Biophysical characterization of HRC peptide analogs interaction with heptad repeat regions of the SARS-coronavirus Spike fusion protein core

J Struct Biol. 2006 Aug;155(2):162-75. doi: 10.1016/j.jsb.2006.03.024. Epub 2006 Apr 27.

Abstract

The Spike (S) protein of SARS-coronavirus (SARS-CoV) mediates viral entry into host cells. It contains two heptad repeat regions, denoted HRN and HRC. We have identified the location of the two interacting HR regions that form the six-helix bundle (B. Tripet, et al, J. Biol. Chem., 279: 20836-20849, 2004). In this study, HRC peptide (1150-1185) was chosen as the region to make structure-based substitutions to design a series of HRC analogs with increased hydrophobicity, helical propensity and electrostatic interactions, or with a covalent constraint (lactam bridge) to stabilize the alpha-helical conformation. Effects of the substitutions on alpha-helical structure of HRC peptides and their abilities to interact with HRN or HRC have been examined by biophysical techniques. Our results show that the binding of the HRC analogs to HRN does not correlate with the coiled-coil stability of the HRC analogs, but their interactions with HRC does correlate with their stability, except for HRC7. This study also suggested three types of potential peptide inhibitors against viral entry can be designed, those that simultaneously inhibit interaction with HRC and HRN and those that are either HRC-specific or HRN-specific. For example, our study shows the important role of alpha-helical structure in the formation of the six-helix bundle where the lactam bridge constrained analog (HRC5) provided the best interaction with HRN. The importance of alpha-helical structure in the interaction with native HRC was demonstrated with analog HRC4 which binds best to HRC.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Circular Dichroism / methods
  • Electrophoresis, Polyacrylamide Gel / methods
  • Membrane Glycoproteins / chemistry*
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Molecular Sequence Data
  • Peptides / chemical synthesis
  • Peptides / chemistry
  • Peptides / metabolism
  • Protein Binding
  • Protein Denaturation
  • Repetitive Sequences, Amino Acid*
  • Sequence Homology, Amino Acid
  • Severe acute respiratory syndrome-related coronavirus / genetics
  • Severe acute respiratory syndrome-related coronavirus / metabolism*
  • Spike Glycoprotein, Coronavirus
  • Surface Plasmon Resonance / methods
  • Temperature
  • Viral Envelope Proteins / chemistry*
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism
  • Viral Fusion Proteins / chemistry*
  • Viral Fusion Proteins / genetics
  • Viral Fusion Proteins / metabolism

Substances

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