Insight into adaptive remodeling of the rotor ring complex of the bacterial flagellar motor

Journal Article · Mon Jan 15 04:00:00 EST 2018 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2017.12.118· OSTI ID:23127441

Kinoshita, Miki; Furukawa, Yukio ^[1]; Uchiyama, Susumu ^[2]; Imada, Katsumi ^[3]; Namba, Keiichi ^[1]; Minamino, Tohru ^[1]

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1. Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadoaka, Suita, Osaka 565-0871 (Japan)
2. Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)
3. Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)

Highlights: • Adaptive remodeling of the flagellar motor ring is responsible for motor switching. • Helix{sub MC} connecting FliG{sub M} and FliG{sub C} is responsible for the switching. • A CW-locked deletion of FliG suppresses the oligomerization of FliG in solution. • The CW-locked deletion reduces the binding affinity of FliG for FliM. • We provide an insight into structural remodeling of the flagellar motor. The bacterial flagellar motor rotates in both counterclockwise (CCW) and clockwise (CW) directions. FliG, FliM and FliN form the C ring on the cytoplasmic face of the MS ring made of a transmembrane protein, FliF. The C ring acts not only as a rotor but also as a switch of the direction of motor rotation. FliG consists of three domains: FliG{sub N}, FliG{sub M} and FliG{sub C}. FliG{sub N} directly binds to FliF. Intermolecular interactions between FliG{sub M} and FliG{sub C} drive FliG ring formation. FliG{sub M} is responsible for the interaction with FliM. FliG{sub C} is involved in the interaction with the stator protein MotA. Adaptive remodeling of the C ring occurs when the motor switches between the CCW and CW states. However, it remained unknown how. Here, we report the effects of a CW-locked deletion mutation (ΔPEV) in FliG of Thermotaoga maritia (Tm-FliG) on FliG–FliG and FliG–FliM interactions. The PEV deletion stabilized the intramolecular interaction between FliG{sub M} and FliG{sub C}, thereby suppressing the oligomerization of Tm-FliG{sub MC} in solution. This deletion also induced a conformational change of Helix{sub MC} connecting FliG{sub M} and FliG{sub C} to reduce the binding affinity of Tm-FliG{sub MC} for FliM. We will discuss adaptive remodeling of the C ring responsible for flagellar motor switching.

• OSTI ID: 23127441
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 1 Vol. 496; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
BACTERIA
CONFORMATIONAL CHANGES
PROTEINS