Second-site mutation outside of the US10-12 domain of Δγ134.5 herpes simplex virus 1 recombinant blocks the shutoff of protein synthesis induced by activated protein kinase R and partially. restores neurovirulence
Second-site mutation outside of the US10-12 domain of Δγ134.5 herpes simplex virus 1 recombinant blocks the shutoff of protein synthesis induced by activated protein kinase R and partially. restores neurovirulence
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DOI：
10.1128/jvi.76.3.942-949.2002
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发表时间：
2002-02-01
影响因子：
5.4
通讯作者：
Roizman, B
中科院分区：
文献类型：
--
作者：
Cassady, KA;Gross, M;Roizman, B
早期的研究表明，单纯疱疹病毒I型（HSV-1）激活蛋白激酶R（PKR），但γ（1）34.5基因产物的产物结合并重定向宿主磷酸酶I，使真核翻译起始因子2（eIF-2 α）的α亚基去磷酸化。因此，gamma（1）34.5基因产物避免了由激活的PKR引起的蛋白质合成关闭的威胁。Deltagamma（1）34.5突变体在人细胞中的连续传代导致分离出两类第二位点补偿突变体。第一个是先前报道的，由U（s）12基因的α启动子与U（s）11基因的编码序列的并列引起。突变体阻断了eIF-2 α的磷酸化，但不能恢复野生型病毒的毒力表型。我们报告了另一类第二位点的补偿突变体，它们不映射到HSV-1基因组的U（s）10-12结构域。该系列中的所有突变体都表现出持续的晚期蛋白质合成，在人类细胞中的较高产量，以及似乎是磷酸酶依赖性的PKR磷酸化降低。eIF-2 α的特异性去磷酸化未得到证实。至少有一个突变体在这一系列表现出部分恢复的毒性表型特征的野生型病毒表型。结果表明，第二个位点的突变反映了激活的功能，旨在阻断干扰素反应途径感染的细胞与目前的HSV的祖先。
Earlier studies have shown that herpes simplex virus type I (HSV-1) activated protein kinase R (PKR) but that the product of the product of the gamma(1)34.5 gene binds and redirects the host phosphatase I to dephosphorylate the alpha subunit of eukaryotic translation initiation factor 2 (eIF-2alpha). In consequence, the gamma(1)34.5 gene product averts the threatened shutoff of protein synthesis caused by activated PKR. Serial passages of Deltagamma(1)34.5 mutants in human cells led to isolation of two classes of second-site, compensatory mutants. The first, reported earlier, resulted from the juxtaposition of the alpha promoter of the U(s)12 gene to the coding sequence of the U(s)11 gene. The mutant blocks the phosphorylation of eIF-2alpha but does not restore the virulence phenotype of the wild-type virus. We report another class of second-site, compensatory mutants that do not map to the U(s)10-12 domain of the HSV-1 genome. All mutants in this series exhibit sustained late protein synthesis, higher yields in human cells, and reduced phosphorylation of PKR that appears to be phosphatase dependent. Specific dephosphorylation of eIF-2alpha was not demonstrable. At least one mutant in this series exhibited a partial restoration of the virulence phenotype characteristic of the wild-type virus phenotype. The results suggest that the second-site mutations reflect activation of fossilized functions designed to block the interferon response pathways in cells infected with the progenitor of present HSV.