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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

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

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


Swarmer cells are longer and have more flagella

Broth - Swimmer

Plate - Swarmer


What are the signals?

How are the signals transduced to elicit cell differentiation?


Flagellar dynamometer controls swarmer cell differentiation

of V. parahaemolyticus

McCarter et al. 1988 Cell 54: 345-351


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


Two flagellar systems

Broth: Fla

Na+ ions

Agar: Laf

H+ ions



Agar

Viscosity

PVP

Broth

PVP

Antibody agglutination

Broth

Induction of laf::lux in:


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?




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


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


  • 3. FlaC mutations

  • 4. Mot mutations


    • Possible Mechanisms expression

    • 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!


    The sodium-driven polar flagellar motor of marine Vibrio expression

    as the mechanosensor that regulates lateral flagellar gene

    expression

    Kawagishi et al., Mol. Microbiol. 20: 693-699, 1999


    Hypothesis expression

    Rotation rate of

    OR

    External force applied against

    the polar flagellum controls laf expression


    H expression+

    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


    Effect of amiloride and its analogs on expression

    Growth

    laf expression


    Effect of expression

    Phenamil Viscosity

    on

    Swimming speed●

    laf expression○



    Conclusion expression

    A decrease in polar flagellar rotation rate, rather than the external force

    applied against the polar flagellum, can trigger swarmer cell differentiation


    How is rotation rate sensed? expression

    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?


    H expression+

    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


    Surface Motility expression

    a) Swarming - flagella

    b) Twitching – Type IV pili

    (Retractile motility)

    c) Gliding - ?

    d) Spreading - passive

    Gliding Movies

    Harshey, Ann Rev. Microbiol. 2003