Banjara Suresh, Caria Sofia, Dixon Linda K, Hinds Mark G, Kvansakul Marc
Department of Biochemistry & Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia.
Pirbright Institute, Pirbright, Surrey, England.
J Virol. 2017 Feb 28;91(6). doi: 10.1128/JVI.02228-16. Print 2017 Mar 15.
Programmed cell death is a tightly controlled process critical for the removal of damaged or infected cells. Pro- and antiapoptotic proteins of the Bcl-2 family are pivotal mediators of this process. African swine fever virus (ASFV) is a large DNA virus, the only member of the family, and harbors A179L, a putative Bcl-2 like protein. A179L has been shown to bind to several proapoptotic Bcl-2 proteins; however, the hierarchy of binding and the structural basis for apoptosis inhibition are currently not understood. We systematically evaluated the ability of A179L to bind proapoptotic Bcl-2 family members and show that A179L is the first antiapoptotic Bcl-2 protein to bind to all major death-inducing mammalian Bcl-2 proteins. We then defined the structural basis for apoptosis inhibition of A179L by determining the crystal structures of A179L bound to both Bid and Bax BH3 motifs. Our findings provide a mechanistic understanding for the potent antiapoptotic activity of A179L by identifying it as the first panprodeath Bcl-2 binder and serve as a platform for more-detailed investigations into the role of A179L during ASFV infection. Numerous viruses have acquired strategies to subvert apoptosis by encoding proteins capable of sequestering proapoptotic host proteins. African swine fever virus (ASFV), a large DNA virus and the only member of the family, encodes the protein A179L, which functions to prevent apoptosis. We show that A179L is unusual among antiapoptotic Bcl-2 proteins in being able to physically bind to all core death-inducing mammalian Bcl-2 proteins. Currently, little is known regarding the molecular interactions between A179L and the proapoptotic Bcl-2 members. Using the crystal structures of A179L bound to two of the identified proapoptotic Bcl-2 proteins, Bid and Bax, we now provide a three-dimensional (3D) view of how A179L sequesters host proapoptotic proteins, which is crucial for subverting premature host cell apoptosis.
程序性细胞死亡是一个严格控制的过程，对于清除受损或感染的细胞至关重要。Bcl-2家族的促凋亡蛋白和抗凋亡蛋白是这一过程的关键调节因子。非洲猪瘟病毒（ASFV）是一种大型DNA病毒，是该病毒家族的唯一成员，它含有一种假定的类Bcl-2蛋白A179L。研究表明，A179L能与多种促凋亡Bcl-2蛋白结合；然而，目前尚不清楚其结合的优先级以及抑制细胞凋亡的结构基础。我们系统地评估了A179L与促凋亡Bcl-2家族成员结合的能力，结果表明A179L是首个能与所有主要诱导死亡的哺乳动物Bcl-2蛋白结合的抗凋亡Bcl-2蛋白。随后，通过确定A179L与Bid和Bax BH3基序结合的晶体结构，我们明确了A179L抑制细胞凋亡的结构基础。我们的研究结果通过将A179L鉴定为首个泛促死亡Bcl-2结合蛋白，为其强大的抗凋亡活性提供了机制上的理解，并为更详细地研究A179L在ASFV感染过程中的作用提供了一个平台。许多病毒通过编码能够隔离促凋亡宿主蛋白的蛋白质来获得颠覆细胞凋亡的策略。非洲猪瘟病毒（ASFV）是一种大型DNA病毒，是该病毒家族的唯一成员，它编码的蛋白A179L具有防止细胞凋亡的功能。我们发现，A179L在抗凋亡Bcl-2蛋白中与众不同，它能够与所有核心的诱导死亡的哺乳动物Bcl-2蛋白发生物理结合。目前，关于A179L与促凋亡Bcl-2成员之间的分子相互作用知之甚少。利用A179L与两种已鉴定的促凋亡Bcl-2蛋白Bid和Bax结合的晶体结构，我们现在提供了一个三维（3D）视角，展示了A179L如何隔离宿主促凋亡蛋白，这对于颠覆宿主细胞过早凋亡至关重要。
