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Poliovirus internal ribosome entry segment structure alterations that specifically affect function in neuronal cells:
Cécile E Malnou1, Tuija A A Pöyry, Richard J Jackson
1Unité de Régulation de la Traduction Eucaryote et Virale, CNRS URA 1966, Institut Pasteur, Paris, France.
Journal of Virology
|October 9, 2002
Summary
Sequence conservation in poliovirus internal ribosome entry segment (IRES) domain V is critical for viral growth. Disrupting GNAA motifs in the bulge-loop impairs translation and viral replication, especially in neuronal cells.
Area of Science:
- Virology
- Molecular Biology
- RNA Structure
Background:
- Poliovirus RNA translation relies on an internal ribosome entry segment (IRES) in its 5' noncoding region.
- Domain V of the IRES contains a conserved bulge-loop with two GNAA motifs, whose structural and functional significance is unclear.
Purpose of the Study:
- To investigate the functional significance of conserved GNAA motifs in the poliovirus IRES domain V bulge-loop.
- To determine the impact of mutations in these motifs on viral viability, RNA structure, and translation initiation.
Main Methods:
- Site-directed mutagenesis of the two GNAA motifs in the IRES domain V.
- Functional analysis of viral mutants: growth kinetics in HeLa and neuronal cells, in vitro translation efficiency.
- Biochemical probing to assess RNA structural changes.
Main Results:
- Mutations affecting both GNAA motifs significantly impaired viral growth and in vitro translation.
- Phenotypic defects were more severe in neuronal cells, revealing temperature sensitivity.
- Mutations caused structural perturbations in domain V, with revertants showing distant compensatory mutations.
Conclusions:
- The conserved GNAA motifs in the IRES domain V bulge-loop are essential for optimal viral replication and translation.
- These motifs likely play a role in maintaining the structural integrity of domain V, potentially through tertiary interactions.