Salmonella: A Disease-Causing Bacteria
by
gvallaster
Last updated 7 years ago
Discipline:
Science Subject:
Biology
Grade:
9,10,11,12


scanning electron mircropscopy of Salmonella entering the cell via Zipper Mechanism
Salmonella:a disease-causing bacteria
Salmonella, a group of bacteria, causes an infection of the intestines. Symptoms show within 6-72 hrs of exposure, often including diarrhoea; which could last for 2-7 days.
Zipper Mechanism
"receptor-mediated entry"
Rck invasin binds to receptor on host cell membrane > phosphorylation of at least 1 tyrosine kinase > activates Class I PI3-kinase > phosphorylates PIP2 to become PIP3 > activates Akt > GTP-Rac1/GTP-Cdc42 are activated > triggers actin polymerization via Arp2/3 complex
without Rck invasin or conformational change salmonella could not enter the host cell, allowing the intestines to function normally
scanning electron micropscopy of Salmonella entering a cell via Trigger Mechanism
ligand = Rck invasin, enzymes = tyrosine kinase/Class I PI3-kinase/Akt, what is being phosphorylized = tyrosine kinase/PIP2
Trigger Mechanism
ligand = conformational change of needle, enzymes = RhoGTPases, proteins = SopE (and other bacterial effectors)/RalA/exocyst complex
Using a TypeIII Secretion System SopE is directly injected into the host cell > SopE binds to RhoGTPases > allowing actin cytoskeleton rearrangement > activares Arp2/3 complexSopE use RalA to manipulate the exocyst complex > formation of ruffles
** the mechanism that controls the activation of GTP-Cdc42 is still unknown so dotted arrows show possible signalling pathways **
ETH Zurich. "How Salmonella Bacteria Cause Diarrhea In Their Host." ScienceDaily. ScienceDaily, 17 October 2009.
Velge, P., A. Wiedemann, M. Rosselin, N. Abed, Z. Boumart, A. M. Chaussé, O. Grépinet, F. Namdari, S. M. Roche, A. Rossignol, and I. Virlogeux-Payant. "Multiplicity of Salmonella Entry Mechanisms, a New Paradigm for Salmonella Pathogenesis." MicrobiologyOpen. Blackwell Publishing Ltd, 15 June 2012. Web. 5 Jan. 2015.
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