title: Two alanine racemase genes in Salmonella typhimurium that differ in structure and function.
abstract: Mutations were isolated in a previously undescribed Salmonella typhimurium gene encoding an alanine racemase essential for utilization of L-alanine as a source of carbon, energy, and nitrogen. This new locus, designated dadB, lies within one kilobase of the D-alanine dehydrogenase locus (dadA), which is also required for alanine catabolism. The dadA and dadB genes are coregulated. Mutants (including insertions) lacking the dadB alanine racemase do not require D-alanine for growth unless a mutation is introduced at a second locus, designated dal. Two genes specifying alanine racemase activity were cloned from S. typhimurium. The two cloned DNA sequences do not cross-hybridize with each other; one was shown to contain the dadB gene.
mesh_terms: D000411:Alanine Racemase / Q000235:genetics*; D000591:Amino Acid Isomerases / Q000235:genetics*; D001483:Base Sequence; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004269:DNA, Bacterial / Q000032:analysis; D005798:Genes, Bacterial; D012486:Salmonella typhimurium / Q000201:enzymology / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D004262:DNA Restriction Enzymes; D000591:Amino Acid Isomerases; D000411:Alanine Racemase