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Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies
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The structure and activity of a monomeric interferon-gamma:alpha-chain receptor signaling complex

M Randal1, A A Kossiakoff

  • 1Graduate Group in Biophysics, University of California, 94000, San Francisco, CA, USA.

Structure (London, England : 1993)
|March 16, 2001
PubMed

Insights

A modified Interferon-gamma (IFN-gamma) molecule, scIFN-gamma, binds effectively to its alpha receptor (IFN-gammaRalpha). This interaction, despite being monovalent, retains significant antiviral activity, suggesting a new signaling pathway.

Area of Science:

  • Immunology
  • Structural Biology
  • Biochemistry

Background:

  • Interferon-gamma (IFN-gamma) is a cytokine that signals through receptor aggregation.
  • IFN-gamma binds IFN-gammaRalpha (high affinity) and IFN-gammaRbeta (low affinity) to form a 1:2:2 signaling complex.
  • Understanding IFN-gamma receptor interactions is key to modulating immune responses.

Purpose of the Study:

  • To determine the structure of a monovalent IFN-gamma variant (scIFN-gamma) complexed with the IFN-gammaRalpha extracellular domain (ECD).
  • To investigate the molecular interactions at the hormone-receptor interface.
  • To assess the biological activity of the scIFN-gamma:IFN-gammaRalpha complex.

Main Methods:

  • Construction of a single-chain monovalent IFN-gamma variant (scIFN-gamma).
  • Complexation of scIFN-gamma with the extracellular domain of IFN-gammaRalpha (ECD).
  • X-ray crystallography to determine the 1:1 complex structure.
  • Antiviral biological assays to evaluate scIFN-gamma activity.

Main Results:

  • The structure of the scIFN-gamma:IFN-gammaRalpha (ECD) 1:1 complex was determined.
  • The interface is characterized by hydrophilic interactions and ordered water networks.
  • scIFN-gamma exhibits significant antiviral activity, despite monovalent binding to IFN-gammaRalpha.

Conclusions:

  • scIFN-gamma binds IFN-gammaRalpha ECD via a highly hydrated interface with specific contacts.
  • The scIFN-gamma:IFN-gammaRalpha complex acts as a productive intermediate, capable of recruiting IFN-gammaRbeta.
  • This suggests a functional 1:1:1 signaling complex mediated by scIFN-gamma, demonstrating its biological relevance.
Abstract

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