Structural view and substrate specificity of papain-like protease from avian infectious bronchitis virus.
Structural view and substrate specificity of papain-like protease from avian infectious bronchitis virus.
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DOI：
10.1074/jbc.m114.628636
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发表时间：
2015-03-13
期刊：
影响因子：
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通讯作者：
Rao Z
中科院分区：
文献类型：
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作者：
Kong L;Shaw N;Yan L;Lou Z;Rao Z
背景：感染家禽造成巨大损失的禽传染性支气管炎病毒（IBV）的木瓜蛋白酶（PLpro）是否具有去泛素化作用尚不清楚。结果：IBV PLpro可切割Lys48-和lys63 -连接的多泛素。晶体结构显示了一组明显不同的结合底物残基。结论：IBV PLpro具有不同于其他PLpro的去泛素化催化效率。意义：研究结果为开发抗病毒药物提供了框架。冠状病毒（cov）的木瓜蛋白酶（PLpro）对在病毒复制中起作用的非结构蛋白进行蛋白水解成熟，并对宿主细胞因子进行去泛素化以破坏抗病毒反应。鸡传染性支气管炎病毒（IBV）是导致鸡支气管炎的病原体，每年给全球家禽业造成巨大的经济损失，它编码一个PLpro。该PLpro的底物特异性尚不清楚。在这里，我们发现IBV PLpro可以将Lys48-和lys63连接的多泛素链降解为单泛素，而不是线性多泛素。为了解释衬底特性，我们以2.15-Å分辨率从IBV中求解了PLpro的晶体结构。整体结构与严重急性呼吸综合征冠状病毒PLpro的结构相似。然而，与缺乏去泛素化酶阻断环（BL） 1的严重急性呼吸综合征CoV PLpro不同，IBV PLpro具有短的bl1样环。由Cys101， His264和Asp275组成的保守催化三联体的进入由灵活的BL2调节。泛素结合的IBV CoV PLpro模型揭示了PLpro底物结合位点的关键差异。特别是，P3和P4亚位以及与泛素β-桶相互作用的残基不同，表明不同的催化效率和底物特异性。我们发现IBV PLpro裂解肽底物kkag -7-氨基-4-甲基香豆素和lrgg -7-氨基-4-甲基香豆素具有不同的催化效率。这些结果表明，IBV PLpro的底物特异性与其他PLpro不同，IBV PLpro可能针对不同的泛素化宿主因子来帮助病毒繁殖。
Background: Whether papain-like protease (PLpro) from avian infectious bronchitis virus (IBV) that infects poultry, causing huge losses, can perform deubiquitination is unknown. Results: IBV PLpro cleaves Lys48- and Lys63-linked polyubiquitin. The crystal structure reveals a markedly different set of residues for binding substrates. Conclusion: IBV PLpro performs deubiquitination with catalytic efficiencies that are different from other PLpros. Significance: Results provide a framework for developing antivirals. Papain-like protease (PLpro) of coronaviruses (CoVs) carries out proteolytic maturation of non-structural proteins that play a role in replication of the virus and performs deubiquitination of host cell factors to scuttle antiviral responses. Avian infectious bronchitis virus (IBV), the causative agent of bronchitis in chicken that results in huge economic losses every year in the poultry industry globally, encodes a PLpro. The substrate specificities of this PLpro are not clearly understood. Here, we show that IBV PLpro can degrade Lys48- and Lys63-linked polyubiquitin chains to monoubiquitin but not linear polyubiquitin. To explain the substrate specificities, we have solved the crystal structure of PLpro from IBV at 2.15-Å resolution. The overall structure is reminiscent of the structure of severe acute respiratory syndrome CoV PLpro. However, unlike the severe acute respiratory syndrome CoV PLpro that lacks blocking loop (BL) 1 of deubiquitinating enzymes, the IBV PLpro has a short BL1-like loop. Access to a conserved catalytic triad consisting of Cys101, His264, and Asp275 is regulated by the flexible BL2. A model of ubiquitin-bound IBV CoV PLpro brings out key differences in substrate binding sites of PLpros. In particular, P3 and P4 subsites as well as residues interacting with the β-barrel of ubiquitin are different, suggesting different catalytic efficiencies and substrate specificities. We show that IBV PLpro cleaves peptide substrates KKAG-7-amino-4-methylcoumarin and LRGG-7-amino-4-methylcoumarin with different catalytic efficiencies. These results demonstrate that substrate specificities of IBV PLpro are different from other PLpros and that IBV PLpro might target different ubiquitinated host factors to aid the propagation of the virus.