Diverse roles for E4orf3 at late times of infection revealed in an E1B 55-kilodalton protein mutant background.
Diverse roles for E4orf3 at late times of infection revealed in an E1B 55-kilodalton protein mutant background.
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E1B 55 千道尔顿蛋白突变体背景揭示了 E4orf3 在感染后期的不同作用。
DOI：
10.1128/jvi.78.18.9924-9935.2004
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发表时间：
2004
影响因子：
5.4
通讯作者：
Ornelles,DavidA
中科院分区：
文献类型：
--
作者：
Shepard,RobinN;Ornelles,DavidA
当在体外培养的细胞中评价时，不能表达早期区域4（E4 orf 3）的开放阅读框3的C种人腺病毒突变体在表型上与野生型病毒无法区分。然而，E4 orf 3基因功能已在其他病毒突变的背景下进行了富有成效的研究。这项研究确定了E4 orf 3蛋白在缺乏早期区域1B 55-kDa蛋白（E1 B-55 K）功能的情况下的不同作用。在E1 B-55 K缺陷的背景下，E4 orf 3蛋白通过增加爆发大小和感染细胞产生病毒的可能性来促进病毒复制。早期病毒基因表达在E1 B-55 K/E4 orf 3双突变病毒感染的细胞中不受损害。用双突变病毒感染的细胞积累病毒DNA的多联体。然而，E1 B-55 K/E4 orf 3双突变体病毒在MO 59 J细胞中的复制并不比在MO 59 K细胞中更好，在MO 59 J细胞中，病毒DNA串联体不积累，在MO 59 K细胞中，病毒DNA串联体产生，这表明病毒DNA串联不是E1 B-55 K/E4 orf 3双突变体病毒的主要生长缺陷。与野生型病毒感染的细胞相比，E1 B-55 K/E4 orf 3双突变体病毒感染的细胞的细胞核和细胞质中的病毒mRNA的积累严重减少。因此，在E1 B-55 K突变体背景下，E4 orf 3蛋白促进晚期病毒RNA的积累并增强晚期基因表达。最后，在E1 B-55 K突变病毒的情况下，E4 orf 3蛋白在感染的中等晚期抑制宿主细胞翻译并保持细胞的活力。
Species C human adenovirus mutants that fail to express open reading frame 3 of early region 4 (E4orf3) are phenotypically indistinguishable from the wild-type virus when evaluated in cells cultured in vitro. However, E4orf3 gene function has been productively studied in the context of additional viral mutations. This study identifies diverse roles for the E4orf3 protein that are evident in the absence of early region 1B 55-kDa protein (E1B-55K) function. In an E1B-55K-deficient background, the E4orf3 protein promotes viral replication by increasing both the burst size and the probability that an infected cell will produce virus. Early viral gene expression is not impaired in E1B-55K/E4orf3 double mutant virus-infected cells. Cells infected with the double mutant virus accumulated concatemers of viral DNA. However, the E1B-55K/E4orf3 double mutant virus did not replicate any better in MO59J cells, in which viral DNA concatemers did not accumulate, than in MO59K cells, in which viral DNA concatemers were produced, suggesting that viral DNA concatenation is not the primary growth defect of the E1B-55K/E4orf3 double mutant virus. Accumulation of viral mRNA in the nucleus and cytoplasm of E1B-55K/E4orf3 double mutant virus-infected cells was severely reduced compared to that on wild-type virus-infected cells. Thus, in an E1B-55K mutant background, the E4orf3 protein promotes the accumulation of late viral RNA and enhances late gene expression. Finally, within the context of an E1B-55K mutant virus, the E4orf3 protein acts to suppress host cell translation and preserve the viability of cells at moderately late times of infection.