Yarrowia Lipolytica PKA activity varies during growth and with different carbon sources

FLORENCIA KRONBERG; MIGUEL ANGEL GALVAGNO; MARIA SUSANA DI BERNARDO DE PASSERON

Mar del Plata, noviembre 17-20

Congreso; 43 Reunión Anual de la SAIB; 2007

Sociedad Argentina de Investigación Bioquímica y Biologí Molecular

It is known that cAMP/PKA signal transduction pathway regulates physiological processes in fungi including growth, metabolism, stress resistance and cell differentiation. In this study, we analyzed the role of this pathway on growth of Yarrowia lipolytica, a dimorphic yeast of biotechnological and basic interest. We measured PKA specific activity (PKAsa) during growth in different carbon sources. It was found that in dextrose, the activity was low at the exponential phase reaching maximal expression when cells entered the stationary state. At this stage the specific activity was around 2.13 ± 0.05 pmol ug-1 min-1 and was strongly dependent on cAMP (ratio with/without cAMP=15). We also assessed the relationship between PKAsa and growth in different carbon sources. We found that with glycerol PKAsa and the activity profile were similar to the values in dextrose medium, while with hexadecane PKAsa was maximal at the exponential stage, strongly decreasing when cells entered the stationary phase. Finally, we compared the PKAsa of cells growing under normal conditions with that of cells deprived of nitrogen (citric acid production medium). We found that under this stressing condition the PKAsa was two-fold higher compared with that of rich medium. Our results suggest that the cAMP/PKA signaling pathway is involved in the metabolism and stress response in this non conventional yeast.