TRANSCRIPTIONAL AND POST-TRANSCRIPTIONAL REGULATION OF PKA SUBUNITS IN Saccharomyces cerevisiae

PAUTASSO C.; PORTELA P; CAÑONERO L; GALELLO F; ROSSI S

Congreso; LII Reunión Anual SAIB; 2016

LII Reunión Anual SAIB

Protein kinase A (PKA) is a broad specificity protein kinase that controls a physiological response following the increment of cAMP as a consequence of a particular stimulus. The specificity of cAMP-signal transduction is maintained by several levels of control acting simultaneously. One of these control levels is the regulation of the expression of each PKA subunit which is regulated at the activity of their promoters, mRNA levels and posttranscriptional processing as degradation. Stabilities of individual transcripts can be regulated in response to environmental conditions such as rapid shifts to different carbon sources and cellular stress. S.cerevisiae PKA holoenzyme contains two catalytic subunits encoded by TPK1, TPK2 and TPK3 genes, and two regulatory subunits encoded by BCY1 gene. We demonstrate that the promoter of each isoform of TPK and of BCY1 is differentially activated during heat shock stress. TPK1 promoter activity is the only one that is positively regulated during this stress. We also measure the half-lives of yeast PKA TPK1 and BCY1 mRNAs upon heat stress. Both mRNAs have different half-lives, being BCY1 mRNA more stable than TPK1 mRNA. During heat shock, TPK1 and BCY1 mRNAs half-lives increase in comparison with the normal situation. We suggest that the exonuclease Xrn1 is involved in the degradation of both BCY1 and TPK1 mRNA degradation.