GLUTAMYL-TRANSFER RNA-SYNTHETASES OF BACILLUS-SUBTILIS 168T AND OF BACILLUS-STEAROTHERMOPHILUS - CLONING AND SEQUENCING OF THE GLTX GENES AND COMPARISON WITH OTHER AMINOACYL-TRANSFER RNA-SYNTHETASES

  • 25 October 1990
    • journal article
    • research article
    • Vol. 265  (30) , 18248-18255
Abstract
The glutamyl-tRNA synthetase (GluRS) of Bacillus subtilis 168T aminoacylates with glutamate its homologous tRNAGlu and tRNAGln in vivo and Escherichia coli tRNA1Gln in vitro (Lapointe, J., Duplain, L., and Proulx, M. (1986) J. Bacteriol. 165, 88-93). The gltX gene encoding this enzyme was cloned and sequenced. It encodes a protein of 483 amino acids with a Mr of 55,671. Alignment of the amino acid sequencs of four bacterial GluRSs (from B. subtilis, Bacillus stearothermophilus, E. coli, and Rhizobium meliloti) gives 20% identity and reveals the presence of several short highly conserved motifs in the first two thirds of these proteins. Conserved motifs are found at corresponding positions in several other aminoacyl-tRNA synthetases. The only sequence similarity between the GluRSs of these Bacillus species and the E. coli glutaminyl-tRNA synthetase (GlnRS), which has no counterpart in the E. coli GluRS, is in a segment of 30 amino acids in the last third of these synthetases. In the three-dimensional structure of the E. coli tRNAGln.cntdot.GlnRS.cntdot.ATP complex, this conserved peptide is near the anti-codon of tRNAGln (Rould, M. A., Perona, J.J., Soll, D., and Steitz, T. A. (1989) Science 246, 1135-1142), suggesting that this region is involved in the specific interactions between these enzymes and the anticodon regions of their tRNA substrates.