Interaction between 25S rRNA A loop and eukaryotic translation initiation factor 5B promotes subunit joining and...

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• 25S rRNA is crucial for yeast 60S ribosomal subunit structure and function.
• Eukaryotic initiation factor 5B (eIF5B) facilitates 60S subunit joining during translation initiation.
• Ribosomal subunit dysfunction can lead to altered translation initiation stringency.

Purpose of the Study:

• Investigate the role of 25S rRNA in start codon selection using yeast models.
• Identify specific rRNA mutations affecting translation initiation.
• Elucidate the interaction between eIF5B and 25S rRNA during initiation.

Main Methods:

• Random mutagenesis to isolate yeast mutants.
• Analysis of translation initiation phenotypes.
• In vitro reconstitution assays to study eIF5B activity.

Main Results:

• Three 25S rRNA mutations (C2879U, U2408C, G1735A) near the ribosome surface caused significant start codon skipping.
• C2879U mutation, affecting the A loop, showed a specific interaction with eIF5B.
• eIF5B overexpression suppressed the C2879U mutation phenotype.
• In vitro assays revealed C2879U reduces eIF5B-catalyzed 60S subunit joining.

Conclusions:

• eIF5B interaction with the peptidyl transferase center A loop enhances translation initiation accuracy.
• Ribosomal mutations can alter translation initiation by affecting subunit joining and complex stability.
• This study provides insights into ribosomal fidelity mechanisms in eukaryotes.