InterPro domain: IPR006050

The photolyase/cryptochrome family consists of flavoproteins that performvarious functions using blue-light photons as an energie source. It is presentin all three domains of life, that is, archaea, eubacteria, and eukaryotes,and hence has arisen very early during evolution to protect genomes againstthe genotoxic effects of ultraviolet light originating from the sun. Thephotolyase/cryptochrome family is divided into two major groups: photolyasesand cryptochromes. Photolyases repaircytotoxic and mutagenic UV-induced photolesions in DNA in many species frombacteria to plants and animals by using a light-dependent repair mechanism. Itinvolves light absorption, electron transfer from an excited reduced anddeprotanated FADH(-) to the flipped-out photolesion, followed by thefragmentation of the photolesions. Cryptochromes are highly related proteinsthat generally no longer repair damaged DNA, but function as photoreceptors.Cryptochromes regulate growth and development in plants and the circadianclock in animals [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ].

Both photolyases and cryptochromes have a bilobal architecture consisting oftwo domains: an N-terminal alpha/beta domain that may contain a light-harvesting chromophore to additionally broaden their activity spectra and a C-terminal alpha-helical catalytic domain comprising the light-sensitive FADcofactor. Diverse classes of antenna chromophores likes 5,10-methenyltetrahydrofolate (MTHF), 8-hydroxydeazaflavin, FMN or FAD have beenidentified in some photolyase/cryptochrome to broaden their activity spectra,whereas many others apparently lack any bound antenna chromophores.

This entry represents the photolyase/cryptochrome alpha/beta domain. It adopts a dinucleotide binding fold with a five-stranded parallel beta sheet flanked on both sides by alpha helices [ 8 , 8 ].

1. Identification of a new cryptochrome class. Structure, function, and evolution. Mol. Cell 11, 59-67
2. Recognition and repair of UV lesions in loop structures of duplex DNA by DASH-type cryptochrome. Proc. Natl. Acad. Sci. U.S.A. 105, 21023-7
3. Localization of transforming growth factor-beta1 and type II receptor in developing normal human prostate and carcinoma tissues. J. Histochem. Cytochem. 46, 379-88
4. The archaeal cofactor F0 is a light-harvesting antenna chromophore in eukaryotes. Proc. Natl. Acad. Sci. U.S.A. 106, 11540-5
5. Crystal structures of an archaeal class II DNA photolyase and its complex with UV-damaged duplex DNA. EMBO J. 30, 4437-49
6. Eukaryotic class II cyclobutane pyrimidine dimer photolyase structure reveals basis for improved ultraviolet tolerance in plants. J. Biol. Chem. 287, 12060-9
7. Purification and characterization of five members of photolyase/cryptochrome family from Cyanidioschyzon merolae. Plant Sci. 185-186, 190-8