Virulence Gene Regulation Flashcards
What are the 8 common environmental factors driving expression of transcriptional regulation in bacteria
temperature
pH
iron availability
other divalent cations Ca++, Mg++, Mn++
carbon and nitrogen sources
cell density: quorum sensing
osmolarity: water availability
oxygen and CO2
What is an operon
one promotor controls expression of several genes
What is regulon
independent genes whose promoter is controlled by the same regulatory protein
What does sigma factor 70 do
housekeeping genes necessary for cell growth
TATAA, TTGACA
N16-19
What does sigma factor 54 do
response to nitrogen limiting conditions
TTGCT, TTGGCAC
N5
What does SigV respond to
lysozyme stress
How does SigV respond to lysozyme stress
- a lysozyme is present
- the protein is cleaved
- sigma factor V binds the cleaved protein
- sigmaV is bound to RNA polymerase and is translated into target genes ????
What control RNA polymerase activity
transcriptional activators and repressors control RNA polymerase activity
Where do transcriptional activators generally bind
generally bind upstream of target promoters
Where do transcriptional repressors generally bind to
operator sequences that either overlap promoter sequences or are positioned downstream of the promoter
Where do transcriptional repressors generally bind to
operator sequences that either overlap promoter sequences or are positioned downstream of the promoter
When is the diphtheria toxin produced
produced in low iron environments
DtxR fur like, represses transcription in the presence of iron
iron regulation of diphtheria toxin
What allows for transcriptional attenuation
coupling of transcription and translation in bacteria allows for transcriptional attenuation
What are RNA regulators specifically Thermosensors
some RNAs form hairpin structures that unfold as temperature rises
the Shine-Dalagarno sequence is only accessible at high temperatures
A heat shock response is governed by ______
RpoH sigma factor 32
is reversible depending on a high or low temperature
high temperature leads to translation
low temperature leads to no translation
????
What do small regulatory RNAs regulate
regulate transcription and translation
How do small regulatory RNAs work
antisense RNA base-pairs to mRNA
usually prevents translation until it is removed by a endonuclease
universal method of gene control that is found in all creatures
What can remove a small regulatory RNA to allow for translation
endonuclease
What type of regulatory molecule is a universal method of gene control that is found in all creatures
small regulatory RNAs
What is a two-component signal transduction complex
a bridge between environmental signals and gene expression
What does quorum sensing allow for
allows cells to survey their environment
What does quorum sensing allow for
allows cells to survey their environment for cells of their own kind and involves the sharing of specific small molecules
once there is a sufficient concentration of the signaling molecule is present, specific gene expression is triggered
What are autoinducers
allow bacteria to determine the relative population size
as population size increases the ore autoinducers are produced
bacteria release small signaling molecules
type of quorum sensing
What happens to the amount of autoinducers as bacterial population increases
as population size increases the ore autoinducers are produced
What are the two main advantages of quorum sneezing
delay the production of virulence factors until the host is unable to respond
colonize new areas when the current region is overpopulated
Does quorum sensing mechanisms differ between gram negative and gram positive bacteria
yes
the signaling systems of gram + and gram - bacteria differ
What are examples of gram + autoinducers
primarily composed of amino acids
they cannot freely traverse membranes
What are examples of gram - autoinducers
Autoinducer I (AI-1): freely diffusible, LuxI/R system
Autoinducers 2 (AI-2): universal in bacteria but only a few resound to it, it is sensed by sensor histidine kinase
