Queuine links translational control in eukaryotes to a micronutrient from bacteria

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Eukaryotes salvage bacterial queuosine (Q34) for tRNA modification.
• Q34 modification in yeast (Schizosaccharomyces pombe) stimulates Dnmt2-dependent C38 methylation.
• The origin and precise function of Q34 in eukaryotic translation remain areas of investigation.

Purpose of the Study:

• To investigate the impact of Q34 modification on translational speed and accuracy in S. pombe.
• To elucidate the downstream effects of Q34 modification on gene expression and cellular function.
• To determine the evolutionary conservation of Q34-mediated regulatory mechanisms.

Main Methods:

• Ribosome profiling in S. pombe to assess translation dynamics.
• Analysis of codon usage and translation efficiency.
• Assessment of mitochondrial function in the absence of Q34.
• Comparative analysis of Dnmt2 regulation in yeast and mice.

Main Results:

• Q34 modification enhances translational speed for C-ending aspartate (GAC) and histidine (CAC) codons, while slowing U-ending asparagine (AAU) and tyrosine (UAU) codons.
• Q34 prevents translation errors by suppressing misreading of the glycine codon GGC.
• Absence of Q34 leads to reduced translation of mitochondrial mRNAs and a mitochondrial defect.
• Q34-dependent stimulation of Dnmt2 is conserved between yeast and mice.

Conclusions:

• Q34 acts as a direct regulator of translational speed and fidelity in eukaryotes.
• This bacterial-derived nutrient plays a crucial role in optimizing protein synthesis and maintaining mitochondrial health.
• The findings reveal a conserved mechanism linking nutrient salvage to fundamental cellular processes.