An aminoacyl-tRNA synthetase-like protein encoded by the Escherichia coli yadB gene glutamylates specifically tRNAAsp
- Daniel Y. Dubois*,
- Mickaël Blaise†,
- Hubert D. Becker†,
- Valérie Campanacci‡,
- Gérard Keith†,
- Richard Giegé†,
- Christian Cambillau‡,
- Jacques Lapointe*,§, and
- Daniel Kern†,§
- *Département de Biochimie et Microbiologie, Faculté de Sciences et de Génie, Centre de Recherche sur la Fonction, la Structure et l'Ingénierie des Protéines, Université Laval, Québec, QC, Canada G1K 7P4; †Département Mécanismes et Macromolécules de la Synthèse Protéique et Cristallogenèse, Unité Propre de Recherche 9002, Institut de Biologie Moléculaire et Cellulaire du Centre National de la Recherche Scientifique, 15 Rue René Descartes, F-67084 Strasbourg Cedex, France; and ‡Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 6098, Centre National de la Recherche Scientifique and Universités d'Aix-Marseille I et II, 31 Chemin J. Aiguier, F-13402 Marseille Cedex 20, France
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Communicated by Dieter Söll, Yale University, New Haven, CT, March 9, 2004 (received for review January 19, 2003)
Abstract
The product of the Escherichia coli yadB gene is homologous to the N-terminal part of bacterial glutamyl-tRNA synthetases (GluRSs), including the Rossmann fold with the acceptor-binding domain and the stem-contact fold. This GluRS-like protein, which lacks the anticodon-binding domain, does not use tRNAGlu as substrate in vitro nor in vivo, but aminoacylates tRNAAsp with glutamate. The yadB gene is expressed in wild-type E. coli as an operon with the dksA gene, which encodes a protein involved in the general stress response by means of its action at the translational level. The fate of the glutamylated tRNAAsp is not known, but its incapacity to bind elongation factor Tu suggests that it is not involved in ribosomal protein synthesis. Genes homologous to yadB are present only in bacteria, mostly in Proteobacteria. Sequence alignments and phylogenetic analyses show that the YadB proteins form a distinct monophyletic group related to the bacterial and organellar GluRSs (α-type GlxRSs superfamily) with ubiquitous function as suggested by the similar functional properties of the YadB homologue from Neisseria meningitidis.
Footnotes
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↵ § To whom correspondence may be addressed. E-mail: jacques.lapointe{at}bcm.ulaval.ca or d.kern{at}ibmc.u-strasbg.fr.
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Abbreviations: aaRS, aminoacyl-tRNA synthetase; GluRS, glutamyl-tRNA synthetase; GlnRS, glutaminyl-tRNA synthetase; AspRS, aspartyl-tRNA synthetase; ND-GluRS, nondiscriminating GluRS; GlxRS, GluRS and GlnRS superfamily; EF-Tu, elongation factor Tu; SC, stem-contact; GoA, glutamol-AMP.
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See Commentary on page 7493.
- Copyright © 2004, The National Academy of Sciences
