Fungal Glucosylceramides: From Structural Components to Biologically Active Targets of New Antimicrobials

The first work reporting synthesis of glucosylceramide (cerebrin, GlcCer) by yeasts was published in 1930. During approximately 70 years members of this class of glycosphingolipids (GSL) were considered merely structural components of plasma membrane in fungi. However, in the last decade GlcCer was reported to be involved with fungal growth, differentiation, virulence, immunogenicity, and lipid raft architecture in at least two human pathogens. Fungal GlcCer are structurally distinct from their mammalian counterparts and enriched at the cell wall, which makes this molecule an effective target for antifungal activity of specific ligands (peptides and antibodies to GlcCer). Therefore, GSL are promising targets for new drugs to combat fungal diseases. This review discusses the most recent information on biosynthesis and role of GlcCer in fungal pathogens

Gomesin, a peptide produced by the spider Acanthoscurria gomesiana, is a potent anticryptococcal agent that acts in synergism with fluconazole

Gomesin is an 18-residue cysteine-rich antimicrobial peptide produced by hemocytes of the spider Acanthoscurria gomesiana. in the present study, the antifungal properties of gomesin against Cryptococcus neoformans, the etiologic agent of cryptococcosis, were evaluated. Gomesin bound to the cell surface of cryptococci, which resulted in cell death associated with membrane permeabilization. Antifungal concentrations of gomesin were not toxic for human brain cells. Supplementation of cryptococcal cultures with the peptide (1 mu M) caused a decrease in capsule expression and rendered fungal cells more susceptible to killing by human brain phagocytes. the possible use of gomesin in combination with fluconazole, a standard antifungal drug, was also evaluated. in association with fluconazole, gomesin concentrations with low antimicrobial activity (0.1-1 mu M) inhibited fungal growth and enhanced the antimicrobial activity of brain phagocytes. These results reveal the potential of gomesin to promote inhibition of cryptococcal growth directly or by enhancing the effectiveness of host defenses.Univ Fed Rio de Janeiro, Inst Microbiol Prof Paulo Goes, Dept Microbiol Geral, Lab Estudos Integrados Bioquim Microbiana, BR-21941590 Rio de Janeiro, BrazilUniv São Paulo, Inst Ciencias Biomed, Dept Parasitol, BR-05508 São Paulo, BrazilUniv Texas, Dept Biol Sci, El Paso, TX 79968 USAUniversidade Federal de São Paulo, Dept Biofis, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, São Paulo, BrazilWeb of Scienc

Extracellular Vesicle-Associated Transitory Cell Wall Components and Their Impact on the Interaction of Fungi with Host Cells

Submitted by Fabricia Pimenta ([email protected]) on 2018-06-29T18:34:23Z No. of bitstreams: 1 ve_Marcio_Rodrigues_etal_CDTS_2016.pdf: 690221 bytes, checksum: a96164d483123b78f71bffabda9ffa1b (MD5)Approved for entry into archive by Fabricia Pimenta ([email protected]) on 2019-01-11T18:29:02Z (GMT) No. of bitstreams: 1 ve_Marcio_Rodrigues_etal_CDTS_2016.pdf: 690221 bytes, checksum: a96164d483123b78f71bffabda9ffa1b (MD5)Made available in DSpace on 2019-01-11T18:29:02Z (GMT). No. of bitstreams: 1 ve_Marcio_Rodrigues_etal_CDTS_2016.pdf: 690221 bytes, checksum: a96164d483123b78f71bffabda9ffa1b (MD5) Previous issue date: 2016-07-08Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Laboratório de Glicobiologia de Eucariotos. Rio de Janeiro, RJ, Brazil.Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Laboratório de Glicobiologia de Eucariotos. Rio de Janeiro, RJ, Brazil.Stony Brook University. Department of Molecular Genetics and Microbiology. Stony Brook, NY, USA / Veterans Administration Medical Center. Northport, NY, USA.Albert Einstein College of Medicine. Department of Microbiology and Immunology and Medicine. Bronx, NY, USA.Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Laboratório de Glicobiologia de Eucariotos. Rio de Janeiro, RJ, Brazil.Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Laboratório de Glicobiologia de Eucariotos. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Centro de Desenvolvimento Tecnológico em Saúde. Rio de Janeiro, RJ, Brazil / Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de Góes. Laboratório de Glicobiologia de Eucariotos. Rio de Janeiro, RJ, Brazil.Classic cell wall components of fungi comprise the polysaccharides glucans and chitin, in association with glycoproteins and pigments. During the last decade, however, system biology approaches clearly demonstrated that the composition of fungal cell walls include atypical molecules historically associated with intracellular or membrane locations. Elucidation of mechanisms by which many fungal molecules are exported to the extracellular space suggested that these atypical components are transitorily located to the cell wall. The presence of extracellular vesicles (EVs) at the fungal cell wall and in culture supernatants of distinct pathogenic species suggested a highly functional mechanism of molecular export in these organisms. Thus, the passage of EVs through fungal cell walls suggests remarkable molecular diversity and, consequently, a potentially variable influence on the host antifungal response. On the basis of information derived from the proteomic characterization of fungal EVs from the yeasts Cryptoccocus neoformans and Candida albicans and the dimorphic fungi Histoplasma capsulatum and Paracoccidioides brasiliensis, our manuscript is focused on the clear view that the fungal cell wall is much more complex than previously thought

