A mutation altering the kinetic responses of the yeast mitochondrial F1-ATPase

Nucleotide-binding proteins, including the mitochondrial F1-ATPase, the ras proteins, and the G-proteins, contain a homologous glycine-rich sequence that is thought to constitute part of the active site. This study reports the effects of a single amino acid replacement of Thr197 to Ser197, which is located at the hinge region of this putative loop, in the yeast Saccharomyces cerevisiae F1-ATPase. This replacement resulted in a 3-fold increase in the specific activity of the enzyme, eliminated the stimulatory effects of oxyanions, and modulated the effects of the inhibitor NaN3 while having little effect on the uni-site ATPase. These results indicate a role of the glycine-rich loop in many of the kinetic responses of the F1-ATPase.