Alphavirus Nucleocapsid Protein Contains a Putative Coiled Coil α-Helix Important for Core Assembly
Alphavirus Nucleocapsid Protein Contains a Putative Coiled Coil α-Helix Important for Core Assembly
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甲病毒核衣壳蛋白含有对核心组装很重要的假定卷曲螺旋 α 螺旋
作者：
R. Perera;K. E. Owen;T. Tellinghuisen;A. Gorbalenya;R. Kuhn
甲病毒核衣壳核心是由衣壳蛋白介导的多种非共价相互作用的能量贡献形成的。该蛋白由一个保守性差的未知功能的N-末端区域和一个在病毒体形成中起主要作用的C-末端保守的自身蛋白酶结构域组成。在这项研究中，一个18个氨基酸的保守区，预测折叠成α-螺旋（螺旋I），并嵌入在一个低复杂性的序列富含碱性和Pro残基，已被确定在甲病毒衣壳蛋白的N-末端区域。在辛德毕斯病毒中，螺旋I跨越残基38至55，并含有三个保守的亮氨酸残基，L38，L45和L52，符合亮氨酸拉链蛋白中明显的七肽氨基酸组织。HexaminI由一个N-末端截短的七肽和两个完整的七肽重复序列组成，其中β-分支残基和保守的亮氨酸残基分别占据螺旋的a和d位置。完全或部分删除螺旋I，或在保守的亮氨酸残基（L45和L52）的单位点取代，引起病毒复制显着减少。突变体病毒对温度的敏感性高于野生型病毒。这些突变病毒也无法在感染细胞的细胞质中积累核心，尽管它们在蛋白质翻译或加工方面没有缺陷。使用体外组装系统对这些突变体进行分析表明，大多数突变体在核心颗粒组装中有缺陷。此外，突变体蛋白质在涉及突变体和野生型蛋白质的体外组装反应中表现出反式显性负表型。我们认为螺旋I通过卷曲螺旋相互作用在核壳核心的组装中发挥着核心作用。这些相互作用可以稳定通过衣壳蛋白的C-末端结构域和基因组RNA的相互作用形成的亚病毒中间体，并有助于病毒体的稳定性。
ABSTRACT The alphavirus nucleocapsid core is formed through the energetic contributions of multiple noncovalent interactions mediated by the capsid protein. This protein consists of a poorly conserved N-terminal region of unknown function and a C-terminal conserved autoprotease domain with a major role in virion formation. In this study, an 18-amino-acid conserved region, predicted to fold into an α-helix (helix I) and embedded in a low-complexity sequence enriched with basic and Pro residues, has been identified in the N-terminal region of the alphavirus capsid proteins. In Sindbis virus, helix I spans residues 38 to 55 and contains three conserved leucine residues, L38, L45, and L52, conforming to the heptad amino acid organization evident in leucine zipper proteins. Helix I consists of an N-terminally truncated heptad and two complete heptad repeats with β-branched residues and conserved leucine residues occupying the a andd positions of the helix, respectively. Complete or partial deletion of helix I, or single-site substitutions at the conserved leucine residues (L45 and L52), caused a significant decrease in virus replication. The mutant viruses were more sensitive to elevated temperature than wild-type virus. These mutant viruses also failed to accumulate cores in the cytoplasm of infected cells, although they did not have defects in protein translation or processing. Analysis of these mutants using an in vitro assembly system indicated that the majority were defective in core particle assembly. Furthermore, mutant proteins showed a trans-dominant negative phenotype in in vitro assembly reactions involving mutant and wild-type proteins. We propose that helix I plays a central role in the assembly of nucleocapsid cores through coiled coil interactions. These interactions may stabilize subviral intermediates formed through the interactions of the C-terminal domain of the capsid protein and the genomic RNA and contribute to the stability of the virion.
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辛德比斯病毒刺突蛋白复合物的组装。
DOI：
10.1006/viro.1996.0229
发表时间：
1996
期刊：
Virology.
影响因子：
--
作者：
Mulvey,M;Brown,DT
通讯作者：
Brown,DT
影响因子：
56.9
作者：
C. Xiong;R. Levis;P. Shen;S. Schlesinger;C. Rice;Henry Huang
通讯作者：
C. Xiong;R. Levis;P. Shen;S. Schlesinger;C. Rice;Henry Huang
影响因子：
56.9
作者：
HARBURY, PB;ZHANG, T;ALBER, T
通讯作者：
ALBER, T
甲病毒出芽依赖于核衣壳和 E2 包膜糖蛋白胞质结构域上的疏水性氨基酸之间的相互作用。
DOI：
10.1006/viro.1997.8480
发表时间：
1997
期刊：
Virology.
影响因子：
--
作者：
Owen,KE;Kuhn,RJ
通讯作者：
Kuhn,RJ
影响因子：
5.7
作者：
Stehle, T;Gamblin, SJ;Harrison, SC
通讯作者：
Harrison, SC