolic pathway gene cluster, including the GlcNAc-6-phosphate deacetylase (DAC1), glucosamine-6-phosphate deaminase (NAG1), and GlcNAc kinase (HXK1) genes, was not able to grow on amino sugars, exhibited highly attenuated virulence in a murine systemic candidiasis model, and was less adherent to human buccal epithelial cells in vitro. No germ tubes were formed by the mutant after induction with GlcNAc, but the mutant exhibited hyperfilamentation under stress-induced filamentation conditions. In addition, the GlcNAc catabolic pathway played a vital role in determining the colony phenotype. Our results imply that this pathway is very important because of its diverse links with pathways involved in virulence and morphogenesis of the organism.
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Affiliation(s)
- P Singh
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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22
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Munro CA, Winter K, Buchan A, Henry K, Becker JM, Brown AJ, Bulawa CE, Gow NA. Chs1 of Candida albicans is an essential chitin synthase required for synthesis of the septum and for cell integrity. Mol Microbiol 2001; 39:1414-26. [PMID: 11251855 DOI: 10.1046/j.1365-2958.2001.02347.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
CaCHS1 of the fungal pathogen Candida albicans encodes an essential chitin synthase that is required for septum formation, viability, cell shape and integrity. The CaCHS1 gene was inactivated by first disrupting one allele using the ura-blaster protocol, then placing the remaining allele under the control of the maltose-inducible, glucose-repressible MRP1 promoter. Under repressing conditions, yeast cell growth continued temporarily, but daughter buds failed to detach from parents, resulting in septumless chains of cells with constrictions defining contiguous compartments. After several generations, a proportion of the distal compartments lysed. The conditional Deltachs1 mutant also failed to form primary septa in hyphae; after several generations, growth stopped, and hyphae developed swollen balloon-like features or lysed at one of a number of sites including the hyphal apex and other locations that would not normally be associated with septum formation. CHS1 therefore synthesizes the septum of both yeast and hyphae and also maintains the integrity of the lateral cell wall. The conditional mutant was avirulent under repressing conditions in an experimental model of systemic infection. Because this gene is essential in vitro and in vivo and is not present in humans, it represents an attractive target for the development of antifungal compounds.
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Affiliation(s)
- C A Munro
- Department of Molecular and Cell Biology, University of Aberdeen, Aberdeen AB25 2ZD, UK
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23
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Klis FM, Groot PD, Hellingwerf K. Molecular organization of the cell wall ofCandida albicans. Med Mycol 2001. [DOI: 10.1080/mmy.39.1.1.8-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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24
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Wang Z, Zheng L, Hauser M, Becker JM, Szaniszlo PJ. WdChs4p, a homolog of chitin synthase 3 in Saccharomyces cerevisiae, alone cannot support growth of Wangiella (Exophiala) dermatitidis at the temperature of infection. Infect Immun 1999; 67:6619-30. [PMID: 10569783 PMCID: PMC97075 DOI: 10.1128/iai.67.12.6619-6630.1999] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/1999] [Accepted: 09/03/1999] [Indexed: 11/20/2022] Open
Abstract
By using improved transformation methods for Wangiella dermatitidis, and a cloned fragment of its chitin synthase 4 structural gene (WdCHS4) as a marking sequence, the full-length gene was rescued from the genome of this human pathogenic fungus. The encoded chitin synthase product (WdChs4p) showed high homology with Chs3p of Saccharomyces cerevisiae and other class IV chitin synthases, and Northern blotting showed that WdCHS4 was expressed at constitutive levels under all conditions tested. Reduced chitin content, abnormal yeast clumpiness and budding kinetics, and increased melanin secretion resulted from the disruption of WdCHS4 suggesting that WdChs4p influences cell wall structure, cellular reproduction, and melanin deposition, respectively. However, no significant loss of virulence was detected when the wdchs4Delta strain was tested in an acute mouse model. Using a wdchs1Delta wdchs2Delta wdchs3Delta triple mutant of W. dermatitidis, which grew poorly but adequately at 25 degrees C, we assayed WdChs4p activity in the absence of activities contributed by its three other WdChs proteins. Maximal activity required trypsin activation, suggesting a zymogenic nature. The activity also had a pH optimum of 7.5, was most stimulated by Mg(2+), and was more inhibited by polyoxin D than by nikkomycin Z. Although the WdChs4p activity had a broad temperature optimum between 30 to 45 degrees C in vitro, this activity alone did not support the growth of the wdchs1Delta wdchs2Delta wdchs3Delta triple mutant at 37 degrees C, a temperature commensurate with infection.
