Role of the amino terminal region of the ϵ subunit of Escherichia coli H+-ATPase (FoF1)

Masayoshi Jounouchi, Michiyasu Takeyama, Takato Noumi, Yoshinori Moriyama, Masatomo Maeda, Masamitsu Futai

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28 Citations (Scopus)


Escherichia coli strain KF148(SD-) defective in translation of the uncC gene for the ε{lunate} subunit of H+-ATPase could not support growth by oxidative phosphorylation due to lack of F1 binding to Fo (M. Kuki, T. Noumi, M. Maeda, A. Amemura, and M. Futai, 1988, J. Biol. Chem. 263, 17,437-17,442). Mutant uncC genes for ε{lunate} subunits lacking different lengths from the amino terminus were constructed and introduced into strain KF148(SD-). F1 with an ε{lunate} subunit lacking the 15 amino-terminal residues could bind to Fo in a functionally competent manner, indicating that these amino acid residues are not absolutely necessary for formation of a functional enzyme. However, mutant F1 in which the ε{lunate} subunit lacked 16 amino-terminal residues showed defective coupling between ATP hydrolysis (synthesis) and H+-translocation, although the mutant F1 showed partial binding to Fo. These findings suggest that the ε{lunate} subunit is essential for binding of F1 to Fo and for normal H+-translocation. Previously, Kuki et al. (cited above) reported that 60 residues were not necessary for a functional enzyme. However, the mutant with an ε{lunate} subunit lacking 15 residues from the amino terminus and 4 residues from the carboxyl terminus was defective in oxidative phosphorylation, suggesting that both terminal regions affect the conformation of the region essential for a functional enzyme.

Original languageEnglish
Pages (from-to)87-94
Number of pages8
JournalArchives of Biochemistry and Biophysics
Issue number1
Publication statusPublished - Jan 1992

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology


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