Purification and Properties of a Plasma Membrane H+-ATPase from the Extremely Acidophilic Alga Dunaliella acidophila.

AUTOR(ES)

Sekler, I.

RESUMO

This paper describes partial purification and characterization of a vanadate-sensitive H+-ATPase from plasma membranes of Dunaliella acidophila, an extremely acidophilic unicellular alga (I. Sekler, H.U. Glaser, U. Pick [1991] J Membr Biol 121: 51-57). Purification is based on the insolubility in and stability of the enzyme in Triton X-100. The purified enzyme is highly enriched in a polypeptide of molecular mass 100 kD, which cross-reacts with antibodies against the plant plasma membrane H+-ATPase. Upon reconstitution into proteoliposomes, the enzyme catalyzes an ATP-dependent electrogenic H+ uptake. ATP hydrolysis is stimulated by lipids, is inhibited by vanadate, diethylstilbestrol, dicyclohexylcarbodiimide, erythrosine, and mercurials, and shows a sharp optimum at pH 6. Unusual properties of this enzyme, by comparison with plant plasma membrane H+-ATPases, are a higher affinity for ATP (Km = 40 [mu]M) and a larger stimulation by K+, which interacts with the enzyme from its cytoplasmic side. Comparative studies with cross-reacting antibodies, prepared against different domains of the plant H+-ATPase, suggest that the central hydrophilic domain containing the catalytic site is more conserved than the C- and N-terminal ends. The high abundance and stability of the plasma membrane H+-ATPase from D. acidophila make it an attractive model system for studies of the structure-function relations and regulation of this crucial enzyme.

Documentos Relacionados

• Primary structure and effect of pH on the expression of the plasma membrane H(+)-ATPase from Dunaliella acidophila and Dunaliella salina.
• Activation of the Dunaliella acidophila plasma membrane H(+)-ATPase by trypsin cleavage of a fragment that contains a phosphorylation site.
• H+-ATPase Activity from Storage Tissue of Beta vulgaris1: IV. N,N′-Dicyclohexylcarbodiimide Binding and Inhibition of the Plasma Membrane H+-ATPase
• Role of the Plasma Membrane H+-ATPase in K+ Transport.
• Fusicoccin Binding to Its Plasma Membrane Receptor and the Activation of the Plasma Membrane H+-ATPase (III. Is There a Direct Interaction between the Fusicoccin Receptor and the Plasma Membrane H+-ATPase?).