New insights on the posttranslational regulation of aldose-6-phosphate reductase: orchestrating carbon flux across glucitol metabolism

HARTMAN MD; FIGUEROA CM; PIATTONI CV; IGLESIAS AA

Mar del Plata

Congreso; XV Congreso Latinoamericano de Fisiología Vegetal y XXX Reunión Argentina de Fisiología Vegetal; 2014

SAFV

Sucrose is the main sugar translocated between source and sink tissues in most plants. Instead, in plants belonging to the Rosaceae family, glucitol (Gol) is the principal photosynthate produced in leaves and exported to non-photosynthetic tissues. The conversion of glucose-6-phosphate to Gol-6-phosphate is the first reaction within Gol metabolism and is catalyzed by aldose-6-phosphate reductase (Ald-6PRase) in photosynthetically active leaves. In this work we studied the postranslational regulation of this enzyme by redox and phosphorylation mechanisms. We found that oxidant agents (including hydrogen peroxide) were able to inactivate the enzyme and also that ATP (and other NTPs) act as metabolic inhibitors. Also, we could identify Ald-6PRase from peach leaves after IMAC-Fe3+ chromatography, which suggests that this enzyme could be in vivo phosphorylated. Furthermore, a partially purified kinase from leaves was able to phosphorylate Ald-6PRase in vitro (in agreement with the IMAC-Fe3+ results), although the effect produced by phosphorylation is still unknown. Altogether our results indicate that Ald-6PRasa could be in vivo modified at the posttranslational level and that the first step on Gol metabolism would be finely regulated by redox and phosphorylation mechanisms.