Mutagenic analysis of the F-0 stator subunits

The a and b subunits constitute the stator elements in the F-o sector of F1 Fo-ATP synthase. Both subunits have been difficult to study by physical mea ns, so most of the information on structure and function relationships in t he a and b subunits has been obtained using mutagenesis in combination with biochemical methods. These approaches were used to demonstrate that the a subunit in association with the ring of c subunits houses the proton channe l through F1Fo-ATP synthase. The map of the amino acids contributing to the proton channel is probably complete. The two b subunits dimerize, forming an extended flexible unit in the peripheral stalk Linking the F-1 and F-o s ectors. The unique characteristics of specific amino acid substitutions aff ecting the a and b subunits suggested differential effects on rotation duri ng F1Fo-ATPase activity.