Lentiviral Vpx accessory factor targets VprBP/DCAF1 substrate adaptor for cullin 4 E3 ubiquitin ligase to enable macrophage infection.
Lentiviral Vpx accessory factor targets VprBP/DCAF1 substrate adaptor for cullin 4 E3 ubiquitin ligase to enable macrophage infection.
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DOI：
10.1371/journal.ppat.1000059
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发表时间：
2008-05-09
期刊：
影响因子：
6.7
通讯作者：
Skowronski J
中科院分区：
文献类型：
--
作者：
Srivastava S;Swanson SK;Manel N;Florens L;Washburn MP;Skowronski J
Vpx 是一种小型病毒体相关衔接蛋白，由灵长类慢病毒 HIV-2/SIVsm 谱系的病毒编码，使这些病毒能够转导单核细胞来源的细胞。这可能反映了 Vpx 能够克服这些细胞中病毒生命周期早期事件的未知障碍，但其潜在机制仍然难以捉摸。使用生化和蛋白质组学方法，我们发现致病性SIVmac 239菌株的Vpx蛋白与三元蛋白复合物相关，该三元蛋白复合物包含基于Cullin 4的E3泛素连接酶的DDB1和VprBP亚基，以及参与E3催化活性调节的DDA1，并且Vpx参与包含VprBP的Cullin 4 E3复合物。我们进一步证明，SIVmac 以及 HIV-2 Vpx 与 VprBP 及其相关的 Cullin 4 复合物相互作用的能力是原代巨噬细胞中 SIVmac RNA 基因组有效逆转录所必需的。引人注目的是，VprBP 水平因 RNA 干扰而减少的巨噬细胞能够抵抗 SIVmac 感染。因此，我们的观察表明，Vpx 与泛素蛋白酶体系统的催化和调节成分相互作用，并证明这些相互作用对于 Vpx 在初级巨噬细胞中实现有效 SIVmac 复制的能力至关重要。此外，他们还确定了 Cullin 4 E3 泛素连接酶的 VprBP/DCAF1 底物受体及其相关蛋白复合物作为该功能的 Vpx 的直接下游效应子。总之，我们的研究结果提出了一个模型，其中 Vpx 侵占 VprBP 相关的 Cullin 4 泛素连接酶，以实现有效的逆转录，从而克服单核细胞衍生细胞中慢病毒复制的阻碍，从而为潜在的分子机制提供新的见解。单核细胞来源的组织巨噬细胞在灵长类慢病毒感染中发挥着至关重要的作用。 HIV-2 和 SIVsm/mac 谱系的人类和猿慢病毒编码一种称为 Vpx 的病毒体结合毒力因子。 Vpx 是建立单核细胞衍生细胞特异性感染所必需的，但潜在的分子机制尚不清楚。在本研究中，我们描述了在没有 Vpx 的情况下 SIVmac 的复制如何被阻断以及 Vpx 如何克服这种阻断。我们发现Vpx是传入RNA基因组的有效逆转录所必需的，这表明Vpx在病毒体进入巨噬细胞后早期发挥作用，可能与病毒体脱壳和/或逆转录相关的事件有关。我们还鉴定了一种 Vpx 相关三元蛋白复合物，它是巨噬细胞中 Vpx 功能的关键介质。该复合物将 Vpx 与介导蛋白质泛素化和降解的细胞机制连接起来。我们一起描述了慢病毒 Vpx 用于实现巨噬细胞逆转录的直接下游效应器、分子机制和暂定机制。我们的研究结果应该会催生控制人类和猿慢病毒巨噬细胞感染的新策略的概念。
Vpx is a small virion-associated adaptor protein encoded by viruses of the HIV-2/SIVsm lineage of primate lentiviruses that enables these viruses to transduce monocyte-derived cells. This probably reflects the ability of Vpx to overcome an as yet uncharacterized block to an early event in the virus life cycle in these cells, but the underlying mechanism has remained elusive. Using biochemical and proteomic approaches, we have found that Vpx protein of the pathogenic SIVmac 239 strain associates with a ternary protein complex comprising DDB1 and VprBP subunits of Cullin 4–based E3 ubiquitin ligase, and DDA1, which has been implicated in the regulation of E3 catalytic activity, and that Vpx participates in the Cullin 4 E3 complex comprising VprBP. We further demonstrate that the ability of SIVmac as well as HIV-2 Vpx to interact with VprBP and its associated Cullin 4 complex is required for efficient reverse transcription of SIVmac RNA genome in primary macrophages. Strikingly, macrophages in which VprBP levels are depleted by RNA interference resist SIVmac infection. Thus, our observations reveal that Vpx interacts with both catalytic and regulatory components of the ubiquitin proteasome system and demonstrate that these interactions are critical for Vpx ability to enable efficient SIVmac replication in primary macrophages. Furthermore, they identify VprBP/DCAF1 substrate receptor for Cullin 4 E3 ubiquitin ligase and its associated protein complex as immediate downstream effector of Vpx for this function. Together, our findings suggest a model in which Vpx usurps VprBP-associated Cullin 4 ubiquitin ligase to enable efficient reverse transcription and thereby overcome a block to lentivirus replication in monocyte-derived cells, and thus provide novel insights into the underlying molecular mechanism. Monocyte-derived tissue macrophages play crucial roles in infection by primate lentiviruses. Human and simian lentiviruses of the HIV-2 and SIVsm/mac lineages encode a virion-bound virulence factor termed Vpx. Vpx is required to establish infection specifically of monocyte-derived cells, but the underlying molecular mechanism is unclear. In this study we characterize how the replication of SIVmac is blocked in the absence of Vpx and how Vpx overcomes this block. We find that Vpx is required for efficient reverse transcription of the incoming RNA genome, suggesting that Vpx acts early following virion entry into the macrophage, probably on events linked to virion uncoating and/or reverse transcription. We also identified a Vpx-associated ternary protein complex that is the key mediator of Vpx function specifically in macrophages. This complex links Vpx to the cellular machinery that mediates protein ubiquitination and degradation. Together, we describe the immediate downstream effector, the molecular machinery and a tentative mechanism that lentiviral Vpx uses to enable reverse transcription in macrophages. Our findings should lead to the conception of new strategies to control macrophage infection by human and simian lentiviruses.
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影响因子：
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