Microbial competition Flashcards
What is the difference between a contact independent & dependent system?
independent = bacteria produce molecule that diffuses through medium & affects other bacteria dependent = requires cell-cell contact
what kind of system are bacteriocins?
what is it for?
why does it have a narrow target range?
what is the structure & what do these domains do?
in what e.coli are they found?
contact independent
toxic proteins - kill of competing bacteria (but often not killed by them as develop immunity)
must bind to surface & become internalised by bacteria which required protein-protein/cell surface receptors so it’s very species specific- often of same species
T = translocation domain = facilitates colicins entering cell R = receptor binding = binds to surface of target cell A = activity = enzyme that degrades part of the cell
What system is bacteriophage?
What does it do?
when the cells lyse, how does this look on a lawn of bacteria?
describe: capsid head tail end of tail tail fibres
what are the 4 steps for how the phage injects DNA?
Contant independent
Attaches to target cell & hijacks cell machinery with genome in head - once enough lyses
clear hole
holds genetic info in protein capsule
made of central tube surrounded by sheaths
end of tail = baseplate from which tail fibres extend
bind to surface bacteria & cell surface receptors
- fibres attach receptors on surface bacteria
- position phage so tail is perpendicular to surface
- tail sheath contracts which drives central tube into membrane
- opening created so DNA translocated through
what is the phage lytic life cycle?
how is the cell lysed?
what is a lysogenic life cycle?
how is it reactivated?
what life cycle to virulent phages have?
temperature phages?
phage infects bacteria & codes for production of more phages to then lyse the cell & release phages
endolytic enzymes
phage infects bacteria & introduces genome into cell which is integrated into the bacterial genome & lays dormant
trigger signals from stress- phage activates & produce more phage particles leading to lysis
lytic only
lytic & lysogenic
what are pyocins?
what is the difference between an S-pyrocin & R-pyrocin?
how do R-pyrocins work then?
how can you alter its specificity?
what system is this?
bacteriocins produced by Pseudomonas aeruginosa
S = colicins with R, T, A domains R = like phage without NA in capsid head
sheath on tail contracts driving it into membrane- makes holes/channels so cell components flow out
specificity through tail fibres- can takes tail fibres from 1 pyocin and put it onto another
contact independent
What does the T6SS secretion system do?
how can you label the T6SS to monitor how quickly it polymerises the structure?
the proteins that are shot out, what are they?
what is the maximum target range of attack?
what does it require?
forms inside of a cell, so when sheaths contract protein spike is shout out of cell & stab nearby cells
label it with GFP
can be toxic at same time- can embed in structure with protein fusion/protein-protein interactions
half its own width (of the predator)- short distance
requires target to be adjacent to predator & stably associated (doesn’t need receptor)
what is contact dependent inhibition?
what are the 4 domains of the CDI protein?
what are the genes in them?
what do they do?
what happens if you grow unrelated bacteria with CDI+ in cell?
grow CDI- with CDI+ of same species?
grow CDI+ with CDI+ of same species?
when 1 bacterial strain inhibits the growth of another
core = with toxic domain
immunity protein & membrane protein
core = cdiA membrane = cdiB immunity = cdiI
cdiI prevents the bacteria producing the protein being targeted by it
cdiB enables cdiA to be displayed on the surface of the cell
because they require target receptors- no inhibition as they are unrelated
is inhibition- related so CDI- lacks cdiI protein so when CDI+ binds, toxin is taken up & growth is inhibited
both express the same immunity protein- so toxin is taken up but neutralised
