Structural analysis of S-ring composed of FliFG fusion proteins in marine Vibrio polar flagellar motor.

Autor:	Takekawa N; Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan., Nishikino T; Institute for protein research, Osaka University, Suita, Osaka, Japan., Kishikawa J-i; Institute for protein research, Osaka University, Suita, Osaka, Japan., Hirose M; Institute for protein research, Osaka University, Suita, Osaka, Japan., Kinoshita M; Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan., Kojima S; Department of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan., Minamino T; Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan., Uchihashi T; Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan., Kato T; Institute for protein research, Osaka University, Suita, Osaka, Japan., Imada K; Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan., Homma M; Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan.; Department of Biomolecular Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan.
Jazyk:	angličtina
Zdroj:	MBio [mBio] 2024 Oct 16; Vol. 15 (10), pp. e0126124. Date of Electronic Publication: 2024 Sep 06.
DOI:	10.1128/mbio.01261-24
Abstrakt:	The marine bacterium Vibrio alginolyticus possesses a polar flagellum driven by a sodium ion flow. The main components of the flagellar motor are the stator and rotor. The C-ring and MS-ring, which are composed of FliG and FliF, respectively, are parts of the rotor. Here, we purified an MS-ring composed of FliF-FliG fusion proteins and solved the near-atomic resolution structure of the S-ring-the upper part of the MS-ring-using cryo-electron microscopy. This is the first report of an S-ring structure from Vibrio , whereas, previously, only those from Salmonella have been reported. The Vibrio S-ring structure reveals novel features compared with that of Salmonella , such as tilt angle differences of the RBM3 domain and the β-collar region, which contribute to the vertical arrangement of the upper part of the β-collar region despite the diversity in the RBM3 domain angles. Additionally, there is a decrease of the inter-subunit interaction between RBM3 domains, which influences the efficiency of the MS-ring formation in different bacterial species. Furthermore, although the inner-surface electrostatic properties of Vibrio and Salmonella S-rings are altered, the residues potentially interacting with other flagellar components, such as FliE and FlgB, are well structurally conserved in the Vibrio S-ring. These comparisons clarified the conserved and non-conserved structural features of the MS-ring across different species.IMPORTANCEUnderstanding the structure and function of the flagellar motor in bacterial species is essential for uncovering the mechanisms underlying bacterial motility and pathogenesis. Our study revealed the structure of the Vibrio S-ring, a part of its polar flagellar motor, and highlighted its unique features compared with the well-studied Salmonella S-ring. The observed differences in the inter-subunit interactions and in the tilt angles between the Vibrio and Salmonella S-rings highlighted the species-specific variations and the mechanism for the optimization of MS-ring formation in the flagellar assembly. By concentrating on the region where the S-ring and the rod proteins interact, we uncovered conserved residues essential for the interaction. Our research contributes to the advancement of bacterial flagellar biology. Competing Interests: The authors declare no conflict of interest.
Databáze:	MEDLINE
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