Recognition of the amber UAG stop codon by release factor RF1

Area of Science:

• Molecular Biology
• Structural Biology
• Genetics

Background:

• Translation termination is a critical process in protein synthesis.
• Release factors (RFs) recognize stop codons and trigger polypeptide release.
• Understanding the structural basis of stop codon recognition is essential for deciphering translation regulation.

Purpose of the Study:

• To elucidate the structural mechanism of stop codon recognition by release factor RF1.
• To provide atomic-level insights into the peptidyl-tRNA hydrolysis reaction catalyzed by RF1.
• To investigate functional interactions between RF1 and ribosomal RNA during termination.

Main Methods:

• X-ray crystallography was used to determine the crystal structure of the termination complex.
• The structure was solved at 3.6-Å resolution.
• Mutational analysis was employed to study functional interactions.

Main Results:

• The crystal structure of release factor RF1 bound to the 70S ribosome in complex with an amber (UAG) codon was determined.
• Conserved elements in domain 2 of RF1 directly recognize the amber codon in the 30S decoding center.
• The GGQ motif's backbone amide of Q230 is positioned to catalyze peptidyl-tRNA hydrolysis.
• Synthetic-negative interactions between RF1 mutations and 23S rRNA helix 69 were observed.

Conclusions:

• The structure provides a detailed mechanism for amber stop codon recognition by RF1.
• The findings clarify the role of the GGQ motif in catalysis during translation termination.
• Structural rearrangements of RF1 and RF2 are crucial for accurate translation termination.