Nucleic Acids Research Advance Access originally published online on January 16, 2009
Nucleic Acids Research 2009 37(5):1589-1601; doi:10.1093/nar/gkn1039
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Nucleic Acids Research, 2009, Vol. 37, No. 5 1589-1601
© 2009 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
Aminoacyl-tRNA recognition by the FemXWv transferase for bacterial cell wall synthesis
1Centre de Recherche des Cordeliers, LRMA, Equipe 12, INSERM, 2Université Pierre et Marie Curie – Paris 6, 3Université Paris Descartes, UMR S 872, 4Synthèse, Structure et Fonction de Molécules Bioactives, CNRS UMR 7613, 5Université Pierre et Marie Curie – Paris 6, UMR 7613, F-75006, Paris, 6Laboratoire des Enveloppes Bactériennes et Antibiotiques, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619 CNRS and 7Université Paris-Sud, F-91405, Orsay, France
*To whom correspondence should be addressed. Tel: +33 1 43 25 00 33; Fax: +33 1 43 25 68 12; Email: michel.arthur{at}crc.jussieu.fr
Received October 8, 2008. Revised December 11, 2008. Accepted December 12, 2008.
Transferases of the Fem family catalyse peptide-bond formation by using aminoacyl-tRNAs and peptidoglycan precursors as donor and acceptor substrates, respectively. The specificity of Fem transferases is essential since mis-incorporated amino acids could act as chain terminators thereby preventing formation of a functional stress-bearing peptidoglycan network. Here we have developed chemical acylation of RNA helices with natural and non-proteinogenic amino acids to gain insight into the specificity of the model transferase FemXWv. Combining modifications in the RNA and aminoacyl moieties of the donor substrate revealed that unfavourable interactions of FemXWv with the acceptor arm of tRNAGly and with L-Ser or larger residues quantitatively accounts for the preferential transfer of L-Ala observed with complete aminoacyl-tRNAs. The main FemXWv identity determinant was identified as the penultimate base pair (G2-C71) of the acceptor arm instead of G3•U70 for the alanyl-tRNA synthetase. FemXWv tolerated a configuration inversion of the C
of L-Ala but not the introduction of a second methyl on this atom. These results indicate that aminoacyl-tRNA recognition by FemXWv is distinct from other components of the translation machinery and relies on the exclusion of bulky amino acids and of the sequence of tRNAGly from the active site.