title: D-serine dehydratase from Escherichia coli. DNA sequence and identification of catalytically inactive glycine to aspartic acid variants.
abstract: We have identified two glycyl residues whose integrity is essential for the catalytic competence of a model pyridoxal 5'-phosphate requiring enzyme, D-serine dehydratase from Escherichia coli. This was accomplished by isolating and sequencing the structural gene from wild type E. coli and from two mutant strains that produce inactive D-serine dehydratase. DNA sequencing indicated the presence of a single glycine to aspartic acid replacement in each variant. The amino acid replacements lie in a glycine-rich region of D-serine dehydratase well removed from pyridoxal 5'-phosphate-binding lysine 118 in the primary structure of the enzyme. The striking effect of these two glycine to aspartic acid replacements on catalytic activity, the conservation of the glycine-rich region in several pyridoxal 5'-phosphate-dependent enzymes that catalyze alpha/beta-eliminations, and the placement of similar glycine-rich sequences in well-characterized active site structures suggest that the glycine-rich region interacts with the cofactor at the active site of the enzyme.
mesh_terms: D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000032:analysis*; D004269:DNA, Bacterial / Q000032:analysis*; D004926:Escherichia coli / Q000201:enzymology*; D005998:Glycine / Q000032:analysis*; D012695:L-Serine Dehydratase / Q000032:analysis / Q000235:genetics*; D008969:Molecular Sequence Data; D009710:Nucleotide Mapping; D011487:Protein Conformation
chemical_list: D004269:DNA, Bacterial; D001224:Aspartic Acid; D012695:L-Serine Dehydratase; D005998:Glycine