Flagella Flashcards
5 types of motility
Swarming Swimming Twitching Gliding Sliding
What structure does...require? > swimming + swarming > twitching > gliding > sliding
Flagella
Pilus retraction
Focal adhesion complexes
Spreading by growth
Fastest swimming bacteria
What happens when tase cells come together?
Thiovvulum majus
= 60 body lengths/sec
Form crystal-like, rotating lattice
= sucks in nearby bacteria
Put into order of length:
Fimbriae
Flagellum
Pili
(long -> short)
Flagellum
Pili
Fimbriae
4 locations of flagella
Polar = 1 end or both
Lophotrichous = lots on 1 end or both
Medial = 1 on the side
Peritirichous = many on the sides
Tumbling
Flagella turn clockwise
- > try to change direction
- > flagella splay = tumble
- > flagella turn anti-clockwise
Energy source for powering flagella
Proton motive force
- flagella increase or decrease rotational speed in relation to strength of proton motive force
Flagella synthesis
50 genes required
- MS ring
- Other proteins + hook
- Filament grows from tip
Features of flagella
Basal body + rings
= anchor to envelope
Hook complex
= connects basal body to filament
Filament = propeller
Motor = drives flagella rotation
Secretion system = exports subunits
ATPase = energy source
Similarity of flagella with T3SS
Derived from common evolutionary ancestor + share 9 homologous constituents
Both arose from common primordial secretion system
Some components have been recruited by gene transfer
Evolutionary insights
- FlgK
= hook junction protein
- internal repeats similar to auto transporter protein 7-60 amino acids
Evolutionary insights
- P-ring assembly chaperone
= FlgA
- similar to Pilus chaperones
Evolutionary insights
- FliJ
has amidase domain
- prepares cell wall for construction
Evolutionary insights
- FliA
= specific sigma factor controlling flagella genes
Regulation of flagella biosynthesis
- early genes
regulatory proteins that control expression of the regulation
Regulation of flagella biosynthesis
- middle genes
control expression of structural components
- HBB complex, T3SS, regulatory genes for late gene expression
Biosynthesis of flagella biosynthesis
- late genes
filament, motor force generators + chemosensory machinery
Random walk
= alternating run and tumbles
e.g. down conc grads of toxins
Taxis
= biased random walk
Bacteria move towards attractant by regulating switch between run + tumble
Signalling + chemotaxis
- MCP
= Methyl-accepting chemotaxis proteins
- bind to specific attractants +/or repellents
Process of signalling + chemotaxis
MCP assisted by CheW
=> stimulates auto-phosphorylation of CheA
CheA transfers P to CheY
CheY+P interacts with switch complex in flagella C ring
How do attractants and repellents affect phosphorylation + run/tumble?
Attractants decrease phosphorylation
-> increases runs
= anti-clockwise
Repellents increase phosphorylation
-> increases tumbles
= clockwise
MCPs in E.coli
MCP homodimers span membrane + sense signals in periplasm
Normally near 1 pole
Different MCPs sense different signals
5 types of pili
Chaperone-Usher pili Type IV pili Type IV secretion pili Type V pili Curli fibres
