Ubiquitination of APOBEC3G by an HIV-1 Vif-Cullin5-Elongin B-Elongin C complex is essential for Vif function
Ubiquitination of APOBEC3G by an HIV-1 Vif-Cullin5-Elongin B-Elongin C complex is essential for Vif function
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DOI：
10.1074/jbc.c500082200
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发表时间：
2005-05-13
影响因子：
4.8
通讯作者：
Uchiyama, T
中科院分区：
文献类型：
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作者：
Kobayashi, M;Takaori-Kondo, A;Uchiyama, T
人类免疫缺陷病毒 1 型 (HIV-1) 病毒粒子感染因子 (Vif) 克服了 APOBEC3G 的抗病毒活性，可保护 HIV-1 DNA 免遭 G 至 A 超突变。 Vif 通过新型 SOCS-box 基序形成由 Cullin5、Elongin B 和 Elongin C (Vif-BC-Cul5) 组成的 SCF 样 E3 泛素连接酶复合物，从而靶向 APOBEC3G 进行泛素化和蛋白酶体降解。在本文中，我们建立了纯化的 Vif-BC-Cul5 复合物的体外泛素缀合测定，并报道 Vif-BC-Cul5 复合物可以在体外充当 APOBEC3G 的 E3 连接酶。 Vif-BC-Cul5 复合物可促进野生型 APOBEC3G 的体外泛素化，但不会促进不与 Vif 相互作用的 D128K 突变体的体外泛素化。我们还研究了几种功能丧失的 Vif 突变体。一种突变体 SLQ144/146AAA 失去了对 APOBEC3G 的活性，因为它由于 SOCS-box 基序的突变而无法形成复合物。其他突变体 C114S 和 C133S 也由于 Vif-BC-Cul5 复合物的 E3 连接酶活性丧失而失去活性，尽管这些突变体保留了与 APOBEC3G 以及 Cul5 复合物结合的能力。这些发现表明 Vif-BC-Cul5 复合物的 E3 泛素连接酶活性对于 Vif 对抗 APOBEC3G 的功能至关重要。
The human immunodeficiency virus type 1 (HIV-1) virion infectivity factor (Vif) overcomes the antiviral activity of APOBEC3G to protect HIV-1 DNA from G-to-A hypermutation. Vif targets APOBEC3G for ubiquitination and proteasomal degradation by forming an SCF-like E3 ubiquitin ligase complex composed of Cullin5, Elongin B, and Elongin C (Vif-BC-Cul5) through a novel SOCS-box motif. In this paper, we have established an in vitro ubiquitin conjugation assay with purified Vif-BC-Cul5 complex and reported that the Vif-BC-Cul5 complex could function as an E3 ligase for APOBEC3G in vitro. A Vif-BC-Cul5 complex promotes the in vitro ubiquitination of the wild type, APOBEC3G but not that of D128K mutant, which does not interact with Vif. We have also investigated several loss-of-function Vif mutants. One mutant, SLQ144/146AAA, lost its activity on APOBEC3G because it could not form a complex due to mutations in SOCS-box motif. Other mutants, C114S and C133S, also lost their activity because of loss of the E3 ligase activity of a Vif-BC-Cul5 complex, although these mutants retained the ability to bind to APOBEC3G as well as Cul5 complex. These findings suggest that the E3 ubiquitin ligase activity of the Vif-BC-Cul5 complex is essential for Vif function against APOBEC3G.