Impaired affinity for phenylalanine in Escherichia coli phenylalanyl-tRNA synthetase mutant caused by Gly-to-Asp exchange in motif 2 of class II tRNA synthetases.
Phenylalanyl-tRNA synthetase (PheRS; alpha 2 beta 2 subunit structure) is a member of class II of tRNA synthetases. We report here the genetic analysis of an Escherichia coli mutant strain which is auxotrophic for phenylalanine because it has a PheRS with a decreased affinity for phenylalanine. The mutant pheS gene encoding the PheRS alpha subunit was cloned and sequenced, and the deviation from the wild-type gene was found to result in a Gly191-to-Asp191 exchange. This alteration is located within motif 2, one of 3 conserved sequence motifs characteristic for class II aminoacyl-tRNA synthetases. Motif 2 may thus participate in the formation of the phenylalanine binding site in PheRS.
Kast
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P
Mikrobiologisches Institut, Eidgenössische Technische Hochschule, Zürich, Switzerland.
Wehrli
C
C
Hennecke
H
H
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics*; D001224:Aspartic Acid / Q000235:genetics; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005822:Genetic Vectors; D005998:Glycine / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010649:Phenylalanine / Q000235:genetics; D010652:Phenylalanine-tRNA Ligase / Q000145:classification / Q000235:genetics*
D000596:Amino Acids; D001224:Aspartic Acid; D010649:Phenylalanine; D010652:Phenylalanine-tRNA Ligase; D005998:Glycine