SARS-coronavirus spike S2 domain flanked by cysteine residues C822 and C833 is important for activation of membrane fusion

Virology. 2009 Oct 25;393(2):265-71. doi: 10.1016/j.virol.2009.07.038. Epub 2009 Aug 29.

Abstract

The S2 domain of the coronavirus spike (S) protein is known to be responsible for mediating membrane fusion. In addition to a well-recognized cleavage site at the S1-S2 boundary, a second proteolytic cleavage site has been identified in the severe acute respiratory syndrome coronavirus (SARS-CoV) S2 domain (R797). C-terminal to this S2 cleavage site is a conserved region flanked by cysteine residues C822 and C833. Here, we investigated the importance of this well conserved region for SARS-CoV S-mediated fusion activation. We show that the residues between C822-C833 are well conserved across all coronaviruses. Mutagenic analysis of SARS-CoV S, combined with cell-cell fusion and pseudotyped virion infectivity assays, showed a critical role for the core-conserved residues C822, D830, L831, and C833. Based on available predictive models, we propose that the conserved domain flanked by cysteines 822 and 833 forms a loop structure that interacts with components of the SARS-CoV S trimer to control the activation of membrane fusion.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Fusion
  • Cell Line
  • Chlorocebus aethiops
  • Conserved Sequence
  • Cricetinae
  • Cysteine / genetics*
  • Humans
  • Membrane Fusion*
  • Membrane Glycoproteins / genetics*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • SARS Virus / genetics*
  • SARS Virus / physiology
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins / genetics*

Substances

  • Membrane Glycoproteins
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins
  • spike glycoprotein, SARS-CoV
  • spike protein, mouse hepatitis virus
  • Cysteine