Antifungal protein PAF severely affects the integrity of the plasma membrane of Aspergillus nidulans and induces an apoptosis-like phenotype.

The small, basic, and cysteine-rich antifungal protein PAF is abundantly secreted into the supernatant by the beta-lactam producer Penicillium chrysogenum. PAF inhibits the growth of various important plant and zoopathogenic filamentous fungi. Previous studies revealed the active internalization of the antifungal protein and the induction of multifactorial detrimental effects, which finally resulted in morphological changes and growth inhibition in target fungi.

Proper folding of the antifungal protein PAF is required for optimal activity.

The Penicillium chrysogenumantifungal protein PAF is secreted into the supernatant after elimination of a preprosequence. PAF is actively internalized into the hyphae of sensitive molds and provokes growth retardation as well as changes in morphology. Thus far, no information is available on the exact mode of action of PAF, nor on the function of its prosequence in protein activity.

Active internalization of the Penicillium chrysogenum antifungal protein PAF in sensitive aspergilli.

The Penicillium chrysogenum antifungal protein PAF inhibits the growth of various filamentous fungi. In this study, PAF was found to localize to the cytoplasm of sensitive aspergilli by indirect immunofluorescence staining. The internalization process required active metabolism and ATP and was prevented by latrunculin B, suggesting an endocytotic mechanism.

Characterization of the Penicillium chrysogenum antifungal protein PAF.

The filamentous fungus Penicillium chrysogenum abundantly secretes the small, highly basic and cysteine-rich protein PAF ( Penicillium antifungal protein). In this study, the antifungal activity of PAF is described. PAF inhibited the growth of a variety of filamentous fungi, including opportunistic human pathogenic and phytopathogenic fungi, whereas bacterial and yeast cells were unaffected.