title: Expression, purification and biochemical characterization of the cytoplasmic loop of PomA, a stator component of the Na(+) driven flagellar motor.
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(+) influx through the PomA/PomB stator complex of Vibrio alginolyticus 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 E. coli, a slight dominant effect was observed on motility. We conclude that the cytoplasmic loop alone retains a certain function.
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Rei
authors: R
authors: Abe-Yoshizumi
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Shiori
authors: S
authors: Kobayashi
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Mizuki
authors: M
authors: Gohara
authors: Laboratory of Biophysics, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors: Kokoro
authors: K
authors: Hayashi
authors: Laboratory of Biophysics, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
authors: Chojiro
authors: C
authors: Kojima
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Seiji
authors: S
authors: Kojima
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Yuki
authors: Y
authors: Sudo
authors: TA Instruments Japan, Inc., 5-2-4, Nishi-gotanda, Shinagawa-ku, Tokyo 141-0031, Japan.
authors: Yasuo
authors: Y
authors: Asami
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Michio
authors: M
authors: Homma
keywords: bacterial flagellum; ion-driven motor; protein interaction; stator