Colicin E3 cleavage of 16S rRNA impairs decoding and accelerates tRNA translocation on Escherichia coli ribosomes

Lancaster, Lorna and Savelsbergh, Andreas and Kleanthous, Colin and Wintermeyer, Wolfgang and Rodnina, Marina (2008) Colicin E3 cleavage of 16S rRNA impairs decoding and accelerates tRNA translocation on Escherichia coli ribosomes. Molecular Microbiology, 69 (2). pp. 390-401. ISSN 0950-382X

Full content URL: http://dx.doi.org/10.1111/j.1365-2958.2008.06283.x

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Item Type:Article
Item Status:Live Archive

Abstract

The cytotoxin colicin E3 targets the 30S subunit of bacterial ribosomes and specifically cleaves 16S rRNA at the decoding centre, thereby inhibiting translation. Although the cleavage site is well known, it is not clear which step of translation is inhibited. We studied the effects of colicin E3 cleavage on ribosome functions by analysing individual steps of protein synthesis. We find that the cleavage affects predominantly the elongation step. The inhibitory effect of colicin E3 cleavage originates from the accumulation of sequential impaired decoding events, each of which results in low occupancy of the A site and, consequently, decreasing yield of elongating peptide. The accumulation leads to an almost complete halt of translation after reading of a few codons. The cleavage of 16S rRNA does not impair monitoring of codon-anticodon complexes or GTPase activation during elongation-factor Tu-dependent binding of aminoacyl-tRNA, but decreases the stability of the codon-recognition complex and slows down aminoacyl-tRNA accommodation in the A site. The tRNA-mRNA translocation is faster on colicin E3-cleaved than on intact ribosomes and is less sensitive to inhibition by the antibiotic viomycin.

Additional Information:The cytotoxin colicin E3 targets the 30S subunit of bacterial ribosomes and specifically cleaves 16S rRNA at the decoding centre, thereby inhibiting translation. Although the cleavage site is well known, it is not clear which step of translation is inhibited. We studied the effects of colicin E3 cleavage on ribosome functions by analysing individual steps of protein synthesis. We find that the cleavage affects predominantly the elongation step. The inhibitory effect of colicin E3 cleavage originates from the accumulation of sequential impaired decoding events, each of which results in low occupancy of the A site and, consequently, decreasing yield of elongating peptide. The accumulation leads to an almost complete halt of translation after reading of a few codons. The cleavage of 16S rRNA does not impair monitoring of codon-anticodon complexes or GTPase activation during elongation-factor Tu-dependent binding of aminoacyl-tRNA, but decreases the stability of the codon-recognition complex and slows down aminoacyl-tRNA accommodation in the A site. The tRNA-mRNA translocation is faster on colicin E3-cleaved than on intact ribosomes and is less sensitive to inhibition by the antibiotic viomycin.
Keywords:Colicin E3, Ribosome, Translation
Subjects:C Biological Sciences > C720 Biological Chemistry
C Biological Sciences > C790 Molecular Biology, Biophysics and Biochemistry not elsewhere classified
C Biological Sciences > C500 Microbiology
Divisions:College of Science > School of Life Sciences
ID Code:7504
Deposited On:11 Feb 2013 16:07

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