BIO206H5 Lecture Notes - Lecture 7: Coding Strand, Royal International Air Tattoo, Transcription Factor Ii D

37 views9 pages
31 Oct 2015
School
Department
Course

For unlimited access to Class Notes, a Class+ subscription is required.

BIO206 Lecture Oct 1, 2014 Transcription of Eukaryotic
Distal Promoters: GC and CAAT boxes
- all these DNA regional
elements are protein
binding sites
- GC box (-200 - -70)
upstream houses a
transcription factor
called SP1, member of
larger protein family called Sp/KLF
- SP1 made up of 785 amino
acids
- Made from 3 zinc finger motifs
oInteract at GC box
- Single a-helix structure
- This loop structure can occupy
many conformations (doesn’t
have a rigid structure)
- There are several His and Cys
which interact with Zn2+ which
makes it a stable structure
- Able to control activity by SP1 protein is by removing the Zinc  able to bind
more efficiently
- Single protein regulate protein in many different ways
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 9 pages and 3 million more documents.

Already have an account? Log in
Enhancers and Repressors
Other regions of DNA attract proteins which
may
Enhance [increase] transcription or
Repress [decrease] transition
Also require:
- transcriptional activators
- mediators
- chromatin remodelling complexes
- histone remodelling complexes
- about 85 proteins required
Transcription Initiation Complex
Eubacteria: core RNA polymerase requires sigma factor to recognize the -10 and -25
regions of the promoter
Eukaryotes: core RNA polymerase II also requires “help” to recognize the promoter:
TFIID (TBP, TAF), TFIIA and TFIIB
General Transcription Factors
General transcription factors (GTFs): are proteins required to recognize promoter and
bind RNA polymerase II
- phosphate groups phospholorate RNA pol II in order to give it
energy to be released to start transcription
Formation of Pre-initiation Complex
- TFIID with the help from TFIIA binds to the TATA box forming
the DA complex
- TFIIB binds next generating the DAB complex
- TFIIF helps RNA polymerase bind to a region from -34 to +17,
now it is DABPolF complex
- Last the TFIIE then TFIIH bind to form the complete pre-
intiation complex = DABPolFEH
-In vitro (test tube) participation of TFIIA seems to be optional
Transcription Initiation
- TFIID bends DNA molecule 80 degrees once bound to the
protein
Structure and Function of TFIID
TFIID contains 17 protein subunits including
- TBP: TATA – box binding protein
oHighly conserved across eukaryotic cells
oAmino acid sequence of TBP is very similar in all
eukaryotes
oBinds to the minor groove of the TATA box
Saddle – shaped TBP lines up with DNA
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 9 pages and 3 million more documents.

Already have an account? Log in
Underside of the saddle
forces open the minor
groove
DNA at TATA box is
bent through 80 degrees
curve
- TAFIIS: TBP- associated factors
specific for class II promoters
- C terminal domain of RNA Pol
II is crucial for processing of
mRNA
CTD coordinates
transcription and
RNA processing
C-Terminal Domain
(CTD) of pol II has
binding sites for
several enzymes
- it is located
near site
whiere
nascent RNA
emerges
- Involved in
all hnRNA
processing:
5’ capping,
splicing, and 3’ poly (A) tail and ACTIVATION of pre-initiation complex
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 9 pages and 3 million more documents.

Already have an account? Log in

Get access

Grade+
$10 USD/m
Billed $120 USD annually
Homework Help
Class Notes
Textbook Notes
40 Verified Answers
Study Guides
1 Booster Class
Class+
$8 USD/m
Billed $96 USD annually
Homework Help
Class Notes
Textbook Notes
30 Verified Answers
Study Guides
1 Booster Class