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Abstract
Fungi are eukaryotic microorganisms that show complex life cycles, including both anamorph and teleomorph stages. Beta-1,3-1,6-glucans (BGs) are major cell wall components in fungi. BGs are also found in a soluble form and are secreted by fungal cells. Studies of fungal BGs extensively expanded from 1960 to 1990 due to their applications in cancer immunotherapy. However, progress in this field slowed down due to the low efficacy of such therapies. In the early 21st century, the discovery of C-type lectin receptors significantly enhanced the molecular understanding of innate immunity. Moreover, pathogen-associated molecular patterns (PAMPs) and pattern recognition receptors (PRRs) were also discovered. Soon, dectin-1 was identified as the PRR of BGs, whereas BGs were established as PAMPs. Then, studies on fungal BGs focused on their participation in the development of deep-seated mycoses and on their role as a source of functional foods. Fungal BGs may have numerous and complex linkages, making it difficult to systematize them even at the primary structure level. Moreover, elucidating the structure of BGs is largely hindered by the multiplicity of genes involved in cell wall biosynthesis, including those for BGs, and by fungal diversity. The present review mainly focused on the characteristics of fungal BGs from the viewpoint of structure and immunological activities.
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Alencar VC, Jabes DL, Menegidio FB, Sassaki GL, de Souza LR, Puzer L, Meneghetti MCZ, Lima MA, Tersariol ILDS, de Oliveira RC, Nunes LR. Functional and Evolutionary Characterization of a UDP-Xylose Synthase Gene from the Plant Pathogen Xylella fastidiosa, Involved in the Synthesis of Bacterial Lipopolysaccharide. Biochemistry 2017; 56:779-792. [PMID: 28125217 DOI: 10.1021/acs.biochem.6b00886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Xylella fastidiosa is a plant-infecting bacillus, responsible for many important crop diseases, such as Pierce's disease of vineyards, citrus variegated chlorosis, and coffee leaf scorch (CLS), among others. Recent genomic comparisons involving two CLS-related strains, belonging to X. fastidiosa subsp. pauca, revealed that one of them carries a frameshift mutation that inactivates a gene encoding an oxidoreductase of the short-chain dehydrogenase/reductase (SDR) superfamily, which may play important roles in determining structural variations in bacterial glycans and glycoconjugates. However, the exact nature of this SDR has been a matter of controversy, as different annotations of X. fastidiosa genomes have implicated it in distinct reactions. To confirm the nature of this mutated SDR, a comparative analysis was initially performed, suggesting that it belongs to a subgroup of SDR decarboxylases, representing a UDP-xylose synthase (Uxs). Functional assays, using a recombinant derivative of this enzyme, confirmed its nature as XfUxs, and carbohydrate composition analyses, performed with lipopolysaccharide (LPS) molecules obtained from different strains, indicate that inactivation of the X. fastidiosa uxs gene affects the LPS structure among CLS-related X. fastidiosa strains. Finally, a comparative sequence analysis suggests that this mutation is likely to result in a morphological and evolutionary hallmark that differentiates two subgroups of CLS-related strains, which may influence interactions between these bacteria and their plant and/or insect hosts.
