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20 Cards in this Set
- Front
- Back
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How are flagella involved in pathogenesis? (5)
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1. Adhesion
2. Motility 3. Biofilm formation 4. Phase variation 5. Mucosal inflammation |
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_____ is the unicellular movement of bacteria across a surface. It requires the rotation of a helical flagellum.
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Swarming
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What is swimming?
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Movement of an individual bacterium in liquid. Powered by rotating flagella.
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____ movement powered by extension of pili, which attach to a surface then retract.
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Twitching.
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Name a bacterial species that moves by twitching.
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Pseudomonas aeruginosa.
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How many genes control the flagellar machinery?
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About 50.
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Rearrange the following events in chronological order :
1. Subunits secreted ; hook grows. 2. Formation of the MS and C-rings. 3. Filament caps and filament subunits are secreted. 4. Formation of the P and L rings. |
2, 4, 1, 3
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The filament in a flagellum consists of about _____ flagellin subunits.
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30 000
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What genes express the proteins required for the stators in the flagellar machinery? How many of these units are there? What genes express the proteins required for the rotor?
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MotA and MotB. Eight. FliG.
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How many rotations per second? How many protons per rotation?
How many protons per second? Speed? |
25 rotations per second.
1000 protons per rotation. 25 000 protons per second. 10-100 micrometers per second. |
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Name the flagellin and flagellar cap proteins of Pseudomonas aeruginosa.
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FliC and FliD.
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What protein from Pseudomonas aeruginosa's flagellum binds to Muc-1, a cell-surface associated mucin?
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FliD
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What bacterium colonizes the airway lumen in cystic fibrosis patients? Explain how this phenomenon occurs.
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Pseudomonas aeruginosa. In CF patients, bacterial colonies are not washed out like in unaffected people as their liquid is much more viscous. Pseudomonas aeruginosa then accumulate in the lumen, and, following quorum sensing, form biofilms where they embed themselves.
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What are biofilms made of? What proportion of bacteria are there in these biofilms? What is the major change that P. aeruginosa undergoes following its embedding into the biofilm?
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Polysaccharides. 15%. Loses its flagellum.
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Explain the flagellar phase variation in Salmonella.
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Salmonella has 2 genes coding for flagellin (FljB and FljC). They differ in their amino acid sequences and have different antigenicities. The default flagellin expressed is FljB. The expression of FljB is driven by a promoter that also expresses FljA, a repressor for FljC. Following DNA inversion of the 966bp promoter region by Hin recombinase, the expression of FljB and FljA is stopped, and FljC is expressed. This allows to escape hosts that are immune to one antigen.
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What signaling mechanism is triggered by activation of TLR5? What does TLR5 recognize?
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NF-kB and MAPK pathways. Flagellin monomers.
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Flagellin monomers from ____ do not cause inflammation. In contrast, flagellin monomers form _____ trigger a robust inflammatory response.
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H. pylori. Salmonella.
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TLR-3 is a dimer made of ____-rich repeats. It recognizes _____
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Leucine. dsRNA.
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Describe how flagellin activates caspase 1 via IPAF?
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Monomeric flagellin recognized by IPAF, a cytoplasmic receptor. Following binding, trimerization of IPAF, which trimerizes. The trimer interacts with procaspase 1 and trigger proteolytic cleavage. This leads to macrophage death and inflammation.
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How do monomeric flagellin subunits get into the cell?
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Secretion systems or intracellular bacteria in phagosome release them into the cytoplasm.
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