Pili and Flagella Flashcards
Explain the 3 Bacteria appendages and what their functions are
1) flagella: locomotion
2) Pili and fimbriae: adhesion
3) Sex pili: Transfer of DNA
Pili are widespread in what classification of bacteria?
Pili is widespread in GRAM NEGATIVE and rare in positiev
True or False, pili are normally Peritrichous along the cell
True (all over the cell surface)
Explain Pili’s structure and mobility
Pili are straight rods unlike flagella (helical)
Pili cant move/rotate unlike flagella
Pili have a simple base unlike flagella which have a complex base
what is the only type of pili that is used for a little bit of motility in pathogenesis?
Type 4 (IV) pili creates a twitching motility which is surface mediated. It is NOT swimming
What is UPEC?
An E. Coli that has specialized Pili that cause urinary tract infections
E. Coli Pap Pili: explain Pap G
G is the actual adhesion at very tip of the pili on the pili fibre
E. Coli Pap Pili: explain Pap F
F is the adhesion adapter that connects the G adhesion to the pili fibre
E. Coli Pap Pili: explain Pap E
E is the major component of the pili fibre
E. Coli Pap Pili: explain Pap K
K is the adapter that connects the pili fibre (mainly E) to the main pilus structure
E. Coli Pap Pili: explain Pap A
Pap A is the bulk of the pilus rod
E. Coli Pap Pili: explain Pap H
anchors the rod (A) to the cell
E. Coli Pap Pili: explain Pap D
Pap D is a chaperone protein inside the periplasmic space
E. Coli Pap Pili: explain Pap C
Pap C is located in the outer membrane and it removes incoming proteins from chaperone Pap D
Explain G-FEKAH’ CD
This is the the order of the PAP regions from furthest from the cell to the periplasm.
Explain Pili synthesis up until Pap C (4 points)
- translated Pap subunits are normally made as precursor with a signal peptide
- signal peptides tell cell it needs to be exported
- as the cell is exported out of the PM, the signal peptide is cut off
- Pap D binds the subunit in the periplasm and delivers it to Pap C in the outer membrane
what occurs if Pap D becomes mutated?
No pilus will form and subunits will degrade in periplasm!!
Explain the second half of Pili synthesis (3 points)
- Pap C creates a donut like spore that feeds the pilus out of the OM
- Assembly starts with furthest out proteins therefore Pap G is the first subunit
- Major shaft proteins come in (Pap A) until one pap H comes which terminates the pilus
how many Pap H does it take to stop pilus growth?
one. On avg pilus have 1000 pap A’s
Explain the gene organization of the pilus. How does A get produced so much more than the other subunits
- there is a transcriptional terminator after the A gene that causes RNA polymerase to fall off.
- small amounts of it pass this and transcript the rest of the genes
what is the force that allows flagella to rotate?
Proton motive force!!
NO ATP IS USED
Explain Monotrichous
Only one flagellum
Polar flagellum ?
there is a flagellum at end of the cell
Amphitrichous?
there is flagella at both ends of the cell
Bi - polar
Lophotrichous?
Cluster of flagella at one or both ends of the cell
Peritrichous?
spread every where
What are the three main components of flagella?
Filament, the hook, and the basal body
What is the major difference between gram negative and gram positive bacteria flagellum?
Negative: basal body is complex with 4 rings
positive: basal body is simple with 2 rings (S and M)
explain the filament structure of flagellum
10,000’s of copies of flagellin
Is capped by Hook Associated protein 2 (HAP2)
explain Flagellin properties
- is deficient in cysteine, and tryptophan
- will dissociate in presence of acid or heat
What is HAP2?
Hook Associated Protein 2 which caps the Filament structure
explain the hook region of flagella
- composed of hook proteins
- has a defined length of 80nm
- HAP1 and HAP3 are at junction between filament and hook
Explain the Basal Body structure in Gram Negative bacteria. Name rings
- composed of a rod and 4 rings
- L, P, S, and M are 4 rings
- gram positive only have S and M
Explain the L ring
In the plane of LPS (outer membrane)
LPS = lipopolysaccharide
Explain the P ring
In the plane of the peptidoglycan layer
Explain the S ring
Supramembraneous, just above PM
Explain the M ring
M ring is in plane with PM
Explain how flagella rotates
- There are 3 switch proteins
- FliN, FliG, and FliM
- Mot A and Mot B are stators which ensure the flagella is stably connected to the PM
- they also form proton gradient for force
how do basal body rings get exported?
they have signal peptides
how do HAPS, flagellin, and hook get exported?
they travel up the interior of the growing filament
Why is HAP2 important
It caps the filament and therefore ensures when the flagella grows that the subunits do not diffuse away.
Explain gene organization of flagella
unlike pili which have one operon controlling the whole structure, E. coli flagella have over 40 genes involved in 10 operons
neither flagella or pili gene control is “Wasteful”
explain the order of transcriptional control?
- input from many signals give the cell an idea of the environment
- then early genes are activated
- then middle genes
- then late genes
explain early genes
Early genes have master control
they are transcriptional activators
explain middle genes
- Middle genes will only transcribe if activated by early genes
- These genes code for basal body formation and hook transportation
Late genes?
must be activated by middle genes
codes for flagella filament
Besides flagella rotation what other types of motility are possible? explain both
1) twitching motility done by type IV pili
- they crawl by extending and shortening pili
2) gliding motility
- expels slime which glides bacteria forwards
explain myxobacteria
A form of bacteria that has both type IV pili and slime for ultra motility
What is the only microbe to have ATP driven legs for motility
mycoplasma mobile
