Identification of a novel structure-specific endonuclease AziN that contributes to the repair of azinomycin B-mediated DNA interstrand crosslinks
Identification of a novel structure-specific endonuclease AziN that contributes to the repair of azinomycin B-mediated DNA interstrand crosslinks
复制标题
鉴定出一种新型结构特异性核酸内切酶 AziN，该酶有助于修复阿齐霉素 B 介导的 DNA 链间交联。
DOI：
10.1093/nar/gkz1067
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发表时间：
2020-01-24
影响因子：
14.9
通讯作者：
He, Jing
中科院分区：
文献类型：
--
作者：
Chen, Xiaorong;Sun, Yuedi;He, Jing
高遗传毒性药物azinomycin B（AZB）诱导的DNA链间交联（ICLs）可导致DNA结构严重紊乱，甚至细胞死亡。然而，产生AZB的链霉菌Sahachiroi似乎几乎不受这种危险的影响，因为它具有多样性和独特的自我保护机制。在这里，我们报告了一个新的核酸内切酶样基因aziN的鉴定，有助于药物的自我保护在S。sahachiroi。AziN表达赋予天然和异源宿主菌株AZB抗性。根据其与药物结合蛋白的同源性，也验证了AziN与AZB之间的特异性结合反应，但未检测到药物螯合和失活作用。有趣的是，由于与药物的高亲和力，AziN被发现表现出与AZB介导的ICL结构的特异性识别和结合能力，进一步诱导DNA链断裂。随后的体外测定证明了AziN的结构特异性核酸内切酶活性，其在AZB-ICL周围的特定位点切割两条受损链。解开AziN的核酸酶活性为阐明AZB-ICL修复的复杂机制提供了一个很好的切入点。
DNA interstrand crosslinks (ICLs) induced by the highly genotoxic agent azinomycin B (AZB) can cause severe perturbation of DNA structure and even cell death. However, Streptomyces sahachiroi, the strain that produces AZB, seems almost impervious to this danger because of its diverse and distinctive self-protection machineries. Here, we report the identification of a novel endonuclease-like gene aziN that contributes to drug self-protection in S. sahachiroi. AziN expression conferred AZB resistance on native and heterologous host strains. The specific binding reaction between AziN and AZB was also verified in accordance with its homology to drug binding proteins, but no drug sequestering and deactivating effects could be detected. Intriguingly, due to the high affinity with the drug, AziN was discovered to exhibit specific recognition and binding capacity with AZB-mediated ICL structures, further inducing DNA strand breakage. Subsequent in vitro assays demonstrated the structure-specific endonuclease activity of AziN, which cuts both damaged strands at specific sites around AZB-ICLs. Unravelling the nuclease activity of AziN provides a good entrance point to illuminate the complex mechanisms of AZB-ICL repair.