Membrane fusion mutants of Semliki Forest virus.
Membrane fusion mutants of Semliki Forest virus.
复制标题
Semliki森林病毒的膜融合突变体。
DOI：
10.1083/jcb.98.1.139
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发表时间：
1984-01
影响因子：
7.8
通讯作者：
Helenius, A
中科院分区：
文献类型：
--
作者：
Kielian, M C;Keranen, S;Kaariainen, L;Helenius, A
以前的报道表明，Semliki森林病毒（SFV）进入细胞依赖于由病毒刺突糖蛋白催化的膜融合反应，并由内体区室中普遍存在的低pH触发。在这项研究中，SFV与核酸酶填充的脂质体的体外pH依赖性融合已被用于选择具有pH条件缺陷的一类新的病毒突变体。当通过多核体形成、与脂质体融合或在质膜上融合进行测定时，所获得的突变体的融合阈值为pH5.5，而野生型的融合阈值为6.2。它们完全能够在标准感染条件下感染细胞，但对增加内吞途径酸性空泡中pH值的亲溶酶体剂更敏感。此外，突变体能够在20摄氏度下穿透并感染幼仓鼠肾-21细胞，这表明内体的pH值低于5.5。结果证实了SFV进入的pH触发的融合的参与，强调酸性内体空泡在此反应中发挥的核心作用，进一步阐明了亲溶酶体弱碱抑制SFV的机制，并证明了突变病毒作为内吞途径的生物pH探针的有用性。
Previous reports have indicated that the entry of Semliki Forest virus (SFV) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low pH prevailing in the endosomal compartment. In this study the in vitro pH-dependent fusion of SFV with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a pH-conditional defect. The mutants obtained had a threshold for fusion of pH 5.5 as compared with the wild- type threshold of 6.2, when assayed by polykaryon formation, fusion with liposomes, or fusion at the plasma membrane. They were fully capable of infecting cells under standard infection conditions but were more sensitive to lysosomotropic agents that increase the pH in acidic vacuoles of the endocytic pathway. The mutants were, moreover, able to penetrate and infect baby hamster kidney-21 cells at 20 degrees C, indicating that the endosomes have a pH below 5.5. The results confirm the involvement of pH-triggered fusion in SFV entry, emphasize the central role played by acidic endosomal vacuoles in this reaction, shed further light on the mechanism of SFV inhibition by lysosomotropic weak bases, and demonstrate the usefulness of mutant viruses as biological pH probes of the endocytic pathway.