CEFOBI   05405
CENTRO DE ESTUDIOS FOTOSINTETICOS Y BIOQUIMICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
¨Analysis of the intraction of subunits of NADP malic enzyes of maize
Autor/es:
SAIGO, M; ROMERO, MA; DRINCOVICH, M.F.; ANDREO, C.S.
Lugar:
TUCUMAN
Reunión:
Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular, SAIB; 2009
Resumen:
Maize NADP-ME protein family has long being studied due to the
essential role of one of the isoforms in carbon fixation (ZmME1).
Even though the sequences in maize are well conserved, the
photosynthetic isoform (ZmME1) is more closely related to a
plastidic enzyme associated with housekeeping functions
(ZmME2). Both isoforms have been extensively compared with
regard to their kinetics and structural features. Besides the kinetic
parameters, the oligomeric states also differ, while ZmME1
aggregates in the form of tetramers, ZmME2 remains as dimers in
solution. Artificially generated chimerical structures allowed us to
identify a region that strongly affects the quaternary structure of
these enzymes. Moreover, we identified in silico some residues
candidates to be involved in the assembly and stabilization of the
tetramer. The aim of this work was to study the contribution of these
residues to the basic kinetic parameters and the quaternary
structure. In this regard, we replaced five residues in ZmME2 by the
analogs found in ZmME1 by site-directed mutagenesis. The
modified proteins were characterized by kinetic analysis and
migration in non-denaturing PAGE. The results show that some
single replacements had little or no effects on the structure, while
two residues had major effects which indicate their involvement in
the dimer assembly.