Expression, purification and biochemical characterization of the cytoplasmic loop of PomA, a stator component of the Na<sup>+</sup> driven flagellar motor

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Author(s)

    • Yoshizumi Rei Abe
    • Division of Biological Science, Graduate School of Science, Nagoya University
    • Kobayashi Shiori
    • Division of Biological Science, Graduate School of Science, Nagoya University
    • Gohara Mizuki
    • Division of Biological Science, Graduate School of Science, Nagoya University
    • Hayashi Kokoro
    • Laboratory of Biophysics, Graduate School of Biological Sciences, Nara Institute of Science and Technology
    • Kojima Chojiro
    • Laboratory of Biophysics, Graduate School of Biological Sciences, Nara Institute of Science and Technology
    • Kojima Seiji
    • Division of Biological Science, Graduate School of Science, Nagoya University
    • Sudo Yuki
    • Division of Biological Science, Graduate School of Science, Nagoya University
    • Homma Michio
    • Division of Biological Science, Graduate School of Science, Nagoya University

Abstract

Flagellar motors embedded in bacterial membranes are molecular machines powered by specific ion flows. Each motor is composed of a stator and a rotor and the interactions of those components are believed to generate the torque. Na<sup>+</sup> influx through the PomA/PomB stator complex of <i>Vibrio alginolyticus</i> is coupled to torque generation and is speculated to trigger structural changes in the cytoplasmic domain of PomA that interacts with a rotor protein in the C-ring, FliG, to drive the rotation. In this study, we tried to overproduce the cytoplasmic loop of PomA (PomA-Loop), but it was insoluble. Thus, we made a fusion protein with a small soluble tag (GB1) which allowed us to express and characterize the recombinant protein. The structure of the PomA-Loop seems to be very elongated or has a loose tertiary structure. When the PomA-Loop protein was produced in <i>E. coli</i>, a slight dominant effect was observed on motility. We conclude that the cytoplasmic loop alone retains a certain function.<br>

Journal

  • BIOPHYSICS

    BIOPHYSICS 9(0), 21-29, 2013

    The Biophysical Society of Japan

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