Repair of the main UV-induced thymine dimeric lesions within Arabidopsis thaliana DNA: evidence for the major involvement of photoreactivation pathways.
The UV-B induced formation of thymine cis-syn cyclobutane dimer and related (6-4) photoproduct was monitored within DNA of cultured cells and plants of Arabidopsis thaliana. This was achieved using a sensitive and accurate HPLC-tandem mass spectrometry assay. It was found that the cyclobutane pyrimidine dimer was formed in a ninefold higher yield than the (6-4) photoproduct. The removal of the lesions was then studied by incubating irradiated cells either in the darkness, under visible light or upon exposure to UV-A radiation. Dark repair of both cyclobutane dimers and (6-4) photoproducts was found to be very ineffective. In contrast, a rapid decrease in the level of photoproducts was observed when UV-B-irradiated cells were exposed to UV-A and, to a lesser extent, to visible light. The removal of (6-4) adducts was found to occur more efficiently. These results strongly suggest that repair of UV-induced photolesions in plants is mainly mediated by photolyases.
Dany
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Département d'Ecophysiologie Végétale et de Microbiologie, Laboratoire de Radiobiologie Végétale, CEA/Cadarache, 13108 Saint-Paul-lez-Durance, France.
Douki
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T
Triantaphylides
C
C
Cadet
J
J
D017360:Arabidopsis / Q000235:genetics; D002478:Cells, Cultured; D004260:DNA Repair; D018744:DNA, Plant / Q000528:radiation effects*; D011740:Pyrimidine Dimers; D014466:Ultraviolet Rays
D018744:DNA, Plant; D011740:Pyrimidine Dimers