Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, BN1 9RQ, UK.
Institute of Medical Biology, Polish Academy of Sciences, Lodowa 106, 93-232, Lodz, Poland.
Nat Commun. 2017 Nov 1;8(1):1251. doi: 10.1038/s41467-017-01365-y.
Prokaryotic Ligase D is a conserved DNA repair apparatus processing DNA double-strand breaks in stationary phase. An orthologous Ligase C (LigC) complex also co-exists in many bacterial species but its function is unknown. Here we show that the LigC complex interacts with core BER enzymes in vivo and demonstrate that together these factors constitute an excision repair apparatus capable of repairing damaged bases and abasic sites. The polymerase component, which contains a conserved C-terminal structural loop, preferentially binds to and fills-in short gapped DNA intermediates with RNA and LigC ligates the resulting nicks to complete repair. Components of the LigC complex, like LigD, are expressed upon entry into stationary phase and cells lacking either of these pathways exhibit increased sensitivity to oxidising genotoxins. Together, these findings establish that the LigC complex is directly involved in an excision repair pathway(s) that repairs DNA damage with ribonucleotides during stationary phase.
原核 Ligase D 是一种保守的 DNA 修复装置，可在静止期处理 DNA 双链断裂。许多细菌物种中也存在同源的 Ligase C（LigC）复合物，但它的功能尚不清楚。本文显示 LigC 复合物与体内核心 BER 酶相互作用，并证明这些因子共同构成了能够修复受损碱基和无碱基位点的切除修复装置。聚合酶成分含有保守的 C 末端结构环，优先与带有 RNA 的短缺口 DNA 中间体结合，并由 LigC 连接形成的缺口完成修复。LigC 复合物的成分（如 LigD）在进入静止期时表达，而缺乏这些途径的细胞对氧化遗传毒物的敏感性增加。这些发现表明，LigC 复合物直接参与了一种在静止期使用核糖核苷酸修复 DNA 损伤的切除修复途径。
