A permease exhibiting a dual role for lysine and biotin uptake in Saccharomyces cerevisiae

Among Saccharomyces cerevisiae strains each defective in one of 11 amino ac id permeases, a lysine permease disruptant (DK) exhibited about 2-fold redu ctions in maximum cell density and fermentation ability compared to the par ent in a synthetic medium. These unusual properties of DK were found to res ult from the requirement of biotin for growth, in contrast to the parent wh ose growth was not dependent on external biotin. The rate of C-14-labeled b iotin uptake and the intracellular free biotin content of DK were 2-2.5 fol d lower than in the parent. We suggest that lysine permease in S. cerevisia e has the ability to transport both lysine and biotin.