International Congress on Yeasts edition:12 location:Kiev, Ukrain date:11-15 August 2008
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Spontaneous conversion of soluble proteins into amorphous aggregates and amyloid fibrils is a major issue in today’s biology and medicine, since the cytotoxic properties of such aggregates appear to be associated with a number of human pathological conditions.
Following a reverse approach, we intend to test the possibility to induce in vivo aggregation of fungal-specific proteins, thereby obtaining functional protein knock-outs, in order to control the growth and/or pathogenicity of Candida albicans.
C. albicans is the most common human fungal pathogen. Infections from this dimorphic fungus range from superficial to life-threatening, systemic mycoses in immunocompromised individuals. Treatments against C. albicans with the commonly available antifungals are hampered by the frequent onset of resistance of the fungus or by intrinsic toxicity of the drugs (amphotericin B). Furthermore, C. albicans has the ability to form highly-structured biofilms with intrinsic resistance to antifungals.
We selected short peptides from different fungal proteins using TANGO, a statistical mechanics algorithm predicting propensity to aggregation, and tested their ability to trigger aggregation of the corresponding native proteins upon overexpression.
After proof-of-principle experiments in baker’s yeast, encouraging, although preliminary, results were obtained in Candida albicans. Expression of a 17-mer peptide from Gsc1p, an essential integral plasma-membrane protein with 1,3-β-glucan synthase activity, caused a dramatic negative effect on the growth of C. albicans.
Expression of an 8-mer peptide from Als3p, a GPI-anchored cell wall adhesin important for biofilm formation, fused to Gfp caused the appearance of aggregated Gfp clumps inside the fungal cells. Investigations on the proficiency of these cells to form biofilms are currently under investigation.
Expression of an 8-mer peptide from Tps2p, a cytoplasmic protein with trehalose-6-phosphate phosphatase activity, caused sensitivity to high temperature; accumulation of trehalose-6 phosphate in these cells is also under investigation.