Changed in translation: mRNA recoding by −1 programmed ribosomal frameshifting

• –1PRF occurs when ribosomes move over a slippery sequence.
• A frameshifting pseudoknot/stem-loop element stalls ribosomes in a metastable state.
• –1PRF may contribute to the quality-control machinery in eukaryotes.
• Trans-acting factors (proteins, miRNAs, or antibiotics) can modulate –1PRF.

Programmed −1 ribosomal frameshifting (−1PRF) is an mRNA recoding event commonly utilized by viruses and bacteria to increase the information content of their genomes. Recent results have implicated −1PRF in quality control of mRNA and DNA stability in eukaryotes. Biophysical experiments demonstrated that the ribosome changes the reading frame while attempting to move over a slippery sequence of the mRNA – when a roadblock formed by a folded downstream segment in the mRNA stalls the ribosome in a metastable conformational state. The efficiency of −1PRF is modulated not only by cis-regulatory elements in the mRNA but also by trans-acting factors such as proteins, miRNAs, and antibiotics. These recent results suggest a molecular mechanism and new important cellular roles for −1PRF.