Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, DK-8000, Aarhus C, Denmark.
Greenland Institute of Natural Resources, Strandgade 91, 2, DK-1401, Copenhagen K, Denmark.
Biochimie. 2023 Mar;206:136-149. doi: 10.1016/j.biochi.2022.10.014. Epub 2022 Nov 2.
Nei Like DNA Glycosylase 1 (NEIL1) is a DNA glycosylase, which specifically processes oxidative DNA damage by initiating base excision repair. NEIL1 recognizes and removes bases, primarily oxidized pyrimidines, which have been damaged by endogenous oxidation or exogenous mutagenic agents. NEIL1 functions through a combined glycosylase/AP (apurinic/apyrimidinic)-lyase activity, whereby it cleaves the N-glycosylic bond between the DNA backbone and the damaged base via its glycosylase activity and hydrolysis of the DNA backbone through beta-delta elimination due to its AP-lyase activity. In our study we investigated our hypothesis proposing that the cancer resistance of the bowhead whale can be associated with a better DNA repair with NEIL1 being upregulated or more active. Here, we report the molecular cloning and characterization of three transcript variants of bowhead whale NEIL1 of which two were homologous to human transcripts. In addition, a novel NEIL1 transcript variant was found. A differential expression of NEIL mRNA was detected in bowhead eye, liver, kidney, and muscle. The A-to-I editing of NEIL1 mRNA was shown to be conserved in the bowhead and two adenosines in the 242Lys codon were subjected to editing. A mass spectroscopy analysis of liver and eye tissue failed to demonstrate the existence of a NEIL1 isoform originating from RNA editing. Recombinant bowhead and human NEIL1 were expressed in E. coli and assayed for enzymatic activity. Both bowhead and human recombinant NEIL1 catalyzed, with similar efficiency, the removal of a 5-hydroxyuracil lesion in a DNA bubble structure. Hence, these results do not support our hypothesis but do not refute the hypothesis either.
Nei 样 DNA 糖基化酶 1（NEIL1）是一种 DNA 糖基化酶，通过启动碱基切除修复来专门处理氧化 DNA 损伤。NEIL1 识别并去除碱基，主要是氧化嘧啶，这些碱基已被内源性氧化或外源性诱变剂损伤。NEIL1 通过糖苷酶/AP（脱嘌呤/脱嘧啶）-裂合酶活性发挥作用，通过其糖苷酶活性在 DNA 骨架和受损碱基之间切割 N-糖苷键，并通过其 AP-裂合酶活性通过β-δ消除水解 DNA 骨架。在我们的研究中，我们调查了我们的假设，即弓头鲸的抗癌能力可能与其更好的 DNA 修复有关，NEIL1 上调或更活跃。在这里，我们报告了三种弓头鲸 NEIL1 的转录变体的分子克隆和特征，其中两种与人类转录本同源。此外，还发现了一种新的 NEIL1 转录变体。在弓头鲸的眼睛、肝脏、肾脏和肌肉中检测到 NEIL mRNA 的差异表达。在弓头鲸中，发现了 NEIL1 mRNA 的 A 到 I 编辑是保守的，并且 242Lys 密码子中的两个腺苷发生了编辑。对肝脏和眼睛组织的质谱分析未能证明存在源自 RNA 编辑的 NEIL1 同工型。重组弓头鲸和人 NEIL1 在大肠杆菌中表达并进行酶活性测定。弓头鲸和人重组 NEIL1 都以相似的效率催化了 DNA 泡结构中 5-羟尿嘧啶损伤的去除。因此，这些结果不支持我们的假设，但也没有反驳该假设。
