No abstract

The ILS1 gene encoding for cytoplasms isoleucyl-tRNA synthetase from Saccharomyces cerevisiae was subcloned from a 5.4-kb insert of the shuttle vector YEpl3 to M 13mp8 and M13mp9. Nucleotide sequence analysis of a 4.3-kb BamHI-Hpal fragment revealed a single open reading frame from which we deduced the amino-acid sequence of the enzyme. Independently obtained amino-acid sequence information from ten tryptic pep tides of the puriried enzyme confirmed the gene-derived structure. The enzyme is comprised of 1073 aminoacids consistent with earlier determinations of its molecular mass. The codon usage of ILS1 is typical of abundant yeast proteins. A significant homology to E. coli isoleucyl-and valyl-tRNA synthetases as well as to yeast valyl-tRNA synthetase was detected. The characteristic aminoacid residues of the aminoacyl-adenylate site and of the potential binding site of the 3'-end of tRNA found in other synthetases are present in the structure.Struktur des Isoleucyl-tRNA-Synthetase-Gens (ILS1) aus Bäckerhefe: DNA-Sequenz, Aminosäure-sequenz von proteoly tischen Peptiden des Enzymes und Vergleich mit bekannten Strukturen anderer A minoacyl'tRNA-Synthetasen.