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Affiliation(s)
- Z Wang
- Section of Molecular Genetics and Microbiology, School of Biological Science and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA
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25
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Braun PC. Nutrient uptake byCandida albicans: the influence of cell surface mannoproteins. Can J Microbiol 1999. [DOI: 10.1139/w99-035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Numerous ultrastructural and biochemical analyses have been performed to characterize the cell wall composition and structure of Candida albicans. However, little investigation has focused on how subtle differences in cell wall structure influence the intracellular transport of amino acids and monosaccharides. In this study C. albicans 4918 and ATCC 10231 were grown in culture conditions capable of modifying surface mannoproteins and induced surface hydrophobic or hydrophilic yeast cell wall states. Subcultures of these hydrophobic and hydrophilic yeasts were subsequently incubated with one of seven L-[3H] amino acids: glycine, leucine, proline, serine, aspartic acid, lysine, or arginine. The transport of [3H] mannose and [3H] N-acetyl-D-glucosamine were also investigated. This study revealed significant strain differences (P [Formula: see text] 0.05) between hydrophilic and hydrophobic yeast transport of these nutrients throughout a 2 h incubation. Hydrophilic cultures of 4918 and ATCC 10231 transported nearly two times more (pmol mg-1dry weight) proline, mannose, and N-acetyl-D-glucosamine than hydrophobic yeast. Hydrophobic cultures preferentially incorporated serine and aspartic acid in both these strains. Strain variation was indicated with the transport of leucine, lysine, and arginine, as follows: experiments showed that hydrophilic 4918 cultures selectively transported leucine, lysine, and arginine, whereas, the hydrophobic ATCC 10231 cultures incorporated these amino acids.Key words: Candida albicans, mannoproteins, amino acid transport.
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26
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Munro CA, Schofield DA, Gooday GW, Gow NAR. Regulation of chitin synthesis during dimorphic growth of Candida albicans. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 2):391-401. [PMID: 9493376 DOI: 10.1099/00221287-144-2-391] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Candida albicans has three genes encoding chitin synthase enzymes. In wild-type strains, the expression of CHS2 and CHS3 peaked 1-2 h after the induction of hyphal growth, whilst mRNA levels in a non-germinative strain, CA2, remained low under the same conditions. CHS1 gene expression did not peak during germ tube formation but remained at low levels in both yeast and hyphal growth. The pattern of gene expression did not predict the changes in measured chitin synthase activities or changes in chitin content during dimorphic transition. Chitin synthase activity increased steadily, and did not peak shortly after germ tube induction, and activity profiles were similar in germ-tube-competent and germ-tube-negative strains. The phenotype of a delta chs2 null mutant suggested that CHS2 encoded the major enzyme activity in vitro and was largely responsible for elevated chitin synthase activities in microsomal preparations from hyphal cells compared to yeast cells. However, CaChs3p was responsible for synthesis of most chitin in both yeast and hyphae. Three independent chitin assays gave markedly different estimates of the relative chitin content of yeast and hyphae and wild-type and chs mutants. Only one of the methods gave a significantly higher chitin content for hyphal compared to yeast cell walls and a lower chitin content for hyphae of the delta chs2 null mutant compared to the parental strain.
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Affiliation(s)
- C A Munro
- Department of Molecular & Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - D A Schofield
- Department of Molecular & Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - G W Gooday
- Department of Molecular & Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - N A R Gow
- Department of Molecular & Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
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27
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Ishii N, Yamamoto M, Yoshihara F, Arisawa M, Aoki Y. Biochemical and genetic characterization of Rbf1p, a putative transcription factor of Candida albicans. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 2):429-435. [PMID: 9043120 DOI: 10.1099/00221287-143-2-429] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A Candida albicans gene encoding a novel DNA-binding protein that bound to the RPG box of Saccharomyces cerevisiae and the telomeric repeat sequence of C. albicans was previously cloned and designated RBF1 (RPG-box-binding factor). In this report, determination of the functional domains of the protein is described. The DNA-binding domain was 140 aa in length, was centrally located between two glutamine-rich regions, and correlated with transcriptional activation in S. cerevisiae. The results, together with the previous finding that showed its predominant localization in the nucleus, suggest that this DNA-binding protein could be a transcription factor. Disruption of the functional RBF1 gene of C. albicans strains caused an alteration in cell morphology to the filamentous form on all solid and liquid media tested. Thus, we speculate that Rbf1p may be involved in the regulation of the transition between yeast and filamentous forms at the level of transcription.
