PARTICIPATION OF RAP1 PROTEIN IN EXPRESSION OF THE SACCHAROMYCES-CEREVISIAE ARGINASE (CAR1) GENE

Regulated expression of the inducible arginase (CAR1) gene of Saccharomyces cerevisiae has been shown to require three upstream activation sequences (UASs) and an upstream repression sequence, URSI. Two of the UAS elements, UAS(C1) and UAS(C2), operate in an inducer-independent manner, while the third, UAS(I), is inducer dependent. UAS(C1) and UAS(C2) were previously shown to contain ABF-1 binding sites that were required for normal transcription. In this work, we demonstrate that UAS(C1) and UAS(C2) also contain two and three sites, respectively, that are able to bind RAP1 protein. RAP1 binding to these sites, however, is significantly weaker than that to sites in TEF2 and HMRE. The effects of mutating the sites individually or in combination suggest that at least three of them, two in UAS(C1) and one in UAS(C2), probably participate in CAR1 expression.