PMID:21062370
| Citation |
Chadani, Y, Ono, K, Ozawa, S, Takahashi, Y, Takai, K, Nanamiya, H, Tozawa, Y, Kutsukake, K and Abo, T (2010) Ribosome rescue by Escherichia coli ArfA (YhdL) in the absence of trans-translation system. Mol. Microbiol. 78:796-808 |
|---|---|
| Abstract |
Although SsrA(tmRNA)-mediated trans-translation is thought to maintain the translation capacity of bacterial cells by rescuing ribosomes stalled on messenger RNA lacking an in-frame stop codon, single disruption of ssrA does not crucially hamper growth of Escherichia coli. Here, we identified YhdL (renamed ArfA for alternative ribosome-rescue factor) as a factor essential for the viability of E. coli in the absence of SsrA. The ssrA-arfA synthetic lethality was alleviated by SsrA(DD) , an SsrA variant that adds a proteolysis-refractory tag through trans-translation, indicating that ArfA-deficient cells require continued translation, rather than subsequent proteolysis of the truncated polypeptide. In accordance with this notion, depletion of SsrA in the ΔarfA background led to reduced translation of a model protein without affecting transcription, and puromycin, a codon-independent mimic of aminoacyl-tRNA, rescued the bacterial growth under such conditions. That ArfA takes over the role of SsrA was suggested by the observation that its overexpression enabled detection of the polypeptide encoded by a model non-stop mRNA, which was otherwise SsrA-tagged and degraded. In vitro, purified ArfA acted on a ribosome-nascent chain complex to resolve the peptidyl-tRNA. These results indicate that ArfA rescues the ribosome stalled at the 3' end of a non-stop mRNA without involving trans-translation. |
| Links |
PubMed Online version:10.1111/j.1365-2958.2010.07375.x |
| Keywords |
Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Deletion; Genes, Bacterial; Genes, Essential; Protein Biosynthesis; RNA, Bacterial/metabolism; RNA-Binding Proteins/genetics; RNA-Binding Proteins/metabolism; Ribosomes/metabolism |
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