Allantoin transport in Saccharomyces cerevisiae is regulated by two induction systems

We show that the allantoin transport system of Saccharomyces cerevisiae responds to two induction systems, one mediated by allophanate or its analog oxalurate and the other mediated by allantoin or its analog hydantoin acetate. The effects of the two inducers were additive in strain M85. Like other allantoin pathway genes, oxalurate-mediated induction of allantoin transport required a functional DAL81 gene product. Hydantoin acetate-mediated induction of the system, on the other hand, occurred normally in dal81 mutants. This suggests that induction was not only mediated by two separate inducers, but also involved different regulatory proteins. Induction is probably a transcriptionally regulated process, because addition of hydantoin acetate or oxalurate to the culture medium increased the steady-state levels of mRNA encoded by a gene required for allantoin transport (DAL4).