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Affiliation(s)
- Nobuya Ishii
- Department of Mycology, Nippon Roche Research Center, Kajiwara 200, Kamakura, Kanagawa-Prefecture, Japan
| | - Mutumi Yamamoto
- Department of Mycology, Nippon Roche Research Center, Kajiwara 200, Kamakura, Kanagawa-Prefecture, Japan
| | - Fumie Yoshihara
- Department of Mycology, Nippon Roche Research Center, Kajiwara 200, Kamakura, Kanagawa-Prefecture, Japan
| | - Mikio Arisawa
- Department of Mycology, Nippon Roche Research Center, Kajiwara 200, Kamakura, Kanagawa-Prefecture, Japan
| | - Yuhko Aoki
- Department of Mycology, Nippon Roche Research Center, Kajiwara 200, Kamakura, Kanagawa-Prefecture, Japan
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28
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Abstract
Fungi and streptomycetes have a similar morphology and in both groups branching appears to be regulated in a similar manner. Both types of hyphae grow by tip extension but streptomycete hyphae never attain the extension rates commonly observed for fungi. Fungal hyphae are able to attain high rates of extension because a very large volume of protoplasm contributes to tip growth and because a vesicular growth system facilitates the rapid assembly of the tip wall. Growth of fungal and streptomycete mycelia involves the duplication of a physiological unit of growth which consists of a tip and a portion of hypha whose average length remains constant. However, it is not clear that growth of such mycelia is truly modular. Although hyphal fusions within a mycelium are common in higher fungi their significance in the organism’s life style is not known. Growth in lower green plants, especially algae, is considered and the question of whether coenocytic algae are modular or not is discussed.
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29
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Jackson DJ, Saunders VA, Humphreys AM. Potential chitinase activating factor from yeast cells of Candida albicans. Lett Appl Microbiol 1996; 23:159-62. [PMID: 8862020 DOI: 10.1111/j.1472-765x.1996.tb00054.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Microsomal chitinase from yeast and hyphal cells of Candida albicans was activated endogenously by incubation at 30 degrees C and exogenously by trypsin. The putative activating factor of yeast cells was separated from chitinase activity by fractionation of lysed protoplasts on an Iodixanol density gradient. The vacuole fraction contained no significant chitinase activity, but was enriched in chitinase activating factor. Activity of microsomal chitinase increased upon incubation with this, but no other gradient factor. Results suggest that the regulatory system governing microsomal chitinase activity, like that governing chitin synthase, involves a 'vacuolar' activating factor in Candida albicans.
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Affiliation(s)
- D J Jackson
- School of Biomolecular Sciences, Liverpool John Moores University, UK
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30
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Jackson D, Saunders V, Gooday G, Humphreys A. Chitinase activities from yeast and hyphal cells of Candida albicans. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0953-7562(96)80163-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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Taramelli D, Malabarba M, Sala G, Basilico N, Cocuzza G. Production of cytokines by alveolar and peritoneal macrophages stimulated byAspergillus fumigatusconidia or hyphae. Med Mycol 1996. [DOI: 10.1080/02681219680000081] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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32
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Marot-Leblond A, Robert R, Senet JM, Palmer T. Purification of a Candida albicans germ tube specific antigen. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 1995; 12:127-36. [PMID: 8589662 DOI: 10.1111/j.1574-695x.1995.tb00184.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In a previous work, Marot-Leblond et al. identified a Candida albicans germ tube-specific antigen by the use of a monoclonal antibody (mAb 3D9.3). In the present report, we used a two-step procedure to obtain a purified preparation of this antigen from a Zymolyase extract of Candida albicans germ tubes. The extract was first fractionated by gel filtration chromatography. The immunoreactive fractions were pooled, and the 3D9.3 antigen was further purified by hydrophobic interaction chromatography using a Phenyl-superose column. Analysis by SDS-PAGE, immunoblotting and Concanavalin A staining, revealed a single, polydisperse band ranging from 110 to 170 kDa. The antigen was purified 126-fold by protein content and 16.4-fold by carbohydrate content. Recovery of the antigen was 6.8% following the two-step purification.
