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bioRxiv · 10.1101/2023.06.28.546849

Cryo-EM of cytoskeletal 'fibril' protein involved in Spiroplasma swimming

Sasajima, Y.·Kato, T.·Miyata, T.·Kiyama, H.·Kawamoto, A.·Makino, F.·Namba, K.·Miyata, M.
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Abstract

Spiroplasma, parasitic or commensal bacteria, can swim by switching the handedness of its helical cell body. A helical cell body is formed by an internal ribbon of MreB, an actin superfamily, and Spiroplasma-specific fibril proteins. Here we have solved the structure of the fibril filament by single-particle cryo-electron microscopy at 3.6 [A] resolution and built its atomic structure. The structure is composed of repeated rings and cylinders. The N-terminal cylinder of the fibril protein shows a structure similar to that of S-adenosylhomocysteine nucleosidase, while the C-terminal ring does not show similarity to other proteins. The filament is nonpolar and flexible, possessing a helical pitch of 700 nm, consistent with cell helicity. Cryo-electron tomography revealed aligned several MreB filaments in the center of the ribbon, flanked by membrane-binding fibril filaments through electrostatic interactions. This study discusses the evolution and roles of the fibril filament.

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Sasajima, Y., Kato, T., Miyata, T., Kiyama, H., Kawamoto, A., Makino, F., Namba, K., Miyata, M.. 2023-06-28. Cryo-EM of cytoskeletal 'fibril' protein involved in Spiroplasma swimming. https://doi.org/10.1101/2023.06.28.546849

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