Low pH induces swiveling of the glycoprotein heterodimers in the Semliki Forest virus spike complex.
Time-resolved cryoelectron microscopy reveals the first step in the conformational changes that enable membrane fusion in Semliki Forest virus. The neutral pH structure reveals a central cavity within the spike complex, plate-like extensions forming a layer above the membrane, and the paths of the paired transmembrane domains connecting the trimeric spikes and pentamer-hexamer clustered capsid subunits. Low pH treatment results in centrifugal movement of E2, the receptor-binding subunit, centripetal movement of E1 to narrow the central cavity initiating the formation of an E1 trimer, and the extension of the E1 fusion sequence toward the target membrane.
Fuller
S D
SD
Structural Biology Programme, European Molecular Biology Laboratory, Heidelberg Federal Republic of Germany.
Berriman
J A
JA
Butcher
S J
SJ
Gowen
B E
BE
D015925:Cryopreservation; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron / Q000379:methods; D008954:Models, Biological; D009068:Movement; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D012672:Semliki forest virus / Q000648:ultrastructure*; D014758:Viral Core Proteins / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000378:metabolism / Q000648:ultrastructure*; D014771:Virion / Q000648:ultrastructure
D014758:Viral Core Proteins; D014759:Viral Envelope Proteins