A third member of the photolyase/blue-light photoreceptor family in Drosophila: a putative circadian photoreceptor

Two photolyases, specific for cyclobutane pyrimidine dimers and (6-4) photoproducts, have been reported in Drosophila. These enzymes share extensive sequence homologies with the plant blue-light photoreceptor. We have now identified a third gene in Drosophila melanogaster with extensive sequence homology to the photolyase gene. The newly identified gene, which we named dCRY, was expressed as a recombinant protein and tested for photolyase activity. The recombinant protein exhibited photochemical properties similar to those of Drosophila pyrimidine dimer and (6-4) photolyases but lacked photolyase activity. In light of recent evidence that blue-light photoreceptors regulate the circadian clock in mammals, we propose that dCRY is the circadian photoreceptor in this organism.