Induction and Functional Analysis of Two Reduced Nicotinamide Adenine Dinucleotide Phosphate-Dependent Glutathione Peroxidase-Like Proteins in Synechocystis PCC 6803 during the Progression of Oxidative Stress1

AUTOR(ES)
FONTE

American Society of Plant Biologists

RESUMO

Synechocystis PCC 6803 contains two types of glutathione peroxidase-like proteins (GPX-1 and GPX-2) that utilize NADPH but not reduced glutathione and unsaturated fatty acid hydroperoxides or alkyl hydroperoxides. The steady-state transcript level of gpx-1 gradually increased under oxidative stress conditions imposed by high light intensity, high salinity, or application of methylviologen or t-butyl hydroperoxide in the wild-type and GPX-2 knock-out mutant (gpx-2Δ) cells. To examine the ability of GPX-1, GPX-2, and thioredoxin peroxidase to scavenge lipid hydroperoxide in vivo, we measured the photosynthetic evolution of O2 and the level of lipid peroxidation in the wild-type and each type of mutant cell after the application of t-butyl hydroperoxide or H2O2. The data reported here indicate that GPX-1 and GPX-2 are essential for the removal of lipid hydroperoxides under normal and stress conditions, leading to the protection of membrane integrity.

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