Lecture 4 - ATP dependent chromatin remodelling

Question 1

cells have multiple remodelling complexes but all have a …… related ATPase

Answer 1

Snf-2 related ATPase

Question 2

which family does Snf-2 belong to?

which 2 enzyme components are the main drivers of ATP-dependent chromatin remodelling in this family?

Answer 2

SF2

helicase and NTP translocase

Question 3

ATP dependent chromatin remodelling uses ATP from which reaction?

to unwrap what? to promote the exchange of what?

Answer 3

from ATP hydrolysis

to unwrap DNA

to promote exchange of histone variants

Question 4

the catalytic subunit of SWI/SNF is called what?

Answer 4

Snf2/Swi2

Question 5

in the presence of DNA or nucleosomes what does Snf2 hydrolyse 1000s of per minute?

Answer 5

ATP molecules

Question 6

which 2 complexes co-operate to remodel chromatin?

Answer 6

HATs and ATP-dependent remodellers

Question 7

true or false, SWI/SNF contains a bromodomain?

Answer 7

true

Question 8

how many SWI/SNF complexes are there in humans?

what are some of their roles?

Answer 8

3

heat shock receptors, glucocorticoid receptors, cell cycle control, tumour suppression, embryo development

Question 9

how many different genes encoding subunits of the SWI/SNF complexes are recurrently
mutated in cancer?

Answer 9

9

Question 10

there are 4 major goups of histone deacetylases. Groups 1, 2 and 4 are ……., dependent on which metal…….

Answer 10

classical, zinc dependent

Question 11

group 3 of histone deacetylases are sirtuins, requiring what as a cofactor?

Answer 11

NAD

Question 12

histone deacetylases have …… activity

Answer 12

repressor

Question 13

what is a histone deacetylase co-repressor complex which is conserved from yeast to mammals?

Answer 13

SIN3

Question 14

name an ATP-dependent remodelling complex which is expressed in most tissues and plays roles in normal differentiation and tumourogenesis?

what type of enzymes does it contain?

Answer 14

NuRD complex, contains histone deacetylases

Question 15

what are the two basic types of chromatin?

Answer 15

euchromatin and heterochromatin

Question 16

euchromatin has the potential to be ……… as it is gene……

Answer 16

potential to be transcribed as it is gene rich

Question 17

is heterochromatin gene rich or gene poor?

Answer 17

gene poor

Question 18

name two chromosomal structures involved in DNA replication/mitosis which contain heterochromatin

Answer 18

centromeres and telomeres

Question 19

heterochromatin is involved in the silencing of transcription, true or false?

Answer 19

true

Question 20

give an example of a chromodomain protein which recognises and binds to methylated lysine residues such as H3 Lys9 me2/3?

Answer 20

HP1

Question 21

the binding of HP1 to heterochromatin prevents the recruitment/activity of which enzyme, involved in transcription initiation?

Answer 21

RNA pol 2

Question 22

heterochromatin is involved in the inactivation of which chromosome (sex chromosome)?

Answer 22

X

Question 23

a Barr body (inactivated X chromosome in females) is assembled into a specific form of what type of chromatin?

Answer 23

heterochromatin

Question 24

which two non coding RNAs control the formation of the Barr body?

Answer 24

Xist and Tsix

Question 25

explain briefly how X chromosome inactivation occurs?

Answer 25

The inactivated X chromosome is seen in the nucleus as a condensed structure (Barr
body)

Barr body is assembled into heterochromatin which is gene poor with transcription silenced