Tetramerization of SAMHD1 is required for biological activity and inhibition of HIV infection.
Tetramerization of SAMHD1 is required for biological activity and inhibition of HIV infection.
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DOI：
10.1074/jbc.m112.443796
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发表时间：
2013-04-12
期刊：
影响因子：
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通讯作者：
Skowronski J
中科院分区：
文献类型：
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作者：
Yan J;Kaur S;DeLucia M;Hao C;Mehrens J;Wang C;Golczak M;Palczewski K;Gronenborn AM;Ahn J;Skowronski J
背景：SAMHD1是一种dgtp激活的dNTPase，在单核细胞和静止T淋巴细胞的逆转录阶段抑制逆转录病毒感染。结果：dgtp诱导的SAMHD1四聚化与其功能激活相关。结论：SAMHD1四聚体是该dNTPase的生物活性形式。意义：了解SAMHD1的功能调控机制对理解先天免疫和抗病毒免疫具有重要意义。SAMHD1是一种dgtp激活的dNTPase，被认为是先天免疫反应的调节剂。在单核细胞及其分化衍生物以及静止细胞中，SAMHD1强烈抑制HIV-1感染，并且在较小程度上抑制HIV-2和猴免疫缺陷病毒（SIV），因为它们的病毒粒子相关毒力因子Vpx指导SAMHD1进行蛋白酶体降解。在这里，我们使用生化和病毒学方法的结合来深入了解人类SAMHD1的功能组织。我们发现具有催化活性的重组dNTPase是dgtp诱导的四聚体。化学交联研究揭示了SAMHD1在人类单核细胞中的四聚体，它强烈地限制了HIV-1感染。SAMHD1在体外维持四聚体状态的倾向是由其位于催化结构域外的C端调节的。因此，我们发现C端是SAMHD1耗尽dNTP池和抑制U937单核细胞中HIV-1感染的全部能力所必需的。有趣的是，人类samhd1c末端包含HIV-2/SIVmac Vpx的对接位点，并且已知是在正向选择下进化的。这一证据表明Vpx靶向SAMHD1中一个功能重要的元件。总之，我们的研究结果表明SAMHD1四聚体是这种dNTPase的生物活性形式，并为SAMHD1的功能组织提供了新的见解。
Background: SAMHD1, a dGTP-activated dNTPase, inhibits retrovirus infection at the reverse transcription step in monocytes and quiescent T lymphocytes. Results: dGTP-induced SAMHD1 tetramerization correlates with its functional activation. Conclusion: SAMHD1 tetramers are the biologically active form of this dNTPase. Significance: Learning how SAMHD1 function is regulated is important for understanding innate and anti-viral immunity. SAMHD1 is a dGTP-activated dNTPase that has been implicated as a modulator of the innate immune response. In monocytes and their differentiated derivatives, as well as in quiescent cells, SAMHD1 strongly inhibits HIV-1 infection and, to a lesser extent, HIV-2 and simian immunodeficiency virus (SIV) because of their virion-associated virulence factor Vpx, which directs SAMHD1 for proteasomal degradation. Here, we used a combination of biochemical and virologic approaches to gain insights into the functional organization of human SAMHD1. We found that the catalytically active recombinant dNTPase is a dGTP-induced tetramer. Chemical cross-linking studies revealed SAMHD1 tetramers in human monocytic cells, in which it strongly restricts HIV-1 infection. The propensity of SAMHD1 to maintain the tetrameric state in vitro is regulated by its C terminus, located outside of the catalytic domain. Accordingly, we show that the C terminus is required for the full ability of SAMHD1 to deplete dNTP pools and to inhibit HIV-1 infection in U937 monocytes. Interestingly, the human SAMHD1 C terminus contains a docking site for HIV-2/SIVmac Vpx and is known to have evolved under positive selection. This evidence indicates that Vpx targets a functionally important element in SAMHD1. Together, our findings imply that SAMHD1 tetramers are the biologically active form of this dNTPase and provide new insights into the functional organization of SAMHD1.