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Affiliation(s)
- Valquíria Campos Alencar
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC) , Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes, SP CEP 08780-911, Brazil
| | - Daniela Leite Jabes
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC) , Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes, SP CEP 08780-911, Brazil
| | - Fabiano Bezerra Menegidio
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC) , Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes, SP CEP 08780-911, Brazil
| | - Guilherme Lanzi Sassaki
- Setor de Ciências Biológicas-Departamento de Bioquímica e Biologia Molecular Laboratório de Química de Carboidratos, Universidade Federal do Paraná (UFPR) , Rua Cel. Francisco H. dos Santos, 100, Curitiba, Paraná CEP 81531-980, Brazil
| | - Lucas Rodrigo de Souza
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC) , Rua Santa Adélia, 166, Santo André, SP CEP 09210-170, Brazil
| | - Luciano Puzer
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC) , Rua Santa Adélia, 166, Santo André, SP CEP 09210-170, Brazil
| | - Maria Cecília Zorél Meneghetti
- Departamento de Bioquímica, Universidade Federal de São Paulo (UNIFESP) , Rua Três de Maio, Vila Clementino, São Paulo CEP 04044-020, Brazil
| | - Marcelo Andrade Lima
- Departamento de Bioquímica, Universidade Federal de São Paulo (UNIFESP) , Rua Três de Maio, Vila Clementino, São Paulo CEP 04044-020, Brazil
| | - Ivarne Luis Dos Santos Tersariol
- Departamento de Bioquímica, Universidade Federal de São Paulo (UNIFESP) , Rua Três de Maio, Vila Clementino, São Paulo CEP 04044-020, Brazil
| | - Regina Costa de Oliveira
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC) , Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes, SP CEP 08780-911, Brazil
| | - Luiz R Nunes
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC) , Rua Santa Adélia, 166, Santo André, SP CEP 09210-170, Brazil
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Duan XC, Lu AM, Gu B, Cai ZP, Ma HY, Wei S, Laborda P, Liu L, Voglmeir J. Functional characterization of the UDP-xylose biosynthesis pathway in Rhodothermus marinus. Appl Microbiol Biotechnol 2015; 99:9463-72. [PMID: 26033773 DOI: 10.1007/s00253-015-6683-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/20/2015] [Accepted: 05/07/2015] [Indexed: 10/23/2022]
Abstract
UDP-glucuronic acid dehydrogenase (UGD) and UDP-xylose synthase (UXS) are the two enzymes responsible for the biosynthesis of UDP-xylose from UDP-glucose. Several UGDs from bacterial sources, which oxidize UDP-glucose to glucuronic acid, have been found and functionally characterized whereas only few reports on bacterial UXS isoforms exist. Rhodothermus marinus, a halothermophilic bacterium commonly found in hot springs, proved to be a valuable source of carbohydrate active enzymes of biotechnological interest, such as xylanases, mannanases, and epimerases. However, no enzymes of R. marinus involved in the biosynthesis or modification of nucleotide sugars have been reported yet. Herein, we describe the cloning and characterization of two putative UGD (RmUGD1 and RmUGD2) and one UXS (RmUXS) isoform from this organism. All three enzymes could be expressed in recombinant form and purified to near homogeneity. UPLC- and NMR-based activity tests showed that RmUGD1 and RmUXS are indeed active enzymes, whereas no enzymatic activity could be detected by RmUGD2. Both RmUGD1 and RmUXS showed a temperature optimum of 60 °C, with almost no loss of activity after 1 h exposure at 70 °C. No metal ions were required for enzymatic activities. Zn(2+) ions strongly inhibited both enzymes. RmUGD1 showed higher salt tolerance and had a higher pH optimum than RmUXS. Furthermore, RmUGD1 was inhibited by UDP-xylose at higher concentrations. By coupling recombinant RmUXS and RmUGD1, UDP-xylose could be successfully synthesized directly from UDP-glucose. The high activity of the herein described enzymes make RmUGD1 and RmUXS the first thermo-tolerant biocatalysts for the synthesis of UDP-glucuronic acid and UDP-xylose.
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Affiliation(s)
- Xu C Duan
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Ai M Lu
- College of Sciences, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Bin Gu
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Zhi P Cai
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Hong Y Ma
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Shuang Wei
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Pedro Laborda
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Li Liu
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China.
| | - Josef Voglmeir
- Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing, People's Republic of China.
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Teixeira PAC, Penha LL, Mendonça-Previato L, Previato JO. Mannoprotein MP84 mediates the adhesion of Cryptococcus neoformans to epithelial lung cells. Front Cell Infect Microbiol 2014; 4:106. [PMID: 25191644 PMCID: PMC4137752 DOI: 10.3389/fcimb.2014.00106] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/18/2014] [Indexed: 01/13/2023] Open
Abstract
The capsule is the most important virulence factor of the fungal pathogen Cryptococcus neoformans. This structure consists of highly hydrated polysaccharides, including glucuronoxylomannan (GXM), and galactoxylomannan (GalXM). It is also composed of mannoproteins (MPs) which corresponds to less than 1% of the capsular weight. Despite MPs being the minority and least studied components, four of these molecules with molecular masses of 115, 98, 88, and 84 kDa were identified and characterized as C. neoformans immunoreactive antigens involved in the pathogenesis, and are potential cryptococcosis vaccine candidates. With the aim to describe the adhesive property of MPs, we cloned and expressed the MP84, a mannoprotein with molecular weight of 84 kDa, on Pichia pastoris yeast, and performed interaction assays of C. neoformans with epithelial lung cells, in the presence or absence of capsule components. Two fungal strains, the wild type, NE-241, and a mutant, CAP67, deficient in GXM production, were used throughout this study. The adhesion assays were completed using epithelial lung cells, A549, and human prostate cancer cells, PC3, as a control. We observed that capsulated wild type (NE-241), and acapsular (CAP67) strains adhered significantly to A549 cells, compared with PC3 cells (p < 0.05). GXM inhibits the NE-241 adhesion, but not the CAP67. In contrast, CAP67 adhesion was only inhibited in the presence of MP84. These results demonstrate the involvement of MP in the adhesion of C. neoformans to epithelial lung cells. We conclude that this interaction possibly involves an adhesion-like interaction between MP on the fungal surface and the complementary receptor molecules on the epithelial cells.
