Analysis of the inducer-responsive CAR1 upstream activation sequence (UASI) and the factors required for its operation

Induced production of arginase (CAR1) enzyme activity and steady-state CAR1 mRNA in Saccharomyces cerevisiae requires wild-type ARG80/ARGRI and ARG81/ARGRII gene products. We demonstrate here that these gene products, along with that of the MCM1 gene, are required for the inducer-dependent UAS_I-A, UAS_I-B and UAS_I-C elements to function but they are not required for operation of inducer-independent CAR1 UAS_C1 or UAS_C2M. Through the use of single and multiple point mutations, the CAR1 UAS_I-B and UAS_I-C elements were demonstrated to be at least 23 bp in length. Moreover, simultaneous mutation of both ends of an elements gave stronger phenotypes than mutations at either end. The center of the element was more sensitive to mutation than were the ends.