Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.
Proc Natl Acad Sci U S A. 2014 Mar 11;111(10):3829-34. doi: 10.1073/pnas.1319245111. Epub 2014 Feb 24.
Viruses have developed a wide range of strategies to escape from the host cells in which they replicate. For egress some archaeal viruses use a pyramidal structure with sevenfold rotational symmetry. Virus-associated pyramids (VAPs) assemble in the host cell membrane from the virus-encoded protein PVAP and open at the end of the infection cycle. We characterize this unusual supramolecular assembly using a combination of genetic, biochemical, and electron microscopic techniques. By whole-cell electron cryotomography, we monitored morphological changes in virus-infected host cells. Subtomogram averaging reveals the VAP structure. By heterologous expression of PVAP in cells from all three domains of life, we demonstrate that the protein integrates indiscriminately into virtually any biological membrane, where it forms sevenfold pyramids. We identify the protein domains essential for VAP formation in PVAP truncation mutants by their ability to remodel the cell membrane. Self-assembly of PVAP into pyramids requires at least two different, in-plane and out-of-plane, protein interactions. Our findings allow us to propose a model describing how PVAP arranges to form sevenfold pyramids and suggest how this small, robust protein may be used as a general membrane-remodeling system.
病毒已经开发出多种策略来逃避其复制的宿主细胞。为了出芽，一些古细菌病毒使用具有 7 重旋转对称性的金字塔结构。病毒相关的金字塔（VAP）由病毒编码的 PVAP 蛋白组装在宿主细胞膜中，并在感染周期结束时打开。我们使用遗传、生化和电子显微镜技术的组合来表征这种不寻常的超分子组装。通过全细胞电子断层扫描，我们监测了感染病毒的宿主细胞的形态变化。亚断层平均揭示了 VAP 结构。通过在来自生命的三个领域的细胞中异源表达 PVAP，我们证明该蛋白可以不加区分地整合到几乎任何生物膜中，在那里它形成 7 重金字塔。我们通过截短突变体中 VAP 形成所必需的蛋白结构域来识别 PVAP，通过它们重塑细胞膜的能力来识别。PVAP 自组装成金字塔至少需要两种不同的、平面内和平面外的蛋白相互作用。我们的发现使我们能够提出一个模型来描述 PVAP 如何排列形成 7 重金字塔，并提出这种小而稳健的蛋白如何可能被用作通用的膜重塑系统。
