Translational readthrough in Tobacco necrosis virus-D

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Tobacco necrosis virus-D (TNV-D) is a plus-strand RNA virus.
• Viral polymerase expression in TNV-D occurs through translational readthrough.

Purpose of the Study:

• To characterize the RNA signals governing translational readthrough in TNV-D.
• To investigate the mechanisms and requirements of TNV-D readthrough in vitro and in vivo.

Main Methods:

• In vitro translation assays using wheat germ extract.
• In vivo studies involving protoplast infections.
• Analysis of RNA-RNA interactions and stem-loop structure stability.

Main Results:

• TNV-D readthrough depends on long-range RNA-RNA interaction between a stem-loop and the 3 -untranslated region.
• Stem-loop stability is crucial for readthrough function.
• Readthrough elements are compatible with UAG and UGA stop codons, but not UAA.
• Heterologous readthrough elements can rescue defects in vitro but not in vivo.
• TNV-D readthrough elements can also mediate translational frameshifting.

Conclusions:

• Identified key determinants for translational readthrough in TNV-D.
• Supported a conserved readthrough mechanism within the Tombusviridae family.
• Highlighted the importance of RNA structure and interactions in viral gene expression.