The C-terminal extension of yeast seryl-tRNA synthetase affects stability of the enzyme and its substrate affinity.
Saccharomyces cerevisiae seryl-tRNA synthetase (SerRS) contains a 20-amino acid C-terminal extension, which is not found in prokaryotic SerRS enzymes. A truncated yeast SES1 gene, lacking the 60 base pairs that encode this C-terminal domain, is able to complement a yeast SES1 null allele strain; thus, the C-terminal extension in SerRS is dispensable for the viability of the cell. However, the removal of the C-terminal peptide affects both stability of the enzyme and its affinity for the substrates. The truncation mutant binds tRNA with 3.6-fold higher affinity, while the Km for serine is 4-fold increased relative to the wild-type SerRS. This indicates the importance of the C-terminal extension in maintaining the overall structure of SerRS.
Weygand-Durasević
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I
Department of Molecular Genetics, Rudjer Bosković Institute, Zagreb, Croatia.
Lenhard
B
B
Filipić
S
S
Söll
D
D
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004795:Enzyme Stability; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D012714:Serine-tRNA Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D012714:Serine-tRNA Ligase