title: Altered control of glutamate dehydrogenases in ornithine utilization mutants of Pseudomonas aeruginosa.
abstract: Two classes of ornithine-nonutilizing (oru) mutants of Pseudomonas aeruginosa PAO were investigated. Strains carrying the oru-310 mutation were entirely unable to grow on L-ornithine as the only carbon and nitrogen source and were affected in the assimilation of a variety of nitrogen sources (e.g., amino acids, nitrate). The oru-310 mutation caused changes in the regulation of the catabolic NAD-dependent glutamate dehydrogenase; this enzyme was no longer inducible by glutamate but instead could be induced by ammonia. The oru-310 locus was cotransducible with car-9 and tolA in the 10 min region of the chromosome. An oru-314 mutant was severely handicapped in ornithine medium but could grow when a good carbon source was added; the mutant also showed pleiotropic growth effects related to nitrogen metabolism. The oru-314 mutation affected the regulation of the anabolic NADP-dependent glutamate dehydrogenase, which was no longer repressed by glutamate but showed normal derepression in the presence of ammonia. The oru-314 locus was mapped by transduction near met-9011 at 55 min. Both oru mutants could grow on L-glutamate, L-proline, or L-ornithine amended with 2-oxoglutarate, albeit slowly. We speculate that insufficient 2-oxoglutarate concentrations might account, at least in part, for the Oru- phenotype of the mutants.
authors.forename: R
authors.initials: R
authors.lastname: Früh
authors.forename: D
authors.initials: D
authors.lastname: Haas
authors.forename: T
authors.initials: T
authors.lastname: Leisinger
mesh_terms: D002874:Chromosome Mapping; D005969:Glutamate Dehydrogenase / Q000235:genetics*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D009154:Mutation; D009952:Ornithine / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development
chemical_list: D005971:Glutamates; D018698:Glutamic Acid; D009952:Ornithine; D005969:Glutamate Dehydrogenase