Reconstitution of adenosine triphosphatase of thermophilic bacterium from purified individual subunits.

1. Five subunits (alpha, beta, gamma, delta, and epsilon) of an ATPase from a thermophilic bacterium PS3 were purified in the presence of 8 M urea by ion exchange chromatography. Then the ATPase activity was reconstituted by mixing the subunit solutions and incubating them at 20-45 degrees, at pH 6.3 to 7.0. 2. Mixtures containing beta + gamma or alpha + beta + delta regained ATP-hydrolyzing activity, but mixtures of alpha + beta and beta + delta did not. Combinations not including beta were all inactive. 3. The ATPase activity reconstituted from alpha + beta + delta was thermolabile and insensitive to NaN3, whereas the activities obtained from mixtures containing beta and gamma were thermostable and sensitive to NaN3, like the native ATPase. 4. The assemblies containing both beta and gamma subunits had the same mobility as the native ATPase molecule on gel electrophoresis, those without the gamma subunit moved more rapidly toward the anode. 5. Subunits epsilon and delta did not inhibit the ATPase activity of either the assembly (alpha + beta + gamma) or the native ATPase.