CONICET | Buscador de Institutos y Recursos Humanos

Amino acids serve not only as precursors for synthesis of proteins and other metabolites, but also as carbon and nitrogen sources. Yeast cells are able to internalize extracellular amino acids since they possess multiple permeases that facilitate their transport. Amino acid utilization is subjected to several regulatory pathways such as GAAC (General Amino Acid Control), TORC1 and amino acid sensor SPS. These pathways operate in parallel and in a coordinated way to generate the correct transcriptional gene response depending on nutrient availability. The aim of this work was to study the expression levels of two amino acid permeases during aging and to analyse if these nutrient-sensitive pathways are involved in their transcriptional regulation. In particular we focused on the Uga4 and Bap2 permeases, responsible for the uptake of the ɣ-aminobutyric acid (GABA) and the branched-chain amino acids, respectively. We used Saccharomyces cerevisiae mutant strains grown under two dietary conditions (without and with all amino acids), and transcriptional activity was measured. We found that in wild type cells UGA4 expression increases along aging in the two growth conditions used, even in the absence of its inducer, GABA, and the GAAC pathway is partially responsible in maintaining these elevated levels. In contrast, BAP2 expression is low and does not vary along aging in wild type cells grown without amino acids and increases along aging in cells grown with amino acids in a Leu3- and Dal81-dependent way. Further research must be done to understand the differential transcriptional profiles found of the permeases studied and the influence they have on lifespan.