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Affiliation(s)
- Pedro A C Teixeira
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Luciana L Penha
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Lucia Mendonça-Previato
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Jose O Previato
- Laboratório de Glicobiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
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UDP-glucuronic acid decarboxylases of Bacteroides fragilis and their prevalence in bacteria. J Bacteriol 2011; 193:5252-9. [PMID: 21804000 DOI: 10.1128/jb.05337-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Xylose is rarely described as a component of bacterial glycans. UDP-xylose is the nucleotide-activated form necessary for incorporation of xylose into glycans and is synthesized by the decarboxylation of UDP-glucuronic acid (UDP-GlcA). Enzymes with UDP-GlcA decarboxylase activity include those that lead to the formation of UDP-xylose as the end product (Uxs type) and those synthesizing UDP-xylose as an intermediate (ArnA and RsU4kpxs types). In this report, we identify and confirm the activities of two Uxs-type UDP-GlcA decarboxylases of Bacteroides fragilis, designated BfUxs1 and BfUxs2. Bfuxs1 is located in a conserved region of the B. fragilis genome, whereas Bfuxs2 is in the heterogeneous capsular polysaccharide F (PSF) biosynthesis locus. Deletion of either gene separately does not result in the loss of a detectable phenotype, but deletion of both genes abrogates PSF synthesis, strongly suggesting that they are functional paralogs and that the B. fragilis NCTC 9343 PSF repeat unit contains xylose. UDP-GlcA decarboxylases are often annotated incorrectly as NAD-dependent epimerases/dehydratases; therefore, their prevalence in bacteria is underappreciated. Using available structural and mutational data, we devised a sequence pattern to detect bacterial genes encoding UDP-GlcA decarboxylase activity. We identified 826 predicted UDP-GlcA decarboxylase enzymes in diverse bacterial species, with the ArnA and RsU4kpxs types confined largely to proteobacterial species. These data suggest that xylose, or a monosaccharide requiring a UDP-xylose intermediate, is more prevalent in bacterial glycans than previously appreciated. Genes encoding BfUxs1-like enzymes are highly conserved in Bacteroides species, indicating that these abundant intestinal microbes may synthesize a conserved xylose-containing glycan.
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Jesus MD, Nicola AM, Chow SK, Lee IR, Nong S, Specht CA, Levitz SM, Casadevall A. Glucuronoxylomannan, galactoxylomannan, and mannoprotein occupy spatially separate and discrete regions in the capsule of Cryptococcus neoformans. Virulence 2010; 1:500-8. [PMID: 21178496 DOI: 10.4161/viru.1.6.13451] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The capsular polysaccharides of Cryptococcus neoformans have historically been divided into three components namely, glucuronoxylomannan (GXM), galactoxylomannan (GalXM), and mannoprotein (MP) but their relative spatial-geographical relationship in the capsule is unknown. To explore this problem would require the capacity for visualizing these components in the capsule. Prior studies have reported serological reagents to GXM and GalXM but no antibodies are available against MPs. Consequently, we immunized Balb/c mice with C. neoformans recombinant mannoprotein 98 and recovered twelve monoclonal antibodies (mAbs) of which one, an IgG2a designated 18F2, bound to intact cells by immunofluorescence. mAb 18F2 bound to the cell wall surface in acapsular and encapsulated cells. Using mAb 18F2 and previously generated antibodies to GXM and GalXM we have established the localization of three capsular components GXM, GalXM and one type of mannoprotein, MP98 on the C. neoformans cell. The results show that MP98, like GalXM, is found near the cell wall and this information allows us to begin to discern the geography of the cryptococcal capsule.