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Affiliation(s)
- A Marot-Leblond
- Laboratoire d'Immunologie-Parasitologie, UFR des Sciences Médicales et Pharmaceutiques, Angers, France
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33
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Tietz HJ, Küssner A, Thanos M, De Andrade MP, Presber W, Schönian G. Phenotypic and genotypic characterization of unusual vaginal isolates of Candida albicans from Africa. J Clin Microbiol 1995; 33:2462-5. [PMID: 7494047 PMCID: PMC228439 DOI: 10.1128/jcm.33.9.2462-2465.1995] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
As expected by its global prevalence, the most frequently isolated species of yeast from vaginal swabs obtained from patients in Africa was Candida albicans, which accounted for 53 of 85 (62.4%) of the isolates from women in Madagascar and 35 of 54 (64.8%) of the culture-positive women in Angola. However, 40% of the Madagascan and 23% of the isolates from Angola, as well as two isolates obtained from one German patient, were not able to utilize the amino sugars glucosamine and N-acetylglucosamine as the sole carbon source. These isolates were able to form germ tubes but did not form chlamydospores. The correct identification as C. albicans was made possible only by using a PCR-based method of DNA fingerprinting. Only minor phenotypic and genotypic variation was observed among these strains. Whether they represent a distinct clone that is found mainly in Africa is not clear. The relevance of the amino sugar catabolic pathway in C. albicans is discussed in view of these results.
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Affiliation(s)
- H J Tietz
- Dermatologische Universitätsklinik und Poliklinik, Universitätsklinikum Charité, Humboldt-Universität, Berlin, Germany
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van der Rest ME, Kamminga AH, Nakano A, Anraku Y, Poolman B, Konings WN. The plasma membrane of Saccharomyces cerevisiae: structure, function, and biogenesis. Microbiol Rev 1995. [PMID: 7603412 DOI: 10.1128/mmbr.59.2.304-322.1995] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The composition of phospholipids, sphingolipids, and sterols in the plasma membrane has a strong influence on the activity of the proteins associated or embedded in the lipid bilayer. Since most lipid-synthesizing enzymes in Saccharomyces cerevisiae are located in intracellular organelles, an extensive flux of lipids from these organelles to the plasma membrane is required. Although the pathway of protein traffic to the plasma membrane is similar to that of most of the lipids, the bulk flow of lipids is separate from vesicle-mediated protein transport. Recent advances in the analysis of membrane budding and membrane fusion indicate that the mechanisms of protein transport from the endoplasmic reticulum to the Golgi and from the Golgi to plasma membrane are similar. The majority of plasma membrane proteins transport solutes across the membrane. A number of ATP-dependent export systems have been detected that couple the hydrolysis of ATP to transport of molecules out of the cell. The hydrolysis of ATP by the plasma membrane H(+)-ATPase generates a proton motive force which is used to drive secondary transport processes. In S. cerevisiae, many substrates are transported by more than one system. Transport of monosaccharide is catalyzed by uniport systems, while transport of disaccharides, amino acids, and nucleosides is mediated by proton symport systems. Transport activity can be regulated at the level of transcription, e.g., induction and (catabolite) repression, but transport proteins can also be affected posttranslationally by a process termed catabolite inactivation. Catabolite inactivation is triggered by the addition of fermentable sugars, intracellular acidification, stress conditions, and/or nitrogen starvation. Phosphorylation and/or ubiquitination of the transport proteins has been proposed as an initial step in the controlled inactivation and degradation of the target enzyme. The use of artificial membranes, like secretory vesicles and plasma membranes fused with proteoliposomes, as model systems for studies on the mechanism and regulation of transport is evaluated.
