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Nucleic Acids Res. 2014 Jan;42(2):1245-56. doi: 10.1093/nar/gkt923. Epub 2013 Oct 16.

Interactions of the TnaC nascent peptide with rRNA in the exit tunnel enable the ribosome to respond to free tryptophan.

Author information

1
Department of Biology, Texas A&M University, College Station, TX 77843, USA, Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA, Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, Chicago, IL 60607, USA, Quantitative Proteomics Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA and Department of Biology, Stanford University, Stanford, CA 94305, USA.

Abstract

A transcriptional attenuation mechanism regulates expression of the bacterial tnaCAB operon. This mechanism requires ribosomal arrest induced by the regulatory nascent TnaC peptide in response to free L-tryptophan (L-Trp). In this study we demonstrate, using genetic and biochemical analyses, that in Escherichia coli, TnaC residue I19 and 23S rRNA nucleotide A2058 are essential for the ribosome's ability to sense free L-Trp. We show that the mutational change A2058U in 23S rRNA reduces the concentration dependence of L-Trp-mediated tna operon induction, whereas the TnaC I19L change suppresses this phenotype, restoring the sensitivity of the translating A2058U mutant ribosome to free L-Trp. These findings suggest that interactions between TnaC residue I19 and 23S rRNA nucleotide A2058 contribute to the creation of a regulatory L-Trp binding site within the translating ribosome.

PMID:
24137004
PMCID:
PMC3902921
DOI:
10.1093/nar/gkt923
[Indexed for MEDLINE]
Free PMC Article

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