Alphavirus genome replication is carried out by the viral replication complex inside modified membrane structures called spherules. The viral nonstructural protein 1 (nsP1) is the only membrane-associated protein that anchors the replication complex to the cellular membranes. Although an internal amphipathic helix of nsP1 is critical for membrane association, the mechanism of nsP1 interaction with membranes and subsequent membrane reorganization is not well understood. We studied the membrane interaction of chikungunya virus (CHIKV) nsP1 and show that both the CHIKV nsP1 protein and the amphipathic peptide specifically bind to negatively charged phospholipid vesicles. Using cryo-electron microscopy, we further show that nsP1 forms a contiguous coat on lipid vesicles and induces structural reorganization, while the amphipathic peptide alone failed to deform the membrane bilayer. This suggests that although amphipathic helix of nsP1 is required for initial membrane binding, the remaining cytoplasmic domain of nsP1 is involved in the subsequent membrane reorganization.

甲病毒基因组复制是通过称为小球的修饰膜结构内的病毒复制复合物进行的。病毒非结构蛋白 1 (nsP1) 是唯一将复制复合物锚定在细胞膜上的膜相关蛋白。尽管 nsP1 的内部两亲螺旋对于膜缔合至关重要，但 nsP1 与膜相互作用以及随后的膜重组的机制尚不清楚。我们研究了基孔肯雅病毒 (CHIKV) nsP1 的膜相互作用，结果表明 CHIKV nsP1 蛋白和两亲性肽均特异性结合带负电荷的磷脂囊泡。使用冷冻电子显微镜，我们进一步表明 nsP1 在脂质囊泡上形成连续的外壳并诱导结构重组，而单独的两亲肽未能使膜双层变形。这表明虽然初始膜结合需要 nsP1 的两亲性螺旋，但 nsP1 剩余的胞质结构域参与随后的膜重组。