TLS Online TPP Program

#Id: 3361

#Unit 3. Fundamental Processes

Photoreactivation; Ultraviolet irradiation causes formation of thymine dimers. Upon exposure to light, DNA photolyase breaks the ring formed between the dimers to restore the two thymine residues.

TLS Online TPP Program

#Id: 3363

#Unit 3. Fundamental Processes

The two chromophores in E. coli photolyase (Mr 54,000), N5 N10-methenyltetrahydrofolylpolyglutamate (MTHF polyGlu) and FADH , perform complementary functions.

TLS Online TPP Program

#Id: 3365

#Unit 3. Fundamental Processes

In reversal, MTHF polyGlu functions as a photoantenna to absorb blue-light photons.

TLS Online TPP Program

#Id: 3368

#Unit 3. Fundamental Processes

In E. coli, DNA Pol IV (DinB) or DNA Pol V (a complex of the proteins UmuC and UmuD0 ) performs translesion synthesis. 

TLS Online TPP Program

#Id: 3369

#Unit 3. Fundamental Processes

DinB and UmuC are members of a distinct family of DNA polymerases found in many organisms known as the Y family of DNA polymerases. There are five translesion polymerases known in humans, four of which belong to the Y family.

TLS Online TPP Program

#Id: 3370

#Unit 3. Fundamental Processes

A human member of the Y family of translesion polymerases (DNA Pol h) correctly inserts two A residues opposite a thymine dimer.