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115  structures 5180  species 0  interactions 11663  sequences 103  architectures

Family: FAD_binding_7 (PF03441)

Summary: FAD binding domain of DNA photolyase

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This is the Wikipedia entry entitled "Photolyase". More...

Photolyase Edit Wikipedia article

DNA photolyase, C-terminal, FAD binding
Photolyase 1qnf.png
A deazaflavin photolyase from Anacystis nidulans, illustrating the two light-harvesting cofactors: FADH− (yellow) and 8-HDF (cyan).
deoxyribodipyrimidine photo-lyase (CPD)
Direct DNA damage.png
A UV radiation induced thymine-thymine cyclobutane dimer (right) is the type of DNA damage which is repaired by DNA photolyase. Note: The above diagram is incorrectly labelled as thymine as the structures lack 5-methyl groups.
EC number4.1.99.3
CAS number37290-70-3
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO

Photolyases (EC 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[1] and for the actual DNA repair.[2] The DNA repair mechanism involving photolyases is called photoreactivation. They mainly convert pyrimidine dimers into a normal pair of pyrimidine bases.


Photolyases bind complementary DNA strands and break certain types of pyrimidine dimers that arise when a pair of thymine or cytosine bases on the same strand of DNA become covalently linked. The bond length of this dimerization is shorter than the bond length of normal B-DNA structure which produces an incorrect template for replication and transcription.[3] The more common covalent linkage involves the formation of a cyclobutane bridge. Photolyases have a high affinity for these lesions and reversibly bind and convert them back to the original bases.


Photolyase is a phylogenetically old enzyme which is present and functional in many species, from the bacteria to the fungi to plants[4] and to the animals.[5] Photolyase is particularly important in repairing UV induced damage in plants. The photolyase mechanism is no longer working in humans and other placental mammals who instead rely on the less efficient nucleotide excision repair mechanism, although they do retain many cryptochromes.[6]

Photolyases are flavoproteins and contain two light-harvesting cofactors. Many photolyases have an N-terminal domain that binds a second cofactor. All photolyases contain the two-electron-reduced FADH−; they are divided into two main classes based on the second cofactor, which may be either the pterin methenyltetrahydrofolate (MTHF) in folate photolyases or the deazaflavin 8-hydroxy-7,8-didemethyl-5-deazariboflavin (8-HDF) in deazaflavin photolyases. Although only FAD is required for catalytic activity, the second cofactor significantly accelerates reaction rate in low-light conditions. The enzyme acts by electron transfer in which the reduced flavin FADH− is activated by light energy and acts as an electron donor to break the pyrimidine dimer.[7]

On the basis of sequence similarities DNA photolyases can be grouped into a few classes:[8][9]

Cryptochrome/photolyase family (2015)[8]





Plant Cry

P. tricornutum CryP]


Eukaryotic 6-4; Animal Cry

  • Class 1 CPD photolyases are enzymes that process cyclobutane pyrimidine dimer (CPD) lesions from Gram-negative and Gram-positive bacteria, the halophilic archaea Halobacterium halobium.
  • Class 2 CPD photolyases also process CPD lesions. They are found in plants like the thale cress Arabidopsis thaliana and the rice.
  • The plant and fungi cryptochromes are similar to Class 1 CPDs. They are blue light photoreceptors that mediate blue light-induced gene expression and modulation of circadian rhythms.
  • Class 3 CPD lyases make up a sister group to the plant cryptochromes, which in turn are a sister group to class 1 CPDs.
  • The Cry-DASH group are CPD lyases highly specific for single-stranded DNA. Members include Vibrio cholerae, X1Cry from Xenopus laevis, and AtCry3 from Arabidopsis thaliana.[5] DASH was initially named after Drosophila, Arabidopsis, Synechocystis, and Human, four taxa initially thought to carry this family of lyases. The categorization has since changed. The "Cry" part of their name was due to initial assumptions that they were cryptochromes.[8]
  • Eukaryotic (6-4)DNA photolyases form a group with animal cryptochromes that control circadian rhythms. They are found in diverse species including Drosophilia and humans. The cryptochromes have their own detailed grouping.[9]
  • Bacterial 6-4 lyases (InterProIPR007357), also known as the FeS-BCP group, form their own outgroup relative to all photolyases.

