Molecular and genetic characterization of the RAD3 gene of Saccharomyces cerevisiae

The RAD3 gene of Saccharomyces cerevisiae is involved in the excision repair of damaged DNA. Strains carrying a radS mutation are highly sensitive to certain types of DNA damage. A fragment of yeast DNA which complemented the UV-light sensitivity of a rad3 strain was isolated and shown by genetic evidence to be the RAD3 gene. Using this cloned gene, it was shown that RAD3 is essential for the viability of haploid cells under normal growth conditions. The RAD3 gene is not inducible by DNA damage. The sequence of the RAD3 gene predicted a protein of 90kd, with a highly negatively charged carboxy terminus, however, deletion analysis demonstrated that this region was not required for either function of RAD3. The sequence also showed some homology to nucleotide binding proteins and to DNA binding proteins