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Affiliation(s)
- Magdia De Jesus
- Department of Microbiology & Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
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Extracellular vesicles from Cryptococcus neoformans modulate macrophage functions. Infect Immun 2010; 78:1601-9. [PMID: 20145096 DOI: 10.1128/iai.01171-09] [Citation(s) in RCA: 185] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cryptococcus neoformans and distantly related fungal species release extracellular vesicles that traverse the cell wall and contain a varied assortment of components, some of which have been associated with virulence. Previous studies have suggested that these extracellular vesicles are produced in vitro and during animal infection, but the role of vesicular secretion during the interaction of fungi with host cells remains unknown. In this report, we demonstrate by fluorescence microscopy that mammalian macrophages can incorporate extracellular vesicles produced by C. neoformans. Incubation of cryptococcal vesicles with murine macrophages resulted in increased levels of extracellular tumor necrosis factor alpha (TNF-alpha), interleukin-10 (IL-10), and transforming growth factor beta (TGF-beta). Vesicle preparations also resulted in a dose-dependent stimulation of nitric oxide production by phagocytes, suggesting that vesicle components stimulate macrophages to produce antimicrobial compounds. Treated macrophages were more effective at killing C. neoformans yeast. Our results indicate that the extracellular vesicles of C. neoformans can stimulate macrophage function, apparently activating these phagocytic cells to enhance their antimicrobial activity. These results establish that cryptococcal vesicles are biologically active.
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Grijpstra J, Tefsen B, van Die I, de Cock H. The Cryptococcus neoformans cap10 and cap59 mutant strains, affected in glucuronoxylomannan synthesis, differentially activate human dendritic cells. ACTA ACUST UNITED AC 2009; 57:142-50. [PMID: 19694810 DOI: 10.1111/j.1574-695x.2009.00587.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The human pathogen Cryptococcus neoformans causes meningo-encephalitis. The polysaccharide capsule is one of the main virulence factors and consists of two distinct polysaccharides: glucuronoxylomannan and galactoxylomannan. The presence of this polysaccharide capsule was previously shown to interfere with maturation of human dendritic cells (DCs), possibly by shielding cell-wall components from interacting with these host immune cells. Here we show that two mutant strains of C. neoformans, both lacking a visible capsule due to a defect in glucuronoxylomannan synthesis, differentially activate human monocyte-derived DCs. Cells from a cap59 mutant, but not of a cap10 mutant strain, induce maturation of DCs as indicated by an increase in the expression of the costimulatory molecules CD80 and CD86, and production of the cytokines interleukin (IL)-10, IL-12p40 and tumor necrosis factor alpha. Interestingly, cap59 mutant cells reassociated with a concentrated culture medium of wild-type C. neoformans had lost their capacity to induce DC maturation. Summarizing, our data suggest that glucuronoxylomannan confers properties to the capsule that protect the fungus against activation of DCs; however, the presence of intact glucuronoxylomannan is not an absolute requirement to prevent activation of DCs.
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Affiliation(s)
- Jan Grijpstra
- Department of Biology, Microbiology, Institute of Biomembranes, Faculty of Science, Utrecht University, Utrecht, The Netherlands
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The capsule of the fungal pathogen Cryptococcus neoformans. ADVANCES IN APPLIED MICROBIOLOGY 2009; 68:133-216. [PMID: 19426855 DOI: 10.1016/s0065-2164(09)01204-0] [Citation(s) in RCA: 321] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The capsule of the fungal pathogen Cryptococcus neoformans has been studied extensively in recent decades and a large body of information is now available to the scientific community. Well-known aspects of the capsule include its structure, antigenic properties and its function as a virulence factor. The capsule is composed primarily of two polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), in addition to a smaller proportion of mannoproteins (MPs). Most of the studies on the composition of the capsule have focused on GXM, which comprises more than 90% of the capsule's polysaccharide mass. It is GalXM, however, that is of particular scientific interest because of its immunological properties. The molecular structure of these polysaccharides is very complex and has not yet been fully elucidated. Both GXM and GalXM are high molecular mass polymers with the mass of GXM equaling roughly 10 times that of GalXM. Recent findings suggest, however, that the actual molecular weight might be different to what it has traditionally been thought to be. In addition to their structural roles in the polysaccharide capsule, these molecules have been associated with many deleterious effects on the immune response. Capsular components are therefore considered key virulence determinants in C. neoformans, which has motivated their use in vaccines and made them targets for monoclonal antibody treatments. In this review, we will provide an update on the current knowledge of the C. neoformans capsule, covering aspects related to its structure, synthesis and particularly, its role as a virulence factor.
