Oxalurate induction of multiple URA3 transcripts in Saccharomyces cerevisiae

The URA3 gene from Saccharomyces cerevisiae is localized on a 1.1-kilobase (kb) DNA fragment. By using this fragment as a hybridization probe, we found that oxalurate, a gratuitous inducer of the allantoin degradative system, also serves to induce URA3 specific RNA. This response is restricted to oxalurate; other conditions which bring about high-level synthesis of the allantoin degradative enzymes did not produce the effect. Two classes of RNA (1.0 and 1.5 kb) were found to be oxalurate induced. Both classes are encoded by the URA3 gene, overlap, and probably do not significantly differ at their 5' termini. Northern blot mapping of the transcripts indicated that the 1.5-kb transcript was likely encoded by sequences extending up to 0.5 kb downstream from the 3' terminus of the 1.0-kb transcript. Analysis of the endpoints of the major 1.0-kb URA3 transcript by S1 nuclease mapping revealed the existence of two 5' termini, separated by 5 to 10 nucleotides, and seven 3' termini, separated by 5 to 20 nucleotides each, over a range of about 70 bases.