Abstract
A new subunit of the yeast ATP synthase (termed subunit h) has been isolated. Amino acid composition and N-terminal sequencing were determined by chemical methods. These data were in agreement with the sequence of the hypothetical protein L8003.20 whose primary structure was deduced from DNA sequencing of the yeast chromosome XII. The amino acid sequence encoded by ATP14 gene is 32 amino acids longer than the mature protein, which contains 92 amino acids corresponding to a calculated mass of 10,408 Da. The protein is hydrophilic and acidic with a calculated pHi of 4.08. It is not apparently related to any subunit described in other ATP synthases. A null mutant was constructed. The mutation was recessive and the mutant strain was unable to grow on glycerol medium. A high percentage of rho- cells arose spontaneously. The mutant mitochondria had no detectable oligomycin-sensitive ATPase activity, but still contained ATPase activity with a catalytic sector dissociated from the membranous components. The mutant mitochondria did not contain subunit h, and the mitochondrially encoded hydrophobic subunit 6 was not present.
Highlights
IntroductionA new subunit of the yeast ATP synthase (termed subunit h) has been isolated
A new subunit of the yeast ATP synthase has been isolated
The enzyme is composed of two sectors: the catalytic sector F1, with subunits ␣, , ␥, ␦, and ⑀, is a hydrophilic portion of the enzyme retaining the ability to hydrolyze ATP when in a soluble form; the F0 sector is embedded in the membrane and is composed of hydrophobic subunits forming a specific proton pathway
Summary
A new subunit of the yeast ATP synthase (termed subunit h) has been isolated. Amino acid composition and N-terminal sequencing were determined by chemical methods These data were in agreement with the sequence of the hypothetical protein L8003.20 whose primary structure was deduced from DNA sequencing of the yeast chromosome XII. The mutant mitochondria had no detectable oligomycin-sensitive ATPase activity, but still contained ATPase activity with a catalytic sector dissociated from the membranous components. The mutant mitochondria did not contain subunit h, and the mitochondrially encoded hydrophobic subunit 6 was not present. A gene potentially encoding for the ATP synthase subunit g was found during S. cerevisiae chromosome XVI sequencing but the protein has not been identified so far. The experiments described in this report focus on a new supernumerary subunit isolated from a highly purified ATP synthase complex of yeast. We report the disruption of the structural gene ATP14 and the consequences of this disruption on the function and the assembly of the complex
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