2.6

Question 1

inhibition of cellular gene expression by several viral proteins (5)

Answer 1

inhibition of transcription by RNA polymerase 2
inhibitbition of polyadenylation
inhibition of RNA export
Inhibition of translation
increase mRNA degredation

Question 2

what increased rates increase mRNA (3)

Answer 2

transcription by RNA pol 2
polyadenylation and splicing
nuclear export

Question 3

what increased rates decrease mRNA (3)

Answer 3

intrinsic turnover
microRNA - promoted degredation
nonsense mediated decay

Question 4

what gets the eIF4E complex and everything (the ribosome) moving (to look for AUG) and scanning for translation

Answer 4

the hydrolysis of ATP to ADP

Question 5

what cat happens without eIF4E

Answer 5

host translation

Question 6

what do PKR and PERK have

Answer 6

kinase activity

Question 7

what do PKR and PERK do

Answer 7

phosphorylate eIF4a

Question 8

the integrated stress response

Answer 8

cellular sigbnals that lead to global shut off of cellular translation initiation through the phosphorylation of eIF2a

Question 9

what happens when eIF2a is phosphorylated

Answer 9

it gets stuck (tightly binds) in eIF4B and translation initiation is inhibited

Question 10

what is eIF2a

Answer 10

forms the complex between tRNA-met and GTP to deliver the initiator tRNA to the 40s ribosome unit

Question 11

how does eIF4B initiate translation

Answer 11

it recycles eIF2a’s GDP to a GTP so eIF2a can recruit the tRNA-Met complex

Question 12

what pathway can viruses activate to inhibit apoptosis and promote translation

Answer 12

ATK

Question 13

activation of PI3K pathways do what

Answer 13

induce clathrin coasted pits and endocytosis

Question 14

3 menthods of virus activation of entry pathways listed

Answer 14

activation of PI3K to induce clathrin coasted pits
allow for membrane fusion by upregulation of RAC
induce cluttering and signalling by lipid rafts to also enhance entry

Question 15

what does RAC do

Answer 15

makes the membrane more flexible and ready for fusion

Question 16

3 inhibition of cellular gene expression by several viral proteins

Answer 16

inhibition of transcription of RNA pol 2
inhibition of translation
increase mRNA degradation

Question 17

3 things needed to initiate translation

Answer 17

the eIF2-tRNA-Met complex
eIF4E
the hydrolysis of ATP to ADP

Question 18

do hosts shut off translation to try and counteract a virus

Answer 18

yes, so this virus needs a way to try and inhibit this

Question 19

what does PERK respond to

Answer 19

overload of proteins in the ER

Question 20

what does PKR respond to

Answer 20

viral infection - dsRNA

Question 21

how many PKR’s are needed to bind dsRNA and induce phosphorylation

Answer 21

2

Question 22

does PKR need to be autophosphorylated first

Answer 22

yes its autophosphorylated when it binds the dsRNA and then its ready to phosphorylate eIF2a

Question 23

3 eIF2a kinases

Answer 23

PERK
PRK
GCN2

Question 24

what is GCN2 induced by

Answer 24

amino acid starvation

Question 25

what does delta E4 do

Answer 25

it pushes the cells metabolism to the consumption of glucose

Question 26

why do viruses benefit from glucose

Answer 26

they have to make lots of things in the cell and most of them require ATP and energy to do. it needs enough ATP to fuel these processes

Question 27

do all viruses push the same metabolism

Answer 27

no they push what they depend on for its needs (either fatty acids, glucose, or acetyl CoA)

Question 28

major hub of carbon metabolism

Answer 28

TCA cycle

Question 29

what cycle leads to precursors to synthesis of many biomolecules

Answer 29

TCA cycle

Question 30

source of energy is stored in most organisms in

Answer 30

lipid droplets

Question 31

any virus that wants to make more fat will turn on what pathway

Answer 31

SREBP1

Question 32

what is SREBP1

Answer 32

transcription activator that turns on genes for fatty acid synthesis

Question 33

how does SREBP1 enter the nucleus

Answer 33

HCMV activates mTOR1. Activated mTOR1 phosphorylates Lipin 1 and then the phosphorylated Lipin 1 cannot inhibit SREBP1 - therefore leading to SREBP1 entering the nucleus and the expression of genes for fatty acid synthesis