P1253814587NVKaU

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Molecular Genetics Bio350/516 Lecture 18, 3/30/06
I. Chapter 11 General Transcription Factors in
Eukaryotes A. Class II factors 1.
Preinitiation complex a. Order of
addition TFIID?TFIIA?TFIIB?TFIIF-RNAP?TFIIE?TFIIH
2. TFIID complex a. TATA
Binding Protein (TBP) 1. A
universal transcription factor? b.
TATA Binding Protein in Archaea
2. A minimalist version of Pol II transcription
apparatus c. TATA Binding Protein
(TBP-)Associated Factors (TAFs) d.
Enhancement of Transcription by Activators
e. Alternatives to TBP 3. TFIIB
4. TFIIF
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Order of Addition
TFIID?TFIIA?TFIIB?TFIIF-RNAP?TFIIE?TFIIH
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Figure 11.4
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TBP Binds in the Minor Groove
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Figure 11.5a
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Figure 11.5b
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Figure 11.5c
Gel Mobility Shift Assay
Human TBP/43 kDa
Yeast TBP/27 kDa
Yeast TBP/27 kDa
Human TBP/43 kDa
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Figure 11.6
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TBP A Universal Transcription Factor?
1. Pol II with TATA boxes 2. TATA-less Pol II
promoters 3. TATA-less Pol III promoters 4.
TATA-less Pol I promoters
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Transcription Apparatus in Archaea
1. TATA boxes at promoters 2. A single Pol
II-like RNA polymerase (similar subunits) 3. TBP
homologs 4. TFIIB homologs (called TFB in
Archaea) 5. TFIIE? (? subunit only) 6. TFIIS
homologs 7. No TAFs
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TBP-Associated Factors (TAFs)
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Figure 11.8a
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Figure 11.8b
Protein-Protein Contacts among TAFs
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Figure 11.9
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Figure 11.13
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Figure 11.15
Drosophila
Human
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Enhancement of Transcription by Activators
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Figure 11.16a
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Figure 11.16b
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Figure 11.16c
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Figure 11.16d
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Alternatives to TBP
1. TRF1 TBP-related factor 1 (Drosophila)
a. Expressed in developing neural tissue b.
Binds to TFIIA and TFIIB c. Own group of
TRF-associated factors (nTAFs) 2. TLFs (TBP-like
factor) a. Lacks phenylalanines found in
TBP 3. TFTC ( TBP-free TAFII-containing complex)
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TFIIB
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Figure 11.19
Upstream domain binds to TBP
Downstream domain binds to TFIIF/RNAP II to help
position RNAP II at start site
Start site
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TFIIF
1. Has 2 subunits RAP30 and RAP70 a) RAP
RNA Polymerase-associated Protein 2. RAP30 binds
to RNAP II a) can also bind to bacterial core
polymerase, but can be displaced by ? 3.
TFIIF prevents RNAP II from binding to non-
specific sites on DNA, restricting it to binding
to preinitiation complexes that are already
on promoters