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Control Of Gene Expression > Chromatin Remodelling And Repression > Flashcards

Chromatin Remodelling And Repression Flashcards

1
Q

What are the readers in the histone code

A

Bromodomains
Chromodomains phD

It’s proteins which read the post translational modifications

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2
Q

Other than acetylation Nd methylation. Which other way can chromatin be remodelled

A

Atp dependant chromatin remodelling

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3
Q

What type of ATPase do all atp dep remodelling complexes have

A

Snf 2

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4
Q

There are 4 subfamilies of the super family 2 atp dep remodelling complexes. What are they

A

Snf2/swi2

ISWI

Chd/mi2

Ino80

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5
Q

What characterises swi2/snf2 remodel complex

A

A bromodomain and a snf2 ATPase

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6
Q

What characterises chd/ mi2 remodeller

A

Chromodomain and a dna binding domain

And the snf 2 ATPase domain

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7
Q

What characterises the ino 80 complex

A

A split ATPase domain

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8
Q

What do remodellers like chd mi2 use ATPase hydrolysis for

A

Sliding, unwrapping, spacing, evicting nucleosomes

And

Histone variant exchanges

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9
Q

What does swi2/snf2 remodellers do using the snf2 ATPase

A

Induce torsions in dna and change the position of dna around nucleosome

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10
Q

What do atp remodelling complexes work with

A

Hats like tra1 which is bound to gcn5 activator

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11
Q

How is bromodomain of snf2 attracted to tra1 HAT

A

Because tra1 has acetylated lsyines around it and the bromodomain of snf2 recognises this

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12
Q

What does hat and atp complexes cooperation do

A

Allow pic recruitment

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13
Q

What genes does snf2 in yeast regulate

A

Genes at end of mitosis

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14
Q

What role does human snf2 have in cell cycle regulation

A

Interacts with cyclin E and Rb (tumour repressor) repressor

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15
Q

What would mutation in snf2 in humans cause

A

Tumours

Snf2 is used for tumour suppression

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16
Q

Snf2 is important for transcription factor expression. Give examples

A

HSF, myoD, glucocorticoid and retinoids receptors

17
Q

Can atp dep remodelling also cause repression of txn

A

Yes

18
Q

Which enzymes are important in repression

A

HDACs and histone methylases HKMT via lys 9 and 28

19
Q

How do HDACs repress

A

Hypoacetylate lysine residues on n terminal tail via hydrolysis

Adds positive charge back to lysine

Dna will tightly bind to nucleosomes

20
Q

Just like hats are co activators with snf2, what are HDACs

A

Co repressors

21
Q

What are class 1,2 and 4 HDACs dependant on

A

Zinc

22
Q

What is class 3 sir 2 HDACs dependant on

A

Nad

23
Q

Which repressor gene that has a dna binding domain forms a complex with HDACs for co repression

A

Ume6 gene

24
Q

Which complex is formed by the corepressors ume6 and rpd3 HDAC

A

Sin3

25
Q

What genes do sin3 repress

A

Meiosis genes

26
Q

Which atp dependant remodeller is a repressor

A

NuRD - mi2/chd family

27
Q

How does nuRD repress

A

Decreases spacing of nucleosomes fotming CLOSED CHROMATIN

28
Q

Does the nuRD repressor also have a HDAC

A

Yes

29
Q

Histone lysine methyl transferases hkmt are repressing if at lys 9 and 28, is this found in heterochromatin

A

Yes

30
Q

Aswell as hkmt at 9 and 28, what other properties does hetereochromatin have

A

Hypoacetylation via HDACs
And
Association with silencing factors

31
Q

How is H3 lys 9me produced in heterochromstin

A

Lys 9 is deacetylated via HDACs

Then a hkmt methylated the lysine 9 (K9)

This is recognised by chromodomain proteins HP1 of tri and di methyl groups

HP1 will form compact nucleosomes and recruit other repressors

32
Q

What is HP1

A

Heterochromatin protein 1 with a chromodomain

33
Q

Which hkmt methylates H3 lysine 9

A

Suvar 39

34
Q

Which reporter gene is used in a reporter silencing assay to analyse heterochromatin

A

Ade6, when expressed it turns white

35
Q

What happens when ade6 is placed in heterochromstin region

A

Switched off and adenine intermediate turns red

36
Q

Which non coding rna is switched on during development to inactivate an X

A

Xist

37
Q

Which hkmt is attracted when xist is switched on for repression

A

H3k27 methylases

38
Q

What does hkmt h3k27 do when recruited by xist to repress x

A

Recruit other silencing factors to inactivate the x

Control Of Gene Expression (13 decks)

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