Glutamine and glutamate synthetase are modified by oxidation in nodules of soybean plants treated with cadmium

BALESTRASSE KB; GALLEGO SM; TOMARO ML

Pinamar-Argentina

Congreso; X PABMB Congress- XLI Annual Meeting of the Argentinean Society for Biochemistry and Molecular Biology Research; 2005

SAIB

Cadmium causes oxidative damage and hence affects nitrogen assimilation. In the present work we tested the relationship between the inactivation of the enzymes involved in nitrogen assimilation pathway (glutamine synthetase (GS)/ glutamate synthase (GOGAT)) and the protein oxidation in nodules of soybean (Glycine max L.) plants under Cd2+ stress. Therefore, the effect of Cd2+ and reduced gluthatione (GSH) on GS and GOGAT activities, and protein abundance and oxidation were analyzed. Under the metal treatment, aminoacids oxidative modification occurred, evidenced by the accumulation of carbonylated proteins, especially those of high molecular weight. When Cd2+ was present in the nutrient solution, although a decrease in GS and GOGAT activities was observed (17% and 52%, respectively, compared to controls), the protein abundance of both enzymes remained similar to control nodules. When GSH was added together with Cd2+ in the nutrient medium, it protected the nodule against cadmium induced oxidative damage, maintaining GS and GOGAT activities close to control values. These results allows us to conclude that the inactivation of the nitrogen assimilation pathway by cadmium in soybean nodules is due to an increment in GS and GOGAT oxidation that can be prevented by the soluble antioxidant GSH