Redox Regulation of Glucitol Dehydrogenase from Peach Fruits

M.D. HARTMAN; C.M. FIGUEROA; A.A. IGLESIAS

Puerto Madryn

Congreso; XLVI Reunión Anual de SAIB; 2010

SAIB

R E D O X R E G U L A T I O N O F G L U C I T O L DEHYDROGENASE FROM PEACH FRUITS Hartman MD, Figueroa CM, IglesiasAA Instituto de Agrobiotecnología del Litoral (UNL-CONICET),  S 3 0 0 0 Z A A S a n t a F e , A r g e n t i n a Glucitol (Gol) is amajor 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. 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.