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Production of extracellular polysaccharides by CAP mutants of Cryptococcus neoformans. EUKARYOTIC CELL 2009; 8:1165-73. [PMID: 19542308 DOI: 10.1128/ec.00013-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The human pathogen Cryptococcus neoformans causes meningoencephalitis. The polysaccharide capsule is one of the main virulence factors and consists of two distinct polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM). How capsular polysaccharides are synthesized, transported, and assembled is largely unknown. Previously, it was shown that mutations in the CAP10, CAP59, CAP60, and CAP64 genes result in an acapsular phenotype. Here, it is shown that these acapsular mutants do secrete GalXM and GXM-like polymers. GXM and GalXM antibodies specifically reacted with whole cells and the growth medium of the wild type and CAP mutants, indicating that the capsule polysaccharides adhere to the cell wall and are shed into the environment. These polysaccharides were purified from the medium, either with or without anion-exchange chromatography. Monosaccharide analysis of polysaccharide fractions by gas-liquid chromatography/mass spectrometry showed that wild-type cells secrete both GalXM and GXM. The CAP mutants, on the other hand, were shown to secrete GalXM and GXM-like polymers. Notably, the GalXM polymers were shown to contain glucuronic acid. One-dimensional (1)H nuclear magnetic resonance confirmed that the CAP mutants secrete GalXM and also showed the presence of O-acetylated polymers. This is the first time it is shown that CAP mutants secrete GXM-like polymers in addition to GalXM. The small amount of this GXM-like polymer, 1 to 5% of the total amount of secreted polysaccharides, may explain the acapsular phenotype.
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Maxson ME, Dadachova E, Casadevall A, Zaragoza O. Radial mass density, charge, and epitope distribution in the Cryptococcus neoformans capsule. EUKARYOTIC CELL 2006; 6:95-109. [PMID: 17114596 PMCID: PMC1800357 DOI: 10.1128/ec.00306-06] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Exposure of Cryptococcus neoformans cells to gamma radiation results in a gradual release of capsular polysaccharide, in a dose-dependent manner. This method allows the systematic exploration of different capsular regions. Using this methodology, capsule density was determined to change according to the radial distribution of glucuronoxylomannan and total polysaccharide, becoming denser at the inner regions of the capsule. Scanning electron microscopy of cells following gamma radiation treatment confirmed this finding. The zeta potential of the capsule also increased as the capsule size decreased. However, neither charge nor density differences were correlated with any change in sugar composition (xylose, mannose, and glucuronic acid) in the different capsular regions, since the proportions of these sugars remained constant throughout the capsule. Analysis of the capsular antigenic properties by monoclonal antibody binding and Scatchard analysis revealed fluctuations in the binding affinity within the capsule but not in the number of antibody binding sites, suggesting that the spatial organization of high- and low-affinity epitopes within the capsule changed according to radial position. Finally, evidence is presented that the structure of the capsule changes with capsule age, since the capsule of older cells became more resistant to gamma radiation-induced ablation. In summary, the capsule of C. neoformans is heterogeneous in its spatial distribution and changes with age. Furthermore, our results suggest several mechanisms by which the capsule may protect the fungal cell against exogenous environmental factors.
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Affiliation(s)
- Michelle E Maxson
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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Bose I, Reese AJ, Ory JJ, Janbon G, Doering TL. A yeast under cover: the capsule of Cryptococcus neoformans. EUKARYOTIC CELL 2003; 2:655-63. [PMID: 12912884 PMCID: PMC178345 DOI: 10.1128/ec.2.4.655-663.2003] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Indrani Bose
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Dugger KO, Galgiani JN, Ampel NM, Sun SH, Magee DM, Harrison J, Law JH. An immunoreactive apoglycoprotein purified from Coccidioides immitis. Infect Immun 1991; 59:2245-51. [PMID: 2050396 PMCID: PMC258002 DOI: 10.1128/iai.59.7.2245-2251.1991] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Deglycosylation of glycoproteins in a lysate of spherules of Coccidioides immitis has permitted purification and partial characterization of a proline-rich pronase-sensitive antigen. Moreover, soluble antigen specifically stimulated lymphocytes from persons with dermal delayed-type hypersensitivity to coccidioidal antigens. When related to reference coccidioidin by tandem two-dimensional immunoelectrophoresis, the antigen fused in the anodal region with a specific reference antigen (antigen 2). It did not show identity with coccidioidal antigens used in conventional serologic assays. Although immunoblots of the purified protein with monospecific rabbit antiserum showed a single antigen at 33 kDa, the parent spherule lysate bound the same antibody in a broad band between 70 and greater than 200 kDa, which could be explained by microheterogeneity of glycosylation. Immunoelectron microscopy using affinity-purified human antibodies localized the antigen to the cell wall and internal septa of spherules. These findings suggest that the apoglycoprotein may be important in human immune responses to coccidioidal infection.
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Affiliation(s)
- K O Dugger
- Medical and Research Services, Veterans Affairs Medical Center, Tucson 85723
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Cole GT, Seshan KR, Franco M, Bukownik E, Sun SH, Hearn VM. Isolation and morphology of an immunoreactive outer wall fraction produced by spherules of Coccidioides immitis. Infect Immun 1988; 56:2686-94. [PMID: 3138180 PMCID: PMC259630 DOI: 10.1128/iai.56.10.2686-2694.1988] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
A previously undescribed, immunoreactive, membranous spherule outer wall (SOW) fraction produced by Coccidioides immitis (strains 634 and 735) grown in culture was isolated. Both this fraction and intact spherules were reactive with sera from coccidioidomycosis patients, as demonstrated by immunofluorescence microscopy. The serological activity of SOW was also demonstrated by its reactivity with human anti-C. immitis tube precipitin in a standardized immunodiffusion assay. Extraction of SOW with the nonionic detergent N-octyl-beta-D-glucopyranoside (OG) permitted the isolation of an OG-soluble fraction which was reactive in the immunodiffusion assay. Rabbit antisera raised against the OG-soluble fraction were used in immunofluorescence and immunoelectron-microscopic studies of the parasitic cycle to confirm that the immunoreactive components of the solubilized fraction of SOW were associated with the inner and outer layers of the spherule wall as well as with distinct cytoplasmic organelles observed in thin sections of spherules. The immunoreactivity of SOW with sera from patients suggested that infected individuals are exposed to this surface wall material isolated from in vitro-grown spherules.
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Affiliation(s)
- G T Cole
- Department of Botany, University of Texas, Austin 78713-7640
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15
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Galgiani JN, Dugger KO, Ampel NM, Sun SH, Law JH. Extraction of serologic and delayed hypersensitivity antigens from spherules of Coccidioides immitis. Diagn Microbiol Infect Dis 1988; 11:65-80. [PMID: 3147833 DOI: 10.1016/0732-8893(88)90075-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have used an aqueous toluene extraction procedure to obtain antigens from mature spherules of Coccidioides immitis. This extract contained many antigens as determined by immunoblotting and two-dimensional immunoelectrophoretic studies. These included antigens with specificity for tube precipitin-type antibodies having molecular weights greater than or equal to 100 KDa. The extract also displayed lymphocyte-transforming activity when tested on human peripheral blood mononuclear leukocytes from donors who react to coccidioidal skin tests but elicited no such stimulation of cells from persons whose coccidioidal skin tests were nonreactive. At high concentrations of the extract, lymphocyte transformation did not occur, a finding that could not be explained by nonspecific toxicity. When gel filtration was employed to separate antigens by size, tube precipitin-like activity and specific coccidioidal delayed-type hypersensitivity displayed overlap, although only the latter activity was apparent in lower molecular weight pools.
