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Publications

Journal Article Preprint Epublish 9 citations

PubMed: 39416179 DOI: 10.1101/2023.09.08.556779

Molecular model of a bacterial flagellar motor in situ reveals a "parts-list" of protein adaptations to increase torque.

bioRxiv

Authors: Tina Drobnič, Eli J Cohen, Tom Calcraft, Mona Alzheimer, Kathrin Froschauer, Sarah Svensson, William H Hoffmann, Nanki Singh, Sriram G Garg, Louie Henderson, Trishant R Umrekar, Andrea Nans, Deborah Ribardo, Francesco Pedaci, Ashley L Nord, Georg K A Hochberg, David R Hendrixson, Cynthia M Sharma, Peter B Rosenthal, Morgan Beeby

Affiliations

  • Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.
  • Tina Drobnič current affiliation: MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
  • Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
  • University of Würzburg, Institute of Molecular Infection Biology, Department of Molecular Infection Biology II, Josef-Schneider-Straße 2/D15, 97080 Würzburg, Germany.
  • Current affiliation: The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China 200031.
  • Centre de Biologie Structurale, Universite de Montpellier, CNRS, INSERM. Montpellier, France.
  • Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
  • Current affiliation: Peptone Ltd, 370 Grays Inn Road, London WC1X 8BB, UK.
  • Structural Biology Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK.
  • Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390.

Abstract

One hurdle to understanding how molecular machines work, and how they evolve, is our inability to see their structures in situ. Here we describe a minicell system that enables in situ cryogenic electron microscopy imaging and single particle analysis to investigate the structure of an iconic molecular machine, the bacterial flagellar motor, which spins a helical propeller for propulsion. We determine the structure of the high-torque Campylobacter jejuni motor in situ, including the subnanometre-resolution structure of the periplasmic scaffold, an adaptation essential to high torque. Our structure enables identification of new proteins, and interpretation with molecular models highlights origins of new components, reveals modifications of the conserved motor core, and explain how these structures both template a wider ring of motor proteins, and buttress the motor during swimming reversals. We also acquire insights into universal principles of flagellar torque generation. This approach is broadly applicable to other membrane-residing bacterial molecular machines complexes.