Properties of N-terminal truncated yeast aspartyl-tRNA synthetase and structural characteristics of the cleaved domain.
Cytoplasmic aspartyl-tRNA synthetase from Saccharomyces cerevisiae is a dimer made up of identical subunits of Mr 64,000 as shown by biochemical and crystallographic analyses. Previous studies have emphasized the high sensitivity of the amino-terminal region (residues 1-32) to proteolytic enzymes. This work reports the results of limited tryptic or chymotryptic digestion of the purified enzyme which gives rise to a truncated species that has lost the first 50-64 residues with full retention of both the activity and the dimeric structure. In contrast the larger tryptic fragment is distinguished from the whole enzyme by its weaker retention on heparin-substituted agarose gels. The cleaved N-terminal part presents peculiar structural features, such as a high content in lysine residues arranged in a palindromic fashion. The properties of the trypsin-modified enzyme and of the cleaved amino-terminal region are discussed in relation to the known structural characteristics of aspartyl-tRNA synthetase and of other eukaryotic aminoacyl-tRNA synthetases.
Lorber
B
B
Institut de Biologie Moléculaire et Cellulaire du Centre National de la Recherche Scientifique, Strasbourg, France.
Mejdoub
H
H
Reinbolt
J
J
Boulanger
Y
Y
Giegé
R
R
D000604:Amino Acyl-tRNA Synthetases / Q000032:analysis*; D001226:Aspartate-tRNA Ligase / Q000032:analysis*; D002384:Catalysis; D002918:Chymotrypsin; D003593:Cytoplasm / Q000201:enzymology; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013329:Structure-Activity Relationship; D014357:Trypsin
D046911:Macromolecular Substances; D010446:Peptide Fragments; D002918:Chymotrypsin; D014357:Trypsin; D000604:Amino Acyl-tRNA Synthetases; D001226:Aspartate-tRNA Ligase