Nucleotide sequence and functional analysis of the RAD1 gene of Saccharomyces cerevisiae.

The RAD1 gene of Saccharomyces cerevisiae is involved in excision repair of damaged DNA. The nucleotide sequence of the RAD1 gene presented here shows an open reading frame of 3,300 nucleotides. Two ATG codons occur in the open reading frame at positions +1 and +334, respectively. Since a deletion of about 2.7 kilobases of DNA from the 5' region of the RAD1 gene, which also deletes the +1 ATG and 11 additional codons in the RAD1 open reading frame, partially complements UV sensitivity of a rad1 delta mutant, we examined the role of the +1 ATG and +334 ATG codons in translation initiation of RAD1 protein. Mutation of the +1 ATG codon to ATC affected the complementation ability of the RAD1 gene, whereas mutation of the +334 ATG codon to ATC showed no discernible effect on RAD1 function. These results indicate that translation of RAD1 protein is initiated from the +1 ATG codon. Productive in-frame RAD1-lacZ fusions showed that the RAD1 open reading frame is expressed in yeasts. The RAD1-encoded protein contains 1,100 amino acids with a molecular weight of 126,360.