Protection against Photooxidative Injury of Tobacco Leaves by 2-Alkenal Reductase. Detoxication of Lipid Peroxide-Derived Reactive Carbonyls

Degradation of lipid peroxides leads to the formation of cytotoxic 2-alkenals and oxenes (collectively designated reactive carbonyls). The novel NADPH-dependent oxidoreductase 2-alkenal reductase (AER; EC 1.3.1.74) from Arabidopsis (Arabidopsis thaliana), which is encoded by the gene At5g16970, cata...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 2005-12, Vol.139 (4), p.1773-1783
Main Authors: Mano, Junichi, Belles-Boix, Enric, Babiychuk, Elena, Inze, Dirk, Torii, Yoshimitsu, Hiraoka, Eiji, Takimoto, Koichi, Slooten, Luit, Asada, Kozi, Kushnir, Sergei
Format: Article
Language:English
Subjects:
2-alkenal reductase
Aldehydes
Base Sequence
Biological and medical sciences
cell nucleus
Chloroplasts
cytosol
DNA, Plant - genetics
Environmental Stress and Adaptation to Stress
enzyme substrates
Enzymes
Fundamental and applied biological sciences. Psychology
gene overexpression
Kinetics
Leaves
Lipid Peroxides - metabolism
Lipids
metabolic detoxification
Metabolism
Molecular Sequence Data
Nicotiana - genetics
Nicotiana - metabolism
Nicotiana - radiation effects
Nicotiana tabacum
Nitrogen metabolism
nucleotide sequences
Oxidative Stress
oxidoreductases
Oxidoreductases - genetics
Oxidoreductases - metabolism
peroxides
Photobiology
Photons
photooxidation
Plant cells
Plant Leaves - metabolism
Plant physiology and development
Plants
Plants, Genetically Modified
Reactive Oxygen Species - metabolism
Substrate Specificity
tobacco
Transgenic plants
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Summary:Degradation of lipid peroxides leads to the formation of cytotoxic 2-alkenals and oxenes (collectively designated reactive carbonyls). The novel NADPH-dependent oxidoreductase 2-alkenal reductase (AER; EC 1.3.1.74) from Arabidopsis (Arabidopsis thaliana), which is encoded by the gene At5g16970, catalyzes the reduction of the [alpha],[beta]-unsaturated bond of reactive carbonyls, and hence is presumed to function in antioxidative defense in plants. Here we show that Arabidopsis AER (At-AER) has a broad substrate spectrum to biologically relevant reactive carbonyls. Besides 2-alkenals, the enzyme recognized as substrates the lipid peroxide-derived oxenes 9-oxo-octadeca-(10E),(12Z)-dienoic acid and 13-oxo-octadeca-(9E),(11Z)-dienoic acid, as well as the potent genotoxin 4-oxo-(2E)-nonenal, altogether suggesting AER has a key role in the detoxification of reactive carbonyls. To validate this conclusion by in vivo studies, transgenic tobacco (Nicotiana tabacum) plants that had 100- to 250-fold higher AER activity levels than control plants were generated. The engineered plants exhibited significantly less damage from either (1) the exogenously administered 4-hydroxy-(2E)-nonenal, (2) treatment with methyl viologen plus light, or (3) intense light. We further show that the At-AER protein fused with the Aequorea victoria green fluorescent protein localizes in cytosol and the nucleus in Bright-Yellow 2 cells. These results indicate that reactive carbonyls mediate photooxidative injury in leaf cells, and At-AER in the cytosol protects the cells by reducing the [alpha],[beta]-unsaturated bond of the photoproduced reactive carbonyls.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.105.070391