Cellular Requirements for Bovine Immunodeficiency Virus Vif-Mediated Inactivation of Bovine APOBEC3 Proteins
Cellular Requirements for Bovine Immunodeficiency Virus Vif-Mediated Inactivation of Bovine APOBEC3 Proteins
复制标题
牛免疫缺陷病毒的细胞需求 Vif 介导的牛 APOBEC3 蛋白失活
DOI：
10.1128/jvi.02072-14
复制
发表时间：
2014-11-01
影响因子：
5.4
通讯作者：
Yu, Xiao-Fang
中科院分区：
文献类型：
--
作者：
Zhang, Wenyan;Wang, Hong;Yu, Xiao-Fang
摘要人类免疫缺陷病毒1型(HIV-1)和猴免疫缺陷病毒(SIV)病毒感染性因子(VIF)形成CRL5 E3泛素连接酶复合体，抑制宿主APOBEC3(A3)蛋白对病毒的限制。灵长类慢病毒Vif复合体由独特的辅因子核心结合因子β(CbF-β)和典型连接酶组分CUL5(CUL5)、Elongin B/C(ELOB/C)和RbX2组成。然而，相关慢病毒牛免疫缺陷病毒(BIV)的Vif蛋白克服宿主A3蛋白的机制尚不清楚。在本研究中，我们发现BIVVif与CUL2(CUL2)、ELOB/C和RBX1相互作用，而不与CbF-β或CUL5相互作用，形成CRL2E3泛素连接酶，并降解限制性的牛A3蛋白(A3Z2Z3和A3Z3)。RNA干扰抑制BIVVif介导的这些A3蛋白的降解，而CUL5或CbF-β则不能。BIV Vif的BC盒突变(Vif SLQ-AAA)或VHL盒突变(Vif Yi-AA)分别不能与ELOB/C或CUL2相互作用，失去了中和牛A3蛋白的能力。此外，CUL2和UBE2M显性负性突变体竞争抑制BIV Vif介导的降解机制。因此，尽管抑制A3蛋白的一般策略在HIV-1/Siv和BIV之间是保守的，但确切的机制可能有很大的不同，只有HIV-1/Siv Vif蛋白需要CBF-β作为辅助因子，HIV-1/Siv Vif使用CUL5-RBX2，BIVVif使用CUL2-RBX1。重要性灵长类慢病毒HIV-1和SIV Vif蛋白形成泛素连接酶复合体，靶向宿主抗病毒APOBEC3蛋白进行降解。然而，非灵长类慢病毒BIV Vif抑制牛APOBEC3蛋白的机制尚不清楚。在本研究中，我们确定了BIVVif介导的牛APOBEC3蛋白的降解机制，发现它不同于HIV-1/SIVVif的机制，因为它不依赖于CBF-β，并且需要不同的泛素连接酶支架蛋白(CUL2-RBX1而不是CUL5-RBX2)。Biv Vif是已知的唯一能与CUL2相互作用的逆转录病毒蛋白。这些信息拓宽了我们对不同慢病毒的Vif蛋白促进病毒感染的不同机制的理解。这种组装BIV Vif-APOBEC3泛素连接酶复合体的新机制促进了我们对宿主E3泛素连接酶的病毒劫持的理解，并说明了慢病毒的进化灵活性。
ABSTRACT Human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) viral infectivity factor (Vif) form a CRL5 E3 ubiquitin ligase complex to suppress virus restriction by host APOBEC3 (A3) proteins. The primate lentiviral Vif complex is composed of the unique cofactor core binding factor β (CBF-β) and canonical ligase components Cullin 5 (CUL5), Elongin B/C (ELOB/C), and RBX2. However, the mechanism by which the Vif protein of the related lentivirus bovine immunodeficiency virus (BIV) overcomes its host A3 proteins is less clear. In this study, we show that BIV Vif interacts with Cullin 2 (CUL2), ELOB/C, and RBX1, but not with CBF-β or CUL5, to form a CRL2 E3 ubiquitin ligase and degrade the restrictive bovine A3 proteins (A3Z2Z3 and A3Z3). RNA interference-mediated knockdown of ELOB or CUL2 inhibited BIV Vif-mediated degradation of these A3 proteins, whereas knockdown of CUL5 or CBF-β did not. BIV Vif with mutations in the BC box (Vif SLQ-AAA) or putative VHL box (Vif YI-AA), which cannot interact with ELOB/C or CUL2, respectively, lost the ability to counteract bovine A3 proteins. Moreover, CUL2 and UBE2M dominant negative mutants competitively inhibited the BIV Vif-mediated degradation mechanism. Thus, although the general strategy for inhibiting A3 proteins is conserved between HIV-1/SIV and BIV, the precise mechanisms can differ substantially, with only the HIV-1/SIV Vif proteins requiring CBF-β as a cofactor, HIV-1/SIV Vif using CUL5-RBX2, and BIV Vif using CUL2-RBX1. IMPORTANCE Primate lentivirus HIV-1 and SIV Vif proteins form a ubiquitin ligase complex to target host antiviral APOBEC3 proteins for degradation. However, the mechanism by which the nonprimate lentivirus BIV Vif inhibits bovine APOBEC3 proteins is unclear. In the present study, we determined the mechanism for BIV Vif-mediated degradation of bovine APOBEC3 proteins and found that it differs from the mechanism of HIV-1/SIV Vif by being CBF-β independent and requiring different ubiquitin ligase scaffolding proteins (CUL2-RBX1 instead of CUL5-RBX2). BIV Vif is the only known retroviral protein that can interact with CUL2. This information broadens our understanding of the distinct mechanisms by which the Vif proteins of different lentiviruses facilitate viral infection. This novel mechanism for assembly of the BIV Vif-APOBEC3 ubiquitin ligase complex advances our understanding of viral hijacking of host E3 ubiquitin ligases and illustrates the evolutionary flexibility of lentiviruses.