Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, 34090 Montpellier, France.
BCM, Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France.
Viruses. 2020 Jun 11;12(6):636. doi: 10.3390/v12060636.
Death domain-associated protein 6 (Daxx) is a multifunctional, ubiquitously expressed and highly conserved chaperone protein involved in numerous cellular processes, including apoptosis, transcriptional repression, and carcinogenesis. In 2015, we identified Daxx as an antiretroviral factor that interfered with HIV-1 replication by inhibiting the reverse transcription step. In the present study, we sought to unravel the molecular mechanism of Daxx-mediated restriction and, in particular, to identify the protein(s) that Daxx targets in order to achieve its antiviral activity. First, we show that the SUMO-interacting motif (SIM) located at the C-terminus of the protein is strictly required for Daxx to inhibit HIV-1 reverse transcription. By performing a quantitative proteomic screen combined with classical biochemical analyses, we found that Daxx associated with incoming HIV-1 cores through a SIM-dependent interaction with cyclophilin A (CypA) and capsid (CA). Daxx was found to reside within a multiprotein complex associated with viral capsids, also containing TNPO3, TRIM5α, and TRIM34. Given the well-known influence of these cellular factors on the stability of HIV-1 cores, we investigated the effect of Daxx on the cytoplasmic fate of incoming cores and found that Daxx prevented HIV-1 uncoating in a SIM-dependent manner. Altogether, our findings suggest that, by recruiting TNPO3, TRIM5α, and TRIM34 and possibly other proteins onto incoming HIV-1 cores through a SIM-dependent interaction with CA-bound CypA, Daxx increases their stability, thus preventing uncoating and reverse transcription. Our study uncovers a previously unknown function of Daxx in the early steps of HIV-1 infection and further illustrates how reverse transcription and uncoating are two tightly interdependent processes.
死亡结构域相关蛋白 6（Daxx）是一种多功能、广泛表达且高度保守的伴侣蛋白，参与许多细胞过程，包括细胞凋亡、转录抑制和致癌作用。2015 年，我们发现 Daxx 是一种抗逆转录病毒因子，通过抑制逆转录步骤干扰 HIV-1 复制。在本研究中，我们试图揭示 Daxx 介导的限制的分子机制，特别是确定 Daxx 靶向的蛋白，以实现其抗病毒活性。首先，我们表明位于蛋白质 C 末端的 SUMO 相互作用基序（SIM）对于 Daxx 抑制 HIV-1 逆转录是严格必需的。通过进行定量蛋白质组学筛选结合经典生化分析，我们发现 Daxx 通过与亲环素 A（CypA）和衣壳（CA）的 SIM 依赖性相互作用与传入的 HIV-1 核心结合。发现 Daxx 存在于与病毒衣壳相关的多蛋白复合物中，还包含 TNPO3、TRIM5α 和 TRIM34。鉴于这些细胞因子对 HIV-1 核心稳定性的众所周知的影响，我们研究了 Daxx 对传入核心的细胞质命运的影响，发现 Daxx 以 SIM 依赖性方式阻止 HIV-1 脱壳。总之，我们的研究结果表明，通过招募 TNPO3、TRIM5α 和 TRIM34，并可能通过与 CA 结合的 CypA 的 SIM 依赖性相互作用将其他蛋白募集到传入的 HIV-1 核心上，Daxx 增加了它们的稳定性，从而阻止脱壳和逆转录。我们的研究揭示了 Daxx 在 HIV-1 感染早期步骤中的一个以前未知的功能，并进一步说明了逆转录和脱壳是两个紧密相互依赖的过程。
