Salmonella: A Disease-Causing Bacteria

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.

Works Cited