GMan - DNA Repair II

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  1. Types of direct DNA repair
    • Nick ligation (ligase)
    • Direct reversal of alkylation
  2. O6 Alkylguaninetransferase I (AGT I)
    • Inducible, adaptive response
    • E. coli alkylation reversal
  3. O6 Alkylguaninetransferase II (AGT II)
    • Constitutively expressed
    • E. coli alkylation reversal
    • Prefers O4 alkylthymine
  4. What do AGT I and AGT II do?
    Remove alkyl groups from 4' and 6' positions on thymine and guanine respectively
  5. Human version of AGT
    O6-Methylguanine DNA methyltransferase (MGMT)
  6. What does MGMT do?
    • Transfers a methyl group from guanine's O6 position
    • Suicide enzyme
  7. CPD
    Cyclobutane pyrimidine dimer
  8. DNA photolyase action
    • Binds to CPDs and waits...
    • Uses incoming UV to resrore DNA stereochemistry
  9. Two broad categories of Excision Repair
    • Base Excision repair
    • Nucleotide Excision repeir
  10. DNA Damage handled by base excision repair
    Deamination, Oxidation, Alkylation
  11. Key enzymes of base excision repair
    • Glycosylatses - Recognize and remove the damaged base (Hydrolyses glycosidic bond)
    • AP Endonuclease - Cleaves the phosphodiester backbone
  12. Glycosylases
    • Many different types
    • Flip out the base and excise
    • Humans: Glycolases remain bound and APE1 nicks the DNA
  13. Glycosylase examples
    • Uracil DNA glycosylase
    • 8-Oxo-G glycosylase
  14. 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)
  15. Enzyme dealing with oxidized DNA
    8-Oxyguanine glycosylase
  16. At what stage(s) in replication does 8-Oxyguanine glycosylase act?
    • Before and after replication
    • On the template strand
  17. When does MYH act (with respect to replication)
    • After replication
    • On the newly synthesized strand (swaps the wrong base for the correct one)
Card Set:
GMan - DNA Repair II
2017-04-14 22:16:54
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