RETRACTED: The antifungal properties of a 2S albumin-homologous protein from passion fruit seeds involve plasma membrane permeabilization and ultrastructural alterations in yeast cells

摘要

Different types of antimicrobial proteins were purified from plant seeds, including chitinases, b-1,3-glucanases, defensins, thionins, lipidtransfer proteins and 2S albumins. It has become clear that these groups of proteins play an important role in the protection of plants from microbialinfection. Recent results from our laboratory have shown that the defense-related proteins from passion fruit seeds, named Pf1 and Pf2 (which showsequence homology with 2S albumins), inhibit fungal growth and glucose-stimulated acidification of the medium by Saccharomyces cerevisiaecells. The aim of this study was to determine whether 2S albumins from passion fruit seeds induce plasma membrane permeabilization and causemorphological alterations in yeast cells. Initially, we used an assay based on the uptake of SYTOX Green, an organic compound that fluorescesupon interaction with nucleic acids and penetrates cells with compromised plasma membranes, to investigate membrane permeabilization in S.cerevisiae cells. When viewed with a confocal laser microscope, S. cervisiae cells showed strong SYTOX Green fluorescence in the cytosol,especially in the nuclei. 2S albumins also inhibited glucose-stimulated acidification of the medium by S. cerevisiae cells, which indicates aprobable impairment of fungal metabolism. The microscopical analysis of the yeast cells treated with 2S albumins demonstrated severalmorphological alterations in cell shape, cell surface, cell wall and bud formation, as well as in the organization of intracellular organelles.# 2006 Elsevier Ireland Ltd. All rights reserved.