Role of Tpk2 catalytic subunit of PKA in mRNA aggregation in Saccharomyces cerevisiae

CARLA BARRAZA; CLARA SOLARI; PAULA PORTELA

Congreso; LI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

We previously showed that catalytic subunit of cAMP dependent Protein Kinase, Tpk2, is involved in processing bodies (PBs) and stress granules (SGs) assembly under stress conditions through its Q-rich N-terminal domain and its kinase activity. It has been demonstrated that several mRNAs are localized in granules in actively growing cells and these granules serve as platforms for PBs formation during glucose starvation. Here, we analyze the role of Tpk2 in the formation of PDC1 mRNA granules in quiescent cells, after severe heat shock or glucose starvation. To assess this, we used strains expressing m-Tagged PDC1 mRNA in Tpk2, tpk2QΔ, or tpk2 kinase dead backgrounds. Analyses of polysome profiles during exponential growth, heat stress or quiescence were similar in all strains. During BIOCELL 39 (Suppl. 2) 2015 stationary phase, PDC1 mRNA is localized in granules, which mostly do not co-localize with SGs or PBs. The kinase activity or Q-rich domain of Tpk2 does not affect these granules. Upon re-feeding the total number of PDC1 mRNA granules increases, showing a similar proportion of co-localization with PBs and SGs. Tpk2 Q-rich domain does not have a role in this process, but tpk2 kinase dead strain presented no increase in PDC1 mRNA granules upon refeeding and a higher association with SGs. Reduction of PDC1 mRNA granules after severe heat stress and glucose starvation was dependent on Tpk2 catalytic activity.