Prokaryotic Transcription Regulation

• Involves regulatory transcription factors

• Bind to DNA in the vicinity of a promoter and affect transcription of one or more nearby genes

• Repressors: inhibit transcription

  • Negative control

• Activators: increase the rate of transcription

  • Positive control

• Transcriptional regulation also involves small effector molecules

  • Small effector molecules: binds to regulatory transcription factor and causes conformational change

  • Determines whether or not regulatory transcription factor can bind to DNA

• Two domains in regulatory transcription factor that respond to small effector molecules

  • Site where protein binds to DNA

  • Site specifically for small effector molecule

The Bacterial Operon

• Operon in bacteria: a cluster of genes under transcriptional control of one promoter

  • Operator: regulatory region of the operon

• Transcribed into mRNA as polycistronic mRNA

  • Polycistronic mRNA: encodes more than one protein

• Allows coordinated regulation of a group of genes with a common function