Literature summary for 4.1.99.13 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.

Search for more literature for 4.1.99.13

Activating Compound

Activating Compound	Comment	Organism	Structure
Dithionite	reduction of the FAD cofactor with dithionite increases the quantum yield of repair	Drosophila melanogaster

Cloned(Commentary)

Cloned (Comment)	Organism
expressed in Escherichia coli as a MBP-PL-(6-4) fusion protein	Drosophila melanogaster

Organism

Organism	UniProt	Comment	Textmining
Drosophila melanogaster	-	-	-

Purification (Commentary)

Purification (Comment)	Organism
fusion protein is purified through a 20-ml amylose column and through heparin-agarose column	Drosophila melanogaster

Reaction

Reaction	Comment	Organism	Reaction ID
(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	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
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

Synonyms	Comment	Organism
(6-4) photolyase	-	Drosophila melanogaster
PL-(6-4)	-	Drosophila melanogaster

Cofactor

Cofactor	Comment	Organism	Structure
FAD	-	Drosophila melanogaster

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Release 2023.1 (January 2023)