The structural complexity of the Gammaproteobacteria flagellar motor is related to the type of its torque-generating stators

Kaplan, M.; Ghosal, D.; Subramanian, P.; Oikonomou, C. M.; Kjaer, A.; Pirbadian, S.; Ortega, D. R.; El-Naggar, M. Y.; Jensen, G. J.

doi:10.1101/369397

bioRxiv · 10.1101/369397

The structural complexity of the Gammaproteobacteria flagellar motor is related to the type of its torque-generating stators

Kaplan, M.·Ghosal, D.·Subramanian, P.·Oikonomou, C. M.·Kjaer, A.·Pirbadian, S.·Ortega, D. R.·El-Naggar, M. Y.·Jensen, G. J.

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Abstract

The bacterial flagellar motor is a cell-envelope-embedded macromolecular machine that functions as a propeller to move the cell. Rather than being an invariant machine, the flagellar motor exhibits significant variability between species, allowing bacteria to adapt to, and thrive in, a wide range of environments. For instance, different torque-generating stator modules allow motors to operate in conditions with different pH and sodium concentrations and some motors are adapted to drive motility in high-viscosity environments. How such diversity evolved is unknown. Here we use electron cryo-tomography to determine the in situ macromolecular structures of the flagellar motors of three Gammaproteobacteria species: Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis MR-1, providing the first views of intact motors with dual stator systems. Complementing our imaging with bioinformatics analysis, we find a correlation between the stator system of the motor and its structural complexity. Motors with a single H+-driven stator system have only the core P- and L-rings in their periplasm; those with dual H+-driven stator systems have an extra component elaborating their P-ring; and motors with Na+- (or dual Na+-H+)- driven stator systems have additional rings surrounding both their P- and L-rings. Our results suggest an evolution of structural complexity that may have enabled pathogenic bacteria like L. pneumophila and P. aeruginosa to colonize higher-viscosity environments in animal hosts.

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Kaplan, M., Ghosal, D., Subramanian, P., Oikonomou, C. M., Kjaer, A., Pirbadian, S., Ortega, D. R., El-Naggar, M. Y., Jensen, G. J.. 2018-07-14. The structural complexity of the Gammaproteobacteria flagellar motor is related to the type of its torque-generating stators. https://doi.org/10.1101/369397

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