INVESTIGADORES
MORENO Silvia Margarita
congresos y reuniones científicas
Título:
Study of the interaction between the R and C subunits of the protein kinase A in the fungus Mucor circinelloides
Autor/es:
OCAMPO, J., GONZALEZ POLO, V., MORENO, S. AND ROSSI, S
Lugar:
Iguazu, Misiones
Reunión:
Congreso; XL Reunion Anual de SAIB; 2004
Institución organizadora:
SAIB
Resumen:
Protein kinase A is a tetramer composed of a dimer of regulatory subunits (R) and two monomeric catalytic subunits (C). In the holoenzyme C interacts with the pseudosubstrate site in R. This pseudosubstrate site and additional contact sites in R render an affinity in the nanomolar range. The affinities between R and C subunits ofPKA are quite different depending on the specie, finding the highest values in Mrouxii and Mcircinel/oides. Our hypothesis is that in the amino-termini region of R subunits exist elements that interact with C subunits that are responsible for the different affinity. The wild type R subunit and two mutant Rl that lacks the N-terminal and R2 that lacks an acidic residues region were cloned and expressed in a S.cerevisiae strain tpk2" tpk3' bcyl' (133). Western-blot analysis and measurement of cAMP binding activity showed that the different R subunits can be expressed and are functional in yeast. Determinations of kinase activity in crude extracts have been made in the strain expressing_ wt R, RI and R2. The total PKA activity is increased in the three expressing strains as compared with the control one 133. The PKA activity ratio determined measuring the activity with and without cAMP was I in the 133 strain and 0.17-0.25 in the strains that expressed the different R. In vivo analysis of a phenotype associated with cAMP-PKA signaling pathway , glycogen accumulation, showed that the expressing R strains have a phenotype which is associated with a inactivation ofPKA. These results indicates that The wt R, R 1 and R2 subunits of M.circinel/oides expressed in S.cerevisiae are functional and interact with tpkl.