Gene Regulation in Prokaryotes Flashcards
Why are prokaryotes able to adapt incredibly rapidly?
Bacteria can transcribe and translate simultaneously
What is gene regulation foundational to in bacteria?
- Pathogenesis
- Antibiotic resistance
- Immune evasion
Example of how bacterial gene regulation is foundational to pathogenesis
Quorum sensing regulated toxin genes in Vibro cholerae
Example of how bacterial gene regulation is foundational to antibiotic resistance
Inducible B-lactamases (which work against B-lactam ABs)
Example of how bacterial gene regulation is foundational to immune evasion
E. coli uses phase variation to alter its pilus structure, preventing antibody recognition.
Neisseria also alters surface antigens via phase variation
What is an operon?
Cluster of co-regulated genes under single promotor, transcribed as one polycistronic mRNA
What is polycistronic mRNA?
One mRNA molecule that encodes multiple proteins
What is a regulon?
Set of genes/operons scattered across a genome but co-regulated by the same regulatory protein
What are promotors?
DNA sequences upstream of genes where RNA polymerase binds- recognised specifically by sigma factors
What are sigma factors?
Bacteria proteins that guide RNA polymerase to the correct promoters under different conditions
How do bacteria use sigma factors to regulate transcription?
Bacteria can swap sigma factors to reprogram transcription in response to environmental changes (e.g. stress, immune pressure, nutrient needs)
What is an example of alternative sigma factors being used by bacteria?
Clostridium difficile uses alternative sigma factors during sporulation and toxin expression
What are operators?
Regulator DNA sequences near the promotor where repressors or activators bind
What do sigma factors allow for (with specific example)?
Allow bacteria to coordinate complex adaptive responses (e.g. biofilm formation)
E.g. both S. aureus and Bacillus use sigma^B to regulate genes needed for biofilm formation
