GMan - DNA Repair II

Home

Get App

Take Quiz

Create

Types of direct DNA repair
- Nick ligation (ligase)
- Direct reversal of alkylation
O⁶ Alkylguaninetransferase I (AGT I)
- Inducible, adaptive response
- E. coli alkylation reversal
O⁶ Alkylguaninetransferase II (AGT II)
- Constitutively expressed
- E. coli alkylation reversal
- Prefers O⁴ alkylthymine
What do AGT I and AGT II do?

Remove alkyl groups from 4' and 6' positions on thymine and guanine respectively
Human version of AGT

O⁶-Methylguanine DNA methyltransferase (MGMT)
What does MGMT do?
- Transfers a methyl group from guanine's O⁶ position
- Suicide enzyme
CPD

Cyclobutane pyrimidine dimer
DNA photolyase action
- Binds to CPDs and waits...
- Uses incoming UV to resrore DNA stereochemistry
Two broad categories of Excision Repair
- Base Excision repair
- Nucleotide Excision repeir
DNA Damage handled by base excision repair

Deamination, Oxidation, Alkylation
Key enzymes of base excision repair
- Glycosylatses - Recognize and remove the damaged base (Hydrolyses glycosidic bond)
- AP Endonuclease - Cleaves the phosphodiester backbone
Glycosylases
- Many different types
- Flip out the base and excise
- Humans: Glycolases remain bound and APE1 nicks the DNA
Glycosylase examples
- Uracil DNA glycosylase
- 8-Oxo-G glycosylase
Two base excision DNA synthesis
- Short patch (pol 1 or pol β, DNA Ligase III)
- Long Patch (pol δ or pol ε, DNA Ligase I)
Enzyme dealing with oxidized DNA

8-Oxyguanine glycosylase
At what stage(s) in replication does 8-Oxyguanine glycosylase act?
- Before and after replication
- On the template strand
When does MYH act (with respect to replication)
- After replication
- On the newly synthesized strand (swaps the wrong base for the correct one)

Author

Ant

330343

Card Set

GMan - DNA Repair II

Description

GMan

Updated

2017-04-14T22:16:54Z