Transcription and RNA Processing

Question 1

Functions of TFIIE? (2)

Answer 1

• recruits TFIIH

- ATPase and helicase activity

Question 2

When does the PIC disassemble?

Answer 2

As RNA Pol II begins transc

Question 3

3 major functions of TFIIH?

Answer 3

1. helicase activity @ promoter
2. phosphorylates Pol II @ CTD
3. recruits NER proteins for repair

Question 4

Molecule involved in Death Cap mushroom poisoning?

Answer 4

Alpha-amanitin

Question 5

Mechanism of of alpha-amanitin? (3)

Answer 5

• cyclic octapeptide poisonous to RNA Pol II
• binds back side of RNA Pol II and restricts its flexibility
• significant reduction of RNA Pol II transcripts and protein

Question 6

Symptoms of alpha-amanitin poisoning? (5)

Answer 6

• mimics flu
• liver damage
• kidney failure
• coma
• death

Question 7

Role of Tat protein in HIV-infected cells?

Answer 7

• encoded by virus

- acts as an anti-termination factor

Question 8

Mechanism of HIV Tat protein? (4)

Answer 8

• Tat binds host’s cyclin T proteins
• Cyclin T activates host CDK9
• CDK 9 phosphorylates CTD of RNA Pol II
• prevents premature termination of HIV transcript

Question 9

How is Tat protein used in ARV AIDS therapy?

Answer 9

Can inhibit Tat activity to inhibit HIV transc

Question 10

Causes of beta-thalassemia? (2)

Answer 10

• mutation(s) in the beta-globin locus

- mutation in splicing junctions

Question 11

Effects of beta-thalassemia? (2)

Answer 11

• impaired RBC function

- proteolysis of subunit

Question 12

Mechanism of beta-thalassemia? (2)

Answer 12

• mutations interfere w/ normal RNA synth/processing

- less beta-globin and more gamma-globin transcribed

Question 13

Modifications to 5’-phosphate end of RNA molec? (3)

Answer 13

1. 7-Methyl-guanosine cap added to 5’-triphosphate end of hnRNA thru 5’,5’-triphos linkage
2. 2’-methylation of 1st ribose sugar
3. 2’-methylation of 2nd ribose sugar

Question 14

Name of primary methyl donor?

Answer 14

S-AdenosylMethionine (SAM)

Question 15

What RNA mod facilitates nuclear export of mRNA?

Answer 15

poly(A) tail

Question 16

Bases in splice donor and acceptor sites?

Answer 16

• donor = GU

- acceptor = AG

Question 17

Components of spliceosome? (2 categories)

Answer 17

• snRNA U1, U2, U4, U5, and U6

- snRNPs

Question 18

Mechanism of Systemic lupus erythematous (SLE)?

Answer 18

• autoimmune disorder that attacks snRNPs, among other things

Question 19

What disease:

- absence of beta-globin expression

Answer 19

Beta-thalassemia Major or Cooley’s anemia

Question 20

What disease:

- reduced expression of beta-globin

Answer 20

Beta(+)-thalassemia or Beta-thalassemia Minor

Question 21

What gene is defective in Dystrophia Myotonica (DM)?

Answer 21

Dystrophia Myotonica Protein Kinase (DMPK) gene

Question 22

Main cause of DM?

Answer 22

mRNA transcript w/ increased trinucleotide repeats 5’-CUG-3’

Question 23

Mechanism of DM? (5)

Answer 23

• inability to export DMPK mRNA from nucleus due to high no. of tri-nt repeats
• muscleblind protein binds CUG repeats inside nucleus
• inhibits CUG binding protein
• increase in CUG-BP expression in nucleus
• mediates aberrant splicing events in adult tissues

Question 24

3 major symptoms of DM? Associated proteins?

Answer 24

1. impaired myocardial contraction – cardiac Troponin T protein (cTNT)
2. insulin resistance – insulin receptor protein (IR)
3. repeated firing of AP (myotonia) –> muscle wasting – muscle-spec Cl- ion channel protein (CIC-1)

Question 25

What SAM cofactors are req’d for 5’-capping? (2)

Answer 25

1. Folate

2. Vit B12

Question 26

Role of RNA Pol II CTD in pre-mRNA processing? (2)

Answer 26

1. 5’-capping catalyzed by complexes assoc w/ CTD

2. cleavage @ futre Poly-A tail site done by endonuclease assoc w/ CTD

Question 27

DM is assoc w/ ?

Answer 27

Embryonic splicing forms of target genes