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Affiliation(s)
- M E van der Rest
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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van der Rest ME, Kamminga AH, Nakano A, Anraku Y, Poolman B, Konings WN. The plasma membrane of Saccharomyces cerevisiae: structure, function, and biogenesis. Microbiol Rev 1995; 59:304-22. [PMID: 7603412 PMCID: PMC239363 DOI: 10.1128/mr.59.2.304-322.1995] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The composition of phospholipids, sphingolipids, and sterols in the plasma membrane has a strong influence on the activity of the proteins associated or embedded in the lipid bilayer. Since most lipid-synthesizing enzymes in Saccharomyces cerevisiae are located in intracellular organelles, an extensive flux of lipids from these organelles to the plasma membrane is required. Although the pathway of protein traffic to the plasma membrane is similar to that of most of the lipids, the bulk flow of lipids is separate from vesicle-mediated protein transport. Recent advances in the analysis of membrane budding and membrane fusion indicate that the mechanisms of protein transport from the endoplasmic reticulum to the Golgi and from the Golgi to plasma membrane are similar. The majority of plasma membrane proteins transport solutes across the membrane. A number of ATP-dependent export systems have been detected that couple the hydrolysis of ATP to transport of molecules out of the cell. The hydrolysis of ATP by the plasma membrane H(+)-ATPase generates a proton motive force which is used to drive secondary transport processes. In S. cerevisiae, many substrates are transported by more than one system. Transport of monosaccharide is catalyzed by uniport systems, while transport of disaccharides, amino acids, and nucleosides is mediated by proton symport systems. Transport activity can be regulated at the level of transcription, e.g., induction and (catabolite) repression, but transport proteins can also be affected posttranslationally by a process termed catabolite inactivation. Catabolite inactivation is triggered by the addition of fermentable sugars, intracellular acidification, stress conditions, and/or nitrogen starvation. Phosphorylation and/or ubiquitination of the transport proteins has been proposed as an initial step in the controlled inactivation and degradation of the target enzyme. The use of artificial membranes, like secretory vesicles and plasma membranes fused with proteoliposomes, as model systems for studies on the mechanism and regulation of transport is evaluated.
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Affiliation(s)
- M E van der Rest
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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Saporito-Irwin SM, Birse CE, Sypherd PS, Fonzi WA. PHR1, a pH-regulated gene of Candida albicans, is required for morphogenesis. Mol Cell Biol 1995; 15:601-13. [PMID: 7823929 PMCID: PMC231914 DOI: 10.1128/mcb.15.2.601] [Citation(s) in RCA: 227] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Candida albicans, like many fungi, exhibits morphological plasticity, a property which may be related to its biological capacity as an opportunistic pathogen of humans. Morphogenesis and alterations in cell shape require integration of many cellular functions and occur in response to environmental signals, most notably pH and temperature in the case of C. albicans. In the course of our studies of differential gene expression associated with dimorphism of C. albicans, we have isolated a gene, designated PHR1, which is regulated in response to the pH of the culture medium. PHR1 expression was repressed at pH values below 5.5 and induced at more alkaline pH. The predicted amino acid sequence of the PHR1 protein was 56% identical to that of the Saccharomyces cerevisiae Ggp1/Gas1 protein, a highly glycosylated cell surface protein attached to the membrane via glycosylphosphatidylinositol. A homozygous null mutant of PHR1 was constructed and found to exhibit a pH-conditional morphological defect. At alkaline pH, the mutant, unlike the parental type, was unable to conduct apical growth of either yeast or hyphal growth forms. This morphological aberration was not associated with defective cytoskeletal polarization or secretion. The results suggest that PHR1 defines a novel function required for apical cell growth and morphogenesis.
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Affiliation(s)
- S M Saporito-Irwin
- Department of Microbiology and Molecular Genetics, California College of Medicine, University of California, Irvine 92717
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37
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Jordan JA. PCR identification of four medically important Candida species by using a single primer pair. J Clin Microbiol 1994; 32:2962-7. [PMID: 7883883 PMCID: PMC264208 DOI: 10.1128/jcm.32.12.2962-2967.1994] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A single pair of primers was used in a PCR assay to amplify and identify the DNAs from four medically important Candida species: C. albicans, C. parapsilosis, C. tropicalis, and C. (Torulopsis) glabrata. The report describes the first successful amplification of a chitin synthase-specific fragment from the four Candida species responsible for more than 90% of all cases of neonatal candidemia. The primer pair sequence was based on that from the C. albicans chitin synthase gene, CHS1 (J. Au-Young and P.W. Robbins, Mol. Microbiol. 4:197-207, 1990). Each of the four amplified products is a single band of a different size. The DNA sequence of each PCR product was determined, and four species-specific probes were synthesized. The DNAs from as few as 10 organisms in 100 microliters of plasma could be detected after amplification and Southern blot analysis. In a retrospective study of 27 paired blood samples from 16 patients with culture-proven candidemia, PCR analysis was successful at detecting and correctly identifying to the species level 26 of the 27 Candida isolates. The speed and accuracy of this PCR-based technology make it a very powerful tool for detecting and diagnosing candidemia. Implementation of this assay for analyzing blood samples should result in the more timely treatment of neonatal candidemia, thereby reducing morbidity and mortality.
