Translational Bypassing – Peptidyl-tRNA Re-pairing at Non-overlapping Sites
Ribosomal bypassing can lead to the translational fusion of non-contiguous ORFs. It involves dissociation of codon:anticodon pairing in the ribosomal P-site followed by mRNA slippage and re-pairing of the retained tRNA anticodon to mRNA at a non-overlapping codon. It is frame independent. The most studied case involves the bypassing of 50 non-coding nucleotides between codons 46 and 47 of phage T4 gene 60 where half the translating ribosomes successfully accomplish the feat. A nascent peptide signal encoded 5′ of the start of the coding gap facilitates the initial codon:anticodon dissociation. An mRNA structure forms in the ribosomal A-site. Only when sequence participating in this structure has passed the ribosomal P-site does the potential for anticodon re-pairing to mRNA at a matched codon arise. After such re-pairing, normal decoding of the A-site codon mediates resumption of standard translation.
KeywordsLanding Site Stem Loop Codon Pairing mRNA Structure Nascent Peptide
This work was supported by NIH grant ROI GM079523.
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