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Home page > Thematics > Recoding to study translation > Frameshifting


One of the main issues for the ribosome is to keep reading the correct reading frame from the start codon to the stop. The reading frame is defined by the start codon, as the genetic code is unpunctuated any shift in the reading frame leads to an aberrant protein.
These spontaneous frameshift errors occur at low level in comparison with missense errors. The ribosome has developed several mechanisms to allow the proper translocation of the tRNA in the different sites.
However programmed frameshift motifs found on specific mRNA disrupt these mechanisms allowing the ribosome to shift in a new reading frame to synthesize a new protein.

-1 Frameshifting

1 frameshifting sites are usually composed by a heptameric slippery sequence of the general structure X XXY YYZ (the initial reading frame is indicated) and by a rich variety of secondary structures, which stimulate –1PRF efficiency (stem loop, kissing loop, pseudoknot…).

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+1 frameshifting

+1 frameshifting sites use a hungry codon (i.e a codon poorly recognized by its cognate tRNA), a stop codon or a secondary structure as stimulatory signals. +1 frameshifting can be also stimulated by a pseudoknot.

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