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Affiliation(s)
- J A Jordan
- Department of Pathology, School of Medicine, Magee-Womens Research Institute, University of Pittsburgh, Pennsylvania 15213
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38
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Abstract
Increased intracellular incorporation of [3H]corticosterone in Candida albicans was dependent on cell surface hydrophobicity. C. albicans strains were grown in culture conditions that induced surface hydrophobicity, and cell wall conditions were evaluated with a polystyrene microsphere assay. Germ tubes, which exhibited the greatest cell surface hydrophobicity, incorporated seven times more radiolabel than the hydrophilic yeast forms. Hydrophobic yeasts contained four times more [3H]corticosterone than their polar counterparts. Hydrophobic yeasts incubated for 48 h on nutrient agar containing corticosterone showed reduced colony size compared with controls. These results demonstrate that environmental factors which augment cell wall hydrophobicity in C. albicans can increase the incorporation of corticosterone, which may influence the metabolic activities in this organism.
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Affiliation(s)
- P C Braun
- Department of Biology, Fairfield University, Connecticut 06430
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Gow NA, Robbins PW, Lester JW, Brown AJ, Fonzi WA, Chapman T, Kinsman OS. A hyphal-specific chitin synthase gene (CHS2) is not essential for growth, dimorphism, or virulence of Candida albicans. Proc Natl Acad Sci U S A 1994; 91:6216-20. [PMID: 8016141 PMCID: PMC44169 DOI: 10.1073/pnas.91.13.6216] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
In the dimorphic fungus Candida albicans, the CHS2 gene encodes a chitin synthase that is expressed preferentially in the hyphal form. Gene disruption of CHS2 in this diploid asexual fungus was achieved by the "ura-blaster" protocol described for Saccharomyces [Alani, E., Cao, L. & Kleckner, N. (1987) Genetics 116, 541-545]. This involves the sequential disruption of multiple alleles by integrative transformation with URA3 as a single selectable marker. After disrupting the first CHS2 allele, the Ura- phenotype was recovered through cis recombination between repeated hisG sequences that flanked the URA3 marker in the disruption cassette, which was then used again to disrupt further CHS2 alleles. This method of gene disruption is well suited to the mutational analysis of this genetically recalcitrant human pathogen. Three rounds of disruption were required, suggesting that the strain SGY243 is triploid for the CHS2 locus. The resulting homozygous delta chs2::hisG null mutants were viable and made germ tubes with a normal morphology. The germ tubes were formed more slowly than parental strains in serum-containing medium and the germinating cells had a 40% reduction in their chitin content compared to germ tubes of the parent strain. The chitin content of the yeast form was not affected. A prototrophic strain of the chs2 null mutant was not attenuated significantly in its virulence when tested in normal and immunosuppressed mice.
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Affiliation(s)
- N A Gow
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139
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40
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Sudoh M, Nagahashi S, Doi M, Ohta A, Takagi M, Arisawa M. Cloning of the chitin synthase 3 gene from Candida albicans and its expression during yeast-hyphal transition. MOLECULAR & GENERAL GENETICS : MGG 1993; 241:351-8. [PMID: 8246889 DOI: 10.1007/bf00284688] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The chitin synthase 3 gene (CACHS3) has been cloned from Candida albicans. The yeast CAL1 gene encoding the chitin synthase 3 of Saccharomyces cerevisiae was used as a probe for the isolation of the gene from C. albicans. The CAL1 homolog was identified in Southern blots of C. albicans genomic DNA and cloned from a C. albicans genomic DNA library. The nucleotide sequences of two partial clones were determined and combined giving a total length of 4610 bp. A continuous open reading frame of 3525 bp encoding a predicted protein of 1175 amino acids and molecular mass of 131 850 daltons was identified. A comparison of the deduced amino acid sequences of CAL1 and the Candida chitin synthase 3 protein showed 59.3% identity. Southern blot analysis indicates that the CACHS3 gene is present in a single copy in the genome and maps to chromosome I. Northern blot analysis shows that expression of chitin synthase 3 gene is dramatically increased during the transition from the yeast to the hyphal form of C. albicans. This change in transcription level strongly suggests that CACHS3 may play a role in Candida morphogenesis.
