Bundock Paul, van Attikum Haico, Hooykaas Paul
Institute of Molecular Plant Sciences, Sectie 2A, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands.
Nucleic Acids Res. 2002 Aug 1;30(15):3395-400. doi: 10.1093/nar/gkf445.
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.
我们从拟南芥中鉴定出了KU70基因的一个假定同源物(AtKU70)。为了研究其在植物中的功能,我们分离出了一个拟南芥株系,该株系的AtKU70中插入了一个T-DNA。对于这种插入纯合的植株看起来正常且可育。在其他生物体中,KU70基因已被证明在由电离辐射(IR)和诸如甲基磺酸甲酯(MMS)等拟辐射化学物质诱导的DNA损伤修复中发挥作用。我们表明AtKU70(-/-)植株对IR和MMS高度敏感,因此AtKU70基因在植物的DNA修复中与在其他生物体中发挥类似作用。KU70基因在维持端粒长度方面也发挥作用。缺乏Ku70的酵母和哺乳动物细胞具有缩短的端粒。当我们研究AtKU70(-/-)植株中的端粒时,我们意外地发现它们比野生型植株中的端粒(2 - 4 kb)长得多(>30 kb)。我们提出了几个假说来解释AtKU70(-/-)植株中端粒的这种延长现象。