Identification of sialic acids on the cell surface of hyphae and yeast forms of the human pathogen Paracoccidioides brasiliensis

Soares, R

doi:10.1016/0378-1097(93)90483-i

Cited by 5 publications

(9 citation statements)

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“…The carboxyl groups of sialic acids present in glycoproteins and glycolipids also seem to contribute strongly to the negative surface charge (James, 1979; Schauer, 1982). In the current study, treatment of yeast forms of P. brasiliensis with neuraminidase resulted in a significant decrease in the negative surface charge, showing that the carboxyl groups of sialic acids, which amount to 3.6 × 10 6 residues per cell (Soares et al ., 1993), effectively contribute to the electronegative surface charge. The enzymic removal of sialic acid residues was more effective with neuraminidase from Vibrio cholerae (54.2% reduction) than with that from Clostridium perfringens (30.5% reduction), suggesting the occurrence of different sialylated structures.…”

Section: Discussionmentioning

confidence: 60%

“…The few reports available on the occurrence of sialic acids in pathogenic fungi suggested their presence in Sporothrix schenckii (Benchimol et al ., 1979; Alviano et al ., 1982; Oda et al ., 1983), Fonsecaea pedrosoi (Souza et al ., 1986) and Cryptococcus neoformans (Hamilton et al ., 1992). We have previouly shown that both yeast and mycelial forms of P. brasiliensis also expressed surface sialic acid units (Soares et al ., 1993). In the present work we extend these studies to establish a correlation between sialic acids and the exposed cell surface anionogenic groups, determining the nature of the sialylated structures expressed in the yeast phase of P. brasiliensis grown in a chemically defined medium.…”

Section: Introductionmentioning

confidence: 99%

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Anionogenic groups and surface sialoglycoconjugate structures of yeast forms of the human pathogen Paracoccidioides brasiliensis

Soares¹,

Silva-Filho

Rozental

et al. 1998

Microbiology

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The surface anionogenic groups and sialoglycoconjugate structures of Paracoccidioides brasiliensis yeast forms were analysed by cell microelectrophoresis, binding assays with lectins and viral particles, ultrastructural cytochemistry, enzymic digestion and flow cytof luorimetry. P. brasiliensis yeast forms, particularly the budding primordia, reacted strongly with cationized ferritin. Binding assays showed that the reaction with sialic-acid-specif ic Limax flaws lectin (LFA) was distributed over the entire P. brasiliensis cell wall. Treatment of yeast forms with neuraminidase significantly reduced their negative surface charge and LFA labelling, which suggests that sialic acid residues are major anionogenic groups exposed on the P. brasiliensis surface. Furthermore, after neuraminidase treatment, labelling with Arachis hypogaea (peanut) agglutinin increased due to unmasking of subterminal /I-D-galactopyranosyl residues. The sialic acid linkages to galactose are a2,6 and a283 as assessed, respectively, by fungal attachment to M1/5 and M1/5 HS8 strains of influenza A virus and binding of Sambucus niger and Maackia amurensis agglutinins. The d , 6 linkage clearly predominated in both experiments. Flow cytof luorimetry analysis revealed the heterogenicity of P. brasiliensis yeast cell populations, which comprised young and mature budding yeasts. Both express binding sites to LFA and Limulus polyphemus agglutinin.

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Section: Discussionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Anionogenic groups and surface sialoglycoconjugate structures of yeast forms of the human pathogen Paracoccidioides brasiliensis

Soares¹,

Silva-Filho

Rozental

et al. 1998

Microbiology

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“…Alternatively, its presence could be tentatively explained by considering sialic acid as a constituent unit of these macromolecules. Sialic acids have mannosamine as part of its structure (Varki, 1992) and have been detected in fungal cell walls (Alviano et al, 1982;Souza et al, 1986;Soares et al, 1993). According to Parsons (1981), sialic acids are easily decomposed by weak acids, and under the hydrolytic conditions we used mannosamine would be released.…”

