title: Cloning and sequencing of the gltX gene, encoding the glutamyl-tRNA synthetase of Rhizobium meliloti A2.
abstract: The gltX gene, coding for the glutamyl-tRNA synthetase of Rhizobium meliloti A2, was cloned by using as probe a synthetic oligonucleotide corresponding to the amino acid sequence of a segment of the glutamyl-tRNA synthetase. The codons chosen for this 42-mer were those most frequently used in a set of R. meliloti genes. DNA sequence analysis revealed an open reading frame of 484 codons, encoding a polypeptide of Mr 54,166 containing the amino acid sequences of an NH2-terminal and various internal fragments of the enzyme. Compared with the amino acid sequence of the glutamyl-tRNA synthetase of Escherichia coli, the N-terminal third of the R. meliloti enzyme was strongly conserved (52% identity); the second third was moderately conserved (38% identity) and included a few highly conserved segments, whereas no significant similarity was found in the C-terminal third. These results suggest that the C-terminal part of the protein is probably not involved in the recognition of substrates, a feature shared with other aminoacyl-tRNA synthetases.
authors.affiliation: Département de Biochimie, Faculté des Sciences et de Génie, Université Laval, Quebec, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Laberge
authors.forename: Y
authors.initials: Y
authors.lastname: Gagnon
authors.forename: L M
authors.initials: LM
authors.lastname: Bordeleau
authors.forename: J
authors.initials: J
authors.lastname: Lapointe
mesh_terms: D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D003001:Cloning, Molecular / Q000379:methods; D003062:Codon; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D005975:Glutamate-tRNA Ligase / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D012231:Rhizobium / Q000201:enzymology* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D001426:Bacterial Proteins; D003062:Codon; D000604:Amino Acyl-tRNA Synthetases; D005975:Glutamate-tRNA Ligase