Sjogren: Lecture 4 Transcription regulation by transcription factors... Flashcards
What is key to know about RNA pol 2?
It has multiple subunits to bind DNA and Perform the steps for transcription of unwinding, Synthesizing RNA from a template, and Proofreading.
What is the initiation complex?
It is a large number of proteins functioning to position RNA polymerase and regulate transcription initiation
Initiation involves TATA binding protein (TBP), other co-activators called TBP-associated factors (TAFs).
RNA polymerase 2 has several cofactor proteins (Transcription Factor “TF”).
What are the transcription factors need to stabilize RNAP 2?
TF2B, TF2F, TF2E and TF2H
Specific TFs serve as activators or repressors/silencers and bind both the transcription activator complex and specific DNA enhancer regions.
What do transcription factors regulate and how?
Transcription.
They regulate the process through multiple interactions possible by their modular structure.
Some TFs bind promoter and enhancer response elements of DNA.
TFs can bind other coactivating TFs, proteins that modify histones/chromatin, or RNA polymerase.
TFs can be activated by signaling molecules (steroid hormones).
What else is important to know about transcription factors (TFs)?
TF specificity is achieved by modularity and TFs are regulated by multiple mechanisms.
What role does chromatin remodeling play?
It has a central role in transcriptional control by regulating the accessibility of condensed DNA to proteins.
What effect does histone acetylation and DNA methylation have on transcription?
Histone acetylation causes activation.
-includes histone acetyl transferases (HATs) and histone deacetylases (HDACs).
DNA methylation causes repression.
How can transcription still be initiated for genes that do NOT have a bona fide TATA box?
TATA binding protein (TBP) is loaded onto AT rich DNA by 16 transcription accessory factors (TAFs).
Combined energy from weak DNA binding to TBP and strong DNA binding to TAFs and TAF associated transcription factors make the interaction of TBP with DNA strong enough to cause a kink in DNA.
The bend is self stabilizing as it forms and the kink is further supported when TF2A and TF2B bind.
What are ADNRs and their relevance to nucleosomes?
ATP-dependent nucleosome remodeling factors )ADNRs reorganize the position of nucleosomes by catalyzing sliding of nucleosomes along the DNA.
EX: important superfamily Swi2/Snf2
What role does DNA methylation play?
DNA methylation represses transcription by forming a binding site for methyl-CpG domains. This domain only recognizes methylated CpG which blocks TFs from binding DNA.
Correlated with gene inactivation.
