INVESTIGADORES
ROSSI Silvia Graciela
congresos y reuniones científicas
Título:
CRYSTAL STRUCTURE OF THE REGULATORY SUBUNIT
Autor/es:
RINALDI , J., WU, J.,YANG, J., ROSSI, S., MORENO, S., TAYLOR, S
Lugar:
Córdoba, Carlos Paz
Reunión:
Congreso; XLIV Reunión Anual SAIB; 2008
Institución organizadora:
Sociedad Argentina de investigaciones Bioquímicas
Resumen:
SB-C03.
CRYSTAL STRUCTURE OF THE REGULATORY SUBUNIT
OF PKA FROM Saccharomyces cerevisiae
Rinaldi J , Wu J , Yang J , Rossi S , Moreno S , Taylor SS
Departamento de Química Biológica, FCEyN-UBA. Chemistry &
Biochemistry Department, UCSD.CA, USA. E-mail:
jrinaldi@qb.fcen.uba.ar
In mammals, the PKA holoenzyme exists as a complex of two
catalytic subunits and a regulatory (R) subunit dimer. R subunits
have a dimerization and docking domain at the N terminus; at the C
terminus, two tandem cAMP-binding domains and in between a
flexible hinge region, including a substrate-like inhibitor sequence
that docks to the active site cleft of the C subunit. Much effort has
been put in studying structure-function relationships in mammalian
PKAs. The aim of this work is to solve the structure of the R subunit
from Saccharomyces cerevisiae, one of the most intensively studied
eukaryotic model organism in signal transduction. Unlike
mammals, that have been shown to have two major classes of R
subunits (I and II), S. cerevisiae has only one R gene. We overexpressed
and purified different deletion mutants of the protein. The
mutant lacking the first 167 residues was crystallized. We report the
crystal structure of the protein bound to cAMP, which we
determined to 2.20 Å resolution and refined to an R factor of 0,200
with an R free factor of 0,263. The new structure shows two tandem
cAMP binding domains, which relative orientation is different from
the one of mammalian R subunits. The two domains are more tightly
bound to each other. The R subunit from S.cerevisiae represent a
new type of R subunit, as it has different features from RI and RII.