The UGA3‐GLT1 intergenic region constitutes a promoter whose bidirectional nature is determined by chromatin organization in Saccharomyces cerevisiae

• Published in: Molecular microbiology Vol. 59; no. 6; pp. 1790 - 1806
• Main Authors: Ishida, Cecilia, Aranda, Cristina, Valenzuela, Lourdes, Riego, Lina, DeLuna, Alexander, Recillas‐Targa, Félix, Filetici, Patrizia, López‐Revilla, Rubén, González, Alicia
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-03-2006; Blackwell Science; Blackwell Publishing Ltd
• Subjects: Amino Acids - metabolism; Base Sequence; Basic-Leucine Zipper Transcription Factors; Biological and medical sciences; Chromatin; Chromatin - chemistry; Chromatin - metabolism; Consensus Sequence; DNA, Intergenic - genetics; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Fungal; Genomics; Glutamate Synthase (NADH) - genetics; Microbiology; Miscellaneous; Molecular Sequence Data; Mutation; Mycology; Nitrogen - metabolism; Point Mutation; Poly dA-dT - metabolism; Promoter Regions, Genetic - genetics; Regulatory Sequences, Nucleic Acid; Repressor Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Transcription Factors - genetics; Transcription Factors - metabolism; Yeast; Fungi; Chromatin; Yeast; Microbiology; Ascomycetes; Saccharomyces cerevisiae; Thallophyta
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2006.05055.x

Summary
Transcription of an important number of divergent genes of Saccharomyces cerevisiae is controlled by intergenic regions, which constitute factual bidirectional promoters. However, few of such promoters have been characterized in detail. The analysis of the UGA3‐GLT1 intergenic region has provided an interesting model to study the joint action of two global transcriptional activators that had been considered to act independently. Our results show that Gln3p and Gcn4p exert their effect upon cis‐acting elements, which are shared in a bidirectional promoter. Accordingly, when yeast is grown on a low‐quality nitrogen source, or under amino acid deprivation, the expression of both UGA3 and GLT1 is induced through the action of both these global transcriptional modulators that bind to a region of the bidirectional promoter. In addition, we demonstrate that chromatin organization plays a major role in the bidirectional properties of the UGA3‐GLT1 promoter, through the action of an upstream Abf1p‐binding consensus sequence and a polydAdTtract. Mutations in these cis‐elements differentially affect transcription of UGA3 and GLT1, and thus alter the overall relative expression. This is the first example of an intergenic region constituting a promoter whose bidirectional character is determined by chromatin organization.