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Affiliation(s)
- M Sudoh
- Department of Mycology, Nippon Roche Research Center, Kanagawa, Japan
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41
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Cohen E. Chitin synthesis and degradation as targets for pesticide action. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 1993; 22:245-261. [PMID: 8431598 DOI: 10.1002/arch.940220118] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Various pesticides are being used to destabilize, perturb, or inhibit crucial biochemical and physiological targets related to metabolism, growth, development, nervous communication, or behavior in pestiferous organisms. Chitin is an eukaryotic extracellular aminosugar biopolymer, massively produced by most fungal systems and by invertebrates, notably arthropods. Being an integral supportive component in fungal cell wall, insect cuticle, and nematode egg shell, chitin has been considered as a selective target for pesticide action. Throughout the elaborate processes of chitin formation and deposition, only the polymerization events associated with the cell membrane compartment are so far available for chemical interference. Currently, the actinomycetes-derived nucleoside peptide fungicides such as the polyoxins and the insecticidal benzoylaryl ureas have reached commercial pesticide status. The polyoxins and other structurally-related antibiotics like nikkomycins are strong competitive inhibitors of the polymerizing enzyme chitin synthase. The exact biochemical lesion inflicted by the benzoylaryl ureas is still elusive, but a post-polymerization event, such as translocation of chitin chains across the cell membrane, is suggested. Hydrolytic degradation of the chitin polymer is essential for hyphal growth, branching, and septum formation in fungal systems as well as for the normal molting of arthropods. Recently, insect chitinase activity was strongly and specifically suppressed by allosamidin, an actimomycetes-derived metabolite. In part, the defense mechanism in plants against invasion of pathogens is associated with induced chitinases. Chitin, chitosan, and their oligomers are able to act as elicitors which induce enhanced levels of chitinases in various plants. Lectins which bind to N-acetyl-D-glucosamine strongly interfere with fungal and insect chitin synthases. Plant lectins with similar properties may be involved in plant-pathogen interaction inter alia by suppressing fungal invasion.
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Affiliation(s)
- E Cohen
- Department of Entomology, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
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Gozalbo D, Dubón F, Sentandreu R. Effect of digitonin on membrane-bound and chitosomal chitin synthetase activity in protoplasts from yeast cells of Candida albicans. Antonie Van Leeuwenhoek 1993; 64:67-74. [PMID: 8274004 DOI: 10.1007/bf00870923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effect of digitonin on chitin synthetase present in membrane (MMF) and cytoplasmic fractions (chitosomes) (CF) from C. albicans yeast protoplasts has been determined. The zymogen is preferentially, but not exclusively, solubilized by digitonin from MMF. Centrifugation of distinct solubilized preparations, containing either zymogen, in vivo active enzyme and/or trypsin activated enzyme, on linear sucrose gradients suggests that both zymogen and trypsin activated enzyme sediment slightly slower than the active enzyme, pointing out differences between the activation processes in vivo and in vitro or, alternatively, that both enzyme activities (active in vivo and zymogenic) correspond to different gene products. The detection of a zymogenic activity under certain conditions (0.5 mg ml-1 of digitonin and 64 micrograms ml-1 of trypsin) also suggests the existence of more than one pool of zymogenic enzyme in the MMF. Digitonin sensitizes the chitosomal (CF) proenzyme to trypsin: activation is enhanced by low digitonin concentrations in the presence of 8 micrograms ml-1 of protease, whereas activity strongly decreases in the presence of 64 micrograms ml-1 of trypsin. Digitonin does not produce zymogen activation per se in absence of exogenous protease. Furthermore, chitosome structure is modified into particles with low buoyant densities.
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Affiliation(s)
- D Gozalbo
- Departament de Microbiologia, Facultat de Farmàcia, Universitat de València, Spain
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Abstract
A number of substances that directly or indirectly affect the cell walls of fungi have been identified. Those that actively interfere with the synthesis or degradation of polysaccharide components share the property of being produced by soil microbes as secondary metabolites. Compounds specifically interfering with chitin or beta-glucan synthesis have proven effective in studies of preclinical models of mycoses, though they appear to have a restricted spectrum of coverage. Semisynthetic derivatives of some of the natural products have offered improvements in activity, toxicology, or pharmacokinetic behavior. Compounds which act on the cell wall indirectly or by a secondary mechanism of action, such as the azoles, act against diverse fungi but are usually fungistatic in nature. Overall, these compounds are attractive candidates for further development.
