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

Life

Liang-Chun Liu²  Frank J. Grundy²  Tina M. Henkin¹ 

[1] Department of Microbiology and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA

关键词: T box;    tRNA;    antitermination;    riboswitch;   

DOI  :  10.3390/life5041567

来源: mdpi

【 摘 要 】

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 tRNA^Ala directs antitermination of the C. acetobutylicum alaS gene in vitro, but the heterologous Bacillus subtilis tRNA^Ala (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 tRNA^Ala species, which indicates that these non-conserved residues contribute to optimal antitermination of the homologous alaS gene. This study suggests that elements in tRNA^Ala may have coevolved with the homologous alaS T box leader RNA for efficient antitermination.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.