DNA Methylation and Transcriptional Regulation - PowerPoint PPT Presentation

1 / 76
About This Presentation
Title:

DNA Methylation and Transcriptional Regulation

Description:

Activation of gene structure. Initiation of transcription. Processing transcript ... Stability of Eukaryotic mRNA. Both the 5' and 3' ends of mRNA are modifed ... – PowerPoint PPT presentation

Number of Views:189
Avg rating:3.0/5.0
Slides: 77
Provided by: lwsc
Category:

less

Transcript and Presenter's Notes

Title: DNA Methylation and Transcriptional Regulation


1
(No Transcript)
2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
DNA Methylation and Transcriptional Regulation
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
Stages of Regulation
20
Antisense sequence of DNA or RNA that
is complementary to mRNA
21
Transcriptional activity
vs.
Post-transcriptional activity
22
Bacteria
Eukaryotes
  • mRNA is transcribed and
  • translated almost simultaneously.
  • Why? Bacterial mRNA usually
  • is unstable and is translated into
  • proteins for only a few minutes.
  • Synthesis and maturation
  • of mRNA occur in the
  • nucleus.
  • After maturation, mRNA
  • is exported to the cytoplasm
  • where it is translated.
  • Relatively stable and continues
  • to be translated for several
  • hours.

23
(No Transcript)
24
Stability of Bacterial mRNA
  • Degradation closely follows translation
  • Degradation begins 1min after transcription
  • 5 end of mRNA starts to decay before 3 end has
    been
  • synthesized
  • Stability of mRNA influences the amount of
    protein
  • expressed
  • Average ½ life of mRNA is 2min.

25
Terminology
Nascent RNA Monocistronic mRNA Polycistronic
mRNA
26
Types of mRNA Regions
  • Coding region
  • 5 UTR (leader sequence)
  • 3 UTR (trailer sequence)
  • Intercistronic region

27
Polycistronic mRNA
28
Eukaryotic mRNA
29
(No Transcript)
30
Stability of Eukaryotic mRNA
  • Both the 5 and 3 ends of mRNA are modifed
    which increases
  • mRNA stability
  • Transported out of nucleus after modification
  • Leaves for cytoplasm 20 min following
    initiation
  • Yeast ½ life 1-60 min
  • Higher eukaryotes ½ life 4-24 hr

31
(No Transcript)
32
  • Specific site of termination?
  • AAUAAA (higher eukaryotes)
  • (located 11-30 nts upstream of
  • poly(A) addition)
  • Deletion of AAUAAA prevents
  • polyadenylation.
  • AAUAAA needed for cleavage
  • and polyadenylation.
  • This process requires endonuclease
  • (CFI and CFII), poly(A) polymerase
  • (PAP), and a specificity component
  • (CPSF) which recognizes AAUAAA.

33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
Gppp pppApNpNp
GpppApNpNp.. pp p
5-5 triphosphate linkage
37
Cap0
38
Polyadenylation
39
3 Polyadenylation
  • 3 terminal stretch of A residues poly(A)
    tail or poly(A)
  • Sequence is not coded in DNA, added to RNA in
    the nucleus
  • after transcription
  • Catalyzed by poly(A) polymerase
  • 200 A residues are added to 3-OH end
  • Associated with poly(A)-binding protein (PABP)

40
Role of poly(A)
  • Stability
  • Removal of poly(A) precedes degradation
  • Removal of poly(A), as well as PABP, inhibits
    translation

41
(No Transcript)
42
Bacterial mRNA Degradation
1)
2)
43
Eukaryotic mRNA Degradation
  • Occurs in the cytoplasm
  • Catalyzed by a multi-enzyme complex 1)
    ribonuclease E,
  • 2) PNPase, 3) helicase

44
(No Transcript)
45
Destabilizing Elements
  • ARE AU-rich element
  • IRE iron response element

46
ARE
47
IRE
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
(No Transcript)
53
(No Transcript)
54
(No Transcript)
55
(No Transcript)
56
(No Transcript)
57
(No Transcript)
58
(No Transcript)
59
(No Transcript)
60
(No Transcript)
61
(No Transcript)
62
(No Transcript)
63
(No Transcript)
64
(No Transcript)
65
(No Transcript)
66
(No Transcript)
67
(No Transcript)
68
(No Transcript)
69
(No Transcript)
70
(No Transcript)
71
(No Transcript)
72
(No Transcript)
73
(No Transcript)
74
(No Transcript)
75
(No Transcript)
76
(No Transcript)
Write a Comment
User Comments (0)
About PowerShow.com