Translation efficiency affects the sequence-independent +1 ribosomal frameshifting by polyamines

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Antizyme (AZ) regulates polyamine levels by interacting with ornithine decarboxylase.
• AZ synthesis requires a programmed +1 ribosomal frameshift at the termination codon.
• Polyamines induce this frameshifting, but the mechanism remains unclear.

Purpose of the Study:

• To elucidate the molecular mechanism of polyamine-dependent +1 ribosomal frameshifting.
• To investigate whether polyamine-induced frameshifting is specific to the Antizyme sequence.
• To explore the relationship between frameshifting, open reading frame length, and translation efficiency.

Main Methods:

• Utilized a human cell-free translation system.
• Employed mutant constructs with sense codons replacing the termination codon.
• Conducted truncation experiments and tested various gene sequences.

Main Results:

• Spermidine induced +1 frameshifting even when the termination codon was replaced with a sense codon.
• Frameshifting occurred promiscuously across different positions and sequences, independent of the original AZ sequence.
• The probability of frameshifting increased with open reading frame length and was inversely correlated with translation efficiency.

Conclusions:

• Polyamines can induce +1 frameshifting in a sequence-independent manner.
• This suggests a broader role for polyamines in translational regulation beyond the Antizyme gene.
• A novel model for polyamine-mediated translational control via sequence-independent frameshifting is proposed.