The depletion of F₁ subunit ε in yeast leads to an uncoupled respiratory phenotype that is rescued by mutations in the proton-translocating subunits of F₀.
The central stalk of the ATP synthase is an elongated hetero-oligomeric structure providing a physical connection between the catalytic sites in F₁ and the proton translocation channel in F₀ for energy transduction between the two subdomains. The shape of the central stalk and relevance to energy coupling are essentially the same in ATP synthases from all forms of life, yet the protein composition of this domain changed during evolution of the mitochondrial enzyme from a two- to a three-subunit structure (γ, δ, ε). Whereas the mitochondrial γ- and δ-subunits are homologues of the bacterial central stalk proteins, the deliberate addition of subunit ε is poorly understood. Here we report that down-regulation of the gene (ATP15) encoding the ε-subunit rapidly leads to lethal F₀-mediated proton leaks through the membrane because of the loss of stability of the ATP synthase. The ε-subunit is thus essential for oxidative phosphorylation. Moreover, mutations in F₀ subunits a and c, which slow the proton translocation rate, are identified that prevent ε-deficient ATP synthases from dissipating the electrochemical potential. Cumulatively our data lead us to propose that the ε-subunit evolved to permit operation of the central stalk under the torque imposed at the normal speed of proton movement through mitochondrial F₀.
Centre National de la Recherche Scientifique, Institut de Biochimie et Génétique Cellulaires, UMR 5095, F-33077 Bordeaux, France Université Victor Segalen Bordeaux 2, Institut de Biochimie et Génétique Cellulaires, UMR 5095, F-33077 Bordeaux, France Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, MI 48201.
Emmanuel
E
Tetaud
François
F
Godard
Marie-France
MF
Giraud
Sharon H
SH
Ackerman
Jean-Paul
JP
di Rago
D060846:Cell Engineering; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D015870:Gene Expression; D005838:Genotype; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010085:Oxidative Phosphorylation; D010641:Phenotype; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics; D000097795:ATPase Inhibitory Protein
D021122:Protein Subunits; D011506:Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000097795:ATPase Inhibitory Protein