INTERACTION OF PKA IN Saccharomyces cervisiae WITH ITS REGULATED TARGET GENES

BACCARINI, L; MORENO, S.; PORTELA, P

Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunion Anual de SAIB; 2008

Sociedad Argentina de Bioquimica y Biologia Molecular

Regulation of gene expression by intracellular stimulus-activated protein kinases is essential for cell adaptation to environmental changes. There are three PKA catalytic subunits in S.cerevisiae: Tpk1, Tpk2 and Tpk3 and one regulatory subunit: Bcy1. We analyzed gene occupancy profiles from the raw data of a genomewide ChIP-Chip analysis of Tpk1 and Tpk2 during growth on glucose, glycerol and oxidative stress (Pokholok et al Science 313:533, 2006). As described, Tpk1 was physically associated with actively transcribed genes and Tpk2 with the promoters of ribosomal protein genes. Occupancy of Tpk3 was not detected. Additionally, we found from the raw data that both Tpk1 and Tpk2 seem to be simultaneously associated to the same regions of some genes upon fermentative metabolism and oxidative stress. The nuclear co-localization of Bcy1 and Tpks upon environmental conditions in which active PKA is required, directs the question about the role of the regulatory subunit in the nucleus. Using ChIP assays we analyzed the role of Bcy1 in the regulation of gene expression and its function in the association with the target genes of Tpk1 and Tpk2. We found that Bcy1 and Tpk1 are associated in a carbon source-dependent manner while Tpk2 remains constitutively bound to genes. Our data suggest that Bcy1 might participate in gene regulation allowing the positioning of the Tpk near the substrate.