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Surface Motility

Surface Motility. a) Swarming - flagella. b) Twitching – Type IV pili (Retractile motility). c) Gliding - ?. d) Spreading - passive. Harshey, Ann Rev. Microbiol. 2003. Swarming Motility 1. Flagella-driven group motility on a surface

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Surface Motility

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  1. Surface Motility a) Swarming - flagella b) Twitching – Type IV pili (Retractile motility) c) Gliding - ? d) Spreading - passive Harshey, Ann Rev. Microbiol. 2003

  2. Swarming Motility 1. Flagella-driven group motility on a surface 2. Cell-density dependent lag prior to initiation of movement Swarming Movies 3. Swarming colony surrounded by a wet film which facilitates movement 4. Swarmer cells are ‘differentiated’- longer and more flagella

  3. Swarmer cells are longer and have more flagella Broth - Swimmer Plate - Swarmer

  4. What are the signals? How are the signals transduced to elicit cell differentiation?

  5. Flagellar dynamometer controls swarmer cell differentiation of V. parahaemolyticus McCarter et al. 1988 Cell 54: 345-351

  6. H+ Na+ High viscosity Low viscosity H+-driven Lateral flagella Na+-driven Polar flagellum Na+-driven Polar flagellum Vibrio parahaemolyticus has two different types of flagella Laf Pof

  7. Two flagellar systems Broth: Fla Na+ ions Agar: Laf H+ ions

  8. Reporter system used in this work

  9. Agar Viscosity PVP Broth PVP Antibody agglutination Broth Induction of laf::lux in:

  10. H+ Na+ High viscosity Low viscosity H+-driven Lateral flagella Na+-driven Polar flagellum Na+-driven Polar flagellum Vibrio parahaemolyticus has two different types of flagella Ab that tether Pof OR Slow motor rotation Laf Pof What if you destabilize the filament?

  11. SDS-PAGE of purified flagella in various strains

  12. EM of mutants with flagellin gene defects DFlaAB FlaC

  13. H+ Na+ High viscosity Low viscosity H+-driven Lateral flagella Na+-driven Polar flagellum Na+-driven Polar flagellum Vibrio parahaemolyticus has two different types of flagella Ab that tether Pof Mot mutations Che mutations Laf Pof

  14. Effect of fla, che and mot mutations on laf::lux expression 1- Fla-; 2- Fla-; 3- Che-; 4- Mot-; 5- Fla- 6- Fla-; 7- Mot-; 8- WT; 9- Fla-; 10- Fla- 11- Fla-; 12- Che-; 13- Che-; 14- Che-; 15- WT WT

  15. Interference with polar flagellar function signals Laf expression • 1. Increasing viscosity • 2. Antibodies • 3. FlaC mutations • 4. Mot mutations

  16. Possible Mechanisms • Slow movement signals chemotaxis in reverse • High viscosity affects subunit assembly: • negative regulation of Laf assembly by FlaC • Flagellar torque imparts torsional force on cell body • All of these are physical signals!

  17. The sodium-driven polar flagellar motor of marine Vibrio as the mechanosensor that regulates lateral flagellar gene expression Kawagishi et al., Mol. Microbiol. 20: 693-699, 1999

  18. Hypothesis Rotation rate of OR External force applied against the polar flagellum controls laf expression

  19. H+ Na+ High viscosity Low viscosity H+-driven Lateral flagella Na+-driven Polar flagellum Na+-driven Polar flagellum Vibrio parahaemolyticus has two different types of flagella Ab that tether Pof Mot mutations Na+ channel blockers Laf Pof

  20. Effect of amiloride and its analogs on Growth laf expression

  21. Effect of Phenamil Viscosity on Swimming speed● laf expression○

  22. Relationship between swimming speed and laf induction

  23. Conclusion A decrease in polar flagellar rotation rate, rather than the external force applied against the polar flagellum, can trigger swarmer cell differentiation

  24. How is rotation rate sensed? Ion flux? But flux is coupled to rotation rate, so hard to separate. Also a marine bug like Vibrio has plenty of sodium around, so decrease in rotation should not affect total sodium flux in cell. Local ion concentration at the polar flagellum? Can this change the charge/conformation of an associated regulator of gene expression? Is assembly still an option?

  25. H+ Na+ High viscosity Low viscosity H+-driven Lateral flagella Na+-driven Polar flagellum Na+-driven Polar flagellum Vibrio parahaemolyticus has two different types of flagella Ab that tether Pof Mot mutations Na+ channel blockers i.e. slow motor rotation Low Iron Laf Pof

  26. Surface Motility a) Swarming - flagella b) Twitching – Type IV pili (Retractile motility) c) Gliding - ? d) Spreading - passive Gliding Movies Harshey, Ann Rev. Microbiol. 2003

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