The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
J Virol. 2012 Nov;86(21):11501-11. doi: 10.1128/JVI.01115-12. Epub 2012 Aug 15.
Many viruses express inhibitors of programmed cell death (apoptosis), thereby countering host defenses that would otherwise rapidly clear infected cells. To counter this, viruses such as adenoviruses and herpesviruses express recognizable homologs of the mammalian prosurvival protein Bcl-2. In contrast, the majority of poxviruses lack viral Bcl-2 (vBcl-2) homologs that are readily identified by sequence similarities. One such virus, myxoma virus, which is the causative agent of myxomatosis, expresses a virulence factor that is a potent inhibitor of apoptosis. In spite of the scant sequence similarity to Bcl-2, myxoma virus M11L adopts an almost identical 3-dimensional fold. We used M11L as bait in a sequence similarity search for other Bcl-2-like proteins and identified six putative vBcl-2 proteins from poxviruses. Some are potent inhibitors of apoptosis, in particular sheeppox virus SPPV14, which inhibited cell death induced by multiple agents. Importantly, SPPV14 compensated for the loss of antiapoptotic F1L in vaccinia virus and acts to directly counter the cell death mediators Bax and Bak. SPPV14 also engages a unique subset of the death-promoting BH3-only ligands, including Bim, Puma, Bmf, and Hrk. This suggests that SPPV14 may have been selected for specific biological roles as a virulence factor for sheeppox virus.
许多病毒表达细胞程序性死亡(凋亡)抑制剂,从而抵抗宿主防御,否则这些宿主防御会迅速清除感染细胞。为了对抗这种情况,腺病毒和疱疹病毒等病毒表达可识别的哺乳动物生存蛋白 Bcl-2 的同源物。相比之下,大多数痘病毒缺乏可通过序列相似性轻松识别的病毒 Bcl-2(vBcl-2)同源物。一种这样的病毒,即兔粘液瘤病毒,是粘液瘤病的病原体,表达一种毒力因子,是一种有效的凋亡抑制剂。尽管与 Bcl-2 的序列相似性很少,但兔粘液瘤病毒 M11L 采用几乎相同的三维折叠。我们使用 M11L 作为诱饵进行序列相似性搜索,以寻找其他 Bcl-2 样蛋白,并从痘病毒中鉴定出六个推定的 vBcl-2 蛋白。其中一些是凋亡的有效抑制剂,特别是绵羊痘病毒 SPPV14,它抑制了多种药物诱导的细胞死亡。重要的是,SPPV14 补偿了牛痘病毒中抗凋亡 F1L 的缺失,并直接作用于细胞死亡介质 Bax 和 Bak。SPPV14 还与一组独特的促死亡 BH3 仅配体结合,包括 Bim、Puma、Bmf 和 Hrk。这表明 SPPV14 可能作为绵羊痘病毒的毒力因子被选择用于特定的生物学作用。