Chitin-Like Molecules Associate with Cryptococcus neoformans Glucuronoxylomannan To Form a Glycan Complex with Previously Unknown Properties

In prior studies, we demonstrated that glucuronoxylomannan (GXM), the major capsular polysaccharide of the fungal pathogen Cryptococcus neoformans, interacts with chitin oligomers at the cell wall-capsule interface. the structural determinants regulating these carbohydrate-carbohydrate interactions, as well as the functions of these structures, have remained unknown. in this study, we demonstrate that glycan complexes composed of chitooligomers and GXM are formed during fungal growth and macrophage infection by C. neoformans. To investigate the required determinants for the assembly of chitin-GXM complexes, we developed a quantitative scanning electron microscopy-based method using different polysaccharide samples as inhibitors of the interaction of chitin with GXM. This assay revealed that chitin-GXM association involves noncovalent bonds and large GXM fibers and depends on the N-acetyl amino group of chitin. Carboxyl and O-acetyl groups of GXM are not required for polysaccharide-polysaccharide interactions. Glycan complex structures composed of cryptococcal GXM and chitin-derived oligomers were tested for their ability to induce pulmonary cytokines in mice. They were significantly more efficient than either GXM or chitin oligomers alone in inducing the production of lung interleukin 10 (IL-10), IL-17, and tumor necrosis factor alpha (TNF-alpha). These results indicate that association of chitin-derived structures with GXM through their N-acetyl amino groups generates glycan complexes with previously unknown properties.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)NIHCenter for AIDS Research at EinsteinUniv Fed Rio de Janeiro, Inst Microbiol Prof Paulo de Goes, Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, Inst Biofis Carlos Chagas Filho, Lab Ultraestrutura Celular Hertha Meyer, BR-21941 Rio de Janeiro, BrazilAlbert Einstein Coll Med, Dept Microbiol & Immunol, Bronx, NY 10467 USAAlbert Einstein Coll Med, Div Infect Dis, Dept Med, Bronx, NY 10467 USAUniversidade Federal de São Paulo, Disciplina Biol Celular, São Paulo, BrazilFiocruz MS, Fundacao Oswaldo Cruz, Ctr Desenvolvimento Tecnol, BR-21045900 Rio de Janeiro, BrazilUniversidade Federal de São Paulo, Disciplina Biol Celular, São Paulo, BrazilNIH: AI033142NIH: AI033774NIH: AI052733NIH: HL059842Web of Scienc

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

The cell wall of the yeast form of the dimorphic fungus Paracoccidioides brasiliensis is enriched with alpha 1,3-glucans. in Cryptococcus neoformans, alpha 1,3-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. (C) 2012 Elsevier Inc. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)NIHCenter for AIDS Research at EinsteinInterhemispheric Research Training Grant in Infectious Diseases, Fogarty International CenterDepartment of EnergyFiocruz MS, CDTS, BR-21040360 Rio de Janeiro, BrazilUniv Fed Rio de Janeiro, Inst Microbiol Prof Paulo de Goes, BR-21941902 Rio de Janeiro, BrazilAlbert Einstein Coll Med, Dept Microbiol & Immunol, Bronx, NY 10461 USAUniversidade Federal de São Paulo, Disciplina Biol Celular, BR-04023062 São Paulo, BrazilUniv Fed Rio de Janeiro, Inst Biofis Carlos Chagas Filho, Lab Ultraestrutura Celular Hertha Meyer, BR-21941903 Rio de Janeiro, BrazilAlbert Einstein Coll Med, Div Infect Dis, Dept Med, Bronx, NY 10461 USAUniversidade Federal de São Paulo, Disciplina Biol Celular, BR-04023062 São Paulo, BrazilNIH: AI033142NIH: AI033774NIH: AI052733NIH: HL059842Interhemispheric Research Training Grant in Infectious Diseases, Fogarty International Center: NIH D43-TW007129Department of Energy: DE-FG-9-93ER-20097Web of Scienc

