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Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
10:05

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle

Published on: March 5, 2019

Dynamic refolding of IFN-gamma mRNA enables it to function as PKR activator and translation template

Smadar Cohen-Chalamish1, Anat Hasson, Dahlia Weinberg

  • 1Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.

Nature Chemical Biology
|October 6, 2009
PubMed

Insights

Interferon-gamma mRNA uses its coding sequence to activate protein kinase PKR, a process that self-regulates its own production. This RNA structure ensures controlled cytokine levels by balancing translation and PKR activation.

Area of Science:

  • Molecular Biology
  • RNA Biology
  • Immunology

Background:

  • Interferon-gamma (IFN-γ) production is tightly regulated.
  • RNA-dependent protein kinase (PKR) activation by IFN-γ mRNA attenuates its translation.
  • Unlike typical riboswitches, the IFN-γ RNA activator involves both the 5' UTR and translated coding regions.

Purpose of the Study:

  • To elucidate the structural mechanisms by which IFN-γ mRNA activates PKR.
  • To understand how the coding sequence contributes to translational regulation.
  • To investigate the role of RNA structure flexibility in IFN-γ synthesis control.

Main Methods:

  • Analysis of the IFN-γ mRNA structure, including the 5' UTR and translated codons.
  • Investigating the role of specific RNA structural elements like kink-turns and pseudoknots.
  • Utilizing gain-of-function mutations to probe RNA conformational dynamics and PKR activation.

Main Results:

  • The IFN-γ RNA activator spans the 5' UTR and 26 translated codons, dedicating coding sequence to PKR activation.
  • A kink-turn motif is essential for forming a pseudoknot critical for PKR activation.
  • Specific helical elements align to form a long RNA helix sufficient for PKR activation.
  • Gain-of-function mutations revealed alternative conformations of the RNA activator.
  • RNA flexibility facilitates refolding, enabling dual function as a translation template and PKR activator.

Conclusions:

  • IFN-γ mRNA possesses a unique regulatory element within its coding sequence that activates PKR.
  • The dynamic nature of this RNA structure allows for efficient refolding, balancing translation and self-regulation.
  • This mechanism prevents excessive production of the inflammatory cytokine IFN-γ.

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