On the mechanism of the reconstitution of F1-depleted ATPase complex with purified F1: possible conformational effects.
The membrane sector (F0) of H+-ATPase was prepared by trypsin and urea treatment of F1-F0 and reconstituted with purified F1. The oligomycin sensitivity of the reconstituted F1-F0 complex obtained by treating F1 or F0 with Mg2+ before binding is much higher than that obtained without Mg2+ treatment. The greater change in the intrinsic fluorescence of the reconstituted F1-F0 complex obtained by Mg2+ treatment suggests that conformational changes may occur during the reconstitution. We deduce that Mg2+ binds to membrane lipids, thus decreasing membrane fluidity and changing the physical state of the lipids to provide a suitable microenvironment for conformational changes in F0. The data also suggest that the conformational change in the F0 portion of the F1-F0 complex can be transmitted to the F1 portion, the conformation of which is in turn altered, resulting in the formation of an F1-F0 complex with high oligomycin sensitivity. On the other hand, Mg2+ may act on F1 directly to induce a suitable conformational change which is then transmitted to F0, resulting in the formation of an H+-ATPase with greater sensitivity to oligomycin.
D000818:Animals; D001665:Binding Sites; D066298:In Vitro Techniques; D008274:Magnesium; D008563:Membrane Lipids; D009206:Myocardium / Q000201:enzymology; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000302:isolation & purification*; D013050:Spectrometry, Fluorescence; D013367:Submitochondrial Particles / Q000201:enzymology; D013552:Swine
D008563:Membrane Lipids; D006180:Proton-Translocating ATPases; D008274:Magnesium