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Poliovirus 2A(Pro) increases viral mRNA and polysome stability coordinately in time with cleavage of eIF4G

Brian J Kempf1, David J Barton

  • 1Department of Microbiology, University of Colorado Denver, School of Medicine, 12800 East 19th Ave., Aurora, CO 80045, USA.

Journal of Virology
|April 11, 2008
PubMed

Insights

Poliovirus protease 2A (2A(Pro)) cleaves translation factors, enabling viral mRNA translation. This protease is essential for viral polysome formation and stability, ensuring efficient viral replication.

Area of Science:

  • Molecular Biology
  • Virology
  • Biochemistry

Background:

  • Poliovirus (PV) translation relies on cap-independent mechanisms due to the virus's uncapped mRNA.
  • PV 2A protease (2A(Pro)) inhibits host cell cap-dependent translation by cleaving eukaryotic initiation factors (eIF4GI and eIF4GII).

Purpose of the Study:

  • To investigate the role of PV 2A(Pro) in viral polysome formation, stability, and mRNA translation.
  • To elucidate the mechanisms by which PV mRNA achieves translation and stability within infected cells.

Main Methods:

  • Site-directed mutagenesis to create a catalytically inactive 2A(Pro) mutant (2A(Cys109Ser)).
  • Analysis of viral polysome assembly and stability in infected cells.
  • Assessment of PV mRNA stability and translation efficiency.

Main Results:

  • 2A(Pro) activity is crucial for the de novo formation and stability of poliovirus polysomes.
  • Cleavage of eIF4G by 2A(Pro) is essential for PV mRNA stability and translation.
  • A catalytically inactive 2A(Pro) mutant impaired viral polysome formation, stability, and PV mRNA stability.
  • 3C protease activity was not required for viral polysome formation or stability.

Conclusions:

  • PV 2A(Pro)-mediated cleavage of eIF4G is a key mechanism for establishing stable viral messenger ribonucleoprotein (mRNP) complexes.
  • Concerted action of 2A(Pro) and poly(rC) binding protein facilitates PV mRNA translation and evasion of cellular degradation pathways.

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