Pre-binding of Small Protein B to a Stalled Ribosome Triggers trans-Translation

To rescue stalled ribosomes, eubacteria employ a molecule, transfer messenger RNA (tmRNA), which functions both as a tRNA and as an mRNA. With the help of small protein B (SmpB), tmRNA restarts protein synthesis and adds by the trans-translation mechanism a peptide tag to the stalled protein to targ...

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Bibliographic Details
Published in:The Journal of biological chemistry 2004-06, Vol.279 (25), p.25978-25985
Main Authors: Hallier, Marc, Ivanova, Natalia, Rametti, Armelle, Pavlov, Michael, Ehrenberg, Måns, Felden, Brice
Format: Article
Language:English
Subjects:
Biochemistry, Molecular Biology
Blotting, Northern
Cell Division
Centrifugation, Density Gradient
Escherichia coli
Escherichia coli - metabolism
Genetic Complementation Test
Immunoblotting
Life Sciences
Mutation
Protein Binding
Protein Biosynthesis
Ribosomes
Ribosomes - chemistry
Ribosomes - metabolism
Ribosomes/chemistry/metabolism
RNA, Bacterial
RNA, Bacterial - chemistry
RNA, Messenger
RNA, Messenger - metabolism
RNA-Binding Proteins
RNA-Binding Proteins - metabolism
RNA-Binding Proteins - physiology
RNA-Binding Proteins/metabolism/physiology
Subcellular Fractions
Sucrose
Sucrose - pharmacology
Time Factors
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Summary:To rescue stalled ribosomes, eubacteria employ a molecule, transfer messenger RNA (tmRNA), which functions both as a tRNA and as an mRNA. With the help of small protein B (SmpB), tmRNA restarts protein synthesis and adds by the trans-translation mechanism a peptide tag to the stalled protein to target it for destruction by cellular proteases. Here, the cellular location and expression of endogenous SmpB were monitored in vivo. We report that SmpB is associated with 70S ribosomes and not in the soluble fraction, independently of the presence of tmRNA. In vitro, SmpB that is pre-bound to a stalled ribosome can trigger initiation of trans-translation. Our results demonstrate the existence of a novel pathway for the entry of tmRNA to the ribosome and for the trans-transfer of a nascent peptide chain from peptidyl-tRNA to charged tmRNA.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M314086200