Proline Residues at the C Terminus of Nascent Chains Induce SsrA Tagging during Translation Termination

The SsrA or tmRNA quality control system relieves ribosome stalling and directs the addition of a degradation tag to the C terminus of the nascent chain. In some instances, SsrA tagging of otherwise full-length proteins occurs when the ribosome pauses at stop codons during normal translation termina...

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Bibliographic Details
Published in:The Journal of biological chemistry 2002-09, Vol.277 (37), p.33825-33832
Main Authors: Hayes, Christopher S, Bose, Baundauna, Sauer, Robert T
Format: Article
Language:English
Subjects:
Codon, Terminator
Escherichia coli Proteins - genetics
Escherichia coli Proteins - metabolism
Proline - metabolism
Protein Biosynthesis
Protein Conformation
Ribosomes - metabolism
RNA, Bacterial - chemistry
RNA, Bacterial - metabolism
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Summary:The SsrA or tmRNA quality control system relieves ribosome stalling and directs the addition of a degradation tag to the C terminus of the nascent chain. In some instances, SsrA tagging of otherwise full-length proteins occurs when the ribosome pauses at stop codons during normal translation termination. Here, the identities of the C-terminal residues of the nascent chain are shown to play an important role in full-length protein tagging. Specifically, a subset of C-terminal Xaa-Pro sequences caused SsrA tagging of the full-length YbeL protein from Escherichia coli . This tagging increased when a less efficient stop codon was used, increased in cells lacking protein release factor-3, and decreased when protein release factor-1 was overexpressed. Incorporation of the analog azetidine-2-carboxylic acid in place of proline suppressed tagging, whereas incorporation of 3,4-dehydroproline increased SsrA tagging of full-length YbeL. These results suggest that the detailed chemical or conformational properties of the C-terminal residues of the nascent polypeptide can affect the rate of translation termination, thereby influencing ribosome pausing and SsrA tagging at stop codons.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M205405200