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Tetrapisispora phaffii killer toxin is a highly specific β-glucanase that disrupts the integrity of the yeast cell wall

Comitini, Francesca and Mannazzu, Ilaria Maria and Ciani, Maurizio (2009) Tetrapisispora phaffiikiller toxin is a highly specific β-glucanase that disrupts the integrity of the yeast cell wall. Microbial Cell Factories, Vol. 8 (55), p. 1-11. ISSN 1475-2859. Article.

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DOI: 10.1186/1475-2859-8-55

Abstract

Background. Killer yeasts have been used to combat contaminating wild yeasts in food, to control pathogenic fungi in plants, and in the medical field, to develop novel antimycotics for the treatment of human and animal fungal infections. Among these killer yeasts, Tetrapisispora phaffii (formerly known as Kluyveromyces phaffii) secretes a glycoprotein known as Kpkt that is lethal to spoilage yeasts under winemaking conditions. In the present study, the mode of action of Kpkt, and the specific damage produced by this toxin on sensitive yeasts is investigated.
Results. The use of castanospermine, a β-glucanase inhibitor, demonstrated that β-glucanase activity is essential for the Kpkt killer activity in vivo. Accordingly, Kpkt has no killer activity on either sensitive yeast spheroplasts or whole sensitive cells in the presence of isosmothic medium (0.8 molar sorbitol). Kpkt induces ultrastructural modifications in the cell wall of sensitive strains, as shown by confocal microscopy, laser-scanning electron microscopy, and atomic force microscopy. The Kpkt killer action is mediated by the glucidic portion of the toxin. This, in turn, appears to be involved both in the stronger cytocidal activity and in the selectivity for the sensitive strain shown by Kpkt compared to laminarinase.
Conclusion. Collectively, these data indicate that the mode of action of Kpkt is directed towards the disruption of cell-wall integrity, and that this is mediated by a highly specific β-glucanase activity. In this, Kpkt differs from other microbial β-glucanases that do not show killer activities.

Item Type:Article
ID Code:3531
Status:Published
Refereed:Yes
Uncontrolled Keywords:Tetrapisispora phaffii, β-glucanase inhibitor, Kluyveromyces phaffii
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/16 Microbiologia agraria
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze ambientali agrarie e biotecnologie agro-alimentari
Publisher:BioMed Central
ISSN:1475-2859
Deposited On:25 Jan 2010 16:11

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