An asymmetric sheath controls flagellar supercoiling and motility in the leptospira spirochete

Kimberley H Gibson (1) , Felipe Trajtenberg (2) , Elsio A. Jr Wunder (3, 4) , Megan R Brady (1) , Fabiana San Martin (2) , Ariel E Mechaly (2) , Zhiguo Shang (1) , Jun Liu (5) , Mathieu Picardeau (6, 7) , Albert Ko (3, 4) , Alejandro Buschiazzo (2, 7) , Charles Vaughn Sindelar (1)

1 YSM - Yale School of Medicine [New Haven, Connecticut]
2 Institut Pasteur de Montevideo
3 YSPH - Yale School of Public Health
4 IGM - Instituto Gonçalo Moniz / Gonçalo Moniz Research Centre - Fiocruz Bahia [Salvador, Brésil]
5 Department of Microbial Pathogenesis
6 Biologie des Spirochètes / Biology of Spirochetes
7 IMiZA - Integrative Microbiology of Zoonotic Agents [Paris and Montevideo]

Spirochete bacteria, including important pathogens, exhibit a distinctive means of swimming via undulations of the entire cell. Motility is powered by the rotation of supercoiled 'endoflagella' that wrap around the cell body, confined within the periplasmic space. To investigate the structural basis of flagellar supercoiling, which is critical for motility, we determined the structure of native flagellar filaments from the spirochete Leptospira by integrating high-resolution cryo-electron tomography and X-ray crystallography. We show that these filaments are coated by a highly asymmetric, multi-component sheath layer, contrasting with flagellin-only homopolymers previously observed in exoflagellated bacteria. Distinct sheath proteins localize to the filament inner and outer curvatures to define the supercoiling geometry, explaining a key functional attribute of this spirochete flagellum.

Mots clés: cryo-tomography; electron cryomicroscopy; infectious disease; leptospira; leptospirosis; microbiology; molecular biophysics; structural biology; x-ray crystallography

Domaines: Microbiologie et Parasitologie; Sciences du Vivant [q-bio]

Kimberley H Gibson, Felipe Trajtenberg, Elsio A. Jr Wunder, Megan R Brady, Fabiana San Martin, et al.. An asymmetric sheath controls flagellar supercoiling and motility in the leptospira spirochete. eLife, 2020, 9, ⟨10.7554/eLife.53672⟩. ⟨pasteur-02549761⟩