Lipid droplet levels vary heterogeneously in response to simulated gastrointestinal stresses in different probiotic Saccharomyces cerevisiae strains

AbstractTo exert their therapeutic action, probiotic Saccharomyces cerevisiae strains must survive harsh digestive environments. Lipid droplets accumulate in cells which undergo stress-inducing situations, supposedly having a protective role. We assessed lipid droplet levels, either naturally accumulated or induced in response to digestive challenges, of probiotic strains S. boulardii, S. cerevisiae A-905, S. cerevisiae Sc47 and S. cerevisiae L11, and of non-probiotic strains S. cerevisiae BY4741 and S. cerevisiae BY4743. Strains 905 and Sc47 had lower and higher lipid droplet levels, respectively, when compared to the remaining strains, showing that higher accumulationof these neutral lipids is not a feature shared by all probiotic Saccharomyces strains. When submitted to simulated gastric or bile salts environments, lipid droplet levels increase in all tested probiotic strains, at least for one to the induced stresses, suggesting that lipid droplets participate in the protective mechanisms against gastrointestinal stresses in probiotic Saccharomyces yeasts

Capsules from Pathogenic and Non-Pathogenic Cryptococcus spp. Manifest Significant Differences in Structure and Ability to Protect against Phagocytic Cells

Capsule production is common among bacterial species, but relatively rare in eukaryotic microorganisms. Members of the fungal Cryptococcus genus are known to produce capsules, which are major determinants of virulence in the highly pathogenic species Cryptococcus neoformans and Cryptococcus gattii. Although the lack of virulence of many species of the Cryptococcus genus can be explained solely by the lack of mammalian thermotolerance, it is uncertain whether the capsules from these organisms are comparable to those of the pathogenic cryptococci. In this study, we compared the characteristic of the capsule from the non-pathogenic environmental yeast Cryptococcus liquefaciens with that of C. neoformans. Microscopic observations revealed that C. liquefaciens has a capsule visible in India ink preparations that was also efficiently labeled by three antibodies generated to specific C. neoformans capsular antigens. Capsular polysaccharides of C. liquefaciens were incorporated onto the cell surface of acapsular C. neoformans mutant cells. Polysaccharide composition determinations in combination with confocal microscopy revealed that C. liquefaciens capsule consisted of mannose, xylose, glucose, glucuronic acid, galactose and N-acetylglucosamine. Physical chemical analysis of the C. liquefaciens polysaccharides in comparison with C. neoformans samples revealed significant differences in viscosity, elastic properties and macromolecular structure parameters of polysaccharide solutions such as rigidity, effective diameter, zeta potential and molecular mass, which nevertheless appeared to be characteristics of linear polysaccharides that also comprise capsular polysaccharide of C. neoformans. The environmental yeast, however, showed enhanced susceptibility to the antimicrobial activity of the environmental phagocytes, suggesting that the C. liquefaciens capsular components are insufficient in protecting yeast cells against killing by amoeba. These results suggest that capsular structures in pathogenic Cryptococcus species and environmental species share similar features, but also manifest significant difference that could influence their potential to virulence

Omics Approaches for Understanding Biogenesis, Composition and Functions of Fungal Extracellular Vesicles

This is the final version. Available on open access from Frontiers Media via the DOI in this recordExtracellular vesicles (EVs) are lipid bilayer structures released by organisms from all kingdoms of life. The diverse biogenesis pathways of EVs result in a wide variety of physical properties and functions across different organisms. Fungal EVs were first described in 2007 and different omics approaches have been fundamental to understand their composition, biogenesis, and function. In this review, we discuss the role of omics in elucidating fungal EVs biology. Transcriptomics, proteomics, metabolomics, and lipidomics have each enabled the molecular characterization of fungal EVs, providing evidence that these structures serve a wide array of functions, ranging from key carriers of cell wall biosynthetic machinery to virulence factors. Omics in combination with genetic approaches have been instrumental in determining both biogenesis and cargo loading into EVs. We also discuss how omics technologies are being employed to elucidate the role of EVs in antifungal resistance, disease biomarkers, and their potential use as vaccines. Finally, we review recent advances in analytical technology and multi-omic integration tools, which will help to address key knowledge gaps in EVs biology and translate basic research information into urgently needed clinical applications such as diagnostics, and immuno- and chemotherapies to fungal infections.NIHPacific Northwest National Laboratory (PNNL)CNPq/Science Without Borders Science Program, BrazilJohns Hopkins Malaria Research InstituteFAPESPCAPESCNPqMedical Research Council (MRC