Contraction transitions of F-1-F-0 ATPase during catalytic turnover

Strong acoustic pressure was applied to submitochondrial particles (SMP) fr om bovine heart in order to drive ATP synthesis by F-1-F-0 complex for the account of sound waves. We observed a net ATP production at two narrow freq uency ranges, about 170 Hz and about 340 Hz, that corresponds to the resona nce oscillations of experimental cuvette when the acoustic pressure had a m agnitude of 100 kPa. The results can be explained quantitatively by contrac tive conformational changes of F-1-F-0 complex during catalytic turnover. N egative staining electron microscopy of SMP preparations was used to visual ize the ADP(Mg2+)-induced conformational changes of F-1-F-0 complex. In the particles with high ATPase activity in the presence of phosphate the facto rs F-1 and F-0 formed a congregated domain plunged into the membrane withou t any observable stalk in between. The presence of ADP(Mg2+) caused a struc tural rearrangement of F-1-F-0 to the essentially different conformation: t he domains F-1 and F-0 were dislodged distinctly from each other and connec ted by a long thin stalk. The latter conformation resembled well the usual bipartite profile of ATPase. The data indicate that besides rotation, the c atalytic turnover of ATP synthase is also accompanied by stretch transition s of F-1-F-0 complex. (C) 1998 Elsevier Science B.V. All rights reserved.