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Title | Organisation of the orthobunyavirus tripodal spike and the structural changes induced by low pH and K during entry. |
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Journal, issue, pages | Nat Commun, Vol. 14, Issue 1, Page 5885, Year 2023 |
Publish date | Sep 21, 2023 |
Authors | Samantha Hover / Frank W Charlton / Jan Hellert / Jessica J Swanson / Jamel Mankouri / John N Barr / Juan Fontana / |
PubMed Abstract | Following endocytosis, enveloped viruses employ the changing environment of maturing endosomes as cues to promote endosomal escape, a process often mediated by viral glycoproteins. We previously ...Following endocytosis, enveloped viruses employ the changing environment of maturing endosomes as cues to promote endosomal escape, a process often mediated by viral glycoproteins. We previously showed that both high [K] and low pH promote entry of Bunyamwera virus (BUNV), the prototypical bunyavirus. Here, we use sub-tomogram averaging and AlphaFold, to generate a pseudo-atomic model of the whole BUNV glycoprotein envelope. We unambiguously locate the Gc fusion domain and its chaperone Gn within the floor domain of the spike. Furthermore, viral incubation at low pH and high [K], reminiscent of endocytic conditions, results in a dramatic rearrangement of the BUNV envelope. Structural and biochemical assays indicate that pH 6.3/K in the absence of a target membrane elicits a fusion-capable triggered intermediate state of BUNV GPs; but the same conditions induce fusion when target membranes are present. Taken together, we provide mechanistic understanding of the requirements for bunyavirus entry. |
External links | Nat Commun / PubMed:37735161 / PubMed Central |
Methods | EM (subtomogram averaging) |
Resolution | 13.0 - 16.0 Å |
Structure data | EMDB-15557: Bunyamwera Virus Gn/Gc Glycoprotein Tripod EMDB-15569: Bunyamwera Virus Gn/Gc Glycoprotein Floor Domain EMDB-15579: Bunyamwera Virus Gn/Gc Glycoprotein pH 6.3/K+ Treated |