Increased telomere length and hypersensitivity to DNA damaging agents in an Arabidopsis KU70 mutant.
We have identified a putative homologue of the KU70 gene (AtKU70) from Arabidopsis thaliana. In order to study its function in plants we have isolated an A.thaliana line that contains a T-DNA inserted into AtKU70. Plants homozygous for this insertion appear normal and are fertile. In other organisms the KU70 gene has been shown to play a role in the repair of DNA damage induced by ionising radiation (IR) and by radiomimetic chemicals such as methylmethane sulfonate (MMS). We show that AtKU70(-/-) plants are hypersensitive to IR and MMS, and thus the AtKU70 gene plays a similar role in DNA repair in plants as in other organisms. The KU70 gene also plays a role in maintaining telomere length. Yeast and mammalian cells deficient for Ku70 have shortened telomeres. When we studied the telomeres in the AtKU70(-/-) plants we found unexpectedly that they were significantly longer (>30 kb) than was found in wild-type plants (2-4 kb). We propose several hypotheses to explain this telomere lengthening in the AtKU70(-/-) plants.
Institute of Molecular Plant Sciences, Sectie 2A, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands. bundock@rulbim.leidenuniv.nl
Paul
P
Bundock
Haico
H
van Attikum
Paul
P
Hooykaas
D000595:Amino Acid Sequence; D034961:Antigens, Nuclear; D017360:Arabidopsis / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology*; D004249:DNA Damage; D004265:DNA Helicases; D018744:DNA, Plant / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D017343:Genes, Plant; D000072200:Ku Autoantigen; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D011836:Radiation Tolerance; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D016615:Telomere / Q000648:ultrastructure*
D034961:Antigens, Nuclear; D029681:Arabidopsis Proteins; D018744:DNA, Plant; D004268:DNA-Binding Proteins; C463462:KU70 protein, Arabidopsis; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C081647:high affinity DNA-binding factor, S cerevisiae; D008741:Methyl Methanesulfonate; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen