Murine Leukemia Virus Glycosylated Gag Reduces Murine SERINC5 Protein Expression at Steady-State Levels via the Endosome/Lysosome Pathway to Counteract SERINC5 Antiretroviral Activity
Murine Leukemia Virus Glycosylated Gag Reduces Murine SERINC5 Protein Expression at Steady-State Levels via the Endosome/Lysosome Pathway to Counteract SERINC5 Antiretroviral Activity
复制标题
鼠白血病病毒糖基化 Gag 通过内体/溶酶体途径降低稳态水平的鼠 SERINC5 蛋白表达，从而抵消 SERINC5 抗逆转录病毒活性
DOI：
10.1128/jvi.01651-18
复制
发表时间：
2019-01-01
影响因子：
5.4
通讯作者：
Zheng, Yong-Hui
中科院分区：
文献类型：
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作者：
Li, Sunan;Ahmad, Iqbal;Zheng, Yong-Hui
与Nef类似，MLV的糖蛋白Gag不仅能增强MLV的复制，而且还能增加HIV-1的感染力。最近的研究发现，糖蛋白Gag和Nef都能拮抗一种新的宿主限制因子Ser5，并促进病毒复制。与Nef相比，Ser5的糖胶原拮抗作用仍然知之甚少。MLV ggGag是结构Gag蛋白的跨膜版本，额外的88个氨基酸前导区域决定了其活性。我们现在发现，糖胶原与活细胞中的Ser5相互作用，并通过受体介导的内吞作用将Ser5内化。Ser5是多泛素化的，并重新定位到内切体和溶酶体，以进行大规模破坏。除了先前发现的基于酪氨酸的分选信号外，我们还发现了两个更重要的残基，用于Ser5的重新定位和下调。我们还发现，在SERINC家族中，Ser5对糖胶原的敏感性是保守的。综上所述，我们的发现强调了内切体/溶酶体途径在病毒蛋白促进病毒复制中的重要作用。摘要糖基化GAG(Glycoylated Gag)是包括小鼠白血病病毒(MLV)在内的大多数伽玛逆转录病毒都表达的一种辅助蛋白。与Nef一样，MLV ggGag不仅可以促进MLV的复制和疾病进展，而且还可以增加人类免疫缺陷病毒1型(HIV-1)的传染性。最近，SERINC5(Ser5)被确定为Nef的靶标，糖化Gag Nef样活性被归因于Ser5的拮抗作用。在这里，我们研究了糖蛋白Gag如何使用MLV糖蛋白和小鼠Ser5蛋白来拮抗Ser5。我们证实了先前的观察结果，即糖甲将Ser5从质膜重新定位到核周斑点间隔，并证实了其Y36XXL39基序在这一过程中的重要作用。我们发现，糖甲在稳态水平降低了Ser5的表达，并发现了另外两个关键的gGag残基，p31和R63，用于下调Ser5。在活细胞中，用双分子荧光互补分析检测到糖甲和血清5的相互作用。Ser5通过受体介导的内吞作用被内化，并通过糖甲酸重定位到Rab5+早期、Rab7+晚期和Rab11+循环内吞体内。虽然糖链不是泛素化的，但Ser5的下调需要Ser5通过K48-和K63-连接的多泛素化，导致溶酶体中Ser5的破坏。虽然P31、Y36、L39和R63不是糖胺与Ser5相互作用所必需的，但它们是Ser5重新定位到溶酶体进行破坏所必需的。此外，尽管小鼠血清1、血清2和血清3表现出很弱的抗病毒活性，但它们也是糖甲酸靶向破坏溶酶体的靶标。我们的结论是，GlyGag具有广泛的活性，通过细胞内含体/溶酶体途径下调SERINC蛋白，从而促进病毒复制。重要性MLV糖蛋白Gag不仅能增强MLV的复制，还能增加HIV-1的感染力，与Nef类似。最近的研究发现，糖蛋白Gag和Nef都能拮抗一种新的宿主限制因子Ser5，并促进病毒复制。与Nef相比，Ser5的糖胶原拮抗作用仍然知之甚少。MLV ggGag是结构Gag蛋白的跨膜版本，额外的88个氨基酸前导区域决定了其活性。我们现在发现，糖胶原与活细胞中的Ser5相互作用，并通过受体介导的内吞作用将Ser5内化。Ser5是多泛素化的，并重新定位到内切体和溶酶体，以进行大规模破坏。除了先前发现的基于酪氨酸的分选信号外，我们还发现了两个更重要的残基，用于Ser5的重新定位和下调。我们还发现，在SERINC家族中，Ser5对糖胶原的敏感性是保守的。综上所述，我们的发现强调了内切体/溶酶体途径在病毒蛋白促进病毒复制中的重要作用。
MLV glycoGag not only enhances MLV replication but also increases HIV-1 infectivity similarly as Nef. Recent studies have discovered that both glycoGag and Nef antagonize a novel host restriction factor Ser5 and promote viral replication. Compared to Nef, the glycoGag antagonism of Ser5 is still poorly understood. MLV glycoGag is a transmembrane version of the structural Gag protein with an extra 88-amino-acid leader region that determines its activity. We now show that glycoGag interacts with Ser5 in live cells and internalizes Ser5 via receptor-mediated endocytosis. Ser5 is polyubiquitinated and relocalized to endosomes and lysosomes for massive destruction. In addition to the previously identified tyrosine-based sorting signal, we find two more important residues for Ser5 relocalization and downregulation. We also find that the Ser5 sensitivity to glycoGag is conserved in the SERINC family. Together, our findings highlight