Deoxyribodipyrimidine photolyase (DNA photolyase) [1, 2] 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[3] DNA photolyases can be grouped into two classes.

The first class containsenzymes from Gram-negative and Gram-positive bacteria, the halophilicarchaebacteria Halobacterium salinarium (Halobacterium halobium), fungi and plants. Class 1 enzymes bindeither 5,10-MTHF (Escherichia coli, fungi, etc.) or 8-HDF (Streptomyces griseus, H. salinarium). There are a number of conserved sequence regions in all known class 1 DNAphotolyases, especially in the C-terminal part.

This family also includes plant cryptochromes 1 (CRY1) and 2 (CRY2),which are blue light photoreceptors that mediate blue light-induced geneexpression.

1. Structure and function of DNA photolyases. Trends Biochem. Sci. 12, 259-61
2. DNA photorepair: chromophore composition and function in two classes of DNA photolyases. Biofactors 2, 207-11
3. A new class of DNA photolyases present in various organisms including aplacental mammals. EMBO J. 13, 6143-51

Deoxyribodipyrimidine photolyase (DNA photolyase) [1, Show more...

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