PKA CATALYTIC SUBUNITS LOCALIZE TO P-BODIES UNDER DIFFERENT GROWTH AND STRESS CONDITIONS

TUDISCA, V; MORENO, S.; PORTELA, P

San Miguel de Tucuman, Tucuman, Argentina

Congreso; XLV Reunion Anual de SAIB; 2009

Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular

PKA is a heterotetramer formed by two regulatory (R) and two catalytic (C) subunits. In S.cerevisiae, the R subunit is encoded by the BCY1 gene, and the C subunits are encoded by three genes functionally partly redundant: TPK1, TPK2 and TPK3. We have observed that during stationary phase, Tpk1 and Bcy1 showed cytoplasmatic localization, whereas Tpk2 and Tpk3 were accumulated in cytoplasmatic foci. Co-localization experiments in cells expressing Bcy1-Red1 and Tpk3-GFP during stationary phase showed that Tpk3-containing granules do not contain Bcy1. Colocalization experiments in cells expressing Tpk2-GFP or Tpk3-GFP and Dcp1-RFP or eIF4E-RFP during stationary phase revealed that Tpk2 and pk3 are associated with P-bodies and EGP-bodies. As part of our analysis, we assessed the localization of Tpk3 in response to glucose starvation, middle and high osmotic stress. Removal of glucose from cells in exponential growth or the addition of KCl triggered the accumulation of Tpk3-GFP containing bodies co-localizing with Dcp1-RFP. However, mild stress conditions (NaCl or ethanol), did not induce the Tpk3 accumulation. We observed that neither of the Tpks is required for P-body assembly. However the deletion of TPK3 accelerates Pbody accumulation upon glucose deprivation, suggesting a role in the control of P-body formation.