title: K2 killer toxin-induced physiological changes in the yeast Saccharomyces cerevisiae.
abstract: Saccharomyces cerevisiae cells produce killer toxins, such as K1, K2 and K28, that can modulate the growth of other yeasts giving advantage for the killer strains. Here we focused on the physiological changes induced by K2 toxin on a non-toxin-producing yeast strain as well as K1, K2 and K28 killer strains. Potentiometric measurements were adjusted to observe that K2 toxin immediately acts on the sensitive cells leading to membrane permeability. This correlated with reduced respiration activity, lowered intracellular ATP content and decrease in cell viability. However, we did not detect any significant ATP leakage from the cells treated by killer toxin K2. Strains producing heterologous toxins K1 and K28 were less sensitive to K2 than the non-toxin producing one suggesting partial cross-protection between the different killer systems. This phenomenon may be connected to the observed differences in respiratory activities of the killer strains and the non-toxin-producing strain at low pH. This might also have practical consequences in wine industry; both as beneficial ones in controlling contaminating yeasts and non-beneficial ones causing sluggish fermentation.
authors.affiliation: Department of Biochemistry, Vytautas Magnus University, Vileikos g. 8, Kaunas 44404, Lithuania.
authors.forename: Irma
authors.initials: I
authors.lastname: Orentaite
authors.affiliation: Department of Biosciences, University of Helsinki, Viikinkaari 9, Helsinki 00014, Finland.
authors.forename: Minna M
authors.initials: MM
authors.lastname: Poranen
authors.affiliation: Department of Biosciences, University of Helsinki, Viikinkaari 9, Helsinki 00014, Finland Institute of Biotechnology, University of Helsinki, Viikinkaari 9, Helsinki 00014, Finland.
authors.forename: Hanna M
authors.initials: HM
authors.lastname: Oksanen
authors.affiliation: Department of Biochemistry, Vytautas Magnus University, Vileikos g. 8, Kaunas 44404, Lithuania.
authors.forename: Rimantas
authors.initials: R
authors.lastname: Daugelavicius
authors.affiliation: Department of Biosciences, University of Helsinki, Viikinkaari 9, Helsinki 00014, Finland Institute of Biotechnology, University of Helsinki, Viikinkaari 9, Helsinki 00014, Finland dennis.bamford@helsinki.fi.
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Bamford
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis; D002462:Cell Membrane / Q000187:drug effects* / Q000502:physiology*; D055646:Killer Factors, Yeast / Q000633:toxicity*; D050296:Microbial Viability / Q000187:drug effects; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010539:Permeability / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*
chemical_list: C073585:K2 killer toxin; D055646:Killer Factors, Yeast; D000255:Adenosine Triphosphate
keywords: L-A virus; intracellular ATP; phenyldicarbaundecaborane; respiration; yeast killer system