Cryptochrome/DNA photolyase, class 1 conserved site, C-terminal Deoxyribodipyrimidine photolyase (DNA photolyase) [<cite idref="PUB00005325"/>, <cite idref="PUB00000740"/>] is a DNArepair enzyme. It binds to UV-damaged DNA containing pyrimidine dimers and,upon absorbing a near-UV photon (300 to 500 nm), breaks the cyclobutane ringjoining the two pyrimidines of the dimer. DNA photolyase is an enzyme thatrequires two choromophore-cofactors for its activity: a reduced FADH2 andeither 5,10-methenyltetrahydrofolate (5,10-MTFH) or an oxidized 8-hydroxy-5-deazaflavin (8-HDF) derivative (F420). The folate or deazaflavin chromophoreappears to function as an antenna, while the FADH2 chromophore is thought tobe responsible for electron transfer. On the basis of sequence similarities[<cite idref="PUB00001269"/>] DNA photolyases can be grouped into two classes. <p>The first class containsenzymes from Gram-negative and Gram-positive bacteria, the halophilicarchaebacteria <taxon tax_id="2242">Halobacterium salinarium</taxon> (Halobacterium halobium), fungi and plants. Class 1 enzymes bindeither 5,10-MTHF (<taxon tax_id="562">Escherichia coli</taxon>, fungi, etc.) or 8-HDF (<taxon tax_id="1911">Streptomyces griseus</taxon>, H. salinarium). There are a number of conserved sequence regions in all known class 1 DNAphotolyases, especially in the C-terminal part.</p><p>This family also includes plant cryptochromes 1 (CRY1) and 2 (CRY2),which are blue light photoreceptors that mediate blue light-induced geneexpression.</p>