ISOLATION AND GENETIC-CHARACTERIZATION OF PGKL KILLER-INSENSITIVE MUTANTS (IKI) FROM SACCHAROMYCES-CEREVISIAE

The linear double stranded DNA plasmid pGKL1 encodes the yeast killer toxin complex (Gunge et al., 1981) of which the killing mechanism is n ot understood, We isolated and characterized eight mutants in Saccharo myces cerevisiae that were insensitive to both the intracellularly exp ressed 28-kDa killer subunit and the native killer toxin complex, Thes e mutations (iki1 through iki5) were all recessive, and classified int o five complementation groups, The iki2 mutation was mapped to a posit ion near the centromere on chromosome XIII. We developed a novel scree ning system to isolate the DNA fragments complementing the iki mutatio ns from a Sccharomyces gene library, and isolated three DNA fragments that complement the iki1, iki3, and iki4 mutations, respectively.