The dynamic envelope of a fusion class II virus: E3 domain of glycoprotein E2 precursor in semliki forest virus provides a unique contact with the fusion protein E1

Shang Rung Wu, Lars Haag, Mathilda Sjöberg, Henrik Garoff, Lena Hammar

Research output: Contribution to journalArticle

7 Citations (Scopus)


In alphaviruses, here represented by Semliki Forest virus, infection requires an acid-responsive spike configuration to facilitate membrane fusion. The creation of this relies on the chaperon function of glycoprotein E2 precursor (p62) and its maturation cleavage into the small external E3 and the membrane-anchored E2 glycoproteins. To reveal how the E3 domain of p62 exerts its control of spike functions, we determine the structure of a p62 cleavage-impaired mutant virus particle (SQL) by electron cryomicroscopy. A comparison with the earlier solved wild type virus structure reveals that the E3 domain of p62SQL forms a bulky side protrusion in the spike head region. This establishes a gripper over part of domain II of the fusion protein, with a cotter-like connection downward to a hydrophobic cluster in its central β-sheet. This finding reevaluates the role of the precursor from being only a provider of a shield over the fusion loop to a structural playmate in formation of the fusogenic architecture.

Original languageEnglish
Pages (from-to)26452-26460
Number of pages9
JournalJournal of Biological Chemistry
Issue number39
Publication statusPublished - 2008 Sep 26


All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this