Roussel Alain, Lescar Julien, Vaney Marie-Christine, Wengler Gisela, Wengler Gerd, Rey Félix A
Laboratoire de Virologie Moléculaire and Structurale, UMR 2472/1157 CNRS-INRA and IFR 115, 91198 Gif-sur-Yvette Cedex, France.
Structure. 2006 Jan;14(1):75-86. doi: 10.1016/j.str.2005.09.014.
Semliki Forest virus (SFV) is enveloped by a lipid bilayer enclosed within a glycoprotein cage made by glycoproteins E1 and E2. E1 is responsible for inducing membrane fusion, triggered by exposure to the acidic environment of the endosomes. Acidic pH induces E1/E2 dissociation, allowing E1 to interact with the target membrane, and, at the same time, to rearrange into E1 homotrimers that drive the membrane fusion reaction. We previously reported a preliminary Calpha trace of the monomeric E1 glycoprotein ectodomain and its organization on the virus particle. We also reported the 3.3 A structure of the trimeric, fusogenic conformation of E1. Here, we report the crystal structure of monomeric E1 refined to 3 A resolution and describe the amino acids involved in contacts in the virion. These results identify the major determinants for the E1/E2 icosahedral shell formation and open the way to rational mutagenesis approaches to shed light on SFV assembly.
辛德毕斯病毒（SFV）被包裹在由糖蛋白E1和E2构成的糖蛋白笼内的脂质双分子层中。E1负责诱导膜融合，这是由暴露于内体的酸性环境引发的。酸性pH值诱导E1/E2解离，使E1与靶膜相互作用，同时重排成驱动膜融合反应的E1同三聚体。我们之前报道了单体E1糖蛋白胞外结构域的初步α-碳原子轨迹及其在病毒颗粒上的组织形式。我们还报道了E1三聚体、融合构象的3.3埃结构。在此，我们报道了单体E1的晶体结构，其分辨率提高到了3埃，并描述了病毒粒子中参与接触的氨基酸。这些结果确定了E1/E2二十面体壳形成的主要决定因素，并为阐明SFV组装的合理诱变方法开辟了道路。
