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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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slide1

Surface Motility

a) Swarming - flagella

b) Twitching – Type IV pili

(Retractile motility)

c) Gliding - ?

d) Spreading - passive

Harshey, Ann Rev. Microbiol. 2003

slide2

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

slide4

What are the signals?

How are the signals transduced to elicit cell differentiation?

slide5

Flagellar dynamometer controls swarmer cell differentiation

of V. parahaemolyticus

McCarter et al. 1988 Cell 54: 345-351

slide6

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

slide7

Two flagellar systems

Broth: Fla

Na+ ions

Agar: Laf

H+ ions

slide9

Agar

Viscosity

PVP

Broth

PVP

Antibody agglutination

Broth

Induction of laf::lux in:

slide10

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?

slide13

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

slide14

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

slide15

Interference with polar flagellar function signals Laf expression

          • 1. Increasing viscosity
        • 2. Antibodies
  • 3. FlaC mutations
  • 4. Mot mutations
slide16

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!
slide17

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

slide18

Hypothesis

Rotation rate of

OR

External force applied against

the polar flagellum controls laf expression

slide19

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

slide21

Effect of

Phenamil Viscosity

on

Swimming speed●

laf expression○

slide23

Conclusion

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

applied against the polar flagellum, can trigger swarmer cell differentiation

slide24

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?

slide25

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

slide26

Surface Motility

a) Swarming - flagella

b) Twitching – Type IV pili

(Retractile motility)

c) Gliding - ?

d) Spreading - passive

Gliding Movies

Harshey, Ann Rev. Microbiol. 2003