Identification of residues involved in the binding of methionine by Escherichia coli methionyl-tRNA synthetase.
Comparison of the amino-acid sequences of several methionyl-tRNA synthetases indicates the occurrence of a few conserved motifs, having a possible functional significance. The role of one of these motifs, centered at position 300 in the E. coli enzyme sequence, was assayed by the use of site-directed mutagenesis. Substitution of the His301 or Trp305 residues by Ala resulted in a large decrease in methionine affinity, whereas the change of Val298 into Ala had only a moderate effect. The catalytic rate of the enzyme was unimpaired by these substitutions. It is concluded that the above conserved amino-acid region is located at or close to the amino-acid binding pocket of methionyl-tRNA synthetase.
Fourmy
D
D
Laboratoire de Biochimie, Unité de Recherche Associée 240 du Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France.
Mechulam
Y
Y
Brunie
S
S
Blanquet
S
S
Fayat
G
G
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000201:enzymology*; D005454:Fluorescence Polarization; D008715:Methionine / Q000378:metabolism*; D008718:Methionine-tRNA Ligase / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation
D008715:Methionine; D008718:Methionine-tRNA Ligase