T3SS Flashcards
What is the key function of the ‘injectisome’?
Delivers bacterial proteins directly to host cell
T3SS are in many gram neg or gram pos?
Gram neg
How are T3SS encoding-genes arranged?
Clustered as part of large pathogenicity island
Where are large pathogenicity islands located? 2 answers
On the chromosome or plasmid
How many different linages of T3SS are there?
At least 7
Key features if T3SS? (5)
- Resistance to innate immune response by triggering apoptosis in macrophages
- Trigger bacterial uptake by non-phagocytic cells by altering actin polymerisation
- Allows invasion/survival in host and adherence
- Changes in pilus to adapt to cell type
- Form symbiotic relationships with plants - mainly for nitrogen fixation
General feature of Chlamydiales family?
Only non-Proteobacteria organisms to have a T3SS
Translocon function?
Interact with host cell
Tip complex function?
‘Caps’ needle filament
Needle filament function?
Passage for proteins
Base function?
Holds the structure in place and spans across the outer and inner membrane
Export apparatus function?
Controls export - gated pore
Cytoplasmic components (sorting platform) function?
Controls/guides protein delivery
Place in order:
- Integration of the two assemblies to one complex. Allows recruitment of cytoplasmic components
- Functional T3SS
- Outer membrane secretin ring joins inner membrane protein
- Secrete early substrates, inner rod and needle filament proteins
- Outer membrane ring and inner membrane complex join
- Inner ring assembles on the inner membrane
1) Outer membrane secretin ring joins inner membrane protein
2) Inner ring assembles on the inner membrane
3) Outer membrane ring and inner membrane complex join
4) Integration of the two assemblies to one complex. Allows recruitment of cytoplasmic components
5) Functional T3SS
6) Secrete early substrates, inner rod and needle filament proteins
Where are T3SS derived from?
Flagella
