Special Adaptations-lecture 24 Flashcards

1
Q

What are the different types of motility?

A

Swarming- involves cellular differentiation and surfactant production
swimming- doesn’t involve surface
twitching: involves type IV pili- cells move slow, produce a twitchy motion
- pili reach out and attach to surface and pull
Gliding: Prok has focal-adhesion complexes on cell surface
Sliding: spread by growth-> secrete surfactant that allows for gliding

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2
Q

Types of surface motility and model organisms for each, gliding and twitching motility

A

Gliding motility: focal adhesions basically motor power bacteria making the cell surface to provide traction

  • focal adhesions oscillate around bacteria
  • model organsims: Cytophaga Sp.

Twitching motility: Extend/retract pilus-> pulls body along

  • pilin is the pills subunit
  • model organism: pseudomonas aeruginosa
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3
Q

What is the molecular model for type IV Pilus function (twitching motility)

A

pilin subunits polymerize to form pilus extension
depolymerase disassembles subunit and causes retraction

Mutants in PillT causes no retraction

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4
Q

Describe Twitching motility in P. Aeruginosa

A

Twitching motility in P. Aeruginosa leads to formation of an exopolysaccharide tail

  • > leaves EPS stain in its wake
  • > when P.Aeruginosa bunds into EPS stain trail, they either stop moving or follow trail
  • Pill A mutant strain does not produce trails

Twitching Bacteria tends to follow the trail

–> Increases the likelihood of bacteria to encounter each other on a 2-D surface and form aggregates

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5
Q

What is swarming motility?

A

Flagella-driven group motility on a surface-usually involves surfactant
–> surfactant is a self induced agent to make surface slippery

In some bacteria, swarmer cells are longer and have more flagella

In other cells, swarmer cells have distinctly different flagella compared to swimmers

—> Phylogenetically widespread, bacillus subtitles can do it too!

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6
Q

What are some common surfactant structures? THINK : LUBE

A

Bacillus Subtilis uses a surfactin
Pseudomonas aeruginosa uses a rhamnolipid
serratia liquefaciens use lipopetides (surfactin and serrawettin)

Not all swarming bacteria produce surfactants (E.coli do not)
They are amphipathic (hydrophobic and hydrophilic)
they reduce surface tension between cell and surface
regulated by quorum sensing

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7
Q

What are common traits of swarming bacteria?

A
  1. The swarming lag: Bacteria do not swarm immediately
    - > to exit the lag, bacteria must:
    - high cell density
    - hyper flagellation
    - nucleation/raft formation (cellulose fibrils)
  2. Cell elongation/hyper flagellation
  3. Colony pattern Formation (bulls eye petri format)
    - proteus bacteria have consolidation zones with bursts of growth and movement
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8
Q

Flagella of Vibrio parahaemolyticus

A

Free swimming flagella:
Sodium driven polar flagellum encoded by Pof, is very long

Surface flagellum:
H+ polar head
lateral flagella encoded by Lab gene-> is thinner and shorter than free swimming flagella

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9
Q

How to differentiate flagellum into light?

A

Use laf-lux transcriptional fusion to create bioluminescence with the enzyme luciferase

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10
Q

What are the key factors impacting flagella expression?

A

Viscosity- impedes flagellum rotation
antibody agglutination-exerts force on flagellum that can create light in non-viscous mediums

Conclusions: Antibiotics that tether Pof or high viscosity lead to differentiation from Na+ flagellum to H+ flagellum

Slow motor rotation or low viscosity causes differentiation into the H+ flagellum

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11
Q

How does phenamil impact flagellum?

A

Phenamil is a sodium channel blocker that will decrease rotation in Na+ flagellum
Impaired turning of basal body-> decrease swimming speed

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12
Q

What is the relationship between swimming speed and laf induction?

A

A decrease in polar flagellar rotation rate, rather than external force applied against flagellum, triggers swarmer cell differentiation

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13
Q

Spirochete motility

A

spirochetes are a corkscrew bacteria that are found in viscous parts of the body (found in dental plaque and Syphillis)
Theres an endoflagellum that wraps around the body on the outside, rotates around protoplasmic cylinder

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14
Q

What is a magnetosome and magnetotaxis?

A

Magnetotaxic bacteria are gram negative bacteria that thrive in microbic conditions

Move faster as field strength increases
move parallel to magnetic field
integrated with aerotaxis(moving in relation to oxygen gradient)

Purpose: help bacteria find toxic-anoxic interface in aquatic systems

Aerotaxis counteracts magnetotaxis when magnetoxic bacteria buries too deep

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15
Q

Explain about gas vacuolated bacteria

A

Gas vesicles can be produced by eubacteria and archaea and are used by phototrophs to move them up and down the water column

Contain proteins to arrange a gas-permeable, but watertight structure

In phototrophic bacteria, gas vacuoles are mainly in phototrophic bacteria and maintain position depending on sun, move away from sun

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