Q-rich region of Tpk2 catalytic subunit of PKA affects stress response

CARLA E. BARRAZA; ADRIANA C. CAMARANO; CLARA A. SOLARI; PAULA PORTELA

Rosario

Congreso; L Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

It has been previously described that the presence of glutamine-and/or asparragine rich (Q/N-rich) domains in P-bodies (PBs) components promotes their efficient accumulation. Catalytic subunit of cAMP dependent Protein Kinase, TpK2, has a Q-rich region in its N-terminus region that is not present in any of the other isoforms, Tpk1 or Tpk3. We analyze whether the Q-rich region had any effect on the Tpk2 aggregation on PBs in response to stress. In vitro kinase assay of affinity purified samples from a strain expressing Tpk2Bcy1-TAP or tpk2QΔBcy1-TAP shows that deletion of Q-rich region does not affect kinase activity or its interaction with the regulatory subunit Bcy1. However, tpk2QΔ-GFP mutant aggregation to cytoplasmic foci is reduced under glucose starvation, severe heat stress and stationary phase. Stress granules and PBs aggregation are affected during stationary phase in strains expressing tpk2QΔ mutant, whereas only PBs granules formation is reduced during heat-shock or glucose starvation. Since the presence of mRNA foci increases cell survival, we tested cell survival of wild type and tpk2QΔ strains under heat stress. We found that tpk2QΔ mutant increases cell survival. Taken together these data suggest that Tpk2 Q-rich domain might be involved in mechanism assembly of PBs and SGs in a stress type-dependent manner.