Substrate specificity of ultraviolet DNA endonuclease (UVDE/Uve1p) from Schizosaccharomyces pombe

Schizosaccharomyces pombe ultraviolet DNA endonuclease (UVDE or Uve1p) has been shown to cleave 5' to UV light-induced cyclobutane pyrimidine dimers ( CPDs) and pyrimidine-pyrimidone (6-4) photoproducts (6-4PP). This endonucle ase is believed to function in the initial step in an alternative excision repair pathway for the removal of DNA damage caused by exposure to UV light . An active truncated form of this protein, Delta 228-Uve1p, has been succe ssfully overexpressed, affinity purified and partially characterized. in th e present study we present data from a detailed substrate specificity trial . We have determined that the substrate range of Uve1p is much greater than was originally believed. We demonstrate that this DNA damage repair protei n is capable of recognizing an array of UV-induced DNA photoproducts (cis-s yn-, trans-syn I- and trans-syn II CPDs, 6-4PP and Dewar isomers) that caus e varying degrees of distortion in a duplex DNA molecule. We also demonstra te that Uve1p recognizes non-UV-induced DNA damage, such as platinum-DNA GG diadducts, uracil, dihydrouracil and abasic sites. This is the first time that a single DNA repair endonuclease with the ability to recognize such a diverse range of lesions has been described. This study suggests that Uve1p and the alternative excision repair pathway may participate broadly in the repair of DNA damage.