[Trans-translation: facts and hypothesis].

Trans-translation is a unique process which switches the synthesis of a polypeptide chain encoded by a nonstop messenger RNA to the mRNA-like domain of tmRNA. It is used in bacterial cells for rescuing the ribosomes arrested during translation of nonstop mRNA and directing this mRNA and the product polypeptide for degradation. tmRNA activity is essential for bacterial survival under adverse conditions, quality-control of translation and regulation of certain physiological pathways. This review will focus on recent advances in trans-translation investigation: the details of tmRNA-SmpB interaction and the structure of the early ribosomal complexes will be characterized; the causes for the empty A site appearance in the translating ribosomes, possible mechanisms of the stalled ribosomes recognition and resume codon determination will be discussed, the proteins degraded nonstop mRNA and tagged peptide will be viewed.