Flashcards in Vibrio cholerae Deck (21)
1
What 5 barriers must cholera cross to cause disease?
1) ingestion
2) gastric acid barrier
3) colonize upper small intestine
4) produce/excrete toxin
5) disseminate in watery diarrhea
2
What 2 components make up the cholera toxin?
1) CtxA
2) CtxB
CTX B forms protein coat around A
A is cleaved into A1 and A2
3
Cholera toxin binds host _____ receptor to get into the cell
GM1
A1 subunit enters cell
4
Once inside the cell, what does A1 do?
modify a G protein to activate adenylyl cyclase
5
What happen to cAMP levels when cholera infects?
INCREASE
6
What virulence factor is involved in colonization?
single polar flagellum (nonmotile strains are less virulent)
7
What happens to the flagellar genes once the bacteria has colonized?
turned off, toxin genes turned on
8
What virulence factors are involved once bacteria has colonized?
1) TCP (toxin colonization pilus)
2) ACF (accessory colonization factors)
9
Activation of the ______ regulon permits synthesis of virulence factors
ToxR
10
True or false: ToxR and ToxS form a regulon
True
11
What determines whether or not the ToxRS operon is on? (aka what turns the promoter on?)
low temp (outside host)
toxR and S are synthesized and incorporated into cytoplasmic membrane
12
Where do ToxR and S go once translated?
into the cytoplasmic membrane
13
What does the R and S stand for?
R = regulator
S = environmental sensor
14
What happens in the stomach once vibrio is swallowed?
high temps inactivated toxRS but the already made proteins still sit in the membrane
15
When and where does the ToxRS regulon turn on?
in host intestine once ToxS has received a signal unique to the intestinal environment
16
Once ToxS gets the signal in the small intestine, what happens downstream?
communicates that info to ToxR which binds to the TCP-ACF element DNA to activate transcription of the colonization virulence factors
17
What is ToxT and what role does it play?
ToxT is part of the tcp operon and it activates expression of the tcp promoter (activating toxT transcription)
it controls most ToxR regulon genes including the tcp operon
18
True or false: toxT autoregulates
True
19
True or false: toxT activates CTX operon
true
20
What 3 things are required by V. cholera virulence?
1) the chromosome (toxRS operon)
2) pathogenicity island (TCP-ACF)
3) temperate or lysogenic bacteriophage (CTX phage carrying ctxAB)
21