Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Spain; Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Spain; Hospital Universitario Reina Sofía, Spain.
Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Spain.
DNA Repair (Amst). 2018 May;65:34-41. doi: 10.1016/j.dnarep.2018.02.011. Epub 2018 Mar 5.
Base excision repair (BER) is a major defense pathway against spontaneous DNA damage. This multistep process is initiated by DNA glycosylases that recognise and excise the damaged base, and proceeds by the concerted action of additional proteins that perform incision of the abasic site, gap filling and ligation. BER has been extensively studied in bacteria, yeasts and animals. Although knowledge of this pathway in land plants is increasing, there are no reports detecting BER in algae. We describe here an experimental in vitro system allowing the specific analysis of BER in the model alga Chlamydomonas reinhardtii. We show that C. reinhardtii cell-free extracts contain the enzymatic machinery required to perform BER of ubiquitous DNA lesions, such as uracil and abasic sites. Our results also reveal that repair can occur by both single-nucleotide insertion and long-patch DNA synthesis. The experimental system described here should prove useful in the biochemical and genetic dissection of BER in algae, and may contribute to provide a broader picture of the evolution and biological relevance of DNA repair pathways in photosynthetic eukaryotes.
碱基切除修复（BER）是一种主要的防御途径，可对抗自发的 DNA 损伤。这个多步骤过程由识别并切除受损碱基的 DNA 糖苷酶启动，并通过其他协同作用的蛋白质来完成碱基切除、缺口填充和连接。BER 在细菌、酵母和动物中已得到广泛研究。尽管人们对陆地植物中这条途径的了解正在增加，但目前尚无关于藻类中存在 BER 的报道。我们在这里描述了一个实验体外系统，允许在模式藻类衣藻中特异性分析 BER。我们表明，衣藻无细胞提取物中含有进行普遍存在的 DNA 损伤（如尿嘧啶和无碱基位点）BER 所需的酶机制。我们的结果还表明，修复可以通过单核苷酸插入和长补丁 DNA 合成来完成。这里描述的实验系统应该有助于藻类中 BER 的生化和遗传分析，并可能有助于更全面地了解光合真核生物中 DNA 修复途径的进化和生物学意义。
