Differential repair of UV damage in a developmentally regulated gene of Dictyostelium discoideum.
The repair of cyclobutane pyrimidine dimers was measured under non-replicating conditions in a 2054-bp fragment of a cAMP-inducible cysteine proteinase (CP2) gene in D. discoideum. Overall genomic repair was unaffected by cAMP. The removal of dimers from CP2 in the wild-type NP2 cells as quantified using T4 endonuclease V was independent of transcription and was the same as in the overall genome. In a UV-sensitive radC mutant in which the rate of overall dimer removal was previously shown to be reduced, the initial rate of dimer removal in the uninduced CP2 gene (-cAMP) was 3-fold lower compared to the induced gene (+cAMP), in which repair was identical to that for the induced and uninduced states of NP2. D. discoideum may have two pathways for repairing dimers. One, effective in the wild-type strain but of reduced efficiency in radC repairs dimers equally well independent of transcription and at about the same rate as in the overall genome. A second pathway, retained in radC, repairs dimers more slowly in the overall genome and in the uninduced CP2 gene while undergoing the wild-type rate of repair in the transcriptionally active gene. Hence radC has reduced ability to repair transcriptionally inactive DNA, a defect similar to that of xeroderma pigmentosum group C.
Mauldin
S K
SK
Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802.
Freeland
T M
TM
Deering
R A
RA
D000818:Animals; D000242:Cyclic AMP; D003503:Cyclobutanes; D003546:Cysteine Endopeptidases / Q000235:genetics; D004249:DNA Damage; D004260:DNA Repair; D004271:DNA, Fungal / Q000096:biosynthesis / Q000528:radiation effects; D004023:Dictyostelium / Q000235:genetics* / Q000528:radiation effects; D015966:Gene Expression Regulation, Fungal; D014466:Ultraviolet Rays
D003503:Cyclobutanes; D004271:DNA, Fungal; D000242:Cyclic AMP; D003546:Cysteine Endopeptidases