Subcellular localization of PKA subunits in Saccharomyces cerevisiae

MORENO S; RECOUVREUX V; PORTELA P

San Diego, California , USA

Congreso; Experimental Biology 2008 -ASBMB; 2008

Ameriican Socienty Biochemistry & Molecular biology

Our aim is to study the complexity of the activation mechanism of PKA in S.cerevisiae focusing on the contribution of specificity of the three different isoforms (Tpk1, Tpk2 and Tpk3) of catalytic subunit in this process. Our data suggest that the specificity of signaling through PKA in yeast could be mediated by a particular subcellular localization of each isoform of Tpk. We found differences in the localization of each Tpk isoform in response to carbon sources and phase of growth. In exponential phase on glucose both Bcy1 and Tpk2 localized in nucleus whereas Tpk1 and Tpk3 showed a mixed pattern nuclearcytoplasmic localization. In exponential phase on glycerol and in stationary phase, the PKA subunits showed an homogeneous cytoplasmatic localization,except Tpk2 and Tpk3 that presented a cytoplasmic punctuate pattern during stationary phase. The re-addition of glucose to cells on stationary phase showed a reduction on the number of cytoplasmatic dots of both Tpk2 and Tpk3, suggesting that this particularly localization is dependent on glucose availability. Additionally, we studied the localization of PKA subunits during osmotic and saline stress. We found that Tpk2 and Bcy1 are exported from the nucleus in response to osmotic stimulus and that Tpk3 alone is exported from the nucleus in response to saline stress