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PMID:18990188

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Citation

Hammarlöf, DL and Hughes, D (2008) Mutants of the RNA-processing enzyme RNase E reverse the extreme slow-growth phenotype caused by a mutant translation factor EF-Tu. Mol. Microbiol. 70:1194-209

Abstract

Salmonella enterica with mutant EF-Tu (Gln125Arg) has a low level of EF-Tu, a reduced rate of protein synthesis and an extremely slow growth rate. Eighty independent suppressor mutations were selected that restored normal growth. In some cases (n= 7) suppression was due to mutations in tufA but, surprisingly, in most cases (n= 73) to mutations in rne, the gene coding for RNase E. These rne mutations alone had only modest effects on growth rate. Fifty different suppressor mutations were isolated in rne, all located in or close to the N-terminal endonucleolytic half of RNase E. Steady state levels of several mRNAs were lower in the mutant tuf strain but restored to wild-type levels in the tuf-rne double mutant. In contrast, the half-lives of mRNAs were unaffected by the tuf mutation. We propose a model where the tuf mutation causes the ribosome following RNA polymerase to pause, possibly in a codon-specific manner, exposing unshielded nascent message to RNase E cleavage. Normal growth rate can be restored by increasing EF-Tu activity or by reducing RNase E activity. Accordingly, RNase E is suggested to act at two distinct stages in the life of mRNA: early, on the nascent transcript; late, on the complete mRNA.

Links

PubMed Online version:10.1111/j.1365-2958.2008.06472.x

Keywords

Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Endoribonucleases/genetics; Endoribonucleases/metabolism; Gene Expression Regulation, Bacterial; Peptide Elongation Factor Tu/genetics; Peptide Elongation Factor Tu/metabolism; Phenotype; Protein Biosynthesis; RNA Processing, Post-Transcriptional; RNA, Bacterial/genetics; RNA, Messenger/genetics; Salmonella typhimurium/enzymology; Salmonella typhimurium/genetics; Salmonella typhimurium/growth & development; Suppression, Genetic

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status


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References

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