Differential localization to cytoplasm, nucleus or P-bodies of yeast PKA subunits under different growth conditions

TUDISCA, V; RECOUVREUX, V; MORENO, S; BOY-MARCOTTE, E; JACQUET, M; PORTELA, P.

EUROPEAN JOURNAL OF CELL BIOLOGY

ELSEVIER GMBH

Año: 2009

0171-9335

Our aim in this work was to further characterize the complexity and specificity of the three different isoforms (Tpk1, Tpk2 and Tpk3) of the catalytic and regulatory (Bcy1) subunits of PKA in Saccharomyces cerevisiae. We thus analyzed the subcellular localization of the PKA subunits in living cells by using strains carrying GFP (green fluorescent protein) fused to each PKA subunit. During exponential growth on glucose, both Bcy1 and Tpk2 localized in the nucleus, whereas Tpk1 and Tpk3 showed a mixed pattern of nucleo-cytoplasmic localization. During exponential growth on glycerol and during stationary phase, the PKA subunits showed mostly cytoplasmic localization, with the peculiarity that Tpk2 and Tpk3, were found associated to P-bodies. Tpk2 and Tpk3 were accumulated into P-bodies upon glucose deprivation. Upon hyperosmotic stress, Tpk3, at least localized to P bodies Deletion of Tpk3 affected the kinetics of P-body formation. Analysis of protein expression showed that the relative expression pattern of each Tpk changes from low levels under fermentative metabolism toward higher levels during stationary phase. The increase in Tpk levels produced an imbalance with Bcy1 levels. Our data suggest that the signaling specificity through PKA in yeast could be mediated by a particular subcellular localization of each isoform of Tpk.