Laboratory of Structural Biology, National Institute of Environmental Health Sciences, US National Institutes of Health, Department of Health and Human Services, North Carolina, USA.
Nat Struct Mol Biol. 2011 Oct 9;18(11):1189-95. doi: 10.1038/nsmb.2146.
DNA ligases finalize DNA replication and repair through DNA nick-sealing reactions that can abort to generate cytotoxic 5'-adenylation DNA damage. Aprataxin (Aptx) catalyzes direct reversal of 5'-adenylate adducts to protect genome integrity. Here the structure of a Schizosaccharomyces pombe Aptx-DNA-AMP-Zn(2+) complex reveals active site and DNA interaction clefts formed by fusing a histidine triad (HIT) nucleotide hydrolase with a DNA minor groove-binding C(2)HE zinc finger (Znf). An Aptx helical 'wedge' interrogates the base stack for sensing DNA ends or DNA nicks. The HIT-Znf, the wedge and an '[F/Y]PK' pivot motif cooperate to distort terminal DNA base-pairing and direct 5'-adenylate into the active site pocket. Structural and mutational data support a wedge-pivot-cut HIT-Znf catalytic mechanism for 5'-adenylate adduct recognition and removal and suggest that mutations affecting protein folding, the active site pocket and the pivot motif underlie Aptx dysfunction in the neurodegenerative disorder ataxia with oculomotor apraxia 1 (AOA1).
DNA 连接酶通过 DNA 缺口封闭反应完成 DNA 复制和修复，该反应可中断产生细胞毒性 5'-腺酰化 DNA 损伤。 Aprataxin（Aptx）通过催化 5'-腺苷酸加合物的直接逆转来保护基因组完整性。本文报道了一个酿酒酵母 Aptx-DNA-AMP-Zn(2+)复合物的结构，揭示了由组氨酸三联体（HIT）核苷酸水解酶与 DNA 小沟结合 C(2)HE 锌指（Znf）融合形成的活性位点和 DNA 相互作用裂隙。Aptx 螺旋“楔形物”探测碱基堆叠以感应 DNA 末端或 DNA 缺口。HIT-Znf、楔形物和“[F/Y]PK”枢轴基序共同作用，扭曲末端 DNA 碱基配对，并将 5'-腺酰基引导至活性位点口袋。结构和突变数据支持楔形物-枢轴-切割 HIT-Znf 催化机制，用于识别和去除 5'-腺酰化加合物，并表明影响蛋白折叠、活性位点口袋和枢轴基序的突变是神经退行性疾病伴动眼运动不能性共济失调 1（AOA1）中 Aptx 功能障碍的基础。
Zotero 插件
