Enhanced activity of galactono-1,4-lactone dehydrogenase and ascorbate–glutathione cycle in mitochondria from complex III deficient Arabidopsis

• DOI: 10.1016/j.plaphy.2011.04.013
• Publication Date: 2011-05-10T00:21:26Z
• Authors: Laura Zsigmond; Bálint Tomasskovics; Veronika Deák; Gábor Rigó; László Szabados; Gábor Bánhegyi; András Szarka
• Keywords: 0106 biological sciences; Oxidoreductases Acting on CH-CH Group Donors; Arabidopsis Proteins; Cell Respiration; Arabidopsis; Ascorbic Acid; Dehydroascorbic Acid; Glutathione; 01 natural sciences; Antioxidants; Mitochondria; Electron Transport Complex III; Ascorbate Peroxidases; Glutathione Reductase; Mutation; NADH, NADPH Oxidoreductases

The mitochondrial antioxidant homeostasis was investigated in Arabidopsis ppr40-1 mutant, which presents a block of electron flow at complex III. The activity of the ascorbate biosynthetic enzyme, L-galactono-1,4-lactone dehydrogenase (EC 1.3.2.3) (GLDH) was elevated in mitochondria isolated from mutant plants. In addition increased activities of the enzymes of Foyer-Halliwell-Asada cycle and elevated glutathione (GSH) level were observed in the mutant mitochondria. Lower ascorbate and ascorbate plus dehydroascorbate contents were detected at both cellular and mitochondrial level. Moreover, the more oxidized mitochondrial redox status of ascorbate in the ppr40-1 mutant indicated that neither the enhanced activity of GLDH nor Foyer-Halliwell-Asada cycle could compensate for the enhanced ascorbate consumption in the absence of a functional respiratory chain.