Transcriptional Regulation and
RNA Processing
RNA Processing

5’CAP

Active
enzyme

Post-translational
modification

mRNA

AAAAAA

RNA Degradation

Protein Degradation
Activators and Repressors
co-A

A

RNAP

+1

RNAP

co-R

R
+1
The Helix-Turn-Helix Motif
• Contain two alpha helices separated by a
loop with a beta turn
• The C-terminal helix fits in...
The Zn-Finger Motif

Zn fingers form a folded beta strand and an alpha helix
that fits into the DNA major groove.
The Leucine Zipper Motif
• Forms amphipathic alpha helix and a coiled-coil
dimer
• Leucine zipper proteins dimerize, eithe...
Transcription Regulation in
Prokaryotes
lac operon
Glucose is E. coli’s
primary carbon source.
But.. it can grow on
different carbon sources.
Diauxic growth of E. coli on a mixture of
lactose + glucose.
The lac I protein
Operator and RNA Polymerase Bind at
Overlapping Sites
Inducer : Allolactose,
produced by side reaction
of lacZ

Lehninger: Principles of Biochemistry, 3rd Ed.
Inducer :
Allolactose,
produced by side
reaction of lacZ


Synthetic molecule
Repression of
the Tryptophan
operon:
A variation of
the theme
Catabolite Repression of lac Operon
(Positive regulation)
Molecular Cell Biology, 4th Edition, Lodish et. al. (2000)
Why does the Lac Operon need
an activator?

Lac promoter has lousy promoter!!!
Splicing of Pre-mRNA
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Transcriptional regulation
Upcoming SlideShare
Loading in …5
×

Transcriptional regulation

353 views

Published on

Published in: Education
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
353
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
0
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Transcriptional regulation

  1. 1. Transcriptional Regulation and RNA Processing
  2. 2. RNA Processing 5’CAP Active enzyme Post-translational modification mRNA AAAAAA RNA Degradation Protein Degradation
  3. 3. Activators and Repressors co-A A RNAP +1 RNAP co-R R +1
  4. 4. The Helix-Turn-Helix Motif • Contain two alpha helices separated by a loop with a beta turn • The C-terminal helix fits in major groove of DNA; N-terminal helix stabilizes by hydrophobic interactions with C-terminal helix
  5. 5. The Zn-Finger Motif Zn fingers form a folded beta strand and an alpha helix that fits into the DNA major groove.
  6. 6. The Leucine Zipper Motif • Forms amphipathic alpha helix and a coiled-coil dimer • Leucine zipper proteins dimerize, either as homo- or hetero-dimers • The basic region is the DNA-recognition site • Basic region is often modeled as a pair of helices that can wrap around the major groove
  7. 7. Transcription Regulation in Prokaryotes
  8. 8. lac operon
  9. 9. Glucose is E. coli’s primary carbon source. But.. it can grow on different carbon sources.
  10. 10. Diauxic growth of E. coli on a mixture of lactose + glucose.
  11. 11. The lac I protein
  12. 12. Operator and RNA Polymerase Bind at Overlapping Sites
  13. 13. Inducer : Allolactose, produced by side reaction of lacZ Lehninger: Principles of Biochemistry, 3rd Ed.
  14. 14. Inducer : Allolactose, produced by side reaction of lacZ
  15. 15.  Synthetic molecule
  16. 16. Repression of the Tryptophan operon: A variation of the theme
  17. 17. Catabolite Repression of lac Operon (Positive regulation)
  18. 18. Molecular Cell Biology, 4th Edition, Lodish et. al. (2000)
  19. 19. Why does the Lac Operon need an activator? Lac promoter has lousy promoter!!!
  20. 20. Splicing of Pre-mRNA

×