Structure of the yeast valyl-tRNA synthetase gene (VASI) and the homology of its translated amino acid sequence with Escherichia coli isoleucyl-tRNA synthetase.
The VASI gene encoding the valyl-tRNA synthetase from yeast was isolated and sequenced. The gene-derived amino acid sequence of yeast valyl-tRNA synthetase was found to be 23% homologous to the Escherichia coli isoleucyl-tRNA synthetase. This is the highest level of homology reported so far between two distinct aminoacyl-tRNA synthetases and is indicative of an evolutionary relationship between these two molecules. Within these homologous sequences, two functional regions could be recognized: the HIGH region which forms part of the binding site of ATP and the KMSKS region which is recognized as the consensus sequence for the binding of the 3'-end of tRNA (Hountondji, C., Dessen, Ph., and Blanquet, S. (1986) Biochemie (Paris) 68, 1071-1078). Secondary structure predictions as well as the presence of both HIGH and KMSKS regions, delineating the nucleotide-binding domain and the COOH-terminal helical domain in aminoacyl-tRNA synthetases of known three-dimensional structure, suggest that the yeast valyl-tRNA synthetase polypeptide chain can be folded into three domains: an NH2-terminal alpha-helical region followed by a nucleotide-binding topology and a COOH-terminal domain composed of alpha-helices which probably carries major sites in tRNA binding.
Jordana
X
X
Chatton
B
B
Paz-Weisshaar
M
M
Buhler
J M
JM
Cramer
F
F
Ebel
J P
JP
Fasiolo
F
F
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D005075:Biological Evolution; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology*; D007533:Isoleucine-tRNA Ligase; D011487:Protein Conformation; D012343:RNA, Transfer / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D014637:Valine-tRNA Ligase / Q000235:genetics*
D004271:DNA, Fungal; D000255:Adenosine Triphosphate; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D007533:Isoleucine-tRNA Ligase; D014637:Valine-tRNA Ligase