Dengue Virus Hijacks a Noncanonical Oxidoreductase Function of a Cellular Oligosaccharyltransferase Complex.
Dengue Virus Hijacks a Noncanonical Oxidoreductase Function of a Cellular Oligosaccharyltransferase Complex.
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DOI：
10.1128/mbio.00939-17
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发表时间：
2017-07-18
期刊：
影响因子：
6.4
通讯作者：
Tai AW
中科院分区：
文献类型：
--
作者：
Lin DL;Cherepanova NA;Bozzacco L;MacDonald MR;Gilmore R;Tai AW
登革热病毒 (DENV) 是全球最常见的虫媒病毒感染，每年估计感染 3.9 亿人。我们采用全基因组聚类规则间隔短回文重复序列 (CRISPR) 筛选来识别 DENV 传播所需的宿主依赖性因子，并确定寡糖转移酶 (OST) 复合物作为 DENV 感染的重要宿主因子。哺乳动物细胞表达两种含有 STT3A 或 STT3B 的 OST。我们发现OST作为寡糖基转移酶的典型催化功能对于DENV感染来说并不是必需的，因为表达催化失活的STT3A或STT3B的细胞能够支持DENV传播。然而，与 STT3B 相关的 OST 亚基 MAGT1 也是 DENV 传播所必需的。 MAGT1 的表达需要 STT3B，催化失活的 STT3B 也能拯救 MAGT1 的表达，这支持了 STT3B 在 DENV 感染情况下稳定 MAGT1 的假设。我们发现 MAGT1 的氧化还原酶 CXXC 活性位点基序对于 DENV 传播是必需的，因为表达 AXXA MAGT1 突变体的细胞无法支持 DENV 感染。有趣的是，表达 MAGT1 的单半胱氨酸 CXXA 或 AXXC 突变体的细胞能够支持 DENV 传播。利用工程化过氧化物酶 APEX2，我们证明了 DENV 感染期间 MAGT1 和 NS1 或 NS4B 之间的紧密接近性。这些结果表明，含有STT3B的OST的氧化还原酶活性对于DENV感染是必需的，这可能指导针对DENV的抗病毒药物的开发。宿主寡糖转移酶 (OST) 复合物已被确定为登革热病毒 (DENV) 复制的重要宿主因子；然而，它们在 DENV 感染期间的功能尚不清楚。之前的一项研究表明，典型的 OST 活性对于 DENV 复制来说是可有可无的，这表明 OST 复合物可以作为 DENV 复制的支架。然而，我们的工作表明，OST 复合物在 DENV 感染期间的一项功能是通过 OST 亚基 MAGT1 提供氧化还原酶活性。我们还表明，MAGT1 在病毒感染期间与 DENV NS1 和 NS4B 相关，表明这些非结构蛋白可能是 MAGT1 氧化还原酶活性的靶标。这些结果提供了对 DENV 感染的细胞生物学的深入了解，这可能指导针对 DENV 的抗病毒药物的开发。
Dengue virus (DENV) is the most common arboviral infection globally, infecting an estimated 390 million people each year. We employed a genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screen to identify host dependency factors required for DENV propagation and identified the oligosaccharyltransferase (OST) complex as an essential host factor for DENV infection. Mammalian cells express two OSTs containing either STT3A or STT3B. We found that the canonical catalytic function of the OSTs as oligosaccharyltransferases is not necessary for DENV infection, as cells expressing catalytically inactive STT3A or STT3B are able to support DENV propagation. However, the OST subunit MAGT1, which associates with STT3B, is also required for DENV propagation. MAGT1 expression requires STT3B, and a catalytically inactive STT3B also rescues MAGT1 expression, supporting the hypothesis that STT3B serves to stabilize MAGT1 in the context of DENV infection. We found that the oxidoreductase CXXC active site motif of MAGT1 was necessary for DENV propagation, as cells expressing an AXXA MAGT1 mutant were unable to support DENV infection. Interestingly, cells expressing single-cysteine CXXA or AXXC mutants of MAGT1 were able to support DENV propagation. Utilizing the engineered peroxidase APEX2, we demonstrate the close proximity between MAGT1 and NS1 or NS4B during DENV infection. These results reveal that the oxidoreductase activity of the STT3B-containing OST is necessary for DENV infection, which may guide the development of antiviral agents targeting DENV. The host oligosaccharyltransferase (OST) complexes have been identified as essential host factors for dengue virus (DENV) replication; however, their functions during DENV infection are unclear. A previous study showed that the canonical OST activity was dispensable for DENV replication, suggesting that the OST complexes serve as scaffolds for DENV replication. However, our work demonstrates that one function of the OST complex during DENV infection is to provide oxidoreductase activity via the OST subunit MAGT1. We also show that MAGT1 associates with DENV NS1 and NS4B during viral infection, suggesting that these nonstructural proteins may be targets of MAGT1 oxidoreductase activity. These results provide insight into the cell biology of DENV infection, which may guide the development of antivirals against DENV.