PMID:15494393
| Citation |
Wower, IK, Zwieb, C and Wower, J (2004) Contributions of pseudoknots and protein SmpB to the structure and function of tmRNA in trans-translation. J. Biol. Chem. 279:54202-9 |
|---|---|
| Abstract |
Bacteria contain transfer-messenger RNA (tmRNA), a molecule that during trans-translation tags incompletely translated proteins with a small peptide to signal the proteolytic destruction of defective polypeptides. TmRNA is composed of tRNA- and mRNA-like domains connected by several pseudoknots. Using truncated ribosomal protein L27 as a reporter for tagging in vitro and in vivo, we have developed exceptionally sensitive assays to study the role of Escherichia coli tmRNA in trans-translation. Site-directed mutagenesis experiments showed that pseudoknot 2 and the abutting helix 5 were particularly important for the binding of ribosomal protein S1 to tmRNA. Pseudoknot 4 not only facilitated tmRNA maturation but also promoted tagging. In addition, the three pseudoknots (pk2 to pk4) were shown to play a significant role in the proper folding of the tRNA-like domain. Protein SmpB enhanced tmRNA processing, suggesting a new role for SmpB in trans-translation. Taken together, these results provide unanticipated insights into the functions of the pseudoknots and protein SmpB during tmRNA folding, maturation, and protein synthesis. |
| Links |
PubMed Online version:10.1074/jbc.M410488200 |
| Keywords |
Base Pairing; Base Sequence; Escherichia coli/genetics; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/physiology; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Nucleic Acid Conformation; Polymerase Chain Reaction; Promoter Regions, Genetic/genetics; Protein Biosynthesis; RNA, Bacterial/chemistry; RNA, Bacterial/genetics; RNA, Bacterial/physiology; RNA, Messenger/chemistry; RNA, Messenger/metabolism; RNA, Transfer/chemistry; RNA, Transfer/metabolism; RNA-Binding Proteins/chemistry; RNA-Binding Proteins/genetics; RNA-Binding Proteins/physiology; Recombinant Fusion Proteins; Ribosomal Proteins/metabolism; Structure-Activity Relationship; Transformation, Genetic |
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