Week 6 - Epigenetics

DNA Methylation - Where

5 methyl cytosine

CpG

DNA Methylation - Process

De Novo DNA methyl transferase - add CH3

Both strands

DNA replication

Hemi-methylated

Maintenance methyl transferase - add matching CH3

Normal C - Deamination

Convert to U

Recognised + repaired

5 methyl C - Deamination

Convert to T

TpG

Not recognised

Histones - N Terminal Tails Properties

Approx 20 aa

Flexible

Charged

Protude

Histone Methylation - Where

Lysine + arginine in tails

Histone Methylation - How Many CH3 per Lysine

1-3

Histone Methylation - Enzymes ADD vs REMOVE

Histone DNA methyl transferase vs lysine-specific demethylase 1

Histone Acetylation - Where

Lysine in tail

Histone Acetylation - How Many per Lysine

1

Histone Acetylation - Enzymes ADD vs REMOVE

Histone acetyl transferase

Histone deacetylase

Phosphorylation - Where

Serine

Phosphorylation - Enzymes ADD vs REMOVE

Kinases vs phosphatases

Ubiquitination - Where

Lysine

76aa protein

Ubiquitination - Enzyme

Ubiquitin conjugating

Histone Code

Histone marks control chromatin

Heterochromatin

Tightly coiled

Condensed

Inactive

Euchromatin

Loosely coiled

Active

Hyperacetylation

Less condensed

Hypermethylation

More condensed

DNA Binding Proteins

Recognise different marks

DNA Binding Domains

Region on DBP that binds to ss/dsDNA

DBPs Control

Transcription

Translation

DNA replication

DNA repair

RNA splicing

Apoptosis