title: Glutathione is required by Rhizobium etli for glutamine utilization and symbiotic effectiveness.
abstract: Here, we provide genetic and biochemical evidence indicating that the ability of Rhizobium etli bacteria to efficiently catabolize glutamine depends on its ability to produce reduced glutathione (l-γ-glutamyl-l-cysteinylglycine [GSH]). We find that GSH-deficient strains, namely a gshB (GSH synthetase) and a gor (GSH reductase) mutant, can use different amino acids, including histidine, alanine, and asparagine but not glutamine, as sole source of carbon, energy, and nitrogen. Moreover, l-buthionine(S,R)-sulfoximine, a GSH synthesis inhibitor, or diamide that oxidizes GSH, induced the same phenotype in the wild-type strain. Among the steps required for its utilization, glutamine uptake, occurring through the two well-characterized carriers (Aap and Bra systems) but not glutamine degradation or respiration, was largely reduced in GSH-deficient strains. Furthermore, GSH-deficient mutants of R. etli showed a reduced symbiotic efficiency. Exogenous GSH was sufficient to rescue glutamine uptake or degradation ability, as well as the symbiotic effectiveness of GSH mutants. Our results suggest a previously unknown GSH-glutamine metabolic relationship in bacteria.
authors: Institute Of Genetics And Biophysics, A Buzzati-Traverso, CNR, Naples, Italy.
authors: Rosarita
authors: R
authors: Taté
authors: Michele
authors: M
authors: Cermola
authors: Anna
authors: A
authors: Riccio
authors: Graciana
authors: G
authors: Diez-Roux
authors: Eduardo J
authors: EJ
authors: Patriarca
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002244:Carbon / Q000378:metabolism; D019069:Cell Respiration / Q000187:drug effects; D003958:Diamide / Q000494:pharmacology; D005973:Glutamine / Q000378:metabolism* / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism*; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D027805:Phaseolus / Q000382:microbiology*; D010641:Phenotype; D042163:Rhizobium etli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D036226:Seedlings / Q000382:microbiology; D013559:Symbiosis
chemical_list: D005973:Glutamine; D003958:Diamide; D019328:Buthionine Sulfoximine; D002244:Carbon; D005978:Glutathione; D009584:Nitrogen