Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA.
Proc Natl Acad Sci U S A. 2012 Sep 4;109(36):14634-9. doi: 10.1073/pnas.1208096109. Epub 2012 Aug 20.
A previously described mammalian cell activity, called VPg unlinkase, specifically cleaves a unique protein-RNA covalent linkage generated during the viral genomic RNA replication steps of a picornavirus infection. For over three decades, the identity of this cellular activity and its normal role in the uninfected cell had remained elusive. Here we report the purification and identification of VPg unlinkase as the DNA repair enzyme, 5'-tyrosyl-DNA phosphodiesterase-2 (TDP2). Our data show that VPg unlinkase activity in different mammalian cell lines correlates with their differential expression of TDP2. Furthermore, we show that recombinant TDP2 can cleave the protein-RNA linkage generated by different picornaviruses without impairing the integrity of viral RNA. Our results reveal a unique RNA repair-like function for TDP2 and suggest an unusual role in host-pathogen interactions for this cellular enzyme. On the basis of the identification of TDP2 as a potential antiviral target, our findings may lead to the development of universal therapeutics to treat the millions of individuals afflicted annually with diseases caused by picornaviruses, including myocarditis, aseptic meningitis, encephalitis, hepatitis, and the common cold.
先前描述的一种哺乳动物细胞活性，称为 VPg 连接酶，可特异性切割在正粘病毒感染的病毒基因组 RNA 复制步骤中产生的独特的蛋白-RNA 共价连接。三十多年来，这种细胞活性及其在未感染细胞中的正常作用仍然难以捉摸。在这里，我们报告了 VPg 连接酶作为 DNA 修复酶，5'-酪氨酸-DNA 磷酸二酯酶 2（TDP2）的纯化和鉴定。我们的数据表明，不同哺乳动物细胞系中的 VPg 连接酶活性与其 TDP2 的差异表达相关。此外，我们表明，重组 TDP2 可以切割不同正粘病毒产生的蛋白-RNA 连接，而不会损害病毒 RNA 的完整性。我们的结果揭示了 TDP2 的独特 RNA 修复样功能，并表明该细胞酶在宿主-病原体相互作用中具有不寻常的作用。基于 TDP2 作为潜在抗病毒靶标的鉴定，我们的发现可能会导致开发通用疗法来治疗每年数百万人因正粘病毒引起的疾病，包括心肌炎、无菌性脑膜炎、脑炎、肝炎和普通感冒。
