Literature summary extracted from
Zhao, X.; Liu, J.; Hsu, D.S.; Zhao, S.; Taylor, J.S.; Sancar, A.
Reaction mechanism of (6-4) photolyase (1997), J. Biol. Chem., 272, 32580-32590.
Activating Compound
EC Number |
Activating Compound |
Comment |
Organism |
Structure |
---|
4.1.99.13 |
Dithionite |
reduction of the FAD cofactor with dithionite increases the quantum yield of repair |
Drosophila melanogaster |
|
Cloned(Commentary)
EC Number |
Cloned (Comment) |
Organism |
---|
4.1.99.13 |
expressed in Escherichia coli as a MBP-PL-(6-4) fusion protein |
Drosophila melanogaster |
Organism
EC Number |
Organism |
UniProt |
Comment |
Textmining |
---|
4.1.99.13 |
Drosophila melanogaster |
- |
- |
- |
Purification (Commentary)
EC Number |
Purification (Comment) |
Organism |
---|
4.1.99.13 |
fusion protein is purified through a 20-ml amylose column and through heparin-agarose column |
Drosophila melanogaster |
Reaction
EC Number |
Reaction |
Comment |
Organism |
Reaction ID |
---|
4.1.99.13 |
(6-4) photoproduct (in DNA) = 2 pyrimidine residues (in DNA) |
The overall repair reaction consists of two distinct steps, one of which is light-independent and the other one light-dependent. In the initial light-independent step, a 6-iminium ion is thought to be generated via proton transfer induced by two histidines highly conserved among the (6-4) photolyases.This intermediate spontaneously rearranges to form an oxetane intermediate by intramolecular nucleophilic attack. In the subsequent light-driven reaction, one electron is believed to be transferred from the fully reduced FAD cofactor (FADH-) to the oxetane intermediate thus forming a neutral FADH radical and an anionic oxetane radical, which spontaneously fractures. The excess electron is then back-transferred to the flavin radical restoring the fully reduced flavin cofactor and a pair of pyrimidine bases |
Drosophila melanogaster |
|
Substrates and Products (Substrate)
EC Number |
Substrates |
Comment Substrates |
Organism |
Products |
Comment (Products) |
Rev. |
Reac. |
---|
4.1.99.13 |
additional information |
binding and catalytic properties of the enzyme are investigated using natural substrates, T[6-4]T and T[6-4]C, and the Dewar isomer of (6-4) photoproduct and substrate analogs s5T[6-4]T/thietane, mes5T[6-4]T, and the N-methyl-3T thietane analog of the oxetane intermediate. The enzyme binds to the natural substrates and to mes5T[6-4]T with high affinity and produces a DNase I footprint of about 20 base pairs around the photolesion. Of the four substrates that bind with high affinity to the enzyme, T[6-4]T and T[6-4]C are repaired with relatively high quantum yields compared with the Dewar isomer and the mes5T[6-4]T which are repaired with 300-400-fold lower quantum yield |
Drosophila melanogaster |
? |
- |
? |
|
Synonyms
EC Number |
Synonyms |
Comment |
Organism |
---|
4.1.99.13 |
(6-4) photolyase |
- |
Drosophila melanogaster |
4.1.99.13 |
PL-(6-4) |
- |
Drosophila melanogaster |
Cofactor
EC Number |
Cofactor |
Comment |
Organism |
Structure |
---|
4.1.99.13 |
FAD |
- |
Drosophila melanogaster |
|