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

Florentine Marx1, Willibald Salvenmoser, Lydia Kaiserer

  • 1Department of Molecular Biology, Medical University of Innsbruck, Peter-Mayr Strasse 4B/III, 6020 Innsbruck, Austria. florentine.marx@uibk.ac.at

Research in Microbiology
|January 8, 2005
PubMed

Insights

The Penicillium chrysogenum antifungal protein (PAF) requires proper folding to inhibit fungal growth. Studies show that correctly folded PAF, when secreted, effectively halts mold development and alters cell structure, highlighting its importance in antifungal activity.

Area of Science:

  • Mycology
  • Protein Biochemistry
  • Molecular Biology

Background:

  • Penicillium chrysogenum antifungal protein (PAF) is secreted and internalized by sensitive molds, causing growth inhibition and morphological changes.
  • The precise mechanism of PAF action and the role of its prosequence remain largely uncharacterized.

Purpose of the Study:

  • To investigate the effects of secreted PAF, pro-PAF, and mature PAF on Aspergillus nidulans.
  • To elucidate the role of the prosequence and proper folding in PAF's antifungal activity.

Main Methods:

  • Genetic transformation of Aspergillus nidulans with truncated paf-coding sequences under an inducible promoter.
  • Indirect immunofluorescence microscopy for protein localization.
  • Proliferation assays and light microscopy for growth analysis.
  • Transmission electron microscopy for ultrastructural examination.
  • Measurement of carbonylated proteins to assess oxidative stress.

Main Results:

  • Recombinant PAF localization varied based on the expressed form: prepro-PAF concentrated at hyphal tips, while pro-PAF and mature PAF distributed intracellularly.
  • Both secreted prepro-PAF and mature PAF induced significant growth retardation in Aspergillus nidulans.
  • Ultrastructural analysis revealed mitochondrial alterations and elevated oxidative stress in hyphae expressing prepro-PAF.
  • The observed effects of recombinant PAF mimicked those of native PAF.

Conclusions:

  • Proper folding of PAF is essential for its antifungal activity.
  • Secreted PAF effectively inhibits fungal growth, suggesting its potential as an antifungal agent.
  • The prosequence may play a role in protein folding or localization, influencing overall activity.

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