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Affiliation(s)
- J N Galgiani
- Medical Service, VA Medical Center, Tucson, AZ 85723
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Cherniak R, Jones RG, Reiss E. Structure determination of Cryptococcus neoformans serotype A-variant glucuronoxylomannan by 13C-n.m.r. spectroscopy. Carbohydr Res 1988; 172:113-38. [PMID: 3280130 DOI: 10.1016/s0008-6215(00)90846-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A series of polysaccharides was derived by physical and chemical methods from an antigenic, O-acetyl-containing, glucuronoxylomannan (GXM), isolated from the growth medium of Cryptococcus neoformans (CDC B2550) serotype A-variant having composition ratios of Man:Xyl:GlcA:OAc = 10:4:3:6. 13C-N.m.r. spectra of derivatives provided new structural evidence for GXM. Treatment of GXM with Li in ethylenediamine gave a xylomannan (XM, with Man:Xyl = 5:2). Smith degradation of XM gave a mannan (M). Ultrasonic treatment of GXM gave GXM-sonicated (GXMS). Treatment of GXM with 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide.HCl and then with NaBH4 gave reduced GXMS (RGXMS), or with aq. trifluoroacetic acid gave partially acid-hydrolyzed GXMS. Periodate oxidation of GXM and NaBH4 reduction of the product gave a polyalcohol-mannan (PM). Treatment of GXMS, RGXMS, and PM with NH4OH at pH 11 gave the respective O-deacetylated analogs. Comparison among the 13C-n.m.r. spectra of GXM, the various derivatives, and reference monosaccharides allowed the following conclusions: M is (1----3)-alpha-D-mannopyranan; XM consists of the M backbone with 91% of the Xyl on nonadjacent Man residues as 2-O-beta-D-Xylp substituents and with 9% as 4-O-D-Xylp substituents on other Man residues. GXM consists of the XM structure, but with non-D-xylosylated Man residues substituted with 2-O-beta-D-GlcpA substituents and with 6-O-acetyl groups distributed approximately equally on Man residues that have other substituents and those that have none. The molecular mechanics program MM2 was used to estimate the relative energies of anomeric orientations of the typical glycosidic linkage in M. The results suggest that 6'-OH----O-2 H-bonding is significant in the minimal-energy orientation of M, with phi = -36 degrees and psi = 51 degrees, and that two other glycosidic orientations may be important in the 2-O- or 6-O-substituted derivatives of M.
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Affiliation(s)
- R Cherniak
- Department of Chemistry, Georgia State University, Atlanta 30303
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Cole GT, Kirkland TN, Sun SH. An immunoreactive, water-soluble conidial wall fraction of Coccidioides immitis. Infect Immun 1987; 55:657-67. [PMID: 3102379 PMCID: PMC260390 DOI: 10.1128/iai.55.3.657-667.1987] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Arthroconidia stripped of their outer, hydrophobic wall layer release an immunoreactive, water-soluble fraction (SCWF), the composition of which is examined in this paper. The immunogenicity of SCWF was determined by its reactivity with anti-Coccidioides immitis complement-fixing antibody and tube precipitin antibody in a standardized immunodiffusion assay as well as reactivity in a lymphocyte proliferation assay. SCWF was shown to be more immunoreactive for immune lymphocytes than selected cytosol and culture supernatant fractions of C. immitis. Rabbit antisera raised against SCWF were used in immunoelectron-microscopic and immunofluorescence studies to confirm that the immunoreactive components of SCWF are primarily associated with the inner conidial wall. The antigenic composition of the conidial wall fraction was characterized by advancing-line immunoelectrophoresis with the previously established coccidioidin reference system. Protein composition was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Chromatographic fractionation of SCWF was performed on a Sephacryl S-300 preparative column. Selected fractions which showed significantly higher immunoreactivity and less complex antigenic composition than whole SCWF were characterized. Two heat-sensitive antigens of Sephacryl fraction 3a were identified. One or both of these antigens may correspond to the complement-fixing antigen, which is potentially important as an immunodiagnostic antigen. Fraction 4 contained a previously described wall-associated antigen (AgCS) which may also be of immunodiagnostic value. We conclude that the conidial envelope is a reservoir of immunoreactive macromolecules which may play significant roles in early stages of infection.
