Eukaryotic transcriptional regulatory elements and RNAP Flashcards
What is the extent of transcriptional regulatory elements in prokaryotes?
Conserved consensus sequences in the core promoter that RNAP binds to and are necessary to initiate transcription. Enhancers are extremely rare and only used for sigma54 factors
Do eukaryotes also have conserved consensus sequences in the core promoters?
Yes, but they aren’t sufficient to initiate transcription on their own. The sequences are less conserved and more diverse in eukaryotes too
What defines how a eukaryotic regulatory element is defined?
How close they are to the core promoter
What are proximal promoter elements?
Regulatory elements that are close upstream to the core promoter
What usually binds to proximal promoter elements?
Transcriptional activators, and sometimes repressors
How important are proximal elements?
Very important. Have to be bound by TFs for any measurable transcription to occur
What are distal regulatory elements?
Regulatory elements that are much further upstream to the core promoter
What types of regulatory elements are considered to be distal elements?
Locus control elements, insulators, silencers, enhancers
How do distal elements make contact with the core promoter when they’re so far away?
DNA looping
What do enhancers do?
Activate gene expression
What do insulators do?
Protect the promoter from regulatory events
What do silencers do?
Repress gene expression
Are distal regulatory elements always upstream of their target genes?
No, can also be downstream or in an intron
Is it more common for a gene to be regulated by a single enhancer or multiple?
Multiple
Why are enhancers so important during events like development?
The combination of enhancers acting on a gene dictate where and when a gene gets expressed. The combination of activated enhancers dictates which tissue the gene gets expressed in
Will a single enhancer target only one gene?
No, multiple genes can compete for the same enhancer. Or the same enhancer can activate multiple genes at the same time
Are the core promoter elements in eukaryotes and prokaryotes homologous?
They’re analogous and have the same function, but are a lot more diverse. That function is being the place where the RNAP holoenzyme binds
What is a TATA box?
A common eukaryotic core promoter element. Found in 30% of promoters
What region is considered to be the core promoter?
+ and - 40 bp from the +1 nucleotide
What technique is used to determine the transcription start site?
5’ RACE analysis
Why are core promoter elements modular?
They each function as their own unit. Can be mixed and matched into promoters of different strength
How many RNAPs do eukaryotes have? How does that compare to prokaryotes?
Eukaryotes have multiple RNAPs that transcribe different things. Prokaryotes only have one that transcribes everything
How are the multiple RNAPs in eukaryotes different from each other? (3 ways)
- Location in the nucleus
- Proteins they interact with
- Promoters they recognize
What does RNAP I transcribe?
rRNA
What does RNAP II transcribe?
mRNA, miRNA, snRNA, sRNA, lncRNA
What does RNAP III transcribe?
tRNA, other types of snRNA and rRNA
How are plants different than animals in terms of RNAP?
They have two extras, RNAP IV and V. They transcribe siRNA
Which eukaryotic RNAP is the best characterized?
RNAP II
How many subunits does eukaryotic RNAP II have? How conserved are they?
10-12 subunits. Highly conserved between eukaryotes
Can the eukaryotic RNAP II holoenzyme bind to a promoter and initiate transcription on its own?
No
