Specific encapsidation of nodavirus RNAs is mediated through the C terminus of capsid precursor protein alpha.
Specific encapsidation of nodavirus RNAs is mediated through the C terminus of capsid precursor protein alpha.
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诺达病毒RNA的特异性衣壳化是通过衣壳前体蛋白α的C末端介导的。
DOI：
10.1128/jvi.72.11.8738-8746.1998
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发表时间：
1998
影响因子：
5.4
通讯作者：
Marshall,D
中科院分区：
文献类型：
--
作者：
Schneemann,A;Marshall,D
鸡舍病毒（FHV）是一种小的二十面体昆虫病毒，具有二部信使RNA基因组。其T=3二十面体衣壳最初由一种单一类型的衣壳前体蛋白α（407个氨基酸）的180个亚基组装而成。组装后，前体颗粒经历一个成熟步骤，其中α亚基在Asn363和Ala364之间自动催化分裂。这种切割产生成熟的外壳蛋白β（363个残基）和γ（44个残基），这是获得病毒粒子感染性所必需的。成熟FHV的x射线结构显示，位于病毒粒子五重轴的γ肽形成一个五聚体螺旋束，这表明该束在FHV剥膜过程中发挥病毒RNA释放的作用。为了为这一假设提供实验支持，我们生成了在前体蛋白α的伽马区域携带缺失的突变外壳蛋白。令人惊讶的是，我们发现这些突变干扰了病毒RNA在组装过程中的特异性识别和包装。产生的颗粒含有大量的细胞rna和不同数量的病毒rna。单位点氨基酸替代突变表明，位于外壳前体蛋白α的402、405和407位置的3个苯丙氨酸对FHV基因组的特异性识别至关重要。因此，除了在脱包衣和RNA递送中假设的作用外，外壳蛋白α的c端区域在组装过程中对FHV RNA的识别中起着重要作用。讨论了这两个功能之间的可能联系。
Flock house virus (FHV) is a small icosahedral insect virus with a bipartite, messenger-sense RNA genome. Its T=3 icosahedral capsid is initially assembled from 180 subunits of a single type of coat protein, capsid precursor protein alpha (407 amino acids). Following assembly, the precursor particles undergo a maturation step in which the alpha subunits autocatalytically cleave between Asn363 and Ala364. This cleavage generates mature coat proteins beta (363 residues) and gamma (44 residues) and is required for acquisition of virion infectivity. The X-ray structure of mature FHV shows that gamma peptides located at the fivefold axes of the virion form a pentameric helical bundle, and it has been suggested that this bundle plays a role in release of viral RNA during FHV uncoating. To provide experimental support for this hypothesis, we generated mutant coat proteins that carried deletions in the gamma region of precursor protein alpha. Surprisingly, we found that these mutations interfered with specific recognition and packaging of viral RNA during assembly. The resulting particles contained large amounts of cellular RNAs and varying amounts of the viral RNAs. Single-site amino acid substitution mutants showed that three phenylalanines located at positions 402, 405, and 407 of coat precursor protein alpha were critically important for specific recognition of the FHV genome. Thus, in addition to its hypothesized role in uncoating and RNA delivery, the C-terminal region of coat protein alpha plays a significant role in recognition of FHV RNA during assembly. A possible link between these two functions is discussed.