Different protein kinase C isoforms are present in the yeast and mycelium forms of Sporothrix schenckii.

Protein kinase C (PKC) plays an important role in the control of proliferation and differentiation of a wide range of cell types, and fungi are no exception. Previous results reported by us on the effects of the phorbol ester, 12-myristate-13-acetate phorbol (PMA) and other PKC effector molecules, on dimorphism in Sporothrix schenckii suggested the presence of this enzyme in the fungus and its involvement in the control of morphogenetic transitions. The work summarized here confirms the presence of PKC in yeast and mycelium extracts of S. schenckii. Different isoforms of this enzyme were found to be present in the yeast and mycelium forms of the fungus and were identified by Western blot analysis using affinity purified anti-PKC isoforms specific antibodies: the gamma and zeta isoforms were detected in both the yeast and mycelium forms of the fungus, while the beta isoform was only detected in the yeast form. The presence of PKC was confirmed biochemically by measuring total enzyme activity in both forms of the fungus. No significant differences were observed for the PKC activity level recorded for both the mycelium and yeast forms of the fungus (p < or = 0.05). These data confirm the presence of PKC activity in Sporothrix schenckii and constitutes the first evidence concerning the differential expression of PKC isoforms in the mycelium and yeast forms of a dimorphic fungus, supporting the possible involvement of this important signal transduction enzyme in the control of morphogenesis in this fungus.