Zymocin, a composite chitinase and tRNase killer toxin from yeast

Abstract

Growth inhibition of Saccharomyces cerevisiae by the plasmid-encoded trimeric (αβγ) zymocin toxin from dairy yeast, Kluyveromyces lactis, depends on a multistep response pathway in budding yeast. Following early processes that mediate cell-surface contact by the chitinase α-subunit of zymocin, later steps enable import of the γ-toxin tRNase subunit and cleavage of target tRNAs that carry modified U34 (wobble uridine) bases. With the emergence of zymocin-like toxins, continued zymocin research is expected to yield new insights into the evolution of yeast pathosystems and their lethal modes of action.