A prion-like domain of Tpk2 catalytic subunit of Protein Kinase A modulates P-body formation in response to stress in budding yeast

BARRAZA C; SOLARI C; RINALDI J; OJEDA L; ROSSI S; ASHE M; PORTELA P

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH

ELSEVIER SCIENCE BV

Año: 2021 vol. 1868

0167-4889

Low complexity regions are involved in the assembly and disassembly of P-bodies (PBs).Saccharomyces cerevisiae contains three genes encoding the protein kinase A (PKA) catalyticsubunit: TPK1, TPK2 and TPK3. Tpk2 and Tpk3 isoforms localize to PBs upon glucose starvationshowing different mechanisms and kinetics of accumulation. In contrast to the other two isoforms,Tpk2 harbours a glutamine-rich prion-like domain (PrLD) at the N-terminus. Here we show that theappearance of Tpk2 foci in response to glucose starvation, heat stress or stationary phase wasdependent on its PrLD. Moreover, the PrLD of Tpk2 was necessary for efficient PB and stressgranule aggregation during stress conditions and in quiescent cells. Deletion of PrLD does not affectthe in vitro and in vivo kinase activity of Tpk2 or its interaction with the regulatory subunit Bcy1.We present evidence that the PrLD of Tpk2 serves as a scaffold domain for PB assembly in a mannerthat is independent of Pat1 phosphorylation by PKA. In addition, a mutant strain where Tpk2 lacksPrLD showed a decrease of turnover of mRNA during glucose starvation. This work thereforeprovides new insight into the mechanism of stress-induced cytoplasmic mRNP assembly, and therole of isoform specific domains in the regulation of PKA catalytic subunit specificity and dynamiclocalization to cytoplasmic RNPs granules.