Conformational Changes of Nucleotide Binding Sites Following Sequential Addition of ADP to Nucleotide-depleted F1-ATPase of Escherichia coli Investigated with 31P NMR Spectroscopy

Nucleotide binding site Oxidative phosphorylation in Escherichia coli is catalyzed by an electron transport system that generates a proton electrochemical gradient across the cytoplasmic membrane and an ATP synthase enzyme that catalyzes the conversion of ADP and Pi to ATP at the expense of a gradient of sufficient magnitude. The ATP synthase of this organism is essentially identical in other bacteria, the mitochondria of eukaryotes and the thylakoids of green plants.1-7 Two func-tionally distinct parts of the protein can be distinguished. These are: (i) the F0 sector, which, in the case of E. coli, comprises three polypeptide chains known as a, b and c, which together form a transmembrane proton channel: (ii) F1 sector which contains five polypeptide chains with relative stoichiometry α3β3γδε