exploitation of actin cytoskeleton by listeria Flashcards
what natural proteins are in cells which trigger actin polymerisation
cell to cell adhesions have a protein called zyxin, which is also associated with actin in cell- there is also vinculin in cell, which is also associated with actin
how listeria gets into cell
listeria gets into cell by endocytosis- the phagosome is then broken down by a LYSIN protein, and is now in the cell
what bacterium has like zyxin/vinculin + relevance
the bacterium has Act A, which looks like zyxin and vinculin (already within cells)- triggers actin polymerisation
polymerisation of actin
actin polymerisation monomers- 3 G actin monomers (each has ATP) bind together to form a filament
-elongation then occurs- monomer added on side NEAR bacteria, and monomers (with ADP on) removed from other end ie at END of comet tail- this pushes bacterium forward
different proteins and relevance
actin binding porteins- some proteins prevent polymerisation, some eg profilin increase polymerisation (replace ADP with ATP)
crosslinking proteins bind adjacent filaments of comet tail (the multiple actin filaments) together, increasing stability
what other proteins causes more motility- how it does this
Acta itself allows some motility- but VASP binding recruits Arp complexes to produce more actin filaments= faster rate of comet tail formation: also recruits profilin= more ATP
what drug prevents polymerisation of actin
cytochalasin
how listeria can infect- what it infects
these bacteria can go to other cells and blood vessels- in blood vessel it gets into monocytes, and it get into foetal/brain cells and infect them(can lead to meningitis)
how body defends against listeria
it’s in cell, so can’t be defeated by antibodies, only cell mediated immunity
which ppl are vulnerable
pregnant/immunosurpressed/those with AIDS vulnerable
where is listeria found- can it survive fridge temperatures
dairy products eg soft cheese, expired foods- they can survive at fridge temperatures
