INVESTIGADORES
ROSSI Silvia Graciela
congresos y reuniones científicas
Título:
Activation of PKA by substrates from Saccharomyces
Autor/es:
SILVIA ROSSI, FIORELLA GALELLO, CONSTANZA PAUTASSO, SILVIA MORENO
Lugar:
San Diego, USA
Reunión:
Congreso; ASBMB Annual Meeting; 2008
Institución organizadora:
ASBMB
Resumen:
Activation of PKA by substrates from Saccharomyces
cerevisiae
cerevisiae
Saccharomyces
cerevisiae
Silvia Rossi, Fiorella Galello, Constanza Pautasso, Silvia Moreno.
Departamento de Química Biológica, Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Buenos Aires,
Argentina
The effectiveness of protein phosphorylation by kinases is believed
to depend on the primary structure of the protein around the
phosphorylation site. Our aim is to assess the best consensus
sequence for yeast Protein kinase A and the participation of the
substrate in yeast holoenzyme activation. We used the proteins
Pyk1, Pyk2 and Nth1, which have been described as PKA
substrates in yeast and have consensus RRXS sequence for PKA
phosphorylation. Five synthetic peptides including the consensus
phosphorylation sequences from these proteins were
phosphorylated in vitro. Three of them behaved as good substrates.
Small differences in peptide sequences resulted in important Km
and Vmax differences. Peptide array was designed to verify the
residues responsible for these differences. The substrate role in the
activation of holoenzyme was also investigated. Activity of
purified PKA in presence of different concentrations of cAMP and
different peptides was assayed. The cAMP A0.5 was different with
each substrate and substrate concentration, indicating that the
primary structure of the substrate plays an important role in the
activation mechanism. The better the substrate the higher the
activation. The activation of PKA was also different when the
activation assays were made using the whole protein as substrate
and compared with the peptide as substrate. Research supported by
UBA, CONICET and ANPCYT grants.