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Structure and Assembly of the Proteus mirabilis Flagellar Motor by Cryo-Electron Tomography

Mohammed Kaplan1, Qing Yao1, Grant J Jensen1,2

  • 1Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.

International Journal of Molecular Sciences
|May 13, 2023
PubMed

Insights

Proteus mirabilis uses a flagellar motor similar to E. coli and Salmonella. This study reveals its structure and dynamic stators, supporting an inside-out assembly pathway.

Area of Science:

  • Microbiology
  • Structural Biology
  • Bacterial Motility

Background:

  • Proteus mirabilis is a Gram-negative bacterium causing urinary tract infections.
  • It exhibits distinct swimming and swarming motility.
  • Understanding its flagellar motor is key to its pathogenesis.

Purpose of the Study:

  • To elucidate the structure of the Proteus mirabilis flagellar motor.
  • To investigate the motor's components and assembly in intact cells.

Main Methods:

  • Cryo-electron tomography (cryo-ET)
  • Subtomogram averaging
  • High-resolution structural analysis of intact bacterial cells

Main Results:

  • The flagellar motor of P. mirabilis is structurally similar to those of E. coli and S. enterica.
  • It lacks periplasmic elaborations found in other gammaproteobacterial motors.
  • No stator density was observed, suggesting dynamic stators.
  • Assembly intermediates support an inside-out assembly pathway.

Conclusions:

  • The P. mirabilis flagellar motor shares conserved features with related bacteria.
  • The dynamic nature of stators and the inside-out assembly pathway are significant findings.
  • This structural insight could inform strategies against P. mirabilis infections.
Keywords:
Proteus mirabilisbacterial flagellar motorcryo-electron tomography

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