Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.
Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China; Breast Tumor Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China.
Structure. 2024 Jun 6;32(6):780-794.e5. doi: 10.1016/j.str.2024.02.014. Epub 2024 Mar 18.
Base excision repair (BER) is a critical genome defense pathway that copes with a broad range of DNA lesions induced by endogenous or exogenous genotoxic agents. AP endonucleases in the BER pathway are responsible for removing the damaged bases and nicking the abasic sites. In plants, the BER pathway plays a critical role in the active demethylation of 5-methylcytosine (5mC) DNA modification. Here, we have determined the crystal structures of Arabidopsis AP endonuclease AtARP in complex with the double-stranded DNA containing tetrahydrofuran (THF) that mimics the abasic site. We identified the critical residues in AtARP for binding and removing the abasic site and the unique residues for interacting with the orphan base. Additionally, we investigated the differences among the three plant AP endonucleases and evaluated the general DNA repair capacity of AtARP in a mammalian cell line. Our studies provide further mechanistic insights into the BER pathway in plants.
碱基切除修复（BER）是一种重要的基因组防御途径，可应对内源性或外源性遗传毒性剂诱导的广泛的 DNA 损伤。BER 途径中的 AP 内切酶负责去除受损碱基并在无碱基位点上进行切口。在植物中，BER 途径在 5-甲基胞嘧啶（5mC）DNA 修饰的主动去甲基化中发挥着关键作用。在这里，我们确定了拟似无碱基位点的含四氢呋喃（THF）的双链 DNA 复合物中拟南芥 AP 内切酶 AtARP 的晶体结构。我们鉴定了 AtARP 中用于结合和去除无碱基位点的关键残基以及与孤儿碱基相互作用的独特残基。此外，我们研究了三种植物 AP 内切酶之间的差异，并在哺乳动物细胞系中评估了 AtARP 的一般 DNA 修复能力。我们的研究为植物中的 BER 途径提供了进一步的机制见解。
