Bacterial regulation L12 Flashcards
regulation is key to adaption because…
bacteria need to adapt to change and new environments, so gene regulation needs to reflect this
bacteria need to avoid host defences
and crucial for survival
what is the cause and effect of regulation
it has control of survival phenotype as needs to be tailored to the needs in the environment
like whether it should prioritise attachment or avoidance - regulation needs to change this according to the environment and what is best to survive
some examples of interactions to protect itself with the host
- preventing being marked for phagocytosis
- secreting toxins to paralyse host defences
- disrupting mucosal integrity
- cytokine production
5.changing/modifying PAMPS
how does infection occur?
from existing genetic factors - chromosome, plasmid, pathogenicity islands
environmental sensing - TCS - LPS modification, quorum sensing - biofilm formation
what is a regulon
a group of genes controlled by a common regulator
examples
- DNA supercoiling
SOS response to DNA damage
- osmotic or oxidative stress response
sporulation
nutrient starvation
virulence
one component systems
has signal, sensor and regulator all in one, and then a regular it responds to
two component systems
has a signal
has a separate sensor and then a regulator
and then a regulon
environmental regulation using 2CS
stimulus response mechanisms - signal transduction and then phosphorylation of RR by SK
gene regulation - interaction of RR phosphorylated to DNA
PhoP/Q example of TCS
when MG2+/CA2+ IS HIGH, system is off, signal so no expression of virulence genes
but when MG2+/CA2+ are low, signal detected by PHOQ (SK) sends signal to PHOP (RR) and then gene expression of virulence genes
biofilm formation
this is a structured community of cells that are closed on in a matrix and adherent to surfaces - this is a pathogenic trait
- protect from host defences, immune evasion and cells can penetrate biofilm
- antibiotic resistance
- surface colonisation
- community behaviour
quorum sensing
a regulatory mechanism that is a cell population density dependent regulation mediated via self generated extracellular signal molecules - autoinducers (AHLS/AIPS)
these activate and repress genes, needing a quorum sensing signal synthase, signal receptor and signal molecule
virulence with quorum sensing
allows community behaviour to control virulence gene expression - help form biofilms, effect inflammatory and immune responses in animals, toxin production
respond to high cell density, so will only do this once enough autoinducers in environment, as can detect them. This allows them to work as a team and be more effective with virulence
