Ubiquitination Upregulates Influenza Virus Polymerase Function
Ubiquitination Upregulates Influenza Virus Polymerase Function
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DOI：
10.1128/jvi.01829-16
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发表时间：
2016-12-01
影响因子：
5.4
通讯作者：
Mehle, Andrew
中科院分区：
文献类型：
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作者：
Kirui, James;Mondal, Arindam;Mehle, Andrew
甲型流感病毒聚合酶在病毒生命周期中起重要作用，指导病毒mRNA和基因组的合成。它是由PA、PB 1和PB 2亚基组成的三聚体复合物，与病毒RNA和核蛋白（NP）结合形成高级核糖核蛋白（RNP）复合物。聚合酶在感染过程中受到时间调节，以确保病毒基因的协调表达以及病毒基因组的复制。各种宿主因素和过程已涉及IAV聚合酶功能的调节，包括翻译后修饰;然而，其机制尚未完全了解。在这里，我们证明了泛素化在刺激聚合酶活性中起着重要作用。我们发现，所有的蛋白质亚基在RNP的泛素化，但泛素化并没有显着改变蛋白质水平。相反，泛素化和活性蛋白酶体增强聚合酶活性。泛素的表达以剂量依赖性方式上调聚合酶功能，导致病毒RNA（vRNA）、cRNA和mRNA的积累增加，并在感染期间增强病毒基因表达。泛素表达直接影响聚合酶活性，而不依赖于核蛋白（NP）或核糖核蛋白（RNP）的组装。泛素化和泛素-蛋白酶体途径在流感病毒感染的多个阶段中发挥关键作用，现在这里提供的数据表明，这些过程调节病毒聚合酶活性独立于蛋白质degradation.IMPORTANCEThe细胞泛素-蛋白酶体途径的影响步骤在整个流感病毒的生命周期。泛素化通过靶向病毒蛋白降解和刺激先天性抗病毒信号通路来抑制复制。泛素化还通过促进病毒进入和病毒体分解来增强复制。我们在这里确定了一个额外的前病毒作用的泛素-蛋白酶体系统，表明所有的蛋白质在病毒复制机器进行泛素化，这是至关重要的最佳病毒聚合酶活性。因此，操纵泛素机制以获得治疗益处可能会在整个感染过程的各个阶段破坏多种病毒蛋白的功能。
The influenza A virus polymerase plays an essential role in the virus life cycle, directing synthesis of viral mRNAs and genomes. It is a trimeric complex composed of subunits PA, PB1, and PB2 and associates with viral RNAs and nucleoprotein (NP) to form higher-order ribonucleoprotein (RNP) complexes. The polymerase is regulated temporally over the course of infection to ensure coordinated expression of viral genes as well as replication of the viral genome. Various host factors and processes have been implicated in regulation of the IAV polymerase function, including posttranslational modifications; however, the mechanisms are not fully understood. Here we demonstrate that ubiquitination plays an important role in stimulating polymerase activity. We show that all protein subunits in the RNP are ubiquitinated, but ubiquitination does not significantly alter protein levels. Instead, ubiquitination and an active proteasome enhance polymerase activity. Expression of ubiquitin upregulates polymerase function in a dose-dependent fashion, causing increased accumulation of viral RNA (vRNA), cRNA, and mRNA and enhanced viral gene expression during infection. Ubiquitin expression directly affects polymerase activity independent of nucleoprotein (NP) or ribonucleoprotein (RNP) assembly. Ubiquitination and the ubiquitin-proteasome pathway play key roles during multiple stages of influenza virus infection, and data presented here now demonstrate that these processes modulate viral polymerase activity independent of protein degradation.IMPORTANCEThe cellular ubiquitin-proteasome pathway impacts steps during the entire influenza virus life cycle. Ubiquitination suppresses replication by targeting viral proteins for degradation and stimulating innate antiviral signaling pathways. Ubiquitination also enhances replication by facilitating viral entry and virion disassembly. We identify here an addition proviral role of the ubiquitin- proteasome system, showing that all of the proteins in the viral replication machinery are subject to ubiquitination and this is crucial for optimal viral polymerase activity. Manipulation of the ubiquitin machinery for therapeutic benefit is therefore likely to disrupt the function of multiple viral proteins at stages throughout the course of infection.