The E. coli enzyme acts by antagonizing the replication helicase in a direction a) manner by direct contact between the DnaB helicase and Tus.

TLS Online TPP Program

#Id: 6121

#Unit 3. Fundamental Processes

The MutT, -M, -Y system handles the consequences of oxidative damage. Major type of chemical damage is caused by oxidation of G to 8-oxo-G

TLS Online TPP Program

#Id: 6122

#Unit 3. Fundamental Processes

The deamination generates a G-T/C-T mismatch pair, MutL and MutS remove T from both G-T and C-T mismatches.

TLS Online TPP Program

#Id: 6123

#Unit 3. Fundamental Processes

Base excision repair is triggered by directly removing a damaged base from DNA. In E.coli, system include

Uracil DNA glycosylases

AP endonuclease

DNA polymerase I 

DNA ligase

TLS Online TPP Program

#Id: 6124

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6125

#Unit 3. Fundamental Processes

Humans have the enzyme hSMUG1, which removes any U residues that occur in single-stranded DNA during replication or transcription.  Two other human DNA glycosylases, TDG and MBD4, remove either U or T residues paired with G, generated by deamination of cytosine or 5-methylcytosine, respectively.

TLS Online TPP Program

#Id: 6126

#Unit 3. Fundamental Processes

DNA glycosylases recognize and remove formamidopyrimidine and 8-hydroxyguanine (both arising from purine oxidation), hypoxanthine (arising from adenine deamination), and alkylated bases such as 3-methyladenine and 7-methylguanine.