The expression of E. coli threonyl-tRNA synthetase is regulated at the translational level by symmetrical operator-repressor interactions

Threonyl-tRNA synthetase from Escherichia coli represses the translation of its own mRNA by binding to the operator region located upstream from the ribosome binding site. The operator contains two stem-loop structures which interact specifically with the homodimeric enzyme. Here, we provide in vitr...

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Bibliographic Details
Published in:The EMBO journal 1996-11, Vol.15 (21), p.5976-5987
Main Authors: Romby, P, Caillet, J, Ebel, C, Sacerdot, C, Graffe, M, Eyermann, F, Brunel, C, Moine, H, Springer, M
Format: Article
Language:English
Subjects:
Escherichia coli
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Summary:Threonyl-tRNA synthetase from Escherichia coli represses the translation of its own mRNA by binding to the operator region located upstream from the ribosome binding site. The operator contains two stem-loop structures which interact specifically with the homodimeric enzyme. Here, we provide in vitro and in vivo evidence that these two stem-loop structures are recognized by the enzyme in an analogous way and mimic the anticodon arm of E. coli tRNA super(Thr). Determination of the stoichiometry of the different RNA-threonyl-tRNA synthetase complexes reveals that two tRNA super(Thr) molecules bind to the enzyme whereas only one thrS operator interacts with the homodimeric enzyme. A model is presented in which the two anticodon-like domains of the operator bind symmetrically to the two tRNA super(Thr) anticodon recognition sites (one per subunit) of the dimeric threonyl-tRNA synthetase. Although symmetrical operator-repressor interactions in transcriptional control are widespread, this report stresses the importance of such interactions in translational regulation of gene expression.
ISSN:0261-4189
DOI:10.1002/j.1460-2075.1996.tb00984.x