Human DNA ligase IV is able to use NAD+ as an alternative adenylation donor for DNA ends ligation
Human DNA ligase IV is able to use NAD+ as an alternative adenylation donor for DNA ends ligation
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DOI：
10.1093/nar/gky1202
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发表时间：
2019-02-20
影响因子：
14.9
通讯作者：
Yu, Xiaochun
中科院分区：
文献类型：
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作者：
Chen, Shih-Hsun;Yu, Xiaochun
已知所有真核DNA连接酶都使用三磷酸腺苷（ATP）进行DNA连接。在此，我们报道了人DNA连接酶IV，DNA双链断裂（DSB）修复的关键酶，能够使用NAD（+）作为双链DNA连接的底物。在体外连接试验中，我们表明重组连接酶IV可以使用ATP和NAD（+）进行DNA连接。对于NAD（+）介导的连接，连接酶IV的BRCA 1 C-末端（BRCT）结构域识别NAD（+）并促进连接酶IV的腺苷酸化，这是连接的第一步。尽管XRCC 4（连接酶IV的功能伴侣）不是NAD（+）介导的腺苷酸化所必需的，但它调节AMP部分从连接酶IV转移到DNA末端。此外，连接酶IV的BRCT结构域中的癌症相关突变破坏了与NAD（+）的相互作用，从而消除了连接酶IV的NAD（+）介导的腺苷酸化和DSB连接。破坏BRCT结构域中的NAD（+）识别位点会损害细胞中的非同源末端连接（NHEJ）。综上所述，我们的研究表明，除了ATP，连接酶IV可能使用NAD（+）作为替代腺苷酸化供体，用于NHEJ修复和维持基因组稳定性。
All the eukaryotic DNA ligases are known to use adenosine triphosphate (ATP) for DNA ligation. Here, we report that human DNA ligase IV, a key enzyme in DNA double-strand break (DSB) repair, is able to use NAD(+) as a substrate for double-stranded DNA ligation. In the in vitro ligation assays, we show that the recombinant Ligase IV can use both ATP and NAD(+) for DNA ligation. For NAD(+)-mediated ligation, the BRCA1 C-terminal (BRCT) domain of Ligase IV recognizes NAD(+) and facilitates the adenylation of Ligase IV, the first step of ligation. Although XRCC4, the functional partner of Ligase IV, is not required for the NAD(+)-mediated adenylation, it regulates the transfer of AMP moiety from Ligase IV to the DNA end. Moreover, cancer-associated mutation in the BRCT domain of Ligase IV disrupts the interaction with NAD(+), thus abolishes the NAD(+)-mediated adenylation of Ligase IV and DSB ligation. Disrupting the NAD(+) recognition site in the BRCT domain impairs non-homologous end joining (NHEJ) in cell. Taken together, our study reveals that in addition to ATP, Ligase IV may use NAD(+) as an alternative adenylation donor for NHEJ repair and maintaining genomic stability.