An expanded class of histidine-accepting viral tRNA-like structures

Area of Science:

• Virology
• Molecular Biology
• Bioinformatics

Background:

• Structured RNA elements are vital in RNA virus genomes, often mediating host interactions and viral replication.
• Viral RNA elements can mimic transfer RNA (tRNA), but the diversity of these mimicry mechanisms remains unclear.
• Histidine-accepting tRNA-like structures (TLS^His) at the 3' termini of some viral RNAs are known to induce RNA genome histidylation and aid infection.

Purpose of the Study:

• To investigate the phylogenetic distribution and diversity of histidine-accepting tRNA-like structures (TLS^His).
• To establish a consensus sequence and structural model for TLS^His elements.
• To explore the functional and structural basis of TLS^His mimicry of canonical tRNAs.

Main Methods:

• Bioinformatic analysis to identify new TLS^His examples across viral genomes.
• Chemical probing to validate the secondary structure of identified TLS^His RNAs.
• In vitro histidylation assays and mutational analyses to confirm function and probe tertiary structure.

Main Results:

• Numerous new TLS^His examples were identified, significantly expanding the known distribution of this RNA element class.
• A rigorous consensus sequence and secondary structure model for TLS^His was established and experimentally validated.
• New TLS^His elements were confirmed to be functional (histidylated in vitro), and evidence for a tRNA-like tertiary interaction was found.

Conclusions:

• The study reveals greater diversity within histidine-accepting tRNA-like structures than previously known.
• The findings provide a validated model for TLS^His and suggest structural parallels with canonical tRNAs.
• This work deepens the understanding of viral RNA structure-function relationships and tRNA mimicry, paving the way for future structural studies.