The Modification of the Conserved GXXXG Motif of the Membrane-spanning Segment of Subunit g Destabilizes the Supramolecular Species of Yeast ATP Synthase

• Published in: The Journal of biological chemistry Vol. 280; no. 32; pp. 29004 - 29010
• Main Authors: Bustos, Diego M., Velours, Jean
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.08.2005; American Society for Biochemistry and Molecular Biology
• Subjects: Adenosine Triphosphate - chemistry; Amino Acid Motifs; Amino Acid Sequence; Blotting, Western; Cell Membrane - metabolism; Cellular Biology; Conserved Sequence; Cross-Linking Reagents - pharmacology; Cysteine - chemistry; Digitonin - chemistry; Dimerization; Disulfides - chemistry; Life Sciences; Microscopy, Electron, Transmission; Mitochondria - metabolism; Mitochondria - ultrastructure; Mitochondrial Proton-Translocating ATPases - chemistry; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Oxygen - chemistry; Oxygen - metabolism; Phenotype; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Proton-Translocating ATPases - chemistry; Proton-Translocating ATPases - metabolism; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - metabolism; Sequence Homology, Amino Acid
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M502140200

The supernumerary subunit g is found in all mitochondrial ATP synthases. Most of the conserved amino acid residues are present in the membrane C-terminal part of the protein that contains a dimerization motif GXXXG. In yeast, alteration of this motif leads to the loss of subunit g and of supramolecular structures of the ATP synthase with concomitant appearance of anomalous mitochondrial morphologies. Disulfide bond formation involving an engineered cysteine in position 109 of subunit g and the endogenous cysteine 28 of subunit e promoted g + g, e + g, and e + e adducts, thus revealing the proximity in the mitochondrial membrane of several subunits e and g. Disulfide bond formation between two subunits g in mitochondria increased the stability of an oligomeric structure of the ATP synthase in digitonin extracts. These data suggest the participation of the dimerization motif of subunit g in the formation of supramolecular structures and is in favor of the existence of ATP synthase associations, in the inner mitochondrial membrane, whose masses are higher than those of ATP synthase dimers.