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Characterisation of the anticryptococcal effect of the FC‐1 toxin produced by Filobasidium capsuligenum
Author(s) -
Keszthelyi A.,
Ohkusu M.,
Takeo K.,
Pfeiffer I.,
Litter J.,
Kucsera J.
Publication year - 2006
Publication title -
mycoses
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.13
H-Index - 69
eISSN - 1439-0507
pISSN - 0933-7407
DOI - 10.1111/j.1439-0507.2006.01227.x
Subject(s) - toxin , microbiology and biotechnology , biology , immunology , chemistry
Summary The basidiomycetous yeast Filobasidium capsuligenum produces a killer toxin (FC‐1) which is highly effective against the opportunistic fungal pathogen Cryptococcus neoformans . The aim of this work was to study the effect of the toxin on C. neoformans cells. The sensitivities of strains representing eight molecular subtypes (VNI–IV and VGI–IV) of the C. neoformans species complex, and of an additional 50 clinical and environmental isolates were determined. Analysis of cellular DNA by laser scanning cytometry and fluorescein isothiocyanate (FITC) staining of the toxin‐treated cells revealed that the killing mechanism of FC‐1 is neither cell cycle‐ nor cell wall biosynthesis‐dependent; rather it may act as an ionophoric protein that disrupts the cytoplasmic membrane function. The competition assay results suggest that β ‐1,6‐glucan in the cell wall may provide the binding site for the killer protein. This anticryptococcal toxin has the potential to be applied as a therapeutic agent for the treatment of cryptococcosis.