Initiation context modulates autoregulation of eukaryotic translation initiation factor 1 (eIF1)

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Eukaryotic translation initiation typically involves scanning by the small ribosome subunit to find a start codon.
• The fidelity of start codon selection is crucial and mediated by complex cellular machinery.
• Eukaryotic initiation factor 1 (eIF1) is a key regulator in this process.

Purpose of the Study:

• To investigate the translation initiation mechanism of eIF1 homologs across diverse eukaryotic taxa.
• To elucidate the role of start codon context in regulating eIF1 levels and gene expression.
• To understand how eIF1 influences the stringency of start codon selection.

Main Methods:

• Analysis of eIF1 homolog translation initiation in various eukaryotes.
• Experimental manipulation of human eIF1 levels to study autoregulation.
• Assessing the impact of eIF1 overexpression on start codon selection stringency.

Main Results:

• Translation of eIF1 homologs initiates from AUG codons in suboptimal sequence contexts.
• A poor start codon context for eIF1 is essential for a negative feedback loop regulating its own translation.
• Overexpression of eIF1 significantly increases the stringency of start codon selection.

Conclusions:

• Variability in start codon selection stringency is a mechanism for gene regulation in eukaryotes.
• The cellular concentration of eIF1 impacts translation initiation through modulation of start codon selection.
• These findings have broad implications for understanding proteome regulation in eukaryotes.