title: The antifungal properties of a 2S albumin-homologous protein from passion fruit seeds involve plasma membrane permeabilization and ultrastructural alterations in yeast cells.
abstract: Different types of antimicrobial proteins were purified from plant seeds, including chitinases, β-1,3-glucanases, defensins, thionins, lipid transfer proteins and 2S albumins. It has become clear that these groups of proteins play an important role in the protection of plants from microbial infection. Recent results from our laboratory have shown that the defense-related proteins from passion fruit seeds, named Pf1 and Pf2 (which show sequence homology with 2S albumins), inhibit fungal growth and glucose-stimulated acidification of the medium by Saccharomyces cerevisiae cells. The aim of this study was to determine whether 2S albumins from passion fruit seeds induce plasma membrane permeabilization and cause morphological alterations in yeast cells. Initially, we used an assay based on the uptake of SYTOX Green, an organic compound that fluoresces upon 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 a probable impairment of fungal metabolism. The microscopical analysis of the yeast cells treated with 2S albumins demonstrated several morphological alterations in cell shape, cell surface, cell wall and bud formation, as well as in the organization of intracellular organelles.
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Agizzio
authors.affiliation: Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil.
authors.forename: Maura
authors.initials: M
authors.lastname: Da Cunha
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil.
authors.forename: André O
authors.initials: AO
authors.lastname: Carvalho
authors.affiliation: Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil; Universidade do Vale do Paraíba, Instituto de Pesquisa e Desenvolvimento, Urbanova, Sao Jose dos Campos, SP, Brasil.
authors.forename: Marco Antônio
authors.initials: MA
authors.lastname: Oliveira
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil.
authors.forename: Suzanna F F
authors.initials: SF
authors.lastname: Ribeiro
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil. Electronic address: valmg@uenf.br.
authors.forename: Valdirene M
authors.initials: VM
authors.lastname: Gomes
keywords: 2S albumins; Antifungal protein; Fungal cell wall; Membrane permeabilization; Saccharomyces cerevisiae