A gene product needed for induction of allantoin system genes in Saccharomyces cerevisiae but not for their transcriptional activation.

Abstract

The allantoin-degradative pathway of Saccharomyces cerevisiae consists of several genes whose expression is highly induced by the presence of allophanic acid. Induced expression requires a functional DAL81 gene product. Analysis of these genes has demonstrated the presence of three cis-acting elements in the upstream regions: (i) an upstream activation sequence (UAS) required for transcriptional activation in an inducerindependent fashion, (ii) an upstream repression sequence (URS) that mediates inhibition of this transcriptional activation, and (iii) an upstream induction sequence (UIS) needed for a response to inducer. The UIS element mediates inhibition of URS-mediated function when inducer is present. We cloned and characterized the DAL81 gene and identified the element with which it was associated. The gene was found to encode a rare 3.2-kilobase-pair mRNA. The amount of DAL81-specific RNA responded neither to induction nor to nitrogen catabolite repression. Deletion of the DAL81 gene resulted in loss of induction but did not significantly affect basal level expression of the DAL7 and DUR1,2 genes or the UAS and URS functions present in plasmid constructions. These data suggest that (i) transcriptional activation of the DAL genes and their responses to inducer are mediated by different factors and cis-acting sequences and (ii) the UIS functions only when a wild-type DAL81 gene product is available.

Functional Domain Mapping and Subcellular Distribution of Dal82p in Saccharomyces cerevisiae

“…DAL81 and DAL82 were first identified genetically as loci required for growth with allantoin pathway nitrogen sources (31,33). Null mutations in either of the loci result in loss of allophanate-dependent transcription (34,35). Mutations in dal81 or dal82 also result in a significant de-crease in basal level expression of the genes they regulate (35)(36)(37).…”

“…Null mutations in either of the loci result in loss of allophanate-dependent transcription (34,35). Mutations in dal81 or dal82 also result in a significant de-crease in basal level expression of the genes they regulate (35)(36)(37).…”

DAL82, a second gene required for induction of allantoin system gene transcription in Saccharomyces cerevisiae

“…The first distinguishing characteristic was observed in the complementation experiments performed during cloning. Complementation of daI81 mutations by a plasmid-borne gene was always found to be poor regardless of the plasmid copy number (2). In no case was the level of induced urea amidolyase activity in a dal81 mutant strain carrying a complementing plasmid ever greater than the wild-type level (2).…”

“…In this instance, inducer (arginine degraded to allophanate within the cell) exclusion cannot be suggested as an explanation for loss of response in the da182 mutant strain. as the DAL81 product documented previously (2,33 (Difco yeast nitrogen base), glucose-proline medium (PRO), glucose-proline medium containing 0.25 mM oxalurate (PRO + OXLU), or glucose-arginine medium (ARG), the cells were harvested and assayed for ,-galactosidase activity (38). The plasmids used in this experiment have been described in detail earlier (38).…”

“…Mutations at the dal80 locus, which result in 10-to 20-fold overproduction of allantoin pathway enzymes, were also shown not to significantly affect DAL81 expression. A dal81 null mutant, generated by deleting the gene, possessed the same physiological characteristics as the point mutant originally characterized (2). Mutation of a second locus, durMIdal82, was reported to affect urea amidolyase activity and DURl,2-specific mRNA levels in a manner similar to dal81 (15).…”