Solution structure analysis of the periplasmic region of bacterial flagellar motor stators by small angle X-ray scattering

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

DOI:https://doi.org/10.1016/J.BBRC.2017.11.194· OSTI ID:23134367

Liew, C. W. ^[1]; Hynson, R. M. ^[2]; Ganuelas, L. A. ^[1]; Shah-Mohammadi, N. ^[2]; Duff, A. P. ^[3]; Kojima, S.; Homma, M. ^[4]

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1. School of Medical Sciences, The University of New South Wales (Australia)
2. Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales (Australia)
3. Australian Nuclear and Science Technology Organisation, Lucas Heights, New South Wales (Australia)
4. Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602 (Japan)

Highlights: • Solution shape of peptidoglycan binding domains from the flagellar motor determined. • Previously unobserved conformational states are revealed. • Suggests a potential structural rearrangement associated with stator activation. • Provides mechanistic insight into how flagellar motor stators are activated. The bacterial flagellar motor drives the rotation of helical flagellar filaments to propel bacteria through viscous media. It consists of a dynamic population of mechanosensitive stators that are embedded in the inner membrane and activate in response to external load. This entails assembly around the rotor, anchoring to the peptidoglycan layer to counteract torque from the rotor and opening of a cation channel to facilitate an influx of cations, which is converted into mechanical rotation. Stator complexes are comprised of four copies of an integral membrane A subunit and two copies of a B subunit. Each B subunit includes a C-terminal OmpA-like peptidoglycan-binding (PGB) domain. This is thought to be linked to a single N-terminal transmembrane helix by a long unstructured peptide, which allows the PGB domain to bind to the peptidoglycan layer during stator anchoring. The high-resolution crystal structures of flagellar motor PGB domains from Salmonella enterica (MotB{sub C2}) and Vibrio alginolyticus (PomB{sub C5}) have previously been elucidated. Here, we use small-angle X-ray scattering (SAXS). We show that unlike MotB{sub C2}, the dimeric conformation of the PomB{sub C5} in solution differs to its crystal structure, and explore the functional relevance by characterising gain-of-function mutants as well as wild-type constructs of various lengths. These provide new insight into the conformational diversity of flagellar motor PGB domains and experimental verification of their overall topology.

• OSTI ID: 23134367
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 2 Vol. 495; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
CRYSTAL STRUCTURE
FILAMENTS
PEPTIDES
SALMONELLA
SMALL ANGLE SCATTERING