Department of Virology, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Nat Commun. 2012;3:1235. doi: 10.1038/ncomms2252.
An RNA virus population generally evolves rapidly under selection pressure, because of high error rates of the viral RNA polymerase. Measles virus, an enveloped RNA virus, has a fusion protein mediating fusion of the viral envelope with the cell membrane. Here we observe that a non-fusogenic recombinant measles virus evolves, after passages, into mutant viruses which regain the ability to induce membrane fusion. Unexpectedly, we identify a mutant virus possessing two types of genomes within a single virion: one genome encoding the wild-type fusion protein, the other a mutant version with a single amino-acid substitution. Neither the wild-type nor mutant protein by itself is able to mediate membrane fusion, but both together exhibit enhanced fusion activity through hetero-oligomer formation. Our results reveal a molecular mechanism for the 'cooperation' between different RNA virus genomes, which may have implications in viral evolution and in the evolution of other macromolecules.
在选择压力下，由于病毒 RNA 聚合酶的高错误率，RNA 病毒群体通常会迅速进化。麻疹病毒是一种包膜 RNA 病毒，其融合蛋白介导病毒包膜与细胞膜的融合。在这里，我们观察到一种非融合性重组麻疹病毒在传代后进化为能够重新获得诱导膜融合能力的突变病毒。出乎意料的是，我们鉴定出一种突变病毒在单个病毒粒子内具有两种类型的基因组：一种基因组编码野生型融合蛋白，另一种基因组是具有单个氨基酸取代的突变体。野生型或突变型蛋白本身都不能介导膜融合，但两者通过异源寡聚体形成共同表现出增强的融合活性。我们的结果揭示了不同 RNA 病毒基因组之间“合作”的分子机制，这可能对病毒进化和其他大分子的进化具有重要意义。
