Aeromonas phages encode tRNAs for their overused codons

Area of Science:

• Microbiology
• Molecular Biology
• Genomics

Background:

• Aeromonas salmonicida, a GC-rich bacterium, is infected by both GC-rich and GC-poor phages.
• GC-rich phages exhibit similar codon usage bias to the host, while GC-poor phages differ significantly.

Purpose of the Study:

• To investigate if phage-encoded transfer RNAs (tRNAs) in Aeromonas phages facilitate the translation of phage proteins.
• To determine if phage-encoded tRNAs align with codon usage bias in phage genes.

Main Methods:

• Comparative analysis of codon usage bias between Aeromonas salmonicida and its infecting phages.
• Bioinformatic identification and analysis of tRNA genes encoded within phage genomes.
• Correlation analysis between phage-encoded tRNAs and codon usage patterns in phage genes.

Main Results:

• GC-rich Aeromonas phages (phiAS7, vB_AsaM-56) showed codon usage bias similar to the host.
• GC-poor Aeromonas phages displayed significant differences in codon usage compared to the host.
• Phage-encoded tRNAs were found to correspond with synonymous codons overused in phage genes, but not in host genes.

Conclusions:

• Phage-encoded tRNAs play a role in optimizing the translation of phage proteins by matching the phage's specific codon usage bias.
• This tRNA-mediated translational efficiency is particularly important for GC-poor phages with divergent codon usage from their bacterial host.