Finnen Renée L, Zhu Mingzhao, Li Jing, Romo Daniel, Banfield Bruce W
Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.
Department of Chemistry, Texas A&M University, College Station, Texas, USA.
J Virol. 2016 Aug 12;90(17):7943-55. doi: 10.1128/JVI.00947-16. Print 2016 Sep 1.
We previously established that cells infected with herpes simplex virus 2 (HSV-2) are disrupted in their ability to form stress granules (SGs) in response to oxidative stress and that this disruption is mediated by virion host shutoff protein (vhs), a virion-associated endoribonuclease. Here, we test the requirement for vhs endoribonuclease activity in disruption of SG formation. We analyzed the ability of HSV-2 vhs carrying the point mutation D215N, which ablates its endoribonuclease activity, to disrupt SG formation in both transfected and infected cells. We present evidence that ablation of vhs endoribonuclease activity results in defects in vhs-mediated disruption of SG formation. Furthermore, we demonstrate that preformed SGs can be disassembled by HSV-2 infection in a manner that requires vhs endoribonuclease activity and that, befitting this ability to promote SG disassembly, vhs is able to localize to SGs. Together these data indicate that endoribonuclease activity must be maintained in order for vhs to disrupt SG formation. We propose a model whereby vhs-mediated destruction of SG mRNA promotes SG disassembly and may also prevent SG assembly.
Stress granules (SGs) are transient cytoplasmic structures that form when a cell is exposed to stress. SGs are emerging as potential barriers to viral infection, necessitating a more thorough understanding of their basic biology. We identified virion host shutoff protein (vhs) as a herpes simplex virus 2 (HSV-2) protein capable of disrupting SG formation. As mRNA is a central component of SGs and the best-characterized activity of vhs is as an endoribonuclease specific for mRNA in vivo, we investigated the requirement for vhs endoribonuclease activity in disruption of SG formation. Our studies demonstrate that endoribonuclease activity is required for vhs to disrupt SG formation and, more specifically, that SG disassembly can be driven by vhs endoribonuclease activity. Notably, during the course of these studies we discovered that there is an ordered departure of SG components during their disassembly and, furthermore, that vhs itself has the capacity to localize to SGs.
我们之前已经确定，感染单纯疱疹病毒2型（HSV-2）的细胞在应对氧化应激时形成应激颗粒（SGs）的能力受到破坏，并且这种破坏是由病毒体宿主关闭蛋白（vhs）介导的，vhs是一种与病毒体相关的核糖核酸内切酶。在此，我们测试了vhs核糖核酸内切酶活性在破坏SG形成过程中的必要性。我们分析了携带点突变D215N（该突变消除了其核糖核酸内切酶活性）的HSV-2 vhs在转染细胞和感染细胞中破坏SG形成的能力。我们提供的证据表明，vhs核糖核酸内切酶活性的缺失导致vhs介导的SG形成破坏存在缺陷。此外，我们证明预先形成的SGs可被HSV-2感染以一种需要vhs核糖核酸内切酶活性的方式拆解，并且，与这种促进SG拆解的能力相符的是，vhs能够定位于SGs。这些数据共同表明，为了使vhs破坏SG形成，必须维持核糖核酸内切酶活性。我们提出了一个模型，即vhs介导的SG mRNA破坏促进SG拆解，并且可能还会阻止SG组装。
应激颗粒（SGs）是细胞在受到应激时形成的短暂细胞质结构。SGs正成为病毒感染的潜在障碍，因此有必要更深入地了解其基本生物学特性。我们确定病毒体宿主关闭蛋白（vhs）是一种能够破坏SG形成的单纯疱疹病毒2型（HSV-2）蛋白。由于mRNA是SGs的核心成分，并且vhs最具特征的活性是作为体内对mRNA特异的核糖核酸内切酶，我们研究了vhs核糖核酸内切酶活性在破坏SG形成过程中的必要性。我们的研究表明，vhs破坏SG形成需要核糖核酸内切酶活性，更具体地说，SG拆解可由vhs核糖核酸内切酶活性驱动。值得注意的是，在这些研究过程中我们发现，SG成分在拆解过程中有一个有序的脱离，此外，vhs自身有定位于SGs的能力。
