Identification, N-terminal region sequencing and similarity analysis of differentially expressed proteins in Paracoccidioides brasiliensis

Paracoccidioides brasiliensis is the causal agent of paracoccidioidomycosis , which is a systemic mycosis in Latin America. This human pathogen is a di morphic fungus existing as mycelium (26 degrees C) and in infected tissues as a yeast form (36 degrees C). The in vitro differentiation process is rev ersible and dependent on temperature shift. In the present study, the total proteins from both forms of P. brasiliensis (isolate Pb01) were analysed b y two-dimensional electrophoresis. Differentially expressed proteins were i dentified. Two of these proteins, PbM46 (mycelium) and PbY20 (yeast), were submitted to automated protein sequencing of their N-terminal regions. The 15 amino acid residue sequence of PbM46, AITKIFALKVYDSSG, is similar to eno lases from several sources, and specially those from Saccharomyces cerevisi ae (80%) and Candida albicans (67%), when compared to the NR database at NC BI using the BLASTP program. The 34 amino acid residue sequence of PbY20, A PKIAIVFYS-LYGHIQKLAEAQKKGIEAAGGTAD, could probably represent an allergen pr otein since it is very similar (90%) to the minor allergen protein of Alter naria alternata and 82% similar to the allergen protein of Cladosporium her barum. This comparative analysis of proteins from mycelium and yeast forms has allowed the identification and characterization of differentially expre ssed proteins, probably related to differential gene expression in P. brasi liensis.