Transcription

1
Transcription
s
a2 b b
RNA polymerase (from E. coli )
Sigma factor
Core
2
Transcription

• Functions of a prokaryotic promoter
• ON/OFF Switch
• Speed Switch
• Alignment

3
Binding of RNA Polymerase to Promoters
How tightly does core enzyme vs. holoenzyme bind
DNA?
4
Transcription Initiation
5
Transcriptional Elongation
6
Termination of TranscriptionInverted Repeats and
Hairpins

• The repeat at right is symmetrical around its
  center shown with a dot
• A transcript of this sequence is
  self-complementary
• Bases can pair up to form a hairpin as seen in
  the lower panel

7
Termination of Transcription
Rho-independent termination
8
Termination of Transcription
Rho-dependent termination
r factor
9
RNA Polymerase binding
Constitutive or basal level transcription
10
Allosteric activation of RNA polymerase
11
Inhibition of transcription
DNA-protein interactions