Murine AKAP7 has a 2',5'-phosphodiesterase domain that can complement an inactive murine coronavirus ns2 gene.
Murine AKAP7 has a 2',5'-phosphodiesterase domain that can complement an inactive murine coronavirus ns2 gene.
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DOI：
10.1128/mbio.01312-14
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发表时间：
2014-07-01
期刊：
影响因子：
6.4
通讯作者：
Silverman RH
中科院分区：
文献类型：
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作者：
Gusho E;Zhang R;Jha BK;Thornbrough JM;Dong B;Gaughan C;Elliott R;Weiss SR;Silverman RH
病毒2‘，5’-磷酸二酯酶(2‘，5’-PDE)通过降解核糖核酸酶的2‘，5’-寡腺苷(2-5A)激活剂，帮助不同的RNA病毒逃避干扰素的抗病毒活性。在43种AKAP亚型中，AKAP7似乎是唯一与病毒2‘，5’-PDE同源的亚型。在这里，我们发现小鼠AKAP7以与小鼠冠状病毒(小鼠肝炎病毒[MHV])A59NS2株和人轮状病毒WAVP3株蛋白相似的动力学方式迅速降解2-5A。为了确定AKAP7是否可以替代病毒的2‘，5’-PDE，我们将AKAP7基因插入到含有灭活的NS2基因的MHV基因组中。AKAP7 PDE结构域或N端截短的AKAP7(都缺乏核定位基序)，但不包括全长AKAP7或突变体AKAP7H185R，PDE结构域恢复了NS2突变体MHV在感染小鼠骨髓巨噬细胞和肝脏中的感染性。有趣的是，AKAP7 PDE结构域和N端缺失的AKAP7存在于细胞质(MHV复制部位)，而全长AKAP7仅在细胞核中观察到。我们认为，宿主AKAP7PDE结构域的病毒获得可能发生在进化过程中，允许不同的RNA病毒拮抗核糖核酸酶L途径。早期病毒与宿主的相互作用决定了感染是否成立，突显了了解调节病毒致病的基本机制的必要性。最近，我们的实验室报道了一种新的干扰素抗病毒反应调节模式。我们发现冠状病毒MHV辅助蛋白NS2拮抗I型干扰素反应，促进病毒复制和肝炎。NS2通过裂解巨噬细胞中核糖核酸酶L的2‘，5’-寡腺苷(2-5A)激活剂而赋予毒力。我们还报道了轮状病毒VP3 C末端结构域(VP3-CTD)裂解2-5A，并可能挽救NS2突变株MHV。在这里，我们报道了一种细胞蛋白AKAP7，它含有一个类似的2‘，5’-磷酸二酯酶(2‘，5’-PDE)结构域，能够恢复表达非活性NS2的嵌合MHV的生长。前病毒效应需要AKAP7 PDE结构域的细胞质定位。我们推测，AKAP7是病毒蛋白的祖先，如NS2和VP3，它们降解2-5A以逃避RNaseL的抗病毒活性。
Viral 2′,5′-phosphodiesterases (2′,5′-PDEs) help disparate RNA viruses evade the antiviral activity of interferon (IFN) by degrading 2′,5′-oligoadenylate (2-5A) activators of RNase L. A kinase anchoring proteins (AKAPs) bind the regulatory subunits of protein kinase A (PKA) to localize and organize cyclic AMP (cAMP) signaling during diverse physiological processes. Among more than 43 AKAP isoforms, AKAP7 appears to be unique in its homology to viral 2′,5′-PDEs. Here we show that mouse AKAP7 rapidly degrades 2-5A with kinetics similar to that of murine coronavirus (mouse hepatitis virus [MHV]) strain A59 ns2 and human rotavirus strain WA VP3 proteins. To determine whether AKAP7 could substitute for a viral 2′,5′-PDE, we inserted AKAP7 cDNA into an MHV genome with an inactivated ns2 gene. The AKAP7 PDE domain or N-terminally truncated AKAP7 (both lacking a nuclear localization motif), but not full-length AKAP7 or a mutant, AKAP7H185R, PDE domain restored the infectivity of ns2 mutant MHV in bone marrow macrophages and in livers of infected mice. Interestingly, the AKAP7 PDE domain and N-terminally deleted AKAP7 were present in the cytoplasm (the site of MHV replication), whereas full-length AKAP7 was observed only in nuclei. We suggest the possibility that viral acquisition of the host AKAP7 PDE domain might have occurred during evolution, allowing diverse RNA viruses to antagonize the RNase L pathway. Early virus-host interactions determine whether an infection is established, highlighting the need to understand fundamental mechanisms regulating viral pathogenesis. Recently, our laboratories reported a novel mode of regulation of the IFN antiviral response. We showed that the coronavirus MHV accessory protein ns2 antagonizes the type I IFN response, promoting viral replication and hepatitis. ns2 confers virulence by cleaving 2′,5′-oligoadenylate (2-5A) activators of RNase L in macrophages. We also reported that the rotavirus VP3 C-terminal domain (VP3-CTD) cleaves 2-5A and that it may rescue ns2 mutant MHV. Here we report that a cellular protein, AKAP7, has an analogous 2′,5′-phosphodiesterase (2′,5′-PDE) domain that is able to restore the growth of chimeric MHV expressing inactive ns2. The proviral effect requires cytoplasmic localization of the AKAP7 PDE domain. We speculate that AKAP7 is the ancestral precursor of viral proteins, such as ns2 and VP3, that degrade 2-5A to evade the antiviral activity of RNase L.