Life and Medical Sciences
Wiley InterScience Backfile Collection 1832-2000
UASNTR, the UAS responsible for nitrogen catabolite repression-sensitive transcriptional activation of many nitrogen catabolic genes in Saccharomyces cerevisiae, has been previously thought to operate only as a pair of closely related dodecanucleotide sites each containing the sequence GATAA at its core. Here we show that a single UASNTR site is also able to combine with another unrelated cis-acting element to mediate transcription as well. In one instance the unrelated cis-acting element was TTTGTTTAC situated upstream of GLN1, while in another the cis-acting element was the one previously shown to bind the PUT3 protein. When a UASNTR site functions in combination with an unrelated site, the regulatory responses observed are a hybrid consisting of characteristics derived from both the UASNTR site and the unrelated site as well. These observations resolve several significant inconsistencies that have plagued studies focused on elucidation of the mechanisms involved in the global regulation of nitrogen catabolism.
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