Mutation of a C-terminal motif affects Kaposi's sarcoma-associated herpesvirus ORF57 RNA binding, nuclear trafficking, and multimerization.
Mutation of a C-terminal motif affects Kaposi's sarcoma-associated herpesvirus ORF57 RNA binding, nuclear trafficking, and multimerization.
复制标题
C 末端基序的突变会影响卡波西肉瘤相关疱疹病毒 ORF57 RNA 结合、核运输和多聚化。
DOI：
10.1128/jvi.00138-11
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发表时间：
2011
影响因子：
5.4
通讯作者：
Taylor A
中科院分区：
文献类型：
--
作者：
Taylor A
卡波西肉瘤相关疱疹病毒（KSHV） ORF57蛋白对病毒裂解复制至关重要。ORF57在多个水平上调控病毒基因表达，增强转录、稳定性、核输出和病毒转录物的翻译。为了增强病毒无内含子转录物的核输出，ORF57 (i)结合病毒无内含子mrna， （ii）穿梭于细胞核、核仁和细胞质之间，以及（iii）与多种细胞核输出蛋白相互作用，进入tap介导的核输出途径。我们研究了无法结合RNA的ORF57蛋白对亚细胞运输、细胞核输出因子招募以及最终细胞核mRNA输出的影响。我们观察到，阻止RNA结合的羧基末端RGG基序突变影响ORF57蛋白的亚细胞定位和核运输，表明它形成亚核聚集体。对突变体的进一步分析表明，尽管它仍然保留了与细胞核输出蛋白相互作用的能力，但它不能从细胞核输出病毒无内含子mrna。此外，计算分子模型和生化研究表明，与野生型蛋白不同，这种突变体无法自我结合。因此，这些结果表明羧基末端RGG基序的突变影响ORF57 RNA结合、核运输和多聚。
The Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 protein is essential for virus lytic replication. ORF57 regulates virus gene expression at multiple levels, enhancing transcription, stability, nuclear export, and translation of viral transcripts. To enhance the nuclear export of viral intronless transcripts, ORF57 (i) binds viral intronless mRNAs, (ii) shuttles between the nucleus, nucleolus, and the cytoplasm, and (iii) interacts with multiple cellular nuclear export proteins to access the TAP-mediated nuclear export pathway. We investigated the implications on the subcellular trafficking, cellular nuclear export factor recruitment, and ultimately nuclear mRNA export of an ORF57 protein unable to bind RNA. We observed that mutation of a carboxy-terminal RGG motif, which prevents RNA binding, affects the subcellular localization and nuclear trafficking of the ORF57 protein, suggesting that it forms subnuclear aggregates. Further analysis of the mutant shows that although it still retains the ability to interact with cellular nuclear export proteins, it is unable to export viral intronless mRNAs from the nucleus. Moreover, computational molecular modeling and biochemical studies suggest that, unlike the wild-type protein, this mutant is unable to self-associate. Therefore, these results suggest the mutation of a carboxy-terminal RGG motif affects ORF57 RNA binding, nuclear trafficking, and multimerization.