Role of the GATA factors Gln3p and Nil1p of Saccharomyces cerevisiae in the expression of nitrogen-regulated genes.

Abstract

We have isolated the NILI gene, whose product is an activator of the transcription of nitrogen-regulated genes, by virtue of the homology of its zinc-finger domain to that of the previously identified activator, the product of GLN3. Disruption of the chromosomal NILI gene enabled us to compare the effects of Gln3p and of Nillp on the expression of the nitrogen-regulated genes GLN1, GDH2, and GAP), coding respectively for glutamine synthetase, NAD-linked glutamate dehydrogenase, and general amino acid permease. Our results show that the nature of GATAAG sequences that serve as the upstream activation sequence elements for these genes determines their abilities to respond to Gln3p and Nillp. The results further indicate that Gln3p is inactivated by an increase in the intracellular concentration of glutamine and that Nillp is inactivated by an increase in intracellular glutamate.The presence of glutamine in the growth medium of Saccharomyces cerevisiae prevents the expression of GLN] and of GDH2, the structural genes for glutamine synthetase and the NADI-linked glutamate dehydrogenase (1). In a medium containing glutamate as a source of nitrogen, the expression of these genes requires the product of GLN3, Gln3p, a protein containing a zinc finger domain homologous to that of GATA factors of avian and mammalian cells, capable of binding to the sequences 5'-GATAAGATAAG-3' and 5'-GATTAGAT-TAG-3' located upstream of GLN1 and GDH2, respectively (1, 2). Deletion of these sequences greatly reduces the expression of these genes. The sequence 5'-GATAA-3' is also found upstream of other nitrogen-regulated genes and is apparently responsible for the activation of the expression of these genes by Gln3p. Another protein, the product of URE2, disables Gln3p in response to an increase in the intracellular concentration of glutamine. Mutants lacking Ure2p express Gln3p-activated genes in the presence of glutamine (1).Among the genes whose transcription can be activated by Gln3p is GAP], the structural gene for the general amino acid permease. This gene is not expressed in media containing glutamine, and the lack of Gln3p greatly diminished its expression in a medium containing glutamate as the source of nitrogen. Nevertheless, the lack of Gln3p did not prevent strong expression of GAP1 in media containing ammonia or urea as source of nitrogen. Apparently, a transcription factor other than Gln3p, which we have named Nillp, is responsible for the activation of transcription of GAP] in media containing these sources of nitrogen (3). Elimination of Ure2p enabled Gln3p, but not Nillp, to activate the transcription of GAP1 in the presence of glutamine (4).Examination of the DNA sequence revealed the presence of five GATAAG sequences within the 650-bp region preceding the translational start site of GAP1. This region was analyzed by making partial deletions from the 5' and 3' ends, fusing the remainder to CYCl-lacZ, and examining the 3-galactosidase levels in wild-type and gln3 mutant cells carrying plasmids containing these fusi...

N-Acetylglucosamine-inducible CaGAP1 encodes a general amino acid permease which co-ordinates external nitrogen source response and morphogenesis in Candida albicans

“…GAATAG/GATA-type sequences which are the binding target of the transcription factor Gln3p were also found in the GAP1 promoter of S. cerevisiae (Miller & Magasanik, 1991). TTGGT or TTGTT plays an auxiliary role in activation of nitrogen-regulated genes by Gln3p (Stanbrough et al, 1995). Another transcription factor, Cph1p/Acprp of C. albicans, a homologue of Ste12p of S. cerevisiae, binds to a heptamer sequence, TGAAACA, referred to as a pheromone responsive element (PRE).…”

“…proline, the amino acid uptake is high (Blinder et al, 1996;Courchesne et al, 1983). In S. cerevisiae, at least five proteins (Ure2p, Dal80p, Gln3p, Nil1p and Nil2p) function co-ordinately to control the transcription of GAP1 (Blinder et al, 1996;Cunningham et al, 1993;Rowen et al, 1997;Stanbrough et al, 1995). The nitrogendependent regulation of GAP1 is complex, occurring not only at the level of GAP1 transcription but also through Gap1p sorting and degradation by ubiquitin-triggered internalization (Springael et al, 1998).…”

Gzf3p, a fourth GATA factor involved in nitrogen‐regulated transcription in Saccharomyces cerevisiae

“…Several independent reports have shown that nitrogen-repression-sensitive transcription of some genes is not entirely Gln3p-dependent (Coffman et a/., 1995;. More recently, a second GATA factor has been discovered, encoded by the NIL 71 GAT7 gene, which is responsible for this Gln3p-independent, nitrogen-repression-sensitive expression (Stanbrough et a/., 1995;Coffman ef a/., 1996). Transcription of the nitrogen-sensitive GAP1 gene encoding general amino acid permease (Jauniaux and Grenson, 1990) is under the positive control of both Gln3p and Nillp.…”

“…In both gln3A and nil7A single mutants, expression of GAP7 remains high on media where the nitrogen source is poor, but it is abolished in the gln3A nil7A double mutant (Stanbrough et a/., 1995;Coffman et al, 1996). Analysis of the single mutants suggested that expression supported by Gln3p alone might be inhibited by high intracellular concentrations of glutamine, Nil1 p-dependent transcription being inhibited by high intracellular glutamate (Stanbrough et a/., 1995). The GATA factor encoded by the UGA431 DALBO gene (Cunningham and Cooper, 1991 ;Coornaert et a/., 1992) was isolated because mutations in this gene cause constitutive expression of inducible genes involved in allantoin (Chilsholm and Cooper, 1982) or y-aminobutyrate (Vissers et a/., 1989) utilization.…”

Hap2-3-5-Gln3 determine transcriptional activation of GDH1 and ASN1 under repressive nitrogen conditions in the yeast Saccharomyces cerevisiae

“…Conversely, in the presence of high-quality nitrogen sources such as glutamine, a decrease in the levels of catabolic enzymes is observed. The reduced expression of the genes coding for enzymes involved in the utilization of poor nitrogen sources is brought about through the action of a regulatory system known as nitrogen catabolite repression (NCR) (Blinder & Magasanik, 1995;Coffman et al, 1995Coffman et al, , 1996Courchesne & Magasanik, 1988;Minehart & Magasanik, 1991) NCR operates through the action of two transcriptional activators, Gln3 and Nil1/ Gat1, and two repressors, Dal80 and Gzf3/Deh1/Nil2 (Minehart & Magasanik, 1991;Stanbrough et al, 1995;Svetlov & Cooper, 1998;Magasanik & Kaiser, 2002), whose expression is regulated by nitrogen levels. In the presence of repressive nitrogen sources, the TOR signalling pathway promotes the association of the GATA transcription factors Gln3 and Gat1 with the cytoplasmic protein Ure2, thus retaining Gln3 and Gat1 in the cytoplasm (Beck & Hall, 1999;Cardenas et al, 1999;Hardwick et al, 1999).…”