Mutation in the hydrophobic domain of ATP synthase subunit 4 (subunit b) of yeast mitochondria disturbs coupling between proton translocation and catalysis.

We introduced mutations to test the function of the hydrophobic sector of subunit 4 from Saccharomyces cerevisiae ATP synthase. Mutations were introduced at the chromosomic locus by homologous transformation of a strain disrupted in the ATP4 gene. The strain carrying the replacement Leu68-Val69-->Arg-Glu did not grow at 37 degrees C owing to a lack of assembly of F1 and Fo sectors at this temperature.