A mammalian tryptophanyl-tRNA synthetase shows little homology to prokaryotic synthetases but near identity with mammalian peptide chain release factor.
Determination of the amino acid sequence of beef pancreas tryptophanyl-tRNA synthetase was undertaken through both cDNA and direct peptide sequencing. A full-length cDNA clone containing a 475 amino acid open reading frame was obtained. The molecular mass of the corresponding peptide chain, 53,728 Da, was in agreement with that of beef tryptophanyl-tRNA synthetase, as determined by physicochemical methods (54 kDa). Expression of this clone in Escherichia coli led to tryptophanyl-tRNA synthetase activity in cell extracts. The open reading frame included two sequences analogous to the consensus sequences, HIGH and KMSKS, found in class I aminoacyl-tRNA synthetases. The homology with prokaryotic and yeast mitochondrial tryptophanyl-tRNA synthetases was low and was limited to the regions of the consensus sequences. However, a 90% homology was observed with the recently described rabbit peptide chain release factor (eRF) [Lee et al. (1990) Proc. Natl. Acad. Sci. 87, 3508-3512]. Such a strong homology may reveal a new group of genes deriving from a common ancestor, the products of which could be involved in tRNA aminoacylation (tryptophanyl-tRNA synthetase) or translation termination (eRF).
Garret
M
M
Institut de Biochimie Cellulaire et Neurochimie du CNRS, Université de Bordeaux II, France.
Pajot
B
B
Trézéguet
V
V
Labouesse
J
J
Merle
M
M
Gandar
J C
JC
Benedetto
J P
JP
Sallafranque
M L
ML
Alterio
J
J
Gueguen
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001412:Bacillus subtilis / Q000201:enzymology*; D002417:Cattle; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology*; D015723:Gene Library; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology; D010446:Peptide Fragments / Q000302:isolation & purification; D010454:Peptide Termination Factors / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D012689:Sequence Homology, Nucleic Acid; D014369:Tryptophan-tRNA Ligase / Q000235:genetics* / Q000378:metabolism
D010446:Peptide Fragments; D010454:Peptide Termination Factors; D011994:Recombinant Proteins; C070289:peptide chain release factor, mammalian; D014369:Tryptophan-tRNA Ligase