Eukaryotic viruses encode the ribosomal protein eL40.

Area of Science:

• Virology
• Molecular Biology
• Genomics

Background:

• Viruses in the Nucleocytoviricota phylum are known for their large size and complex genomes.
• These viruses possess diverse metabolic capabilities, including encoding numerous proteins involved in mRNA translation.
• However, no viral genes encoding ribosomal proteins, essential for translation, had been identified.

Purpose of the Study:

• To investigate the presence of ribosomal protein genes in eukaryotic viruses.
• To characterize novel genes identified in the giant virus FloV-SA2.
• To explore the functional implications of viral-encoded ribosomal proteins and other unique viral genes.

Main Methods:

• Bioinformatic analysis of the FloV-SA2 viral genome.
• Gene discovery and characterization, focusing on the eL40 gene.
• Phylogenetic analysis to identify related genes in other viruses.
• Metagenomic data analysis to assess the prevalence of identified genes in uncultivated viruses.
• Identification and characterization of viral rhodopsin genes.

Main Results:

• The discovery of the eL40 gene in the eukaryotic virus FloV-SA2, representing the first instance of a virus encoding a ribosomal protein.
• Confirmation that the eL40 gene is present and expressed in other uncultivated marine giant viruses.
• Identification of a "group II" viral rhodopsin in FloV-SA2, a light-activated protein previously found only in metagenomes.
• FloV-SA2 exhibits a unique combination of viral-encoded translational machinery and light-activated proteins.

Conclusions:

• The finding of viral-encoded ribosomal proteins challenges previous understandings of viral biology and the central dogma.
• FloV-SA2 serves as a crucial model for understanding how giant viruses interact with and manipulate eukaryotic host cell metabolism.
• The presence of viral rhodopsin suggests novel viral strategies for energy acquisition or signaling within host cells.