DNA photolyase, N-terminal is an evolutionary conserved

protein domain In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist o ...

. This domain binds a light harvesting

chromophore A chromophore is the part of a molecule responsible for its color. The color that is seen by our eyes is the one not absorbed by the reflecting object within a certain wavelength spectrum of visible light. The chromophore is a region in the molec ...

that enhanced the spectrum of

photolyase Photolyases () are DNA repair enzymes that repair damage caused by exposure to ultraviolet light. These enzymes require visible light (from the violet/blue end of the spectrum) both for their own activation and for the actual DNA repair. The DN ...

cryptochrome Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields ...

light absorption, i.e. an antenna. It adopts the

rossmann fold The Rossmann fold is a tertiary fold found in proteins that bind nucleotides, such as enzyme cofactors FAD, NAD+, and NADP+. This fold is composed of alternating beta strands and alpha helical segments where the beta strands are hydrogen bonde ...

. The cofactor may be either the

pterin Pterin is a heterocyclic compound composed of a pteridine ring system, with a " keto group" (a lactam) and an amino group on positions 4 and 2 respectively. It is structurally related to the parent bicyclic heterocycle called pteridine. Pterins ...

5,10-Methenyltetrahydrofolate (MTHF, ) in ''folate photolyases'' () or the deazaflavin 8-hydroxy-7,8-didemethyl-5-deazariboflavin (8-HDF, ) in ''deazaflavin photolyases'' (). The 8-HDF ligand usually binds into this domain (next to the C-terinal half), while MHF tends to bind to an outside groove of this domain. A structural signature for 8-HDF binding has been produced, highlighting amino acid residues that determine which antenna a photolyase can use. Experiments on a ''Thermus thermophilus'' protein with this domain () shows that artificial substrates can be alternatively used for a modified absorption spectra. It naturally binds FMN in a pose similar to 8-HDF. In addition, many cryptochromes, especially those from animals, bind no cofactors at this domain. Even though few eukaryotes (and no animals) can synthesize 8-HDF on their own, many lineages nevertheless use deazaflavin photolyases. They probably receive 8-HDF from their endosymbiotic microbes. Unlike many bacterial deazaflavin photolyases that accepts FMN as well as 8-HDF, one such enzyme from the fruit fly only accepts 8-HDF. The FeS-BCP N-terminal domain is homologous to this domain. Instead of an organic cofactor, its chromophore is an iron-sulphur cluster.

Examples

Human proteins containing this domain include: *

CRY1 Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fiel ...

CRY2 Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields ...

References

Protein domains {{protein-stub