Environmental stress causes oxidative damage to plant mitochondria leading to inhibition of glycine decarboxylase.
A cytotoxic product of lipid peroxidation, 4-hydroxy-2-nonenal (HNE), rapidly inhibited glycine, malate/pyruvate, and 2-oxoglutarate-dependent O2 consumption by pea leaf mitochondria. Dose- and time-dependence of inhibition showed that glycine oxidation was the most severely affected with a K(0.5) of 30 microm. Several mitochondrial proteins containing lipoic acid moieties differentially lost their reactivity to a lipoic acid antibody following HNE treatment. The most dramatic loss of antigenicity was seen with the 17-kDa glycine decarboxylase complex (GDC) H-protein, which was correlated with the loss of glycine-dependent O2 consumption. Paraquat treatment of pea seedlings induced lipid peroxidation, which resulted in the rapid loss of glycine-dependent respiration and loss of H-protein reactivity with lipoic acid antibodies. Pea plants exposed to chilling and water deficit responded similarly. In contrast, the damage to other lipoic acid-containing mitochondrial enzymes was minor under these conditions. The implication of the acute sensitivity of glycine decarboxylase complex H-protein to lipid peroxidation products is discussed in the context of photorespiration and potential repair mechanisms in plant mitochondria.
Taylor
Nicolas L
NL
Plant Molecular Biology Group, School of Biomedical and Chemical Sciences, Faculty of Life and Physical Sciences, The University of Western Australia, Crawley, WA 6009, Western Australia, Australia.
Day
David A
DA
Millar
A Harvey
AH
D000447:Aldehydes / Q000494:pharmacology; D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D004777:Environment; D005998:Glycine / Q000378:metabolism; D050959:Glycine Decarboxylase Complex; D050961:Glycine Decarboxylase Complex H-Protein; D050841:Glycine Dehydrogenase (Decarboxylating); D007700:Kinetics; D015227:Lipid Peroxidation; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D018384:Oxidative Stress / Q000502:physiology*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D018532:Pisum sativum; D018515:Plant Leaves / Q000201:enzymology
D000447:Aldehydes; D050961:Glycine Decarboxylase Complex H-Protein; D000594:Amino Acid Oxidoreductases; D050959:Glycine Decarboxylase Complex; D050841:Glycine Dehydrogenase (Decarboxylating); C027576:4-hydroxy-2-nonenal; D005998:Glycine