Structure and interactions at the viral surface of the envelope protein E1 of Semliki Forest virus.
Roussel, A., Lescar, J., Vaney, M.C., Wengler, G., Wengler, G., Rey, F.A.(2006) Structure 14: 75-86
- PubMed: 16407067 
- DOI: https://doi.org/10.1016/j.str.2005.09.014
- Primary Citation of Related Structures:  
2ALA - PubMed Abstract: 
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.
Organizational Affiliation: 
Laboratoire de Virologie Moléculaire and Structurale, UMR 2472/1157 CNRS-INRA and IFR 115, 91198 Gif-sur-Yvette Cedex, France.