Escherichia coli ATP synthase (F-ATPase): catalytic site and regulation of H1 translocation

We discuss our recent results on the Escherichia coli F-ATPase, in particular its catalytic site in the /3 subunit and regulation of H+ transport by the y subunit. Affinity labelling experiments suggest that /3Lys-155 in the glycine-rich sequence is near the y-phosphate moiety of ATP bound at the catalytic site. The enzyme loses activity upon introduction of missense mutations in /9Lys-155 or /3Thr-156 and changes catalytic properties upon introduction of other mutations. By analysis of mutations and their pseudo revertants, residues £Ser-174, ^SGlu-192 and /3Val-198 were found to be located near the glycine-rich sequence. The combined approaches of chemical labelling and genetics have been fruitful in visualizing the structure of the catalytic site. Analysis of mutations in the y subunit suggests that this subunit has an essential role in coupling catalysis with proton translocation