Ivanova L, Schlesinger M J
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093.
J Virol. 1993 May;67(5):2546-51. doi: 10.1128/JVI.67.5.2546-2551.1993.
The assembly and budding of Sindbis virus, a prototypic member of the alphavirus subgroup in the family Togaviridae, requires a specific interaction between the nucleocapsid core and the membrane-embedded glycoproteins E1 and E2. These glycoproteins are modified posttranslationally by the addition of palmitic acid, and inhibitors of acylation interfere with this budding process (M.J. Schlesinger and C. Malfer, J. Biol. Chem. 257:9887-9890, 1982). This report describes the use of site-directed mutagenesis to identify two of the acylation sites in the E2 glycoprotein as the cysteines near the carboxyl terminus of the protein which is oriented to the cytoplasmic domain of this type 1 transmembrane protein. Additional mutations were made at two prolines within a hydrophobic sequence of E2 that is highly conserved among several alphaviruses, and the mutant viruses were aberrant in assembly and particle formation. These data support earlier studies indicating that the native structure of the cytoplasmic domain of E2 is essential for proper assembly of this enveloped virus.
辛德毕斯病毒是披膜病毒科甲病毒亚组的原型成员，其装配和出芽需要核衣壳核心与膜嵌入糖蛋白E1和E2之间的特定相互作用。这些糖蛋白在翻译后通过添加棕榈酸进行修饰，酰化抑制剂会干扰这种出芽过程（M.J.施莱辛格和C.马尔弗，《生物化学杂志》257:9887 - 9890，1982）。本报告描述了使用定点诱变来鉴定E2糖蛋白中的两个酰化位点，即该蛋白羧基末端附近的半胱氨酸，该末端朝向这种1型跨膜蛋白的胞质结构域。在E2疏水序列中的两个脯氨酸处进行了额外的突变，该序列在几种甲病毒中高度保守，突变病毒在装配和颗粒形成方面异常。这些数据支持了早期的研究，表明E2胞质结构域的天然结构对于这种包膜病毒的正确装配至关重要。
