THE LINEAR-PLASMID-ENCODED TOXIN PRODUCED BY THE YEAST PICHIA-ACACIAE- CHARACTERIZATION AND COMPARISON WITH THE TOXIN OF KLUYVEROMYCES-LACTIS

The toxin produced by Pichia acaciae was purified and its properties c ompared to those of the toxin from Kluyveromyces lactis. Like this tox in, the P. acaciae toxin is a protein comprised of three subunits (mol ecular masses 110, 39 and 38 kDa) with an associated chitinase activit y and a pH optimum between 7.0 and 7.5 P. acaciae toxin also caused G1 cell cycle arrest. Of the thirteen recessive alleles that provided re sistance in Saccharomyces cerevisiae to K. lactis toxin, only three al so conferred resistance to P. acaciae toxin. Similarities and differen ces in the interactions of the two toxins with yeast cells are discuss ed.