Functional Characterization of Proteins Involved in Thioredoxin System Operating in Peach Fruit

M.D. HARTMAN; D.G. ARIAS; N. SASONI; C.M. FIGUEROA; A.A. IGLESIAS

Rosario

Congreso; 50th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2014

SAIB

Redox regulation plays a significant role in a wide range of biological processes. Thus, in order to maintain redox equilibrium, cells have developed many compartmentalized enzymatic antioxidant systems. NADPH-dependent thioredoxin reductases (NTRs) are regulatory enzymes determining the redox state of thioredoxins (TRXs): once reduced, TRX is able to reduce target proteins. We cloned the genes coding for NTR (PpeNTR) and cytosolic TRX (PpeTRXh) in peach fruit and purified the recombinant proteins. PpeNTR was unable to directly reduce the chemical DTNB, but in presence of recombinant PpeTRXh the system was fully active (with a maximum at pH 7.5). Interestingly, NADPH and NADH were used as electron donor with a similar catalytic efficiency. PpeNTR showed a high catalytic efficiency for reducing the homologous PpeTRXh but the ability to reduce the ortholog E. coli NTR was significantly lower. The capacity of PpeNTR to catalyze the reversible transference of reduction equivalents a thermodynamic coherence between the calculated reduction potential of PpeNTR, the corresponding potential for PpeTRXhsystem for the transference of reduction equivalents in plants.