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Life 2015, 5(4), 1567-1582;

Non-Conserved Residues in Clostridium acetobutylicum tRNAAla Contribute to tRNA Tuning for Efficient Antitermination of the alaS T Box Riboswitch

Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
Author to whom correspondence should be addressed.
Academic Editor: Lluís Ribas de Pouplana
Received: 24 August 2015 / Revised: 16 September 2015 / Accepted: 18 September 2015 / Published: 28 September 2015
(This article belongs to the Special Issue Evolution of tRNA)
Full-Text   |   PDF [2591 KB, uploaded 28 September 2015]   |  


The T box riboswitch regulates expression of amino acid-related genes in Gram-positive bacteria by monitoring the aminoacylation status of a specific tRNA, the binding of which affects the folding of the riboswitch into mutually exclusive terminator or antiterminator structures. Two main pairing interactions between the tRNA and the leader RNA have been demonstrated to be necessary, but not sufficient, for efficient antitermination. In this study, we used the Clostridium acetobutylicum alaS gene, which encodes alanyl-tRNA synthetase, to investigate the specificity of the tRNA response. We show that the homologous C. acetobutylicum tRNAAla directs antitermination of the C. acetobutylicum alaS gene in vitro, but the heterologous Bacillus subtilis tRNAAla (with the same anticodon and acceptor end) does not. Base substitutions at positions that vary between these two tRNAs revealed synergistic and antagonistic effects. Variation occurs primarily at positions that are not conserved in tRNAAla species, which indicates that these non-conserved residues contribute to optimal antitermination of the homologous alaS gene. This study suggests that elements in tRNAAla may have coevolved with the homologous alaS T box leader RNA for efficient antitermination. View Full-Text
Keywords: T box; tRNA; antitermination; riboswitch T box; tRNA; antitermination; riboswitch

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Liu, L.-C.; Grundy, F.J.; Henkin, T.M. Non-Conserved Residues in Clostridium acetobutylicum tRNAAla Contribute to tRNA Tuning for Efficient Antitermination of the alaS T Box Riboswitch. Life 2015, 5, 1567-1582.

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