Mating-type locus control of killer toxins from Kluyveromyces lactis and Pichia acaciae

• Published in: FEMS yeast research Vol. 6; no. 3; pp. 404 - 413
• Main Authors: Klassen, Roland, Jablonowski, Daniel, Stark, Michael J.R, Schaffrath, Raffael, Meinhardt, Friedhelm
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2006; Oxford University Press
• Subjects: cell cycle; Cell proliferation; Diploids; diploidy; Genes, Mating Type, Fungal; haploidy; Heterozygote; Histone deacetylase; Histone Deacetylase Inhibitors; Histone Deacetylases - genetics; Histone Deacetylases - physiology; killer; Killer Factors, Yeast; Kluyveromyces lactis; Kluyveromyces marxianus var. lactis; linear plasmid; loci; Mating; Mating Factor; Mating types; Mutagenesis, Insertional; Mutants; Mutation; Mycotoxins - toxicity; Peptides - genetics; Peptides - physiology; Pichia; protein subunits; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - physiology; Sexual reproduction; silencing; Silent Information Regulator Proteins, Saccharomyces cerevisiae - genetics; Silent Information Regulator Proteins, Saccharomyces cerevisiae - physiology; Sirtuin 2; Sirtuins - genetics; Sirtuins - physiology; Toxins; Yeast; yeasts; zymocin; zymocin; killer; linear plasmid; silencing
• DOI: 10.1111/j.1567-1364.2005.00006.x
• ISSN: 1567-1356

Killer-toxin complexes produced by Kluyveromyces lactis and Pichia acaciae inhibit cell proliferation of Saccharomyces cerevisiae. Analysis of their actions in haploid MAT[alpha] cells revealed that introduction of the opposite mating-type locus (MATa) significantly suppressed antizymosis. Together with resistance expressed by MATa/MAT[alpha] diploids, the reciprocal action of MATa or MAT[alpha] in haploids of opposite mating types suggests that these killer toxins may be subject to MAT locus control. Congruently, derepressing the silent mating-type loci, HMR and HML, by removing individual components of the histone deacetylase complex Sir1[-]4, either by transposon-tagging or by chemically inactivating the histone deacetylase catalytic subunit Sir2, yields toxin resistance. Consistent with MAT control of toxin action, killer-toxin-insensitive S. cerevisiae mutants (kti) become mating-compromised despite resisting the toxins' cell-cycle effects. Mating inhibition largely depends on the time point of toxin application to the mating mixtures and is less pronounced in Elongator mutants, whose resistance to the toxins' cell-cycle effects is the result of toxin-target process deficiencies. In striking contrast, non-Elongator mutants defective in early-response events such as toxin import/activation hardly recover from toxin-induced mating inhibition. This study reveals a novel effect of yeast killer toxins on mating and sexual reproduction that is independent of their impact on cellular proliferation and cell-cycle progression.