Topological and functional study of subunit h of the F1Fo ATP synthase complex in yeast Saccharomyces cerevisiae.
Subunit h, a 92-residue-long, hydrophilic, acidic protein, is a component of the yeast mitochondrial F1Fo ATP synthase. This subunit, homologous to the mammalian factor F6, is essential for the correct assembly and/or functioning of this enzyme since yeast cells lacking it are not able to grow on nonfermentable carbon sources. Chemical cross-links between subunit h and subunit 4 have previously been shown, suggesting that subunit h is a component of the peripheral stalk of the F1Fo ATP synthase. The construction of cysteine-containing subunit h mutants and the use of bismaleimide reagents provided insights into its environment. Cross-links were obtained between subunit h and subunits alpha, f, d, and 4. These results and secondary structure predictions allowed us to build a structural model and to propose that this subunit occupies a central place in the peripheral stalk between the F1 sector and the membrane. In addition, subunit h was found to have a stoichiometry of one in the F1Fo ATP synthase complex and to be in close proximity to another subunit h belonging to another F1Fo ATP synthase in the inner mitochondrial membrane. Finally, functional characterization of mitochondria from mutants expressing different C-terminal shortened subunit h suggested that its C-terminal part is not essential for the assembly of a functional F1Fo ATP synthase.
Fronzes
Rémi
R
Institut de Biochimie et Génétique Cellulaires du Centre National de la Recherche Scientifique, UMR5095, Université Victor Segalen Bordeaux 2, 1 rue Camille Saint-Saëns, 33077 Bordeaux cedex, France.
Chaignepain
Stéphane
S
Bathany
Katell
K
Giraud
Marie-France
MF
Arselin
Geneviève
G
Schmitter
Jean-Marie
JM
Dautant
Alain
A
Velours
Jean
J
Brèthes
Daniel
D
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D003432:Cross-Linking Reagents / Q000737:chemistry; D003545:Cysteine / Q000235:genetics; D004789:Enzyme Activation; D007425:Intracellular Membranes / Q000201:enzymology; D008239:Lysine / Q000235:genetics; D008301:Maleimides / Q000737:chemistry; D008928:Mitochondria / Q000201:enzymology; D025261:Mitochondrial Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry; D013388:Succinimides / Q000737:chemistry; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry
D003432:Cross-Linking Reagents; D008301:Maleimides; D010446:Peptide Fragments; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D013388:Succinimides; C091579:VMA8 protein, S cerevisiae; C075594:1,6-bismaleimidohexane; C101128:ATP14 protein, S cerevisiae; C474451:F1F0-ATP synthase; D025262:Vacuolar Proton-Translocating ATPases; D025261:Mitochondrial Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase; C011240:dithiobis(succinimidylpropionate); D008239:Lysine; D003545:Cysteine; C023860:N,N'-2-phenylenedimaleimide