title: Biochemical and genetic characterization of L-glutamate transport and utilization in Salmonella typhimurium LT-2 mutants.
abstract: Two systems for L-glutamate transport were found in Salmonella typhimurium LT-2 GltU+ (glutamate utilization) mutants. The first one is similar to the glt system previously described in Escherichia coli; by transductional analysis the structural gene, gltS, coding for the transport protein was located at minute 80 of the chromosome as part of the operon gltC-gltS, and its regulator, the gltR gene, near minute 90; the gltS gene product transports both L-glutamate and L-aspartate, is sodium independent, and is beta-hydroxyaspartate sensitive. The second transport system, whose structural gene was called gltF and is located at minute 0, was L-glutamate specific, sodium independent, and alpha-methylglutamate sensitive. Two aspartase activities occurred in S. typhimurium LT-2: the first one was present only in the GltU+ mutants, had a pH 6.4 optimum, was essential for both L-glutamate and L-aspartate metabolism, and mapped at minute 94, close to the ampC gene. The second one had a pH 7.2 optimum, could be induced by several amino acids, and thus may have a general role in nitrogen metabolism.
authors.forename: J
authors.initials: J
authors.lastname: Alvarez-Jacobs
authors.forename: M
authors.initials: M
authors.lastname: de la Garza
authors.forename: M V
authors.initials: MV
authors.lastname: Ortega
mesh_terms: D027322:Amino Acid Transport System X-AG; D001224:Aspartic Acid / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D005796:Genes; D005798:Genes, Bacterial; D005838:Genotype; D005971:Glutamates / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid; D007700:Kinetics; D009154:Mutation; D010641:Phenotype; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism; D012964:Sodium / Q000494:pharmacology; D013045:Species Specificity
chemical_list: D027322:Amino Acid Transport System X-AG; D005971:Glutamates; D001224:Aspartic Acid; D018698:Glutamic Acid; D012964:Sodium