Multiple positive and negative cis-acting elements mediate induced arginase (CAR1) gene expression in Saccharomyces cerevisiae.

Expression of the arginase (CAR1) gene in Saccharomyces cerevisiae is induced by arginine or its analog homoarginine. Induction has been previously shown to require a negatively acting upstream repression sequence, which maintains expression of the gene at a low level in the absence of inducer. The objective of this work was to identify the cis-acting elements responsible for CAR1 transcriptional activation and response to inducer. We identified three upstream activation sequences (UASs) that support transcriptional activation in a heterologous expression vector. Two of these UAS elements function in the absence of inducer, whereas the third functions only when inducer is present. One of the inducer-independent UAS elements exhibits significant homology to the Sp1 factor-binding sites identified in simian virus 40 and various mammalian genes.