title: Inhibition of F1-ATPase rotational catalysis by the carboxyl-terminal domain of the ϵ subunit.
abstract: Escherichia coli ATP synthase (F0F1) couples catalysis and proton transport through subunit rotation. The ϵ subunit, an endogenous inhibitor, lowers F1-ATPase activity by decreasing the rotation speed and extending the duration of the inhibited state (Sekiya, M., Hosokawa, H., Nakanishi-Matsui, M., Al-Shawi, M. K., Nakamoto, R. K., and Futai, M. (2010) Single molecule behavior of inhibited and active states of Escherichia coli ATP synthase F1 rotation. J. Biol. Chem. 285, 42058-42067). In this study, we constructed a series of ϵ subunits truncated successively from the carboxyl-terminal domain (helix 1/loop 2/helix 2) and examined their effects on rotational catalysis (ATPase activity, average rotation rate, and duration of inhibited state). As expected, the ϵ subunit lacking helix 2 caused about ½-fold reduced inhibition, and that without loop 2/helix 2 or helix 1/loop 2/helix 2 showed a further reduced effect. Substitution of ϵSer(108) in loop 2 and ϵTyr(114) in helix 2, which possibly interact with the β and γ subunits, respectively, decreased the inhibitory effect. These results suggest that the carboxyl-terminal domain of the ϵ subunit plays a pivotal role in the inhibition of F1 rotation through interaction with other subunits.
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan. Electronic address: nakanim@iwate-med.ac.jp.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Nakanishi-Matsui
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Sekiya
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan.
authors.forename: Shio
authors.initials: S
authors.lastname: Yano
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Nishitokuta 2-1-1, Yahaba, Iwate 028-3694, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Futai
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D055162:Biocatalysis; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D021122:Protein Subunits; D006180:Proton-Translocating ATPases / Q000737:chemistry* / Q000235:genetics; D017384:Sequence Deletion
chemical_list: D029968:Escherichia coli Proteins; D021122:Protein Subunits; D000255:Adenosine Triphosphate; C496259:F0F1-ATPase epsilon subunit, E coli; D006180:Proton-Translocating ATPases
keywords: ATP Synthase; ATPase; Bioenergy; Carboxyl-terminal Domain; Escherichia coli (E. coli); F1-ATPase; Protein Structure; Rotational Catalysis; Single-particle Analysis; ϵ Subunit