The structure of tobacco ringspot virus: a link in the evolution of icosahedral capsids in the picornavirus superfamily
The structure of tobacco ringspot virus: a link in the evolution of icosahedral capsids in the picornavirus superfamily
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DOI：
10.1016/s0969-2126(98)00018-5
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发表时间：
1998-02-01
期刊：
影响因子：
5.7
通讯作者：
Johnson, JE
中科院分区：
文献类型：
--
作者：
Chandrasekar, V;Johnson, JE
背景：烟草环斑病毒（TRSV）是二十面体RNA植物病毒中蠕传病毒属的成员，它会在水果作物中引发疾病。蠕传病毒、豇豆花叶病毒和小RNA病毒被归类于小RNA病毒超家族。豇豆花叶病毒和小RNA病毒的晶体结构以及TRSV亚基的分子量（足以容纳三个β - 桶状结构域）表明，蠕传病毒可能代表了小RNA病毒衣壳从T = 3二十面体病毒进化过程中的一个环节。这一进化过程被认为涉及衣壳蛋白基因的三倍化，以编码一个具有三个结构域的多聚蛋白，随后在结构域间连接区域形成切割位点。对TRSV开展结构研究是为了确定TRSV亚基是否对应于所提出的未切割的具有三个结构域的多聚蛋白。
结果：TRSV的3.5埃分辨率结构显示，衣壳蛋白由三个通过延伸的多肽共价连接的β - 桶状结构域组成。TRSV中结构域的连接顺序证实了所提出的切割前的豇豆花叶病毒和小RNA病毒衣壳多聚蛋白的连接方式。TRSV和豇豆花叶病毒中相应结构域之间的结构差异局限于外表面环、结构域间连接多肽和N末端。TRSV和豇豆花叶病毒内的三个不同结构域在结构层面上比小RNA病毒内的三个单独结构域具有更紧密的相关性。
结论：结构研究结果证实了蠕传病毒、豇豆花叶病毒和小RNA病毒的衣壳多聚蛋白从一个共同祖先分歧进化的观点。在各种蠕传病毒中发现了一些保守的残基，其中一些稳定了TRSV衣壳蛋白亚基中三个结构域的四级结构。在TRSV外表面鉴定出两个保守区域，然而，需要进行突变研究来了解它们的功能意义。由相同线虫种类传播的蠕传病毒在病毒表面不具有氨基酸组成相似的区域。
Background: Tobacco ringspot virus (TRSV) is a member of the nepovirus genus of icosahedral RNA plant viruses that cause disease in fruit crops, Nepoviruses, comoviruses and picornaviruses are classified in the picornavirus superfamily. Crystal structures of comoviruses and picornaviruses and the molecular mass of the TRSV subunit (sufficient to accommodate three beta-barrel domains) suggested that nepoviruses may represent a link in the evolution of the picornavirus capsids from a T = 3 icosahedral virus. This evolutionary process is thought to involve triplication of the capsid protein gene, to encode a three-domain polyprotein, followed by development of cleavage sites in the interdomain linking regions. Structural studies on TRSV were initiated to determine if the TRSV subunit corresponds to the proposed uncleaved three-domain polyprotein.Results: The 3.5 Angstrom resolution structure of TRSV shows that the capsid protein consists of three beta-barrel domains covalently linked by extended polypeptides. The order of connectivity of the domains in TRSV confirms the proposed connectivity for the precleaved comovirus and picornavirus capsid polyprotein. Structural differences between equivalent domains in TRSV and comoviruses are confined to the external surface loops, interdomain connecting polypeptides and N termini. The three different domains within TRSV and comoviruses are more closely related at the structural level than the three individual domains within picornaviruses.Conclusions: The structural results confirm the notion of divergent evolution of the capsid polyproteins of nepoviruses, comoviruses and picornaviruses from a common ancestor. A number of residues were found to be conserved among various nepoviruses, some of which stabilize the quaternary structure of the three domains in the TRSV capsid protein subunit, Two conserved regions were identified on the external surface of TRSV, however, mutational studies will be needed to understand their functional significance. Nepoviruses transmitted by the same nematode species do not share regions with similar amino acid composition on the viral surface.