Protonophoric activity of eutypine, a toxin from Eutypa lata, in plant mitochondria
| Autor: | François Moreau, Joelle Eychenne, Jacques Davy de Virville, Corine Deswarte, Jean-Paul Roustan, Jean Fallot |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Carbonyl Cyanide m-Chlorophenyl Hydrazone
Protonophore Biophysics Oxidative phosphorylation Biology Mitochondrion medicine.disease_cause Biochemistry Membrane Potentials Oxygen Consumption Ascomycota medicine Mode of action Molecular Biology Cells Cultured NADPH-Ferrihemoprotein Reductase Membrane potential Toxin Depolarization Intracellular Membranes Mycotoxins Galactosyltransferases Electron transport chain Mitochondria Succinate Dehydrogenase Kinetics Alkynes Benzaldehydes Fruit |
| Zdroj: | Archives of biochemistry and biophysics. 334(2) |
| ISSN: | 0003-9861 |
| Popis: | Eutypine is a toxin produced by Eutypa lata, the causal agent of the dying-arm disease of grapevine. We have previously shown that this toxin behaves as a lipophylic weak acid (p K = 6.2) and induces drastic changes in both the respiration and energy balance of grapevine cells. In the present study, the molecular mode of action of eutypine at the mitochondrial level, using methyl-eutypine, the unprotonable derivative of the toxin, has been investigated. The effects of these molecules on mitochondrial respiration and membrane potential were compared using isolated mitochondria from grapevine cells in suspension cultures or potato tuber mitochondria. Eutypine induces marked stimulation of oxygen consumption and a depolarizing effect, while methyl-eutypine exhibits a very small effect on both the rate of oxygen uptake and membrane potential. For high eutypine concentrations, a mixed effect corresponding to a direct inhibition of electron transport and uncoupling can be observed. In addition, below 200 μ M , eutypine displays a linear relationship between oxidation rate and membrane potential similar to that of the classical protonophore carbonyl cyanide- m -chlorophenylhydrazone (CCCP). However, unlike CCCP, eutypine induces a potential-dependent proton conductance that can be due to the potential-dependent migration of the dissociated form of the toxin across the membrane. It is concluded that eutypine uncouples mitochondrial oxidative phosphorylation and decreases the ADP/O ratio in grapevine cells by increasing the proton leaks via a cyclic protonophore mechanism. The physiological aspects of these results are discussed. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect