Identification of novel functional regions within the spike glycoprotein of MHV-A59 based on a bioinformatics approach.
Identification of novel functional regions within the spike glycoprotein of MHV-A59 based on a bioinformatics approach.
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DOI：
10.1016/j.virusres.2014.05.023
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发表时间：
2014-08-30
期刊：
影响因子：
5
通讯作者：
Leibowitz JL
中科院分区：
文献类型：
--
作者：
Kaufman G;Liu P;Leibowitz JL
通过分析与 FcγR 的序列相似性来鉴定 MHV-A59 刺突 (S) 蛋白内的功能区域。 C547 取代消除了单克隆抗体对切割 S 的识别。 S 中残基 547 和 581-586 的取代可防止恢复活病毒。 S 中 562/589 和 667/687 位的氨基酸替换会影响病毒复制。 S 中残基 939 的替换会影响病毒的融合特性。小鼠肝炎病毒（MHV）是一种单链正链RNA病毒，能够促进小鼠发生急性和慢性疾病。 MHV 刺突蛋白 (S) 是主要的毒力决定因子，除了与细胞受体结合以介导细胞进入并促进病毒通过细胞-细胞融合传播到邻近细胞外，它还是 FcγRII 受体的分子模拟物。 MHV S 蛋白对 FcγRII 的这种分子模拟也出现在其他谱系 2a β 冠状病毒中，但人类冠状病毒 HCoV-OC43 除外。在这项工作中，我们进行了突变分析，试图鉴定对 FcγRII 分子模拟至关重要的刺突糖蛋白内的特定氨基酸序列。尽管我们未能成功分离出在该特性上存在特定缺陷的突变病毒，但我们发现了一些具有有趣表型的突变。第 547 位半胱氨酸突变为丙氨酸，以及残基 581-586 处的丙氨酸替换是致命的。用相应的 HCoV-OC43 残基亮氨酸替换脯氨酸 939，降低了 MHV 诱导细胞-细胞融合的能力，为早期提出的残基 929-944 构成 MHV S 蛋白的融合肽的提议提供了实验支持。
Identification of functional regions within MHV-A59 spike (S) protein through analysis of sequence similarities with FcγR. C547 substitution abolishes the recognition of cleaved S by monoclonal antibodies. Substitution of residues 547 and 581–586 in S prevents the recovery of a viable virus. Amino acid replacements at positions 562/589 and 667/687 in S affect viral replication. Replacement of residue 939 in S affects the fusogenic properties of the virus. Mouse Hepatitis Virus (MHV) is a single-stranded positive sense RNA virus with the ability to promote acute and chronic diseases in mice. The MHV spike protein (S) is a major virulence determinant which in addition to binding to cellular receptors to mediate cell entry and facilitate virus spread to adjacent cells by cell–cell fusion, also is a molecular mimic of the FcγRII receptor. This molecular mimicry of FcγRII by the MHV S protein is also exhibited by other lineage 2a betacoronaviruses, with the exception of the human coronavirus HCoV-OC43. In this work we undertook a mutational analysis to attempt to identify specific amino acid sequences within the spike glycoprotein crucial for molecular mimicry of FcγRII. Although we were unsuccessful in isolating mutant viruses which were specifically defective in that property, we identified several mutations with interesting phenotypes. Mutation of the cysteine in position 547 to alanine and alanine replacements at residues 581–586 was lethal. Replacing proline 939 with the corresponding HCoV-OC43 residue, leucine, decreased the ability MHV to induce cell–cell fusion, providing experimental support for an earlier proposal that residues 929–944 make up the fusion peptide of the MHV S protein.