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Updated: Jul 2, 2026

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA
Published on: July 6, 2012
Translational bypassing without peptidyl-tRNA anticodon scanning of coding gap mRNA
Norma M Wills1, Michelle O'Connor, Chad C Nelson
1Department of Human Genetics, University of Utah, Salt Lake City, UT, USA.
Abstract:
Half the ribosomes translating the mRNA for phage T4 gene 60 topoisomerase subunit bypass a 50 nucleotide coding gap between codons 46 and 47. The pairing of codon 46 with its cognate peptidyl-tRNA anticodon dissociates, and following mRNA slippage, peptidyl-tRNA re-pairs to mRNA at a matched triplet 5' adjacent to codon 47, where translation resumes. Here, in studies with gene 60 cassettes, it is shown that the peptidyl-tRNA anticodon does not scan the intervening sequence for potential complementarity. However, certain coding gap mutants allow peptidyl-tRNA to scan sequences in the bypassed segment. A model is proposed in which the coding gap mRNA enters the ribosomal A-site and forms a structure that precludes peptidyl-tRNA scanning of its sequence. Dissipation of this RNA structure, together with the contribution of 16S rRNA anti-Shine-Dalgarno sequence pairing with GAG, facilitates peptidyl-tRNA re-pairing to mRNA.
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