Molecular cloning and characterization of a cDNA encoding the N-acetyl-β-D-glucosaminidase homologue ofParacoccidioidesbrasiliensis

In silico identification of glycosylphosphatidylinositol-anchored proteins in Paracoccidioides spp

Aim: To predict glycosylphosphatidylinositol (GPI)-anchored proteins in the genome of Paracoccidioides brasiliensis and Paracoccidioides lutzii. Materials & methods: Five different bioinformatics tools were used for predicting GPI-anchored proteins; we considered as GPI-anchored proteins those detected by at least two in silico analysis methods. We also performed the proteomic analysis of P. brasiliensis cell wall by mass spectrometry. Results: Hundred GPI-anchored proteins were predicted in P. brasiliensis and P. lutzii genomes. A series of 57 proteins were classified in functional categories and 43 conserved proteins were reported with unknown functions. Four proteins identified by in silico analyses were also identified in the cell wall proteome. Conclusion: The data obtained in this study are important resources for future research of GPI-anchored proteins in Paracoccidioides spp. to identify targets for new diagnostic tools, drugs and immunological tests.

Paracoccin from Paracoccidioides brasiliensis; purification through affinity with chitin and identification of N-acetyl-beta-D-glucosaminidase activity

The dimorphic fungus Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, the most frequent systemic mycosis in Latin America. Our group has been working with paracoccin, a P. brasiliensis lectin with MM 70 kDa, which is purified by affinity with immobilized N-acetylglucosamine (GlcNAc). Paracoccin has been described to play a role in fungal adhesion to extracellular matrix components and to induce high and persistent levels of TNFalpha and nitric oxide production by macrophages. In the cell wall, paracoccin colocalizes with the beta-1,4-homopolymer of GlcNAc into the budding sites of the P. brasiliensis yeast cell. In this paper we present a protocol for the chitin-affinity purification of paracoccin. This procedure provided higher yields than those achieved by means of the technique based on the affinity of this lectin with GlcNAc and had an impact on downstream assays. SDS-PAGE and Western blot analysis revealed similarities between the N-acetylglucosamine- and chitin-bound fractions, confirmed by MALDI-TOF-MS of trypsinic peptides. Western blot of two-dimensional gel electrophoresis of the yeast extract showed a major spot with M(r) 70,000 and pI approximately 5.63. Moreover, an N-acetyl-beta-D-glucosaminidase activity was reported for paracoccin, thereby providing new insights into the mechanisms that lead to cell wall remodelling and opening new perspectives for its structural characterization.

Functional genome of the human pathogenic fungus Paracoccidioides brasiliensis

Paracoccidioides brasiliensis is a dimorphic and thermo-regulated fungus which is the causative agent of paracoccidioidomycosis, an endemic disease widespread in Latin America. Pathogenicity is assumed to be a consequence of the cellular differentiation process that this fungus undergoes from mycelium to yeast cells during human infection. In an effort to elucidate the molecular mechanisms involved in this process a network of Brazilian laboratories carried out a transcriptome project for both cell types. This review focuses on the data analysis yielding a comprehensive view of the fungal metabolism and the molecular adaptations during dimorphism in P. brasiliensis from analysis of 6022 groups, related to expressed genes, which were generated from both mycelium and yeast phases.