Centre de Biochimie Structurale (CBS), INSERM, CNRS, Univ Montpellier, France.
Nanoscale. 2019 Mar 28;11(13):6036-6044. doi: 10.1039/c8nr07269h.
Membrane partition and remodeling play a key role in numerous cell mechanisms, especially in viral replication cycles where viruses subvert the plasma membrane to enter and escape from the host cell. Specifically assembly and release of HIV-1 particles require specific cellular components, which are recruited to the egress site by the viral protein Gag. We previously demonstrated that HIV-1 assembly alters both partitioning and dynamics of the tetraspanins CD9 and CD81, which are key players in many infectious processes, forming enriched areas where the virus buds. In this study we correlated super resolution microscopy mapping of tetraspanins with membrane topography delineated by atomic force microscopy (AFM) in Gag-expressing cells. We revealed that CD9 is specifically trapped within the nascent viral particles, especially at buds tips, suggesting that Gag mediates CD9 and CD81 depletion from the plasma membrane. In addition, we showed that CD9 is organized as small membrane assemblies of few tens of nanometers that can coalesce upon Gag expression.
膜的分区和重塑在众多细胞机制中起着关键作用，特别是在病毒复制周期中，病毒会颠覆质膜以进入和逃离宿主细胞。具体来说，HIV-1 颗粒的组装和释放需要特定的细胞成分，这些成分被病毒蛋白 Gag 招募到出芽部位。我们之前的研究表明，HIV-1 组装改变了四跨膜蛋白 CD9 和 CD81 的分区和动力学，CD9 和 CD81 是许多感染过程中的关键参与者，形成了富含病毒出芽的区域。在这项研究中，我们将超分辨率显微镜对四跨膜蛋白的映射与原子力显微镜（AFM）描绘的膜拓扑结构相关联，在表达 Gag 的细胞中进行研究。我们揭示了 CD9 被特异性地捕获在新形成的病毒颗粒中，特别是在芽突的尖端，这表明 Gag 介导了 CD9 和 CD81 从质膜中的耗竭。此外，我们还表明，CD9 被组织成几十纳米的小膜组装体，在 Gag 表达时可以融合。
