Interplay between transcription factors acting on S. cerevisiae UGA genes

CARDILLO SABRINA BEATRIZ; CAROLINA EDITH LEVI; PALAVECINO MARCOS; BERMUDEZ MORETTI MARIANA; CORREA GARCIA SUSANA

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2012

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Gamma-aminobutyric acid (GABA) transport and catabolism in Saccharomyces cerevisiae are subject to a complex transcriptional control that depends on the nutritional status of the cells. The expression of the genes that form the UGA regulon is inducible by GABA and sensitive to Nitrogen Catabolite Repression (NCR). GABA induction of these genes is mediated by Uga3 and Uga35/Dal81 transcription factors whereas GATA factors are responsible for NCR. Here we show that all members of the UGA regulon share the activation mechanism. Our results show that both Uga3 and Uga35/Dal81 interact with UGA genes in a GABA-dependent manner, and that they depend on each other for the interaction with their target promoters and the transcriptional activation. The typical DNA-binding domain Zn(II)2-Cys6 of Uga35/Dal81 is unnecessary for its activity and Uga3 acts as a bridge between Uga35/Dal81 and DNA. The trans-activation activity of the GATA factor Gln3 is exerted by its interaction with UGA promoters in response to GABA, indicating that Uga3, Uga35/Dal81 and Gln3 all act in concert inducing the expression of UGA genes. So, some interplay between the factors responsible for GABA induction and those responsible for NCR in the regulation of the three UGA genes is here proposed.