Neither helix in the coiled coil region of the axle of F1-ATPase plays a significant role in torque production

Mohammad Delawar Hossain, Shou Furuike, Yasushi Maki, Kengo Adachi, Toshiharu Suzuki, Ayako Kohori, Hiroyasu Itoh, Masasuke Yoshida, Kazuhiko Kinosita*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    34 Citations (Scopus)


    F1-ATPase is an ATP-driven rotary molecular motor in which the central γ-subunit rotates inside the cylinder made of α 3β3 subunits. The amino and carboxy termini of the γ-subunit form the axle, an α-helical coiled coil that deeply penetrates the stator cylinder. We previously truncated the axle step by step, starting with the longer carboxy terminus and then cutting both termini at the same levels, resulting in a slower yet considerably powerful rotation. Here we examine the role of each helix by truncating only the carboxy terminus by 25-40 amino-acid residues. Longer truncation impaired the stability of the motor complex severely: 40 deletions failed to yield rotating the complex. Up to 36 deletions, however, the mutants produced an apparent torque at nearly half of the wild-type torque, independent of truncation length. Time-averaged rotary speeds were low because of load-dependent stumbling at 120° intervals, even with saturating ATP. Comparison with our previous work indicates that half the normal torque is produced at the orifice of the stator. The very tip of the carboxy terminus adds the other half, whereas neither helix in the middle of the axle contributes much to torque generation and the rapid progress of catalysis. None of the residues of the entire axle played a specific decisive role in rotation.

    Original languageEnglish
    Pages (from-to)4837-4844
    Number of pages8
    JournalBiophysical Journal
    Issue number10
    Publication statusPublished - 2008 Nov 15

    ASJC Scopus subject areas

    • Biophysics


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