Cercospora beticola Toxins (X. Inhibition of Plasma Membrane H+-ATPase by Beticolin-1).

AUTOR(ES)

Simon-Plas, F.

RESUMO

Beticolin-1 is a toxin produced by the fungus Cercospora beticola. The chemical structure of this toxin was previously elucidated. The effects of beticolin-1 on purified corn root plasma membrane H+-ATPase were studied in a solubilized form or were reconstituted into liposome membranes. The ATP hydrolysis activity of the purified solubilized enzyme was inhibited by micromolar concentrations of beticolin-1, and this inhibition was noncompetitive with respect to ATP. When this purified enzyme was inserted into liposome membranes, a competitive inhibition of the H+-ATPase hydrolysis activity by beticolin-1 was observed. The effect of beticolin-1 on the formation of H+-ATPase-phosphorylated intermediate was also studied. With the purified enzyme in its solubilized form, the level of phosphorylated intermediate was not affected by the presence of beticolin-1, whereas micromolar concentrations of the toxin led to a marked inhibition of its formation when the enzyme was reconstituted into liposomes. These data suggest that (a) the plasma membrane H+-ATPase is a direct target for beticolin-1, and (b) the kinetics of inhibition and the effect on the phosphorylated intermediate are linked and both depend on the lipid environment of the enzyme.

Documentos Relacionados

• H+-ATPase Activity from Storage Tissue of Beta vulgaris1: IV. N,N′-Dicyclohexylcarbodiimide Binding and Inhibition of the Plasma Membrane H+-ATPase
• Inhibition and Labeling of the Plant Plasma Membrane H+-ATPase with N-Ethylmaleimide 1
• Role of the Plasma Membrane H+-ATPase in K+ Transport.
• Trehalose-Mediated Inhibition of the Plasma Membrane H+-ATPase from Kluyveromyces lactis: Dependence on Viscosity and Temperature
• Plasma Membrane H+-ATPase in Maize Roots Induced for NO3- Uptake.