Influence of Kex1p and Kex2p proteases on the function of Saccharomyces cerevisiae K2 preprotoxin

Abstract

Studies of dependence of Saccharomyces cerevisiae K2 killing and immunity properties modulated by the action of Kex1p and Kex2p enzymes showed that the lack of Kex1p carboxypeptidase 10 times decreased toxin activity, and the deficiency of Kex2p endopeptidase completely removed killing ability. The obtained data confirm requirement of both Kex1p and Kex2p peptidases for functional K2 toxin production. The immunity of mutated strains bearing the K2 killer gene was investigated by evaluating the amount of viable cells subjected to the externally applied K2 toxin. K2-specific immunity was found to be completely independent of the action of Kex1p and slightly dependent on Kex2p functioning, suggesting not only the importance of precursor in resistance formation, but also of toxin involvement. Keywords: Saccharomyces cerevisiae, killer toxin, immunity, Kex1p, Kex2p proteases