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Affiliation(s)
- R F Hector
- Cutter Biological, Berkeley, California 94710
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44
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Gozalbo D, Dubón F, Sentandreu R. Chitin synthetase activity is bound to the plasma membrane and to a cytoplasmic particulate fraction inCandida albicansgerm tube cells. FEMS Microbiol Lett 1992. [DOI: 10.1111/j.1574-6968.1992.tb05472.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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45
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Chapman T, Kinsman O, Houston J. Chitin biosynthesis in Candida albicans grown in vitro and in vivo and its inhibition by nikkomycin Z. Antimicrob Agents Chemother 1992; 36:1909-14. [PMID: 1416881 PMCID: PMC192208 DOI: 10.1128/aac.36.9.1909] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
An N-acetyl-D-[14C]glucosamine radiolabel incorporation assay has been used to monitor chitin biosynthesis in whole cells of Candida albicans both in vitro and in vivo in two different mouse infection models, one using the peritoneal cavity as a chamber in which to add and retrieve cells and the other using infected kidneys. Specific labeling of chitin in alkali-insoluble material was confirmed by chitinase digestion, analysis of acid hydrolysates, and the use of nikkomycin Z as a probe. Nikkomycin Z was shown to strongly inhibit chitin biosynthesis in C. albicans grown in vitro and in vivo in both models. This demonstrates that nikkomycin Z-susceptible chitin synthase activity is present in C. albicans when the fungus is in its pathogenic state in vivo. The limited use of nikkomycin as a therapeutic agent is discussed.
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Affiliation(s)
- T Chapman
- Division of Microbiology, Glaxo Group Research Ltd., Greenford, Middlesex, United Kingdom
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46
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Mishra P, Bolard J, Prasad R. Emerging role of lipids of Candida albicans, a pathogenic dimorphic yeast. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1127:1-14. [PMID: 1627629 DOI: 10.1016/0005-2760(92)90194-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It is clear that C. albicans lipids have gained tremendous importance in recent years. In addition to being a barrier for entrance of various metabolites, it also provides the site of action for the synthesis of enzyme(s) involved in cell wall morphogenesis and antifungal action. While alterations in lipid composition during a yeast to mycelia transition have been observed, in most of the studies, lipid fluctuations reported could have been due to various environmental factors involved in the induction of morphogenesis [4,5]. A clear understanding of lipid biosynthesis and metabolic blocks due to antifungal action is likely to shed further light on selective interactions of antifungals. Despite the multifacet role of lipids in various functions of this pathogenic yeast, their exact involvement is poorly understood. The situation is little better with regard to ergosterol and its metabolism. Ergosterol is, indeed, important for anti-candidal activity and appears to be involved in the morphogenesis of C. albicans. The fluctuation in phospholipid composition have led to altered properties of plasma membrane namely, membrane fluidity, transport activities and drug sensitivity, which suggest that-a critical level of individual phospholipid is important for proper functioning of the plasma membrane. What the exact role is of individual phospholipid is far from clear. Many unanswered questions relating to the role of PI and sphingomyelin in signal transduction, involvement of phospholipases in the maintenance of phospholipid composition, and role of lipid transfer proteins in assembly and asymmetry of lipids are some aspects which merit further work.
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Affiliation(s)
- P Mishra
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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47
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Transcription of the single actin gene ofCandida albicans during the yeast-to-mycelium conversion. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0147-5975(92)90022-j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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48
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Deshpande MV. Proteinases in fungal morphogenesis. World J Microbiol Biotechnol 1992; 8:242-50. [DOI: 10.1007/bf01201871] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/1991] [Accepted: 01/10/1992] [Indexed: 11/29/2022]
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49
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Segal E, Kremer I, Dayan D. Inhibition of adherence of Candida albicans to acrylic by a chitin derivative. Eur J Epidemiol 1992; 8:350-5. [PMID: 1397199 DOI: 10.1007/bf00158567] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The purpose of this study was to assess the effect of a chitin derivative (CSE) on the adherence of Candida albicans to acrylic. Fungal adherence to acrylic dentures is considered an essential step in the development of denture stomatitis. Adherence of C. albicans to acrylic pieces (5 x 5mm) was assessed microscopically using a calibrated ocular objective and expressed as number of adherent yeasts/mm2 of acrylic. CSE was prepared from commercial chitin (crab shell) and from chitin isolated from C. albicans blastospores. The effect of both CSE types on the adherence of C. albicans to acrylic was examined in two experimental systems: CSE present during the adherence assay and acrylic pieces pretreated with CSE prior to the assay. Both CSE types exerted a significant inhibitory effect when tested in the two experimental systems. These findings are significant for possible prevention of denture stomatitis.
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Affiliation(s)
- E Segal
- Department of Human Microbiology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel
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50
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Gozalbo D, Dubón F, Sentandreu R. Evidence for the involvement of acylglycerides on chitin synthetase activity inCandida albicans. FEMS Microbiol Lett 1991. [DOI: 10.1111/j.1574-6968.1991.tb04716.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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