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Dromer F, Salamero J, Contrepois A, Carbon C, Yeni P. Production, characterization, and antibody specificity of a mouse monoclonal antibody reactive with Cryptococcus neoformans capsular polysaccharide. Infect Immun 1987; 55:742-8. [PMID: 3546139 PMCID: PMC260404 DOI: 10.1128/iai.55.3.742-748.1987] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Two monoclonal immunoglobulin G1 antibodies reacting with Cryptococcus neoformans capsular polysaccharide (CNPS) were produced in mice by using a carefully defined procedure for immunization with unmodified CNPS purified from C. neoformans serotype A. Since the antibodies were found to have the same pattern of specificity, only one of them (E1) is described. This anti-CNPS monoclonal antibody reacted with the glucuronoxylomannan component of CNPS but not with the constituent monosaccharides or with the mannose alpha(1----3)-linked oligosaccharide structures present on CNPS. E1 appeared to be specific for C. neoformans serotype A by agglutination of whole cells; it was specific for soluble CNPS A by gel immunoprecipitation. However, indirect immunofluorescence and competitive-binding enzyme-linked immunosorbent assay experiments showed low levels of cross-reactivity with serotypes B and D but not with serotype C. Concentrations 10,000 times higher for serotypes B and D cells than for serotype A cells were required for a 50% inhibition of E1 anti-CNPS A activity as measured by enzyme-linked immunosorbent assay. Among the other yeasts tested, a cross-reaction was only detected with Trichosporon beigelii. The four serotypes of C. neoformans could be distinguished based on intensities and patterns of fluorescence in an indirect immunofluorescence assay using the monoclonal anti-CNPS A antibody. Monoclonal anti-CNPS A antibodies could be useful for fundamental studies on the glucuronoxylomannan structure, as well as for clinical applications such as serotyping and possibly the serological diagnosis of cryptococcosis.
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Cox RA, Britt LA, Michael RA. Isolation of Coccidioides immitis F antigen by immunoaffinity chromatography with monospecific antiserum. Infect Immun 1987; 55:227-32. [PMID: 3098685 PMCID: PMC260307 DOI: 10.1128/iai.55.1.227-232.1987] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Detection of antibody to Coccidioides immitis F antigen is of proved value in the diagnosis of coccidioidomycosis. This antibody is demonstrable by use of an immunodiffusion assay with reference coccidioidin antigen and antiserum to C. immitis. Using a combination of lectin affinity and immunoaffinity chromatography, we isolated the F antigen from coccidioidin and prepared monospecific antibody to the purified antigen. The availability of these reagents will enable the development of a sensitive and specific assay for detecting serologic reactivity to this antigen.
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Miyakawa Y, Kagaya K, Fukazawa Y, Soe G. Production and characterization of agglutinating monoclonal antibodies against predominant antigenic factors for Candida albicans. J Clin Microbiol 1986; 23:881-6. [PMID: 3519660 PMCID: PMC268742 DOI: 10.1128/jcm.23.5.881-886.1986] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Two clones, CA4-2 and CA5-4, which produced agglutinating monoclonal immunoglobulin M (IgM) antibodies (MAbs) against mannan antigens of Candida albicans serotype A, were established. The specificity of each MAb was determined by slide agglutination tests for cross-reactivity patterns against the homologous and six other strains of Candida and a strain of Torulopsis: C. albicans serotype B, C. tropicalis, C. guilliermondii, C. krusei, C. parapsilosis, C. pseudotropicalis, and Torulopsis glabrata. The MAb produced by CA4-2 reacted with the homologous, C. tropicalis, and T. glabrata strains, whereas the MAb produced by CA5-4 reacted with the homologous, C. albicans serotype B, and C. tropicalis strains. These results are consistent with results obtained by comparative experiments with several strains of each serotype or species. Specificity of these two MAbs by agglutination was also consistent with the cross-reactivity patterns demonstrated by indirect immunofluorescence staining. The competitive binding experiments by immunofluorescence staining with two MAbs and polyclonal factor sera (PAb factors) 5 and 6 suggested that the MAb from clone CA4-2 did not completely correspond to PAb factor 6 and that the MAb from CA5-4 was distinct from PAb factor 5 in its manner of binding to determinants (the latter was designated 5b), Cross-reactivity patterns, however, furnished evidence that these two MAbs could replace the known PAb factors 6 and 5, respectively, as reagents for aid in the identification of the strains of C. albicans and their serotypes.
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