Characterization of a gene involved in DNA repair in Arabidopsis thaliana

[307930]虽然我们对细菌和哺乳动物系统中的DNA修复机制了解很多，但对植物中DNA修复的分子机制知之甚少。本研究的重点是研究模式高等植物拟南芥中一个参与甲基化碱基修复的蛋白的生化和分子描述。一个参与修复植物甲基化碱基的cDNA克隆被插入到一个修复3-甲基腺嘌呤缺陷的大肠杆菌菌株中，因此该细菌对烷基化剂甲基甲烷磺酸盐的致命作用变得更有抵抗力，这表明该cDNA编码3-甲基腺嘌呤糖基化酶。本提案的目的是最终确定修复活性的性质，确定该基因在体内对甲基化剂的抗性中的作用，并研究该基因的调控。基因突变是生物多样性的来源，而选择正是依据这种多样性而起作用的。许多突变，包括许多自然发生的突变，都是DNA损伤的间接结果。这种突变的谱是由多种修复机制的相互作用决定的，本研究的结果将使我们深入了解植物中的一种这样的机制。＊＊＊

9307930 Britt While much is known about the mechanisms of DNA repair in bacterial and mammalian systems, very little is understood about the molecular mechanisms of DNA repair in plants. This proposal focuses on the biochemical and molecular description of a protein involved in the repair of methylated bases in the model higher plant Arabidopsis thaliana. A cDNA clone involved in the repair of methylated bases in the plant has been inserted into a strain of E. coli defective in the repair of 3-methyladenine whereupon the bacterium becomes more resistant to the lethal effects of the alkylating agent methylmethane sulfonate suggesting that the cDNA encodes a 3-methyladenine glycosylase. The objectives of this proposal are to conclusively determine the nature of the repair activity and to determine the role of this gene in resistance to methylating agents in vivo and to study the regulation of the gene. %%% Genetic mutation is the source of diversity upon which selection acts. Many mutations, including many naturally occurring mutations, are produced as an indirect result of DNA damage. The spectrum of such mutations is determined by the interaction of a variety of repair mechanisms and the results of this study will give insight into one such mechanism in plants. ***