title: Antifungal activity of the ribosome-inactivating protein BE27 from sugar beet (Beta vulgaris L.) against the green mould Penicillium digitatum.
abstract: The ribosome-inactivating protein BE27 from sugar beet (Beta vulgaris L.) leaves is an apoplastic protein induced by signalling compounds, such as hydrogen peroxide and salicylic acid, which has been reported to be involved in defence against viruses. Here, we report that, at a concentration much lower than that present in the apoplast, BE27 displays antifungal activity against the green mould Penicillium digitatum, a necrotrophic fungus that colonizes wounds and grows in the inter- and intracellular spaces of the tissues of several edible plants. BE27 is able to enter into the cytosol and kill fungal cells, thus arresting the growth of the fungus. The mechanism of action seems to involve ribosomal RNA (rRNA) N-glycosylase activity on the sarcin-ricin loop of the major rRNA which inactivates irreversibly the fungal ribosomes, thus inhibiting protein synthesis. We compared the C-terminus of the BE27 structure with antifungal plant defensins and hypothesize that a structural motif composed of an α-helix and a β-hairpin, similar to the γ-core motif of defensins, might contribute to the specific interaction with the fungal plasma membranes, allowing the protein to enter into the cell.
authors.affiliation: Department of Biochemistry and Molecular Biology and Physiology, Faculty of Sciences, University of Valladolid, 47011, Valladolid, Spain.
authors.forename: Lucía
authors.initials: L
authors.lastname: Citores
authors.affiliation: Department of Biochemistry and Molecular Biology and Physiology, Faculty of Sciences, University of Valladolid, 47011, Valladolid, Spain.
authors.forename: Rosario
authors.initials: R
authors.lastname: Iglesias
authors.affiliation: Laboratory of Research on Proteins, Faculty of Exact and Natural Sciences and Surveying, National University of the Northeast (UNNE), 3400, Corrientes, Argentina.
authors.forename: Carolina
authors.initials: C
authors.lastname: Gay
authors.affiliation: Department of Biochemistry and Molecular Biology and Physiology, Faculty of Sciences, University of Valladolid, 47011, Valladolid, Spain.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Ferreras
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000494:pharmacology*; D027461:Beta vulgaris / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology*; D003198:Computer Simulation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010407:Penicillium / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D054788:Ribosome Inactivating Proteins / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D010940:Plant Proteins; D054788:Ribosome Inactivating Proteins
keywords: apoplast; defensin; green mould; plant defence; pokeweed antiviral protein (PAP); polynucleotide:adenosine glycosylase; rRNA N-glycosylase