Structural aspects of trans‐translation

Abstract

Summarytrans-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 mRNAlike 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 templateswitching process.

Small RNAs Regulate Primary and Secondary Metabolism in Gram-negative Bacteria

“…Another class of protein-binding sRNAs is exemplified by transfer-messenger RNA (tmRNA) involved in trans-translation, a mechanism to rescue stalled ribosomes in bacteria (68,69). Defective mRNAs that lack the termination signals allowing ribosome release cause stalling of the ribosomes and results in a general loss of translational efficiency, and accumulation of aberrant mRNA and nascent peptides (70,71).…”

tRNA/mRNA Mimicry by tmRNA and SmpB inTrans-Translation

“…These ribosomal processes should involve extensive changes in the conformation of tmRNA [75] as well as in the modes of interactions of tmRNA with SmpB and the ribosome [76, 77]. According to chemical probing studies, secondary structure elements of tmRNA remain intact in a few steps of trans -translation including pre- and posttranslocation states [77–79]. Another study has suggested 1 : 1 stoichiometry of tmRNA to SmpB throughout the processes of translation for the tag peptide [80].…”

Regulation of Bacterial Metabolism by Small RNAs Using Diverse Mechanisms

“…CsrB/CsrC-like RNAs are discussed in more detail below. Still other classes include transfer-messenger RNA (tmRNA), a protein-binding RNA involved in trans-translation, a mechanism to rescue ribosomes stalled on damaged or untranslatable mRNAs in bacteria (23,49,113). In addition, some protein-binding sRNAs directly inhibit the activities of toxin proteins and are classified as type III antitoxins (11,27).…”