Dal81 mediates hierarchical utilization of poor nitrogen sourcen in Saccharomyces cerevisiae

PALAVECINO MARCOS; CORREA GARCÍA SUSANA; BERMÚDEZ MORETTI MARIANA

CABA

Congreso; Reunión de la Sociedad Argentina de Investigaciones en Bioquimica y Biología molecular; 2013

Abstract Dal81 mediates hierarchical utilization of poor nitrogen sources in Saccharomyces cerevisiae Marcos Palavecino, Susana Correa García and Mariana Bermúdez Moretti Departamento de Química Biológica, FCEN, UBA; IQUIBICEN, CONICET. Nitrogen is an essential nutrient for all life forms. The yeast Saccharomyces cerevisiae can use a broad variety of compounds as nitrogen sources. Expression of genes involved in the utilization of poor nitrogen sources is repressed in the presence of rich nitrogen sources. This mechanism has been extensively studied and is known as nitrogen catabolite repression (NCR). Recently, a hierarchical utilization of poor nitrogen sources has been proposed. Dal81/Uga35 is a transcription factor involved in the regulation of genes expressing proteins that participate in the incorporation and metabolism of several poor nitrogen sources such as gamma-aminobutyric acid, urea, allantoin and amino acids. The aim of this work was to determine if there is a hierarchical activation in the use of poor nitrogen sources and to study the role of the transcription factor Dal81 in the establishment of this hierarchy. For this purpose, expression levels of different inducible permeases such as Uga4, Agp1, Bap2, Dal7 and Dur3, and the interaction between Dal81 and the regulatory regions of their genes were measured using RT-qPCR and ChIP assays, respectively. Results clearly show that genes needed for leucine utilization are in a higher level that those for gamma-aminobutyric acid, urea and allantoin and that this hierarchy depends on Dal81.