the important role of endosome/lysosome pathway in the enhancement of viral replication by viral proteins. ABSTRACT Glycosylated Gag (glycoGag) is an accessory protein expressed by most gammaretroviruses, including murine leukemia virus (MLV). MLV glycoGag not only enhances MLV replication and disease progression but also increases human immunodeficiency virus type 1 (HIV-1) infectivity as Nef does. Recently, SERINC5 (Ser5) was identified as the target for Nef, and the glycoGag Nef-like activity has been attributed to the Ser5 antagonism. Here, we investigated how glycoGag antagonizes Ser5 using MLV glycoMA and murine Ser5 proteins. We confirm previous observations that glycoMA relocalizes Ser5 from plasma membrane to perinuclear punctated compartments and the important role of its Y36XXL39 motif in this process. We find that glycoMA decreases Ser5 expression at steady-state levels and identify two other glycoGag crucial residues, P31 and R63, for the Ser5 downregulation. The glycoMA and Ser5 interaction is detected in live cells using a bimolecular fluorescence complementation assay. Ser5 is internalized via receptor-mediated endocytosis and relocalized to Rab5+ early, Rab7+ late, and Rab11+ recycling endosomes by glycoMA. Although glycoMA is not polyubiquitinated, the Ser5 downregulation requires Ser5 polyubiquitination via the K48- and K63-linkage, resulting in Ser5 destruction in lysosomes. Although P31, Y36, L39, and R63 are not required for glycoMA interaction with Ser5, they are required for Ser5 relocalization to lysosomes for destruction. In addition, although murine Ser1, Ser2, and Ser3 exhibit very poor antiviral activity, they are also targeted by glycoMA for lysosomal destruction. We conclude that glycoGag has a broad activity to downregulate SERINC proteins via the cellular endosome/lysosome pathway, which promotes viral replication. IMPORTANCE MLV glycoGag not only enhances MLV replication but also increases HIV-1 infectivity similarly as Nef. Recent studies have discovered that both glycoGag and Nef antagonize a novel host restriction factor Ser5 and promote viral replication. Compared to Nef, the glycoGag antagonism of Ser5 is still poorly understood. MLV glycoGag is a transmembrane version of the structural Gag protein with an extra 88-amino-acid leader region that determines its activity. We now show that glycoGag interacts with Ser5 in live cells and internalizes Ser5 via receptor-mediated endocytosis. Ser5 is polyubiquitinated and relocalized to endosomes and lysosomes for massive destruction. In addition to the previously identified tyrosine-based sorting signal, we find two more important residues for Ser5 relocalization and downregulation. We also find that the Ser5 sensitivity to glycoGag is conserved in the SERINC family. Together, our findings highlight the important role of endosome/lysosome pathway in the enhancement of viral replication by viral proteins.