Schröfelbauer Bärbel, Hakata Yoshiyuki, Landau Nathaniel R
Infectious Disease Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037-1099, USA.
Proc Natl Acad Sci U S A. 2007 Mar 6;104(10):4130-5. doi: 10.1073/pnas.0610167104. Epub 2007 Feb 28.
The Vpr accessory protein of HIV-1 induces a response similar to that of DNA damage. In cells expressing Vpr, the DNA damage sensing kinase, ATR, is activated, resulting in G(2) arrest and apoptosis. In addition, Vpr causes rapid degradation of the uracil-DNA glycosylases UNG2 and SMUG1. Although several cellular proteins have been reported to bind to Vpr, the mechanism by which Vpr mediates its biological effects is unknown. Using tandem affinity purification and mass spectrometry, we identified a predominant cellular protein that binds to Vpr as the damage-specific DNA-binding protein 1 (DDB1). In addition to its role in the repair of damaged DNA, DDB1 is a component of an E3 ubiquitin ligase that degrades numerous cellular substrates. Interestingly, DDB1 is targeted by specific regulatory proteins of other viruses, including simian virus 5 and hepatitis B. We show that the interaction with DDB1 mediates Vpr-induced apoptosis and UNG2/SMUG1 degradation and impairs the repair of UV-damaged DNA, which could account for G(2) arrest and apoptosis. The interaction with DDB1 may explain several of the diverse biological functions of Vpr and suggests potential roles for Vpr in HIV-1 replication.
HIV-1的辅助蛋白Vpr可引发类似于DNA损伤的反应。在表达Vpr的细胞中，DNA损伤感应激酶ATR被激活，导致G2期阻滞和细胞凋亡。此外，Vpr会使尿嘧啶-DNA糖基化酶UNG2和SMUG1迅速降解。尽管已有报道称几种细胞蛋白可与Vpr结合，但Vpr介导其生物学效应的机制尚不清楚。我们利用串联亲和纯化和质谱分析，鉴定出一种与Vpr结合的主要细胞蛋白为损伤特异性DNA结合蛋白1（DDB1）。除了在受损DNA修复中发挥作用外，DDB1还是一种E3泛素连接酶的组成部分，该酶可降解众多细胞底物。有趣 的是，DDB1是包括猿猴病毒5和乙肝病毒在内的其他病毒的特定调节蛋白的作用靶点。我们发现，与DDB1的相互作用介导了Vpr诱导的细胞凋亡和UNG2/SMUG1降解，并损害了紫外线损伤DNA的修复，这可能是导致G2期阻滞和细胞凋亡的原因。与DDB1的相互作用可能解释了Vpr的多种生物学功能，并提示了Vpr在HIV-复制中的潜在作用。
