Interaction between heptad repeat 1 and 2 regions in spike protein of SARS-associated coronavirus: implications for virus fusogenic mechanism and identification of fusion inhibitors

Lancet. 2004 Mar 20;363(9413):938-47. doi: 10.1016/S0140-6736(04)15788-7.


Background: Studies on the fusion-inhibitory peptides derived from the heptad repeat 1 and 2 (HR1 and HR2) regions of the HIV-1 envelope glycoprotein gp41 provided crucial information on the viral fusogenic mechanism. We used a similar approach to study the fusogenic mechanism of severe-acute-respiratory-syndrome-associated coronavirus (SARS-CoV).

Methods: We tested the inhibitory activity against infection of two sets of peptides corresponding to sequences of SARS-CoV spike protein HR1 and HR2 regions and investigated the interactions between the HR1 and HR2 peptides by surface plasmon resonance, sedimentation equilibration analysis, circular dichroism, native polyacrylamide-gel electrophoresis, size exclusion high-performance liquid chromatography, and computer-aided homology modelling and molecule docking analysis.

Findings: One peptide, CP-1, derived from the HR2 region, inhibited SARS-CoV infection in the micromolar range. CP-1 bound with high affinity to a peptide from the HR1 region, NP-1. CP-1 alone had low alpha-helicity and self-associated to form a trimer in phosphate buffer (pH 7.2). CP-1 and NP-1 mixed in equimolar concentrations formed a six-helix bundle, similar to the fusogenic core structure of HIV-1 gp41.

Interpretation: After binding to the target cell, the transmembrane spike protein might change conformation by association between the HR1 and HR2 regions to form an oligomeric structure, leading to fusion between the viral and target-cell membranes. At the prefusion intermediate state, CP-1 could bind to the HR1 region and interfere with the conformational changes, resulting in inhibition of SARS-CoV fusion with the target cells. CP-1 might be modifiable to increase its anti-SARS-CoV activity and could be further developed as an antiviral agent for treatment or prophylaxis of SARS-CoV infection.

MeSH terms

  • Anti-HIV Agents / chemistry
  • Anti-HIV Agents / pharmacology
  • Cells, Cultured
  • Chemical Fractionation
  • Chromatography, High Pressure Liquid
  • Circular Dichroism
  • Electrophoresis, Polyacrylamide Gel
  • HIV Envelope Protein gp41 / chemistry
  • HIV Envelope Protein gp41 / drug effects
  • HIV Envelope Protein gp41 / metabolism
  • HIV Envelope Protein gp41 / pharmacology
  • Humans
  • Membrane Fusion / drug effects
  • Membrane Fusion / physiology*
  • Membrane Glycoproteins / chemistry*
  • Membrane Glycoproteins / metabolism
  • Membrane Glycoproteins / pharmacology
  • Oligopeptides / chemistry
  • Oligopeptides / drug effects
  • Oligopeptides / metabolism
  • Protein Conformation / drug effects
  • SARS Virus / chemistry*
  • SARS Virus / drug effects
  • SARS Virus / metabolism
  • Sequence Homology, Nucleic Acid
  • Severe Acute Respiratory Syndrome / drug therapy
  • Severe Acute Respiratory Syndrome / metabolism*
  • Severe Acute Respiratory Syndrome / prevention & control
  • Spike Glycoprotein, Coronavirus
  • Surface Plasmon Resonance
  • Viral Envelope Proteins / chemistry*
  • Viral Envelope Proteins / metabolism
  • Viral Envelope Proteins / pharmacology
  • Viral Fusion Proteins / chemistry*
  • Viral Fusion Proteins / metabolism


  • Anti-HIV Agents
  • CP-1 peptide
  • HIV Envelope Protein gp41
  • Membrane Glycoproteins
  • Oligopeptides
  • Spike Glycoprotein, Coronavirus
  • Viral Envelope Proteins
  • Viral Fusion Proteins