New insights into the regulation of the Saccharomyces cerevisiae UGA4 gene: two parallel pathways participate in carbon-regulated transcription

Abstract

The Saccharomyces cerevisiae UGA4 gene, which encodes the c-aminobutyric acid (GABA) and d-aminolaevulinic acid (ALA) permease, is well known to be regulated by the nitrogen source. Its expression levels are low in the presence of a rich nitrogen source but are higher when a poor nitrogen source is used. In addition, GABA can induce UGA4 expression when cells are grown with proline but not when they are grown with ammonium. Although vast amounts of evidence have been gathered about UGA4 regulation by nitrogen, little is known about its regulation by the carbon source. Using glucose and acetate as rich and poor carbon source respectively, this work aimed to shed light on hitherto unclear aspects of the regulation of this gene. In poor nitrogen conditions, cells grown with acetate were found to have higher UGA4 basal expression levels than those grown with glucose, and did not show UGA4 induction in response to GABA. Analysis of the expression and subcellular localization of the transcription factors that regulate UGA4 as well as partial deletions and site-directed mutations of the UGA4 promoter region suggested that there are two parallel pathways that act in regulating this gene by the carbon source. Furthermore, the results demonstrate the existence of a new factor operating in UGA4 regulation.

Interplay between the transcription factors acting on the GATA- and GABA-responsive elements of Saccharomyces cerevisiae UGA promoters

“…Gln3 transcription factor is important for the transactivation of the UGA4 gene in response to GABA (André et al, 1995;Luzzani et al, 2007), whereas its importance for UGA1 induction is controversial. While Talibi et al (1995) reported a 60 % reduction of UGA1 induction in the absence of Gln3, Daugherty et al (1993) reported that this GATA factor does not participate in UGA1 regulation.…”

Uga3 and Uga35/Dal81 Transcription Factors Regulate UGA4 Transcription in Response to γ-Aminobutyric Acid and Leucine

“…The UAS GABA mut-lacZ fusion gene contains the UGA4 sequence, positions Ϫ583 to ϩ15 with respect to the ATG initiation codon, with an altered UAS GABA element, where the core sequence GCCGGCGGC was replaced by ATTAGTAAT (the changed positions are underlined). All these constructions were previously described by Luzzani et al (33). The UAS GABA del-lacZ fusion gene generated using the strategy described by Strachan and Read (38a) contains the UGA4 sequence, positions Ϫ583 to ϩ15 with respect to the ATG initiation codon, with the sequence GCCGGCGGC deleted from the UAS GABA element.…”

Limited vegetative compatibility as a cause of somatic recombination in Trichoderma pseudokoningii

“…The sequence obtained after amplification with primer P7 has shown higher similarity (78%) to the protein sequence of a gamma-aminobutiric acid (GABA) transport protein of Candida albicans . In Sacharomyces serevisiae , the UGA4 gene, which showed homology to GABA/polyamine transporter gene from C. albicans , encodes the gamma-aminobutyric acid (GABA) and δ-aminolaevulinic acid (ALA) permease and its expression is regulated by the N and C source (31). The UGA4 protein is located at the vacuolar membrane and catalyses the transport of the gamma-aminobutyric acid (GABA) and putrescine (53).…”

“…The UGA4 protein is located at the vacuolar membrane and catalyses the transport of the gamma-aminobutyric acid (GABA) and putrescine (53). The gamma-aminobutyric acid (GABA) transport protein in S. serevisiae supports cell growth with the GABA as the sole N source and, therefore, may also be related to adaptation to starvation (31, 53). It was demonstrated that the expression of the UGA 4 gene is repressed by extracellular amino acids and is mediated by a multicomponent amino acid sensor complex known as SPS sensor, localized at the plasma membrane (34).…”