2nd Feb - Transcription VI

Question 1

What are the four key stages of productive transcription?

Answer 1

Recruitment
Initiation
Clearance of the promoter
Elongation

Question 2

Who won the nobel prize in Chemistry in 2006?

Answer 2

Richard Kornberg for the molecular basis of eukaryotic transcription

Question 3

Why is RNAP II nicknamed a poor enzyme?

Answer 3

It has few intrinsic functions (unwinding the DNA, RNA synthesis and proof-reading nascent RNA) it relies on auxillary factors for the rest

Question 4

What are the GTFs required for eukaryotic transcription?

Answer 4

TFIID
TFIIB
TFIIF
TFIIE
TFIIH

Question 5

Describe TFIID

Answer 5

A eukaryotic general transcription factor, that is composed of TBP and 12 TAFs, which bends DNA by about 90 degrees

Question 6

Describe TFIIB

Answer 6

A eukaryotic general transcription factor which binds the TBP, Pol II and promoter DNA to help fix TSS

Question 7

Describe TFIIF

Answer 7

Binds the coding strand to keep the transcription bubble open

Question 8

Describe TFIIE

Answer 8

Recruits TFIIH

Question 9

Describe TFIIH

Answer 9

Helicase activity unwinds the DNA strands creating the transcription bubble and its kinase activity removes the mediator

Question 10

What percentage of promoters contain a TATA box?

Answer 10

30%

Question 11

Is TBP required in TATA less promoters?

Answer 11

Yes it is still required to bind and bend the promoter

Question 12

What are the core Pol II promoter elements?

Answer 12

BRE - TFIIB recognition element
TATA Box
Initiator (Inr)
Downstream core promoter element (DPE)

Question 13

What is the role of a transcriptional activator?

Answer 13

To recruit co-activators which modify histones

Question 14

What is a mediator?

Answer 14

A central control panel in RNAPII transcription which processes and transduces transcriptional regulatory information in all eukaryotes

Question 15

What is the function of TBPs bending of the promoter?

Answer 15

It wraps the DNA around RNAP II and C-terminal domain of TFIIB placing the TSS in the active site vicinity

Question 16

What is the eukaryotic pre-initiation complex composed of?

Answer 16

RNA polymerase II and six general transcription factors: TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH.

Question 17

What is the role of RNAP II’s CTD in promoter clearance?

Answer 17

It contains a heptad repeat YSPTSPS which mediator subunits, elongation factors, 5’ capping and splicing factors use as a docking site.

Mediator subunits promote TFIIH associated CDK-7 phosphorylation of Ser5 –> promoter clearance and mediator dissociation

Question 18

What is the function of promoter proximal pausing?

Answer 18

Allows 5’ cap addition

Question 19

Which factors cause promoter proximal pausing?

Answer 19

DSIF and Negative elongation factor (NELF) help stall the polymerase +20 - +40bp downstream of the TSS and the mRNA is capped

Question 20

What regulates P-TEFb and how?

Answer 20

nc 7SKRNA, it phosphorylates the CTD and NELF and DSIF allowing it to remove NELF and DSIF and recruit Elongin and ELL

Question 21

What is the function of SETd2?

Answer 21

It binds the CTD and adds H3K6me3 which is recognised by HDAC1

Question 22

What is FACT?

Answer 22

Facilitates Chromatin transcription helps RNAP get past nucleosomes