title: Characterization of a Williopsis saturnus var. mrakii high molecular weight secreted killer toxin with broad-spectrum antimicrobial activity.
abstract: Williopsis saturnus var. mrakii MUCL 41968 secretes a killer toxin (WmKT), which is active against a wide range of pathogens. From the W. saturnus var. mrakii MUCL 41968 culture supernatant a protein of 85 kDa with killer activity was purified to homogeneity. The purified protein was demonstrated to be a killer toxin since it displays the toxin activity and cross-reacts with mAbKT4, a monoclonal antibody that blocks WmKT activity. Its partial amino acid sequencing revealed that WmKT might be related to yeast SUN proteins, but not to other killer toxins described. Immunofluorescence studies using polyclonal antibodies raised against purified WmKT revealed that it acts by binding to the cell surface of sensitive strains. We showed that WmKT is inactive against mutant strains of Saccharomyces cerevisiae deficient in the synthesis of beta-glucans, indicating that these polysaccharides constitute the target of the toxin. WmKT was demonstrated to induce rapid lethal cell permeation, since strong propidium iodide labelling was shown for sensitive strains treated with the killer toxin. These findings indicate that WmKT is a novel killer toxin whose molecular characterization may lead to the development of new wide-spectrum antimicrobial compounds.
authors.affiliation: Département de Microbiologie des Ecosystèmes, IFR17, Institut Pasteur de Lille, 1 rue Calmette, BP 245, 59019 Lille, France. Cyril.Guyard@pasteur-lille.fr
authors.forename: Cyril
authors.initials: C
authors.lastname: Guyard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Séguy
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Cailliez
authors.forename: Hervé
authors.initials: H
authors.lastname: Drobecq
authors.forename: Luciano
authors.initials: L
authors.lastname: Polonelli
authors.forename: Eduardo
authors.initials: E
authors.lastname: Dei-Cas
authors.forename: Annick
authors.initials: A
authors.lastname: Mercenier
authors.forename: Franco D
authors.initials: FD
authors.lastname: Menozzi
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D055646:Killer Factors, Yeast; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009183:Mycotoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D000890:Anti-Infective Agents; D005656:Fungal Proteins; D055646:Killer Factors, Yeast; D009183:Mycotoxins; D029701:Saccharomyces cerevisiae Proteins