E. coli Flashcards
What are the eight acronyms for the pathovars of E. coli, and where do they colonize?
ETEC (enterotoxigenic) - small bowel
EIEC (enteroinvasive) - large bowel
EPEC (enterpathogenic) - small bowel
EHEC (enterohemorrhagic) - large bowel
EAEC (enteroaggregative) - large bowel, small bowel
DAEC (diffusely adherent) - small bowel
UPEC (uropathogenic) - bloodstream, bladder, kidney
NMEC (neonatal meningitis) - brain, bloodstream
How does E. coli Nissle function as a probiotic?
Doesn’t produce toxin
Inhibits growth of pathogenic bacteria
Reduces pathogenic invasion
What do the five B subunits of the Shiga toxin entail?
Three distinct binding sites that interact with the trisaccharide moiety of the glycosphingolipid Gb3 in the extracellular leaflet of the target cell plasma membranes
What does the A subunit of the Shiga toxin entail?
A specific RNA N-glycosidase activity which removes an adenosine from the 30 region of the 28S rRNA of the 60S ribosomal subunit, inhibiting protein synthesis.
How is STX trafficked to the interior of eukaryotic cells?
Retrograde trafficking
Internalized by endocytosis
Avoids fusion with lysosomes
Move through the golgi and into the ER
Cleaved, goes to cytoplasm
How does STX intoxicate cells at the cellular level?
Disrupts binding site for EF-2 and EF-1 on 60s ribosome
What is the LEE, and what four general virulence factors does it encode four?
Locus of enterocyte effacement
1. Type three secretion system (T3SS)
2. Effector proteins (injected into host cell)
3. Adhesins (stick to intestinal lining)
4. Regulators to control expression of above
What is the function of EspB and where is it found?
Found in plasma membrane and cytosol
pore-forming translocon component
microvillus effacement
antiphagocytosis
disruption of adherent junctions
What is the function of Tir and where is it found?
plasma membrane
receptor for intimin
actin pedestal formation
regulates activities of Map and EspG
What is the function of EspG and where is it found?
cytosol, golgi
disrupts microtubles, tight junctions and paracellular permeability
sequesters ADP-ribosylating factor (Arf) to modulate GTPase signalling stimulates p21-activated kinases (PAKs) to inhibit endomembrane trafficking, binds GM130 and inactivates Rab1 to disrupt golgi structure and protein secretion
induces calpain protease and necrosis in absence of Tir
What is the Nle effector?
Non LEE encoded effectors
What is an example of an NleG family and how does it intoxicate cells?
NleG5-1 effector targets mediator complex via Med15 subunit
Acts as an E3 ubiquitin ligase
Ubiquinates Med15
Mediator complex unable to link transcription factors with RNA polymerase
Disruption of host protein synthesis
