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
Transcription Initiation
4
Transcriptional Elongation
5
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

6
Termination of Transcription
Rho-independent termination
7
Termination of Transcription
Rho-dependent termination
r factor
8
RNA Polymerase binding
Constitutive or basal level transcription
9
Allosteric activation of RNA polymerase
10
Inhibition of transcription
DNA-protein interactions
11
Negative Control of the lac Operon
12
Proposed CAP-cAMP Activation of lac Transcription