IAL   21557
INSTITUTO DE AGROBIOTECNOLOGIA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Redox regulation of glucitol dehydrogenase from peach fruits
Autor/es:
MATÍAS D. HARTMAN; CARLOS M. FIGUEROA; ALBERTO A. IGLESIAS
Lugar:
Puerto Madryn, Argentina
Reunión:
Congreso; XLVI Reunión Anual de la SAIB; 2010
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y BM
Resumen:
Glucitol (Gol) is a major photosynthate in plants
from the Rosaceae family. This polyol is synthesized in mature leaves and then
translocated to heterotrophic tissues, such as fruits and young leaves, where
it is converted into fructose in a reaction catalyzed by Gol dehydrogenase
(GolDHase, EC 1.1.1.14). Despite the importance of this enzyme for carbon
partitioning in these plants, little is known about its regulation. Therefore,
we cloned the gene encoding for GolDHase from peach (Prunus persica) fruits (PpeGolDHase)
and expressed it in Escherichia coli cells. Kinetic parameters obtained
with the recombinant protein were similar to those reported for the enzyme
purified from apple and pear fruits. PpeGolDHase was inhibited by Cu2+,
Hg2+, Ni2+ and Zn2+, with I0.5
of 0.031, 0.096, 15.8 and 43.9 μM, respectively. Loss of activity was observed
when PpeGolDHase was incubated with diamide, H2O2
and oxidized glutathione (k´´ values were 12.3, 6.93 and 0.086 M-1s-1,
respectively). Interestingly, the activity of the oxidized enzyme was recovered
by reduction with thioredoxin (from E. coli and wheat leaf) and reduced
glutathione. Considering that Gol accumulation has been related with abiotic
stress tolerance, we hypothesized that PpeGolDHase could be inhibited
under oxidative stress, thus maintaining levels of Gol high enough to exert a
protective role as a hydroxyl-radical scavenger.