Structural aspects of trans-translation.

trans-Translation is a process which the bacterial cells apply to rescue the ribosomes that are arrested during the translation of damaged mRNA and to get rid of the mRNA and the product polypeptide. In the course of trans-translation, the mRNA-like domain of tmRNA replaces the nonstop messenger RNA bound to the ribosome. Although several structural elements of tmRNA and SmpB known to be essential for correct determination of resume codon, the molecular mechanism of trans-translation is not well understood. Computer modeling has been used to develop a model for the spatial organization of the tmRNA inside the ribosome at different stages of trans-translation leading to a proposal for the mechanism of the template-switching process.