title: The tmRNA-tagging mechanism and the control of gene expression: a review.
abstract: The tmRNA-mediated trans-translation system is a unique quality control system in eubacteria that combines translational surveillance with the rescue of stalled ribosomes. During trans-translation, the chimeric tmRNA molecule--which acts as both tRNA and mRNA--is delivered to the ribosomal A site by a ribonucleoprotein complex of SmpB and EF-Tu-GTP, allowing the stalled ribosome to switch template and resume translation on a small coding sequence inside the tmRNA molecule. As a result, the aberrant protein becomes tagged by a sequence that is a target for proteolytic degradation. Thus, the system elegantly combines ribosome recycling with a clean-up function when triggered by truncated transcripts or rare codons. In addition, recent observations point to a specific regulation of the translation of a small number of genes by tmRNA-mediated inhibition or stimulation. In this review, we discuss the most prominent biochemical and structural aspects of trans-translation and then focus on the specific role of tmRNA in stress management and cell-cycle control of morphologically complex bacteria.
authors.affiliation: ProteoNic, Niels Bohrweg 11-13, 2333 CA Leiden, The Netherlands.
authors.forename: Sharief
authors.initials: S
authors.lastname: Barends
authors.forename: Barend
authors.initials: B
authors.lastname: Kraal
authors.forename: Gilles P
authors.initials: GP
authors.lastname: van Wezel
mesh_terms: D000818:Animals; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D005786:Gene Expression Regulation; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis / Q000235:genetics / Q000502:physiology*; D021381:Protein Transport / Q000235:genetics / Q000502:physiology; D059748:Proteolysis; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D012329:RNA, Bacterial; C096222:tmRNA