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) photo products, have been reported in Drosophila, These enzymes share extensive s equence homologies with the plant blue-light photoreceptor, We have now ide ntified a third gene in Drosophila melano-gasfer with extensive sequence ho mology to the photolyase gene. The newly identified gene, which we named dC RY, was expressed as a recombinant protein and tested for photolyase activi ty. The recombinant protein exhibited photochemical properties similar to t hose of Drosophila pyrimidine dimer and (6-4) photolyases but lacked photol yase activity. In light of recent evidence that blue-light photoreceptors r egulate the circadian clock in mammals, we propose that dCRY is the circadi an photoreceptor in this organism.