Coronavirus mRNA synthesis involves fusion of non-contiguous sequences

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Coronaviruses, such as mouse hepatitis virus (MHV), possess a positive-stranded RNA genome.
• Viral RNA synthesis, including genomic and subgenomic messenger RNAs (mRNAs), occurs within the host cell's cytoplasm.
• The structure of MHV mRNAs involves leader and body sequences that are not adjacent on the viral genome.

Purpose of the Study:

• To elucidate the mechanism of subgenomic mRNA formation in MHV-infected cells.
• To investigate the process by which non-contiguous RNA sequences are joined during viral RNA synthesis.

Main Methods:

• Analysis of viral RNA synthesis in MHV-infected host cells.
• Characterization of the structure of genomic and subgenomic RNAs.
• Investigating the role of viral polymerase in RNA ligation.

Main Results:

• MHV genomic RNA and six subgenomic mRNAs are synthesized in the host cell cytoplasm.
• MHV mRNAs consist of leader and body sequences that are non-contiguous on the genome.
• RNA fusion appears to be mediated by a specific 'polymerase jumping' event.

Conclusions:

• The synthesis of MHV subgenomic mRNAs involves a novel mechanism of RNA ligation.
• The 'polymerase jumping' event is crucial for fusing non-contiguous RNA sequences, enabling the formation of functional mRNAs.