Cloning and analysis of a cDNA encoding mammalian arginyl-tRNA synthetase, a component of the multisynthetase complex with a hydrophobic N-terminal extension.
In mammalian cells, the nine aminoacyl-tRNA synthetases (aaRS) specific for the amino acids (aa) Glu, Pro, Ile, Leu, Met, Gln, Lys, Arg and Asp are associated within a multienzyme complex. Arginyl-tRNA synthetase (ArgRS) is characterized by the occurrence of two structurally distinct forms of that enzyme: a complexed (approximately 74 kDa) and a free (approximately 60 kDa) form. The cDNA encoding the 74-kDa species of ArgRS from Chinese hamster ovary cells has been isolated and sequenced. The deduced aa sequence shows 38% identity to the homologous bacterial enzyme but displays an N-terminal polypeptide extension composed of 73 aa, which is absent in the free form of mammalian ArgRS. Two regions of this extension are predicted to be alpha-helical, leading to the clustering of Leu and Ile residues on one side of the helices. This suggests that the N-terminal domain is involved in the assembly of the 74-kDa species of ArgRS within the multisynthetase complex through hydrophobic interactions. By using the isolated cDNA, a Northern blot analysis showed a single mRNA species. Thus, there is a possibility that the free and complexed forms of ArgRS are encoded by the same gene.
Lazard
M
M
Laboratoire d'Enzymologie, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
Mirande
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001126:Arginine-tRNA Ligase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D004247:DNA; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017433:Protein Structure, Secondary; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014867:Water / Q000737:chemistry
D009097:Multienzyme Complexes; D014867:Water; D004247:DNA; D001126:Arginine-tRNA Ligase