Relation between genomic and capsid structures in RNA viruses.

Area of Science:

• Computational biology
• Virology
• Genomics

Background:

• RNA secondary structure plays a crucial role in various biological processes, including viral genome organization and replication.
• Understanding the factors that influence RNA folding is essential for deciphering viral assembly mechanisms.

Purpose of the Study:

• To develop and utilize a novel computer program for calculating RNA secondary structures.
• To investigate the folding probabilities of viral RNA genomes and compare them with random sequences.
• To explore the evolutionary implications of RNA base composition and its relation to viral genome folding.

Main Methods:

• Development of a new computational program for RNA secondary structure prediction.
• Analysis of secondary structures for 20 different viral RNA genomes.
• Comparison of folding probabilities between actual viral RNA sequences and their corresponding random sequences with identical base composition.

Main Results:

• Viral RNA genomes, particularly those of icosahedral capsid viruses, demonstrated significantly higher folding probabilities compared to helical capsid viruses.
• All analyzed viral RNA genomes exhibited greater folding stability than their randomized counterparts.
• In contrast, most chromosomal gene transcripts showed lower folding probabilities than random sequences.
• A notable correlation was observed between viral genome folding, capsid structure, and base sequence composition.

Conclusions:

• The findings suggest that viral capsid structure information is encoded not only in capsid proteins but also within the genome's base sequence.
• The higher folding probability of viral RNAs compared to random sequences implies an evolutionary selection for specific base compositions.
• The study posits a link between base ratios, RNA folding, and the encapsidation process, indicating an evolutionary significance of base composition in viral genomes.