Transcription regulation of PKA subunits in Saccharomyces cerevisiae under heat shock

PAUTASSO, CONSTANZA; CAÑONERO, LUCIANA; ROSSI, SILVIA

Mendoza, Mendoza

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Yeast respond to environmental changes by transduction cascades that in general allow regulating gene expression. The aim of this work is to contribute to the knowledge of the cAMP/PKA pathway in S.cerevisiae, studying the expression regulation of PKA catalytic and regulatory subunits, TPK1, TPK2 and TPK3, and BCY1, under stress conditions. Using TPKs-LacZ and BCY1-LacZ fusion genes, we found that the activity level of TPK1 and Bcy1 promoters occurred near the diaxic-shift. In contrast, TPK2 and Bcy1 promoters activities were higher at the beginning of the log phase. We also demonstrated that there is a mechanism of negative autoregulation on PKA subunits expression that involves a PKA signaling in an isoform specific way. Under heat and saline stress conditions TPK1 showed an increment in its promoter activity, while TPK2, TPK3 and BCY1 remained constant. Studies with several deletion mutants involved in the stress signal transduction pathway showed differences among promoters. TPK1 and BCY1 were positively regulated by Rim15 and Gis1, TPK1 was also positively regulated by Yak1 and Msn2/4. Results of ChIP assay s showed the presence of Msn2 and Gis1, in the TPK1 promoter transcriptionally active. Any of these factors are regulators of TPK2 and TPK3 promoters. These results were confirmed by mRNAs quantification.