Incision and postincision steps of pyrimidine dimer removal in excision-defective mutants of Saccharomyces cerevisiae

Publisher Website
Google Scholar
Abstract
A temperature-sensitive mutant, cdc9, defective in polynucleotide DNA ligase activity, accumulates low-MW DNA fragments (as measured by sedimentation of DNA in alkaline sucrose gradients) at the nonpermissive temperature after irradiation with UV light. This phenotype of cdc9 is a sensitive indicator of successful incision during excision repair of dimers. In strains containing excision-defective mutations in any of 9 genes in combination with the cdc9 mutation, the absence of low-MW DNA at the nonpermissive temperature after UV treatment suggests that these mutants are incision defective; the presence of low-MW DNA indicates that the mutants are defective in a step after incision. With rad1, rad2, rad3, rad4 and rad10 mutants, the MW of the DNA remained unchanged after UV irradiation and incubation at the restrictive temperature, despite the presence of the cdc9 mutation; these mutants are therefore incision defective. Low-MW DNA was observed in rad14 cdc9 and rad16 cdc9 strains. With the rad16 strain, the accumulation of low-MW DNA correlated with the amount of excision taking place, in the rad14 mutant strain, no evidence of dimer removal was obtained. In a step after incision, rad14 is likely to be defective.

This publication has 30 references indexed in Scilit: