Proteins interacting with protein kinase A from Saccharomyces crevisiae

ROSSI, SILVIA; GALELLO, FIORELLA; GONZALEZ BARDECI, NICOLÁS; MORENO, SILVIA

Congreso; XLVII Reunión anual Sociedad Argentina de SAIB 2011; 2011

SAIB

Subcellular targeting through the association with adaptor and scaffolding proteins has emerged as a key mechanism in signaling specificity. Compartmentalization of cAMP-PKA pathway is maintained by Akinase anchoring proteins (AKAPs) which interact with PKA regulatory subunit (R). PKA AKAPs in mammals are classified in RII, RI or dual specificity. In S.cerevisiae the anchoring of PKAis poorly understood. We have identified proteins that tether the R subunit (Bcy1) from yeast PKA, in vitro and in vivo. The acharacterization of the Bcy1-binding domains showed that although -helices were predicted, they do not show the characteristics of the amphipathic helix of PKA AKAPs. The key residues for the interaction are positively charged residues. These characteristics are shared with RISR (RI Specifier Region) present in dual specificity AKAPs. The amino termini of R subunits constitute the so called D/D domain, responsible for its dimerization and its interaction with anchoring proteins. Chemical crosslinking experiments confirm that Bcy1 exists as a dimer, via its N-terminus. The N-terminus of Bcy1 is necessary for the interaction with the tethering proteins of yeast PKA. The modelling by homology of the N-terminus of Bcy1 shows that it shares with its counterparts the residues important for dimerization but that the exposed surface has characteristics of its own.