The Fusion glycoprotein shell of Semliki Forest virus: an icosahedral assembly primed for fusogenic activation at endosomal pH.
Semliki Forest virus (SFV) has been extensively studied as a model for analyzing entry of enveloped viruses into target cells. Here we describe the trace of the polypeptide chain of the SFV fusion glycoprotein, E1, derived from an electron density map at 3.5 A resolution and describe its interactions at the surface of the virus. E1 is unexpectedly similar to the flavivirus envelope protein, with three structural domains disposed in the same primary sequence arrangement. These results introduce a new class of membrane fusion proteins which display lateral interactions to induce the necessary curvature and direct budding of closed particles. The resulting surface protein lattice is primed to cause membrane fusion when exposed to the acidic environment of the endosome.
Lescar
J
J
Laboratoire de Génétique des Virus, CNRS-UPR 9053, 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
Roussel
A
A
Wien
M W
MW
Navaza
J
J
Fuller
S D
SD
Wengler
G
G
Wengler
G
G
Rey
F A
FA
D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D019281:Dimerization; D011992:Endosomes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008561:Membrane Fusion; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012672:Semliki forest virus / Q000737:chemistry* / Q000648:ultrastructure*; D014759:Viral Envelope Proteins / Q000737:chemistry; D014760:Viral Fusion Proteins / Q000737:chemistry*
D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; C065696:glycoprotein E, Flavivirus