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44 Cards in this Set
- Front
- Back
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How are flagella involved in pathogenesis?
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Motility
Adhesion to and invasion of host cells Flagella and biofilms Flagellar phase variation Mucosal inflammatory response to flagellin |
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How are bacterial motile?
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Can use their flagella to swim
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How many genes are required for the flagellar machinery to be expressed?
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about 50
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How are bacteria motile?
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They attach with their flagella
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What are examples of motile bateria?
Non motile? |
Motile: E. coli (many flagella), Pseudomonas aeruginosa (single flagellum)
Non motile: S. aureus |
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Do bacteria have flagella when they're in a biofilm?
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No, don't swim in biofilm, .: don't need flagella
->When biofilm disperses, bacteria produce the genes for flagella |
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Why is flagellin important in producing inflammation?
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1) TLR5 -> extracelllular receptor
2) Intracellular receptor Both these work together to produce inflammation |
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What are the 2 flagellin genes important for motility?
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FliC
FljB |
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What happens to mutants that don't have FliC or Fljb?
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No motility
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Why is the expression of flagellar motility genes tightly regulated?
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Assure ordered ptn assembly
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How are the flagellar machinery genes transcribed?
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First: early genes
then intermediate genes then late genes |
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What do the early genes code for?
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Rings (get channel formation)
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What are the late genes for?
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Hook and filament ptns
-> go through channels to outside to form the flagella |
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Where are the early transmb ptn transported through?
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Sec-pathway
->go from cytoplasm (where synthesized) to periplasm (where assembled) |
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How are the later ptns transported outside ?
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The Flagellar-specific export path
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How many flagellin subunits does the filament have?
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30,000
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Where does the E for flagellin rotation come from?
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Mb gradient of H+
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Where do H+ move through?
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8 independent force-generating units (Mot ptns)
-> These form the Stator (stationary part of the motor) |
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What do the H+ interact with?
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ring of ~32 FliG ptns that form the Rotor
(drives the rotation) |
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How many rotations/sec?
H+/rotation? Speed? |
250 rotations/sec
1000 H+/rotation Speed: 15-100um/sec |
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How many flagella does P. aeruginosa have?
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1 polar flagellum
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What is FliC?
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Flagellin
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What is FliD?
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Flagellar cap ptn
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What does P.aeruginosa do in cystic fibrosis patients?
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Colonizes the airway lumen
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What does FliD bind to?
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Mucin (MUC-1), a cell surface-associated mucin
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How is a biofilm produced?
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Unattached cells --> Attach to the surface => Surface growth
->get attached monolayer (where they move with appendages other than flagella) =>bacteria produce Type IV pili (glide along surface by extending and retracting the pili) ->Form a microcolony ->use quorum sensing to sense their env't Once in a biofilm, they no longer swim, .: they usually don't express flagella |
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What is a biofilm?
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Bacteria embedded in a matrix consisting mostly of secreted polysac
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What happens in flagellar phase variation of Salmonella?
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Depending on which phase flagella dev'p is in, different Fli genes will be expressed
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What are the 2 genes coding for flagellin?
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FljB and FliC
(Don't need both, onl one or the other) |
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What is FljA?
What does it do? |
Transcriptional repressor
Lines up with promoter of FliC and represses, so only 1 gene (Flj B) is transcribed |
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What is the 996 bp segment of Salmonella?
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promoter for fljB and fljA
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What happens from this gene is inverted?
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Orientation of the promoter dif, .: dont make Flj A/B .: no fjA to repress T of FliC
-> Transcribe FliC ->if Flj T, FljA blocks FliC -> If promoter of Flj inverted, no FljA, .: get FliC |
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What is the purpose of flagellar phase variation?
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Ab made vs FljB wont recognize FliC
.: Bacteria can evade host for longer |
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What does Hin recombinase do?
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Catalyzes the inversion of the Flj promoter
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What does TLR5 do?
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senses flagellin monomers
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What happens during signalling through TLR5?
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Activation of NF-kB and MAPK paths that turn on T of genes involved in innate and adaptive immunity
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Do the flagellin monomers from Heliobacter pylori cause inflammation?
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No
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Why are there different lvls of inflammation produced by flagellin?
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Dif bacteria use different genes to transcribe the flagellin
.: different response |
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What kind of a response is triggered by Salmonella flagellin monomers?
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Robust inflammatory response (IL-8 and other chemokines)
This attracts PMNs |
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What do TLRs recognize?
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PAMPs (pathogen associated molecular patterns)
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What is Ipaf?
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Cytoplasmic receptor of flagellin
Part of NOD-like receptors |
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What happens when flagellin interacts with Lpaf?
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Activates Caspase-1
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What happens when TLR5 interats with flagellin?
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Interacts with MyD88, which gets rid of IkB and allows NF-kB to translocate into the nucleus and trigger innate I.S and start the adaptive response
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LIST of TLRs on pg 11
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LIST of TLRs on pg 11
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