Purification and Characterization of a Glycerol-Resistant CF0-CF1 and CF1-ATPase from the Halotolerant Alga Dunaliella bardawil1

摘要

The isolation of the chloroplast ATP synthase complex (CF0-CF1) and of CF1 from Dunaliella bardawil is described. The subunit structure of the D. bardawil ATPase differs from that of the spinach in that the D. bardawil α subunit migrates ahead of the β subunit and ε-migrates ahead of subunit II of CF0 when separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The CF1 isolated from D. bardawil resembles the CF1 isolated from Chladmydomonas reinhardi in that a reversible, Mg2+-dependent ATPase is induced by selected organic solvents. Glycerol stimulates cyclic photophosphorylation catalyzed by D. bardawil thylakoid membranes but inhibits photophosphorylation catalyzed by spinach thylakoid membranes. Glycerol (20%) also stimulates the rate of ATP-Pi exchange catalyzed by D. bardawil CF0-CF1 proteoliposomes but inhibits the activity with the spinach enzyme. The ethanol-activated, Mg2+-ATPase of the D. bardawil CF1 is more resistant to glycerol inhibition than the octylglucoside-activated, Mg2+-ATPase of spinach CF1 or the ethanol-activated, Mg2+-dependent ATPase of the C. reinhardi CF1. Both cyclic photophosphorylation and ATP-Pi exchange catalyzed by D. bardawil CF0-CF1 are more sensitive to high concentrations of NaCl than is the spinach complex.