Department of Medical Protein Research, VIB, Department of Biochemistry, Ghent University, A. Baertsoenkaai 3, 9000 Ghent.
Nucleic Acids Res. 2010 Apr;38(6):1902-12. doi: 10.1093/nar/gkp1154. Epub 2009 Dec 16.
The host restriction factor Apobec3G is a cytidine deaminase that incorporates into HIV-1 virions and interferes with viral replication. The HIV-1 accessory protein Vif subverts Apobec3G by targeting it for proteasomal degradation. We propose a model in which Apobec3G N-terminal domains symmetrically interact via a head-to-head interface containing residues 122 RLYYFW 127. To validate this model and to characterize the Apobec3G-Apobec3G and the Apobec3G-Vif interactions, the mammalian protein-protein interaction trap two-hybrid technique was used. Mutations in the head-to-head interface abrogate the Apobec3G-Apobec3G interaction. All mutations that inhibit Apobec3G-Apobec3G binding also inhibit the Apobec3G-Vif interaction, indicating that the head-to head interface plays an important role in the interaction with Vif. Only the D128K, P129A and T32Q mutations specifically affect the Apobec3G-Vif association. In our model, D128, P129 and T32 cluster at the edge of the head-to-head interface, possibly forming a Vif binding site composed of two Apobec3G molecules. We propose that Vif either binds at the Apobec3G head-to-head interface or associates with an RNA-stabilized Apobec3G oligomer.
宿主限制因子 APOBEC3G 是一种胞嘧啶脱氨酶，可整合到 HIV-1 病毒粒子中并干扰病毒复制。HIV-1 辅助蛋白 Vif 通过将 APOBEC3G 靶向蛋白酶体降解来破坏 APOBEC3G。我们提出了一个模型，其中 APOBEC3G 的 N 端结构域通过包含残基 122 RLYYFW 127 的头对头界面以对称方式相互作用。为了验证该模型并表征 APOBEC3G-APOBEC3G 和 APOBEC3G-Vif 相互作用，使用了哺乳动物蛋白-蛋白相互作用陷阱双杂交技术。头对头界面中的突变会使 APOBEC3G-APOBEC3G 相互作用失效。所有抑制 APOBEC3G-APOBEC3G 结合的突变也抑制了 APOBEC3G-Vif 相互作用，这表明头对头界面在与 Vif 的相互作用中起着重要作用。只有 D128K、P129A 和 T32Q 突变特异性影响 APOBEC3G-Vif 结合。在我们的模型中，D128、P129 和 T32 聚集在头对头界面的边缘，可能形成由两个 APOBEC3G 分子组成的 Vif 结合位点。我们提出，Vif 要么结合在 APOBEC3G 的头对头界面上，要么与 RNA 稳定的 APOBEC3G 寡聚体结合。
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