Encapsidation of viral DNA requires the adenovirus L1 52/55-kilodalton protein
Encapsidation of viral DNA requires the adenovirus L1 52/55-kilodalton protein
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DOI：
10.1128/jvi.72.10.7860-7870.1998
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发表时间：
1998-10-01
影响因子：
5.4
通讯作者：
Imperiale, MJ
中科院分区：
文献类型：
--
作者：
Gustin, KE;Imperiale, MJ
以前的工作表明，腺病毒L152kDa蛋白是病毒颗粒组装所必需的，尽管它在组装过程中的确切作用尚不清楚。然而，52/55 kDa蛋白的早期表达表明，它在感染的早期可能还有其他作用。为了揭示52/55-kDa蛋白在早期可能发挥的作用并更好地鉴定其在组装中的作用，构建了一个不能表达52/55-kDa蛋白的突变腺病毒(H5pm8001)。DNA复制和晚期蛋白质合成的开始和程度分析表明，H5pm8001感染的293细胞与5型腺病毒(Ad5)感染的细胞同时进入感染晚期。有趣的是，H5pm8001感染的细胞显示出略低水平的复制病毒DNA和晚期蛋白，这表明虽然不是必需的，但52/55 kDa蛋白在感染期间确实增强了这些活性。对主要的Late和IVa2启动子产生的转录本的分析表明，与Ad5感染的细胞相比，感染H5pm8001的细胞在感染后18小时略有减少，在以后的时间不明显。对H5pm8001细胞中形成的颗粒的分析表明，可以形成空衣壳，这表明52/55 kDa蛋白不具有支架蛋白的功能。随后对这些颗粒的表征表明，它们缺乏任何相关的病毒DNA。这些发现表明，52/55 kDa蛋白是介导病毒DNA与空衣壳之间稳定结合所必需的，并提示它在DNA包埋过程中发挥作用。
Previous work demonstrated that the adenovirus L1 52/55-kDa protein is required for assembly of viral particles, although its exact role in the assembly process is unclear. The 52/55-kDa protein's early expression, however, suggests that it might have other roles at earlier times during infection. To uncover any role the 52/55-kDa protein might have at early times and to better characterize its role in assembly, a mutant adenovirus incapable of expressing the 52/55-kDa protein was constructed (H5pm8001). Analysis of the onset and extent of DNA replication and late protein synthesis revealed that H5pm8001-infected 293 cells entered the late stage of infection at the same time as did adenovirus type 5 (Ad5)-infected cells. Interestingly, H5pm8001-infected cells displayed slightly lower levels of replicated viral DNA and late proteins, suggesting that although not required, the 52/55-kDa protein does augment these activities during infection. Analysis of transcripts produced from the major late and IVa2 promoters indicated a slight reduction in H5pm8001-infected compared to Ad5-infected cells at 18 h postinfection that was not apparent at later times. Analysis of particles formed in H5pm8001 cells revealed that empty capsids could form, suggesting that the 52/55-kDa protein does not function as a scaffolding protein. Subsequent characterization of these particles demonstrated that they lacked any associated viral DNA. These findings indicate that the 52/55 kDa-protein is required to mediate stable association between the viral DNA and empty capsid and suggest that it functions in the DNA encapsidation process.