Biochemical and electron microscopic characterization of the F 1F 0 ATP Synthase from the hyperthermophilic eubacterium Aquifex aeolicus

Abstract

The F 1F 0 ATP synthase has been purified from the hyperthermophilic eubacterium Aquifex aeolicus and characterized. Its subunits have been identified by MALDI-mass spectrometry through peptide mass fingerprinting and MS/MS. It contains the canonical subunits α, β, γ, δ and ε of F 1 and subunits a and c of F 0. Two versions of the b subunit were found, which show a low sequence homology to each other. Most likely they form a heterodimer. An electron microscopic single particle analysis revealed clear structural details, including two stalks connecting F 1 and F 0. In several orientations the central stalk appears to be tilted and/or kinked. It is unclear whether there is a direct connection between the peripheral stalk and the δ subunit.