NOVEL DNA-BINDING PROTEINS HIGHLY SPECIFIC TO UV-DAMAGED DNA-SEQUENCES FROM EMBRYOS OF DROSOPHILA-MELANOGASTER

Three new proteins which selectively bind to UV-damaged DNA were identified and purified to near homogeneity from UV-irradiated Drosophila melanogaster embryos through several column chromatographies, These proteins, tentatively designated as D-DDB P1, P2 and P3, can be identified as different complex bands in a gel shift assay by using UV-irradiated TC-31 probe DNA, Analysis of the purified D-DDB P1 fraction by native or SDS-polyacrylamide gel electrophoresis and FPLC-Superose 6 gel filtration demonstrated that it is a monomer protein which is a 30 kDa polypeptide, The D-DDB P2 protein is a monopolypeptide with a molecular mass of 14 kDa, Both D-DDB P1 and P2 highly prefer binding to UV-irradiated DNA, and have almost no affinity for non-irradiated DNA, Gel shift assays with either UV-irradiated DNA probes demonstrated that D-DDB P1 may show a preference for binding to (6-4) photoproducts, while D-DDB P2 may prefer binding to pyrimidine dimers, Both these proteins require magnesium ions for binding, D-DDB P1 is an ATP-preferent protein, These findings are discussed in relation to two recently described [Todo and Ryo (1991) Mutat, Res., 273, 85-93; Todo et al, (1993) Nature, 361, 371-374] DNA-binding factors from Drosophila cell extracts, A possible role for these DNA-binding proteins in lesion recognition and DNA repair of UV-induced photoproducts is discussed.