Active DNA photolyase encoded by a baculovirus from the insect Chrysodeixis chalcites

The genome of Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV) contains two open reading frames, Cc-phrl and Cc-phr2, which encode putative class 11 CPD-DNA photolyases. CPD-photolyases repair UV-induced pyrimidine cyclobutane dimers using visible light as an energy source. Expression of Cc-phr2 provided photolyase deficient Escherichia coli cells with photoreactivating activity indicating that Cc-phr2 encodes an active photolyase, in contrast, Cc-phrl did not rescue the photolyase deficiency. Cc-phr2 was overexpressed in E. coli and the resulting photolyase was purified till apparent homogeneity. Spectral measurements indicated the presence of FAD, but a second chromophore appeared to be absent. Recombinant Cc-phr2 photolyase was found to bind specifically FO (8-hydroxy7,8-didemethyl-5-deazariboflavin), which is an antenna chromophore present in various photolyases.. After reconstitution, FAD and FO were present in approximately equimolar amounts. In reconstituted photolyase the FO chromophore is functionally active as judged from the increase in the in vitro repair activity. This study demonstrates for the first time that a functional photolyase is encoded by an insect virus, which may have implications for the design of a new generation of baculoviruses with improved performance in insect pest control. (c) 2008 Elsevier B.V. All rights reserved.