Clostridium pasteurianum F 1 F o ATP Synthase: Operon, Composition, and Some Properties

Abstract

ABSTRACT The atp operon encoding F 1 F o ATP synthase in the fermentative obligate anaerobic bacterium Clostridium pasteurianum was sequenced. It consisted of nine genes arranged in the order atpI (i), atpB (a), atpE (c), atpF (b), atpH (δ), atpA (α), atpG (γ), atpD (β), and atpC (ε), which was identical to that found in many bacteria. Reverse transcription-PCR confirmed the presence of the transcripts of all nine genes. The amount of ATPase activity in the membranes of C . pasteurianum was low compared to what has been found in many other bacteria. The F 1 F o complexes solubilized from membranes of C . pasteurianum and Escherichia coli had similar masses, suggesting similar compositions for the F 1 F o complexes from the two bacteria. Western blotting experiments with antibodies raised against the purified subunits of F 1 F o detected the presence of eight subunits, α, β, γ, δ, ε, a, b, and c, in the F 1 F o complex from C . pasteurianum . The F 1 F o complex from C . pasteurianum was activated by thiocyanate, cyanate, or sulfhydryl compounds; inhibited by sulfite, bisulfite, or bicarbonate; and had tolerance to inhibition by dicyclohexylcarbodiimide. The target of thiol activation of the F 1 F o complex from C . pasteurianum was F 1 . Thiocyanate and sulfite were noncompetitive with respect to substrate Mg ATP but competitive with respect to each other. The F 1 and F o parts of the F 1 F o complexes from C . pasteurianum and E . coli bound to each other, but the hybrid F 1 F o complexes were not functionally active.