The non-class 2 branch of CPDs tend to be grouped into class 1 in some systems such as PRINTS (PR00147). Although the members of the smaller groups are agreed upon, the phylogeny can vary greatly among authors due to differences in methodology, leading to some confusion with authors who try to fit everything (sparing FeS-BCP) into a two-class classification.[9] The cryptochromes form a polyphyletic group including photolyases that have lost their DNA repair activity and instead control circadian rhythms.[8][9]


Adding photolyase from a blue-green algae Anacystis nidulans, to HeLa cells partially reduced DNA damage from UVB exposure.[10]

Human proteins containing this domain



The systematic name of this enzyme class is deoxyribocyclobutadipyrimidine pyrimidine-lyase. Other names in common use include photoreactivating enzyme, DNA photolyase, DNA-photoreactivating enzyme, DNA cyclobutane dipyrimidine photolyase, DNA photolyase, deoxyribonucleic photolyase, deoxyribodipyrimidine photolyase, photolyase, PRE, PhrB photolyase, deoxyribonucleic cyclobutane dipyrimidine photolyase, phr A photolyase, dipyrimidine photolyase (photosensitive), and deoxyribonucleate pyrimidine dimer lyase (photosensitive). This enzyme belongs to the family of lyases, specifically in the "catch-all" class of carbon-carbon lyases.


  1. ^ Yamamoto J, Shimizu K, Kanda T, Hosokawa Y, Iwai S, Plaza P, Müller P (October 2017). "Loss of Fourth Electron-Transferring Tryptophan in Animal (6-4) Photolyase Impairs DNA Repair Activity in Bacterial Cells". Biochemistry. 56 (40): 5356–5364. doi:10.1021/acs.biochem.7b00366. PMID 28880077.
  2. ^ Thiagarajan V, Byrdin M, Eker AP, Müller P, Brettel K (June 2011). "Kinetics of cyclobutane thymine dimer splitting by DNA photolyase directly monitored in the UV". Proceedings of the National Academy of Sciences of the United States of America. 108 (23): 9402–7. doi:10.1073/pnas.1101026108. PMC 3111307. PMID 21606324.
  3. ^ Garrett RH, Grisham CM (2010). Biochemistry. Brooks/Cole, Cengage Learning. ISBN 978-0-495-10935-8. OCLC 984382855.
  4. ^ Teranishi, M., Nakamura, K., Morioka, H.,Yamamoto, K. and Hidema, J. (2008). "The native cyclobutane pyrimidine dimer photolyase of rice is phosphorylated". Plant Physiology. 146 (4): 1941–1951. doi:10.1104/pp.107.110189. PMC 2287361. PMID 18235036.
  5. ^ a b Selby CP, Sancar A (November 2006). "A cryptochrome/photolyase class of enzymes with single-stranded DNA-specific photolyase activity". Proceedings of the National Academy of Sciences of the United States of America. 103 (47): 17696–700. doi:10.1073/pnas.0607993103. PMC 1621107. PMID 17062752.
  6. ^ Lucas-Lledó JI, Lynch M (May 2009). "Evolution of mutation rates: phylogenomic analysis of the photolyase/cryptochrome family". Molecular Biology and Evolution. 26 (5): 1143–53. doi:10.1093/molbev/msp029. PMC 2668831. PMID 19228922.
  7. ^ Sancar A (June 2003). "Structure and function of DNA photolyase and cryptochrome blue-light photoreceptors". Chemical Reviews. 103 (6): 2203–37. doi:10.1021/cr0204348. PMID 12797829.
  8. ^ a b c d Scheerer P, Zhang F, Kalms J, von Stetten D, Krauß N, Oberpichler I, Lamparter T (May 2015). "The class III cyclobutane pyrimidine dimer photolyase structure reveals a new antenna chromophore binding site and alternative photoreduction pathways". The Journal of Biological Chemistry. 290 (18): 11504–14. doi:10.1074/jbc.M115.637868. PMC 4416854. PMID 25784552.
  9. ^ a b c d Rivera AS, Ozturk N, Fahey B, Plachetzki DC, Degnan BM, Sancar A, Oakley TH (April 2012). "Blue-light-receptive cryptochrome is expressed in a sponge eye lacking neurons and opsin". The Journal of Experimental Biology. 215 (Pt 8): 1278–86. doi:10.1242/jeb.067140. PMC 3309880. PMID 22442365.
  10. ^ Kulms D, Pöppelmann B, Yarosh D, Luger TA, Krutmann J, Schwarz T (July 1999). "Nuclear and cell membrane effects contribute independently to the induction of apoptosis in human cells exposed to UVB radiation". Proceedings of the National Academy of Sciences of the United States of America. 96 (14): 7974–9. doi:10.1073/pnas.96.14.7974. PMC 22172. PMID 10393932.

Further reading

  • Eker AP, Fichtinger-Schepman AM (1975). "Studies on a DNA photoreactivating enzyme from Streptomyces griseus II. Purification of the enzyme". Biochim. Biophys. Acta. 378 (1): 54–63. doi:10.1016/0005-2787(75)90136-7. PMID 804322.
  • Sancar GB, Smith FW, Reid R, Payne G, Levy M, Sancar A (1987). "Action mechanism of Escherichia coli DNA photolyase. I. Formation of the enzyme-substrate complex". J. Biol. Chem. 262 (1): 478–85. PMID 3539939.
  • Setlow JK, Bollum FJ (1968). "The minimum size of the substrate for yeast photoreactivating enzyme". Biochim. Biophys. Acta. 157 (2): 233–7. doi:10.1016/0005-2787(68)90077-4. PMID 5649902.

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FAD binding domain of DNA photolyase Provide feedback

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Literature references

  1. Tamada T, Kitadokoro K, Higuchi Y, Inaka K, Yasui A, de Ruiter PE, Eker AP, Miki K , Nat Struct Biol 1997;4:887-891.: Crystal structure of DNA photolyase from Anacystis nidulans. PUBMED:9360600 EPMC:9360600

  2. Mees A, Klar T, Gnau P, Hennecke U, Eker AP, Carell T, Essen LO;, Science. 2004;306:1789-1793.: Crystal structure of a photolyase bound to a CPD-like DNA lesion after in situ repair. PUBMED:15576622 EPMC:15576622

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR005101

This entry represents a multi-helical domain found in the C terminus of the cryptochrome proteins and DNA photolyases. It acts as a FAD-binding domain [ PUBMED:12535521 ].

The cryptochrome and photolyase families consist of structurally related flavin adenine dinucleotide (FAD) proteins that use the absorption of blue light to accomplish different tasks. The photolyasess use the blue light for light-driven electron transfer to repair UV-damaged DNA, while the cryptochromes are blue-light photoreceptors involved in the circadian clock for plants and animals [ PUBMED:25910181 , PUBMED:26352435 ].

DNA photolyases are DNA repair enzymes that repair mismatched pyrimidine dimers induced by exposure to ultra-violet light. They bind to UV-damaged DNA containing pyrimidine dimers and, upon absorbing a near-UV photon (300 to 500 nm), they catalyse dimer splitting, breaking the cyclobutane ring joining the two pyrimidines of the dimer so as to split them into the constituent monomers; this process is called photoreactivation. DNA photolyases require two choromophore-cofactors for their activity. All monomers contain a reduced FAD moiety, and, in addition, either a reduced pterin or 8-hydroxy-5-diazaflavin as a second chromophore. Either chromophore may act as the primary photon acceptor, peak absorptions occurring in the blue region of the spectrum and in the UV-B region, at a wavelength around 290nm [ PUBMED:7604260 , PUBMED:15213381 ].

Domain organisation

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Seed source: SCOP
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Griffiths-Jones SR
Number in seed: 448
Number in full: 11663
Average length of the domain: 187.50 aa
Average identity of full alignment: 35 %
Average coverage of the sequence by the domain: 36.54 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 27.0 27.0
Trusted cut-off 27.0 27.0
Noise cut-off 26.9 26.9
Model length: 203
Family (HMM) version: 17
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Species distribution

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Archea Archea Eukaryota Eukaryota
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Viroids Viroids Unclassified sequence Unclassified sequence


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the FAD_binding_7 domain has been found. There are 115 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A0R0HV48 View 3D Structure Click here
A0A1D6GYW3 View 3D Structure Click here
A0A1D6H3E5 View 3D Structure Click here
A0A1D6HB67 View 3D Structure Click here
A0A1D6P5I6 View 3D Structure Click here
A0A2R8QLW6 View 3D Structure Click here
A4HTU9 View 3D Structure Click here
A4I8R0 View 3D Structure Click here
A4QN37 View 3D Structure Click here
A9CJC9 View 3D Structure Click here
B0S7X5 View 3D Structure Click here
B0WRR9 View 3D Structure Click here
B8A2L5 View 3D Structure Click here
B8K2A4 View 3D Structure Click here
D0FZ12 View 3D Structure Click here
D0FZ14 View 3D Structure Click here
D0FZ20 View 3D Structure Click here
E7FFE4 View 3D Structure Click here
F1QHM9 View 3D Structure Click here
F1R1X1 View 3D Structure Click here
F1R2R7 View 3D Structure Click here
I1JUL6 View 3D Structure Click here
I1LVY6 View 3D Structure Click here
I1NI99 View 3D Structure Click here
K7L7W1 View 3D Structure Click here
K7MD52 View 3D Structure Click here
K7TXG5 View 3D Structure Click here
K7VU84 View 3D Structure Click here
O48652 View 3D Structure Click here
O77059 View 3D Structure Click here
P00914 View 3D Structure Click here
P05066 View 3D Structure Click here
P25078 View 3D Structure Click here
P27526 View 3D Structure Click here
P57386 View 3D Structure Click here
P61497 View 3D Structure Click here
P77967 View 3D Structure Click here
P97784 View 3D Structure Click here
Q04449 View 3D Structure Click here
Q0E2Y1 View 3D Structure Click here