Flashcards in Virulence Mechanisms of gene regulation 1 Deck (11)
What is a virulence factor?
any bacterial property required for entry, growth, or survival in a host
-examples-capsule, adhesins, acid tolerance factors, enzymes to synthesize unavailable nutrients, adapt to stomach
What are pathogenicity islands?
large, localized regions of chromosomes missing in related non-pathogens
What are the steps of transcription initiation?
STEP 1: formation of closed complex
-core RNA polymerase+sigma factor (promoter-binding)= holoenzyme
STEP 2: formation of open complex (RNA polymerase pulls strands apart)
STEP 3: Initiation and elongation
-sigma factor falls off
What does the sigma factor do?
enables specific binding of RNA polymerase to gene promoter
What is the glucose cAMP relationship?
decrease glucose increase cAMP
What does the lacR do?
expressed constitutively and makes repressor protein
Where does the repressor bind and what does it do?
the operon and blocks binding of RNA polymerase by steric hindrance
What happens when lactose is present and glucose is low?
1. inducer (lactose) binds the repressor
2. repressor doesn't bind operon
3. activator interacts with RNA polymerase increasing RNA polymerase binding affinity
3. co-activator-cAMP binds activator (CRP) and increases affinity for binding site
The probability of transcription initiation increases as the stability of what increases?
-activators increase stability
-repressors decrease stability
PhoQ and Tox S are?