title: Structure and interactions at the viral surface of the envelope protein E1 of Semliki Forest virus.
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.
authors.affiliation: Laboratoire de Virologie Moléculaire and Structurale, UMR 2472/1157 CNRS-INRA and IFR 115, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Roussel
authors.forename: Julien
authors.initials: J
authors.lastname: Lescar
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Vaney
authors.forename: Gisela
authors.initials: G
authors.lastname: Wengler
authors.forename: Gerd
authors.initials: G
authors.lastname: Wengler
authors.forename: Félix A
authors.initials: FA
authors.lastname: Rey
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D006023:Glycoproteins; D006639:Histidine / Q000235:genetics; D008055:Lipids / Q000502:physiology; D008561:Membrane Fusion / Q000502:physiology; D050576:Membrane Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012672:Semliki forest virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: C494127:E1 glycoprotein, Semliki forest virus; D006023:Glycoproteins; D008055:Lipids; D050576:Membrane Fusion Proteins; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D006639:Histidine