Section: Resultsmentioning

confidence: 99%

Amino sugars in fungal melanins and soil humic acids

Coelho¹,

Sacramento²

1997

European J Soil Science

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Humic acids from six Brazilian topsoils (three Latosols and three Podzols) and five soil fungal melanins were hydrolysed and the released amino sugars qualitatively and quantitatively determined by capillary gas-liquid chromatography. Melanins were obtained from liquid culture media, synthesized with nitrate or asparagine as a source of N, of Stachybotrys atra, Aspergillus glaucus, Eurotium echinulatum and Hendersonula toruloidea. Glucosamine (48-60%), galactosamine (39-52%), and traces of mannosamine were detected in all humic acids. The total amino sugar content ranged from 1351 to 2287 mg kg-'. In the fungal melanins analysed, mostly glucosamine (80-99%) and trace to small amounts of galactosamine and mannosamine (

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“…P. brasiliensis mycelia were cultivated in Sabouraud broth with shaking for 7 days at 25 °C. Filamentous cells were collected and washed by filtration as previously described (Soares et al, 1993). S. cerevisiae and C. albicans yeast cells were cultivated for 48 h in Sabouraud broth with shaking, followed by centrifugation and washing.…”

Section: Methodsmentioning

confidence: 99%

A Paracoccidioides brasiliensis glycan shares serologic and functional properties with cryptococcal glucuronoxylomannan

Albuquerque

Cordero

Fonseca

et al. 2012

Fungal Genetics and Biology

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The cell wall of the yeast form of the dimorphic fungus Paracoccidioides brasiliensis is enriched with α1,3-glucans. In Cryptococcus neoformans, α1,3-glucans interact with glucuronoxylomannan (GXM), a hetero polysaccharide that is essential for fungal virulence. In this study, we investigated the occurrence of P. brasiliensis glycans sharing properties with cryptococcal GXM. Protein database searches in P. brasiliensis revealed the presence of sequences homologous to those coding for enzymes involved in the synthesis of GXM and capsular architecture in C. neoformans. In addition, monoclonal antibodies (mAbs) raised to cryptococcal GXM bound to P. brasiliensis cells. Using protocols that were previously established for extraction and analysis of C. neoformans GXM, we recovered a P. brasiliensis glycan fraction composed of mannose and galactose, in addition to small amounts of glucose, xylose and rhamnose. In comparison with the C. neoformans GXM, the P. brasiliensis glycan fraction components had smaller molecular dimensions. The P. brasiliensis components, nevertheless, reacted with different GXM-binding mAbs. Extracellular vesicle fractions of P. brasiliensis also reacted with a GXM-binding mAb, suggesting that the polysaccharide-like molecule is exported to the extracellular space in secretory vesicles. An acapsular mutant of C. neoformans incorporated molecules from the P. brasiliensis extract onto the cell wall, resulting in the formation of surface networks that resembled the cryptococcal capsule. Coating the C. neoformans acapsular mutant with the P. brasiliensis glycan fraction resulted in protection against phagocytosis by murine macrophages. These results suggest that P. brasiliensis and C. neoformans share metabolic pathways required for the synthesis of similar polysaccharides and that P. brasiliensis yeast cell walls have molecules that mimic certain aspects of C. neoformans GXM. These findings are important because they provide additional evidence for the sharing of antigenically similar components across phylogenetically distant fungal species. Since GXM has been shown to be important for the pathogenesis of C. neoformans and to elicit protective antibodies, the finding of similar molecules in P. brasiliensis raises the possibility that these glycans play similar functions in paracoccidiomycosis.

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Identification of sialic acids on the cell surface of hyphae and yeast forms of the human pathogen Paracoccidioides brasiliensis

Cited by 5 publications

References 5 publications

Anionogenic groups and surface sialoglycoconjugate structures of yeast forms of the human pathogen Paracoccidioides brasiliensis

Anionogenic groups and surface sialoglycoconjugate structures of yeast forms of the human pathogen Paracoccidioides brasiliensis

Amino sugars in fungal melanins and soil humic acids

A Paracoccidioides brasiliensis glycan shares serologic and functional properties with cryptococcal glucuronoxylomannan

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