Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA.
Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN 55455, USA.
Cell Rep. 2019 Oct 29;29(5):1057-1065.e4. doi: 10.1016/j.celrep.2019.09.057.
HIV-1 Vif hijacks a cellular ubiquitin ligase complex to degrade antiviral APOBEC3 enzymes and PP2A phosphatase regulators (PPP2R5A-E). APOBEC3 counteraction is essential for viral pathogenesis. However, Vif also functions through an unknown mechanism to induce G2 cell cycle arrest. Here, deep mutagenesis is used to define the Vif surface required for PPP2R5 degradation and isolate a panel of separation-of-function mutants (PPP2R5 degradation-deficient and APOBEC3G degradation-proficient). Functional studies with Vif and PPP2R5 mutants were combined to demonstrate that PPP2R5 is, in fact, the target Vif degrades to induce G2 arrest. Pharmacologic and genetic approaches show that direct modulation of PP2A function or depletion of specific PPP2R5 proteins causes an indistinguishable arrest phenotype. Vif function in the cell cycle checkpoint is present in common HIV-1 subtypes worldwide and likely advantageous for viral pathogenesis.
HIV-1 Vif 劫持一种细胞泛素连接酶复合物，以降解抗病毒 APOBEC3 酶和 PP2A 磷酸酶调节剂 (PPP2R5A-E)。APOBEC3 的拮抗作用对于病毒发病机制至关重要。然而，Vif 也通过未知的机制发挥作用，诱导 G2 细胞周期停滞。在这里，深度诱变用于定义 PPP2R5 降解所需的 Vif 表面，并分离出一组分离功能突变体（PPP2R5 降解缺陷和 APOBEC3G 降解有效）。用 Vif 和 PPP2R5 突变体进行的功能研究表明，PPP2R5 实际上是 Vif 降解以诱导 G2 停滞的靶标。药理学和遗传学方法表明，直接调节 PP2A 功能或耗尽特定的 PPP2R5 蛋白会导致无法区分的停滞表型。Vif 在细胞周期检查点的功能存在于全球常见的 HIV-1 亚型中，可能有利于病毒发病机制。
