Repair of 6-4 photoproducts in Saccharomyces cerevisiae.
We have developed a dot blot immunoassay for UV photoproducts which distinguishes 6-4 photoproducts from cyclobutane dimers. The assay uses a polyclonal antiserum that is specific for UV-irradiated DNA. Cyclobutane dimers are measured in DNA samples which have been treated with hot alkali to destroy 6-4 photoproducts. 6-4 Photoproducts are measured using blots that have been incubated in photoreactivating enzyme to eliminate cyclobutane dimers. A combination of the two treatments leaves no detectable antigenic lesions. Wild-type S. cerevisiae repairs 6-4 photoproducts, in the genome overall, more rapidly than cyclobutane dimers. The most sensitive alleles of rad1, rad2, rad3 and rad4 are completely unable to repair either kind of photoproduct. We conclude that 6-4 photoproducts are repaired by essentially the same mechanism as are cyclobutane dimers.
McCready
S
S
Department of Plant Sciences, University of Oxford, UK.
Cox
B
B
D000818:Animals; D002417:Cattle; D004260:DNA Repair; D003720:Densitometry; D007118:Immunoassay; D010777:Photochemistry; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000528:radiation effects; D014466:Ultraviolet Rays