PH-INDUCED ALTERATIONS IN THE FUSOGENIC SPIKE PROTEIN OF SEMLIKI FOREST VIRUS
PH-INDUCED ALTERATIONS IN THE FUSOGENIC SPIKE PROTEIN OF SEMLIKI FOREST VIRUS
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DOI：
10.1083/jcb.101.6.2284
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发表时间：
1985-01-01
影响因子：
7.8
通讯作者：
HELENIUS, A
中科院分区：
文献类型：
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作者：
KIELIAN, M;HELENIUS, A
塞姆利基森林病毒的刺突糖蛋白在弱酸性 pH（pH < 6.2）条件下介导病毒包膜和含胆固醇靶膜之间的膜融合。融合反应对于感染周期至关重要，催化病毒从酸性内体区室渗透。为了确定病毒刺突糖蛋白在融合反应中的作用，使用蛋白酶消化和脂质体和非离子洗涤剂的结合测定来研究刺突在酸性pH下的构象变化。还开发了一种方法来制备刺突的两个跨膜亚基糖多肽E1和E2的片段，其缺乏疏水性锚定肽。与完整的刺突不同，这些片段是单体的，因此可用于获取有关单个亚基构象变化的信息。结果表明，E1 和 E2 在融合 pH 值下都会发生不可逆的构象变化，E1 的构象变化除了酸性 pH 值外，还取决于胆固醇的存在，并且尖峰的溶解度特性没有发生重大变化。基于这些发现，得出的结论是融合涉及尖峰的两个亚基，并且 E1 赋予立体特异性甾醇需求。此外，结果表明，塞姆利基森林病毒的酸诱导融合在重要方面不同于流感病毒，流感病毒是蛋白质介导的膜融合的另一种明确的模型系统。
The spike glycoproteins of Semliki Forest virus mediate membrane fusion between the viral envelope and cholesterol-containing target membranes under conditions of mildly acidic pH (pH < 6.2). The fusion reaction is critical for the infectious cycle, catalyzing virus penetration from the acidic endosome compartment. To define the role of the viral spike glycoproteins in the fusion reaction, conformation changes in the spikes at acid pH were studied using protease digestion and binding assays to liposomes and nonionic detergent. A method was also developed to prepare fragments of both transmembrane subunit glycopolypeptides of the spike, E1 and E2, which lacked the hydrophobic anchor peptides. Unlike the intact spikes the fragments were monomeric and therefore useful for obtaining information on conformational changes in individual subunits. The results showed that both E1 and E2 undergo irreversible conformation changes at the pH of fusion, that the conformational change of E1 depends, in addition to acid pH, on the presence of cholesterol, and that no major changes in the solubility properties of the spikes takes place. On the basis of these findings it was concluded that fusion involves both subunits of the spike and that E1 confers the stereo-specific sterol requirement. The results indicated, moreover, that acid-induced fusion of Semliki Forest virus differs in important respects from that of influenza virus, another well-defined model system for protein-mediated membrane fusion.