Why adherence of Yersinia pseudotuberculosis and Listeria monocytogenes to host
ID: 35074 • Letter: W
Question
Why adherence of Yersinia pseudotuberculosis and Listeria monocytogenes to host cells is independent of the actin cytoskeleton although host cell cytoskeleton is perturbed during invasion?
a) Adherence of the bacteria involves cell receptors that are not involved in cell adhesion or cytoskeleton.
b) Cells targeted by these bacteria typically in mitosis, thus they do not have organized cytoskeleton
c) Initial contact and adherence of the bacteria involves only the bacterial ligand and its adhesion receptor.
d) None of the above
Which of the following is not correct for Yersinia invasion?
a) Yersinia utilizes an invasin that is an outer membrane protein on the bacteria.
b) Yersinia utilizes an invasin that contains a RGD motif that binds to host cell integrin
c) Yersinia utilizes an invasin that has higher affinity for host cell integrin than native ligand in the tissue.
d) Yersinia utilizes an invasin that induces cell signaling in the host cell through integrin oligomerization and clustering.
Most bacteria are successfully removed from urogenital tract, however Neisseria gonorrhoeae manages to promote its colonization at the tissue.
a) N. gonorrhoeae has evolved to utilize the components of urine as nutrients.
b) N. gonorrhoeae has an enzyme that covalently binds the bacteria to the extracellular matrix in the tissue
c) N. gonorrhoeae suppresses exfoliation of mucosal epithelium in the urogenital tract.
d) All of the above
Please give explanation for your answer choice. Thank you!
Explanation / Answer
1. d. none of the above.
The actin-based movement of Listeria monocytogenes within and between host cell is as follows- These bacteria induce the assembly of actin-rich tails in the host cell cytoplasm, which enable them to move rapidly. Motile bacteria spread from cell to cell by forming membrane-enclosed protrusions that are engulfed by neighboring cells. Fluorescence micrograph of the bacteria moving in a cell that has been stained to reveal both bacteria and actin filaments.
2. b) Yersinia utilizes an invasin that contains a RGD motif that binds to host cell integrin
Molecular mechanisms for actin nucleation by various pathogens. The bacteria Listeria monocytogenes moves intracellularly using actin polymerization. To induce actin nucleation, all of these pathogens recruit and activate the ARP complex , although each pathogen uses a different recruitment strategy. L. monocytogenes expresses a surface protein, ActA, that directly binds to and activates the ARP complex. The phosphorylated protein then recruits Nck, which binds WIP. WIP binds N-WASp, which recruits and activates the ARP complex. The more complicated cascade used by vaccinia is thought to closely resemble how the ARP complex is activated by chemotactic factors in motile eucaryotic cells. Despite these distinct molecular strategies, the actin comet tails formed by all three pathogens look very similar, and the pathogens move at similar speeds inside infected cells
3. d. all of the above.
Neisseria gonorrhoeae does not thrive in the environment and grows in a CO2 environment, therefore, the urethra, cervix, rectum, and throat are the main sites of infection. Once the gonococci gain entrance into the mucous membranes of these areas, they target columnar non-ciliated epithelial cells.
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