Oral Presentation 14th Lorne Infection and Immunity 2024

Molecular structure of the intact bacterial flagellar basal body (#6)

Steven Johnson 1 2 , Emily Furlong 1 3 , Justin C Deme 1 2 , Ashley L Nord 4 5 , Joseph Casear 1 , Fabienne FV Chevance 6 , Richard M Berry 5 , Kelly T Hughes 6 , Susan M Lea 1 2
  1. Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
  2. Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
  3. Research School of Biology, Australian National University, Canberra, ACT, Australia
  4. Centre de Biologie Structurale, INSERM, CNRS, Univerite de Montpellier, Montpellier, France
  5. Department of Physics, University of Oxford, Oxford, UK
  6. Department of Biology, University of Utah, Salt Lake City, Utah, USA

Bacterial flagella self-assemble a strong, multi-component drive shaft that couples rotation in the inner membrane to the microns-long flagellar filament that powers bacterial swimming in viscous fluids. We solved structures of the intact Salmonella flagellar basal body, using cryo-electron microscopy to resolutions between 2.2 and 3.7 Å. The structures reveal molecular details of how 173 protein molecules of 13 different types assemble into a complex spanning two membranes and a cell wall. The helical drive shaft at one end is intricately interwoven with the inner membrane rotor component, and at the other end passes through a molecular bearing that is anchored in the outer membrane via interactions with the lipopolysaccharide. The in situ structure of a protein complex capping the drive shaft provides molecular insight into the assembly process of this molecular machine.