Evolutionary conservation of excision repair in Schizosaccharomyces pombe: evidence for a family of sequences related to theSaccharomyces cerevisiaeRAD2 gene

Abstract

Cells mutated at the rad13 locus In the fission yeast, Schizosaccharomyces pombe are deficient In excision-repair of UV damage. We have cloned the S. pomberad 13 gene by its ability to complement the UV sensitivity of a rad 13 mutant. The gene Is not essential for cell proliferation. Sequence analysis of the cloned gene revealed an open reading-frame of 1113 amino acids with structural homology to the RAD2 gene of the distantly related Saccharomycescerevlslae . The sequence similarity is confined to three domains, two close to the N-terminus of the encoded protein, the third being close to the C-terminus. The central region of about 500 amino acids shows little similarity between the two organisms. The first and third domains are also found in a related yet distinct pair of homologous S. pombe /S. cerevisiae DNA repair genes (rad2/YKL510), which have only a very short region between these two conserved domains. Using the polymerase chain reaction with degenerate primers, we have isolated fragments from a gene homologous to rad13/RAD 2 from Aspergillus nidulans . These findings define new functional domains involved In excision-repair, as well as identifying a conserved family of genes related to RAD2.