Photolyase

Definition

Photolyase is an enzyme that repairs DNA damage caused by ultraviolet (UV) light through a process called photoreactivation. It specifically targets and reverses cyclobutane pyrimidine dimers (CPDs).

5 Must Know Facts For Your Next Test

1. Photolyase requires visible light to activate its repair function.
2. It binds to damaged DNA at the site of CPDs and uses the energy from light to cleave the dimer.
3. Photolyase is found in many organisms, including bacteria, plants, and animals but is notably absent in placental mammals.
4. The enzyme has two chromophore groups that absorb light: a folate and a flavin adenine dinucleotide (FAD).
5. Photolyase is highly specific for UV-induced CPDs and does not repair other types of DNA damage.

Review Questions

Related terms

Cyclobutane Pyrimidine Dimers (CPDs): DNA lesions caused by UV light where two adjacent pyrimidines become covalently bonded.

Nucleotide Excision Repair (NER): A DNA repair mechanism that removes bulky lesions like thymine dimers not repaired by photoreactivation.

Ultraviolet (UV) Light: A type of electromagnetic radiation that can cause DNA damage such as CPDs.