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Sendai virus Y proteins are initiated by a ribosomal shunt

P Latorre1, D Kolakofsky, J Curran

  • 1Department of Genetics and Microbiology, University of Geneva Medical School (CMU), CH1211 Geneva, Switzerland.

Molecular and Cellular Biology
|August 26, 1998
PubMed

Insights

Sendai virus mRNA uses ribosomal choice and mRNA editing to create eight proteins. A ribosomal shunt mechanism delivers scanning complexes directly to specific start codons for Y proteins.

Area of Science:

  • Molecular Biology
  • Virology
  • Genetics

Background:

  • Sendai virus P/C mRNA exhibits complex translation, producing multiple proteins from a single mRNA.
  • This process involves a combination of alternative translation initiation and mRNA editing.
  • Understanding these mechanisms is crucial for viral replication and pathogenesis.

Purpose of the Study:

  • To elucidate the distinct translational mechanisms governing the expression of P and C proteins from Sendai virus mRNA.
  • To investigate the role of ribosomal scanning and alternative initiation sites in generating the C-terminal nested set of polypeptides.
  • To identify the specific pathways responsible for the expression of Y1 and Y2 proteins.

Main Methods:

  • Site-directed mutagenesis to alter initiation codons (ACG to ATG) and surrounding sequences.
  • Analysis of protein expression using Western blotting or similar techniques.
  • Investigating translational initiation mechanisms through mutational analysis and observation of translation product profiles.

Main Results:

  • Leaky scanning explains initiation at the first three start sites (ACG81, ATG114, ATG183).
  • Ribosomal shunt or discontinuous scanning is responsible for initiation at ATG183 (Y1) and ATG201 (Y2).
  • Y proteins are expressed even when start codons are mutated, and internal ATG codons in the P ORF are ignored, indicating privileged start sites for Y proteins.

Conclusions:

  • Sendai virus employs sophisticated translational control mechanisms, including leaky scanning and ribosomal shunting.
  • The ribosomal shunt mechanism efficiently directs translation to specific start codons for Y proteins, bypassing other potential initiation sites.
  • These findings provide insights into the complex regulation